<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:1a41f4e1-d648-43e3-8579-9e649d7366f5,g:0e95fe84-672a-415c-93d4-619aeb4a5d6a-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/ConsolidatedStatementofStockholdersEquity" xlink:type="simple" xlink:href="rock-20240930.xsd#ConsolidatedStatementofStockholdersEquity"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/ConsolidatedStatementofStockholdersEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_0b4cd59a-e0de-4708-9317-67ba6fbfad6f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_a779b084-bebb-4aae-b1d2-274b6848d13d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_0b4cd59a-e0de-4708-9317-67ba6fbfad6f" xlink:to="loc_us-gaap_StatementTable_a779b084-bebb-4aae-b1d2-274b6848d13d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_8d7b7451-8dad-4f7a-885c-1e58c2ac33cf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_a779b084-bebb-4aae-b1d2-274b6848d13d" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_8d7b7451-8dad-4f7a-885c-1e58c2ac33cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_8d7b7451-8dad-4f7a-885c-1e58c2ac33cf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_8d7b7451-8dad-4f7a-885c-1e58c2ac33cf" xlink:to="loc_us-gaap_EquityComponentDomain_8d7b7451-8dad-4f7a-885c-1e58c2ac33cf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_dc6de71d-8522-427b-a2e1-1c7557f70f9a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_8d7b7451-8dad-4f7a-885c-1e58c2ac33cf" xlink:to="loc_us-gaap_EquityComponentDomain_dc6de71d-8522-427b-a2e1-1c7557f70f9a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_dc147ae2-e1e2-4845-8b51-309990bac43d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_dc6de71d-8522-427b-a2e1-1c7557f70f9a" xlink:to="loc_us-gaap_CommonStockMember_dc147ae2-e1e2-4845-8b51-309990bac43d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_27a88314-0063-4b97-b818-2f9d292c5421" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_dc6de71d-8522-427b-a2e1-1c7557f70f9a" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_27a88314-0063-4b97-b818-2f9d292c5421" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_ecd64ea4-3e46-44f9-80b4-30a350d4fe75" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_dc6de71d-8522-427b-a2e1-1c7557f70f9a" xlink:to="loc_us-gaap_RetainedEarningsMember_ecd64ea4-3e46-44f9-80b4-30a350d4fe75" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_692e965f-c0d4-4770-aa25-f2aa28b575ad" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_dc6de71d-8522-427b-a2e1-1c7557f70f9a" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_692e965f-c0d4-4770-aa25-f2aa28b575ad" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_cdabdb16-569e-4625-81cb-59e42c45e5e0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_dc6de71d-8522-427b-a2e1-1c7557f70f9a" xlink:to="loc_us-gaap_TreasuryStockCommonMember_cdabdb16-569e-4625-81cb-59e42c45e5e0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_742a0794-72cc-47d8-9c35-1c9449b65d08" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0b4cd59a-e0de-4708-9317-67ba6fbfad6f" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_742a0794-72cc-47d8-9c35-1c9449b65d08" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_3242490a-e905-4588-8808-a39f65ecb462" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_742a0794-72cc-47d8-9c35-1c9449b65d08" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_3242490a-e905-4588-8808-a39f65ecb462" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_4f6fa52e-f124-42bf-aadc-8555d3292849" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_742a0794-72cc-47d8-9c35-1c9449b65d08" xlink:to="loc_us-gaap_StockholdersEquity_4f6fa52e-f124-42bf-aadc-8555d3292849" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_ff931609-2ce1-405c-9cb3-dcd25e80e3e4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_742a0794-72cc-47d8-9c35-1c9449b65d08" xlink:to="loc_us-gaap_TreasuryStockCommonShares_ff931609-2ce1-405c-9cb3-dcd25e80e3e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_1054f882-f5c8-40db-9b0b-98a7f9723bb9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_742a0794-72cc-47d8-9c35-1c9449b65d08" xlink:to="loc_us-gaap_NetIncomeLoss_1054f882-f5c8-40db-9b0b-98a7f9723bb9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_86e5dc55-2dd7-445a-92c9-053ece926159" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_742a0794-72cc-47d8-9c35-1c9449b65d08" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_86e5dc55-2dd7-445a-92c9-053ece926159" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_759e7c6a-ffac-469b-9365-12a8e8b2b91b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_742a0794-72cc-47d8-9c35-1c9449b65d08" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_759e7c6a-ffac-469b-9365-12a8e8b2b91b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_4e668983-675d-4953-a11c-3f7826370672" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_742a0794-72cc-47d8-9c35-1c9449b65d08" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_4e668983-675d-4953-a11c-3f7826370672" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_d3c55537-9a6b-4526-ae6f-d9c392a2ac10" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_742a0794-72cc-47d8-9c35-1c9449b65d08" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_d3c55537-9a6b-4526-ae6f-d9c392a2ac10" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_2aa2384c-f52c-447f-aefa-561c6b4124a3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_742a0794-72cc-47d8-9c35-1c9449b65d08" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_2aa2384c-f52c-447f-aefa-561c6b4124a3" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_TreasuryStockValueAcquiredExciseTaxAmountCostMethod_f6bd089d-719a-4b2e-b544-2e4d4d7ecc3d" xlink:href="rock-20240930.xsd#rock_TreasuryStockValueAcquiredExciseTaxAmountCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_742a0794-72cc-47d8-9c35-1c9449b65d08" xlink:to="loc_rock_TreasuryStockValueAcquiredExciseTaxAmountCostMethod_f6bd089d-719a-4b2e-b544-2e4d4d7ecc3d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_62a48a34-8755-4e5f-92b6-711188dc447f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_742a0794-72cc-47d8-9c35-1c9449b65d08" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_62a48a34-8755-4e5f-92b6-711188dc447f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_618bb70c-c373-457e-a765-8994e2f376d4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_742a0794-72cc-47d8-9c35-1c9449b65d08" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_618bb70c-c373-457e-a765-8994e2f376d4" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_cce08e83-56ef-441e-abbd-6606a6e6c0b8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_cfdeff06-5da3-4986-b0bc-60e2ac8932fc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_1d921d04-1d22-4b26-805d-e05fd8a6d11c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockCommonShares"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/RevenueNarrativeDetails" xlink:type="simple" xlink:href="rock-20240930.xsd#RevenueNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/RevenueNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_e02718bb-8344-4d36-be35-f706395412e4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_387411d8-6f8a-40dc-9528-bd8dbec529ba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_e02718bb-8344-4d36-be35-f706395412e4" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_387411d8-6f8a-40dc-9528-bd8dbec529ba" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_b9085f96-74dd-469f-8e1b-77631c0e6b93" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_387411d8-6f8a-40dc-9528-bd8dbec529ba" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_b9085f96-74dd-469f-8e1b-77631c0e6b93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_7678b7ce-5b03-4b33-bedc-d1ba8d313bf2" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_387411d8-6f8a-40dc-9528-bd8dbec529ba" xlink:to="loc_srt_RangeAxis_7678b7ce-5b03-4b33-bedc-d1ba8d313bf2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_7678b7ce-5b03-4b33-bedc-d1ba8d313bf2_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_7678b7ce-5b03-4b33-bedc-d1ba8d313bf2" xlink:to="loc_srt_RangeMember_7678b7ce-5b03-4b33-bedc-d1ba8d313bf2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_912464f4-eb01-48d1-92ed-b05706571ffb" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_7678b7ce-5b03-4b33-bedc-d1ba8d313bf2" xlink:to="loc_srt_RangeMember_912464f4-eb01-48d1-92ed-b05706571ffb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_c2152fd5-f4ed-4338-b8c4-a8d508e5f368" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_912464f4-eb01-48d1-92ed-b05706571ffb" xlink:to="loc_srt_MaximumMember_c2152fd5-f4ed-4338-b8c4-a8d508e5f368" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_04ea4977-a5ca-4a94-bfe3-495566066671" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_e02718bb-8344-4d36-be35-f706395412e4" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_04ea4977-a5ca-4a94-bfe3-495566066671" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_ContractWithCustomerLiabilityCurrentUnearnedRevenue_26b82b66-4094-4ff4-941e-2774960f7a68" xlink:href="rock-20240930.xsd#rock_ContractWithCustomerLiabilityCurrentUnearnedRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_e02718bb-8344-4d36-be35-f706395412e4" xlink:to="loc_rock_ContractWithCustomerLiabilityCurrentUnearnedRevenue_26b82b66-4094-4ff4-941e-2774960f7a68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_ContractWithCustomerLiabilityIncludingNewContractRevenueRecognized_e5c563dd-9816-4d08-9079-5c6d1c064a68" xlink:href="rock-20240930.xsd#rock_ContractWithCustomerLiabilityIncludingNewContractRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_e02718bb-8344-4d36-be35-f706395412e4" xlink:to="loc_rock_ContractWithCustomerLiabilityIncludingNewContractRevenueRecognized_e5c563dd-9816-4d08-9079-5c6d1c064a68" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_c4124dc8-5402-4611-b066-cc8f82b9e9aa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_e02718bb-8344-4d36-be35-f706395412e4" xlink:to="loc_us-gaap_ContractWithCustomerLiability_c4124dc8-5402-4611-b066-cc8f82b9e9aa" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/RevenueNarrativeDetails_1" xlink:type="simple" xlink:href="rock-20240930.xsd#RevenueNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/RevenueNarrativeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_e02718bb-8344-4d36-be35-f706395412e4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_387411d8-6f8a-40dc-9528-bd8dbec529ba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_e02718bb-8344-4d36-be35-f706395412e4" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_387411d8-6f8a-40dc-9528-bd8dbec529ba" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_7678b7ce-5b03-4b33-bedc-d1ba8d313bf2" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_387411d8-6f8a-40dc-9528-bd8dbec529ba" xlink:to="loc_srt_RangeAxis_7678b7ce-5b03-4b33-bedc-d1ba8d313bf2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_7678b7ce-5b03-4b33-bedc-d1ba8d313bf2_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_7678b7ce-5b03-4b33-bedc-d1ba8d313bf2" xlink:to="loc_srt_RangeMember_7678b7ce-5b03-4b33-bedc-d1ba8d313bf2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_912464f4-eb01-48d1-92ed-b05706571ffb" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_7678b7ce-5b03-4b33-bedc-d1ba8d313bf2" xlink:to="loc_srt_RangeMember_912464f4-eb01-48d1-92ed-b05706571ffb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_c2152fd5-f4ed-4338-b8c4-a8d508e5f368" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_912464f4-eb01-48d1-92ed-b05706571ffb" xlink:to="loc_srt_MaximumMember_c2152fd5-f4ed-4338-b8c4-a8d508e5f368" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_04ea4977-a5ca-4a94-bfe3-495566066671" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_e02718bb-8344-4d36-be35-f706395412e4" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_04ea4977-a5ca-4a94-bfe3-495566066671" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_ContractWithCustomerLiabilityCurrentUnearnedRevenue_26b82b66-4094-4ff4-941e-2774960f7a68" xlink:href="rock-20240930.xsd#rock_ContractWithCustomerLiabilityCurrentUnearnedRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_e02718bb-8344-4d36-be35-f706395412e4" xlink:to="loc_rock_ContractWithCustomerLiabilityCurrentUnearnedRevenue_26b82b66-4094-4ff4-941e-2774960f7a68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_ContractWithCustomerLiabilityIncludingNewContractRevenueRecognized_e5c563dd-9816-4d08-9079-5c6d1c064a68" xlink:href="rock-20240930.xsd#rock_ContractWithCustomerLiabilityIncludingNewContractRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_e02718bb-8344-4d36-be35-f706395412e4" xlink:to="loc_rock_ContractWithCustomerLiabilityIncludingNewContractRevenueRecognized_e5c563dd-9816-4d08-9079-5c6d1c064a68" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_c4124dc8-5402-4611-b066-cc8f82b9e9aa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_e02718bb-8344-4d36-be35-f706395412e4" xlink:to="loc_us-gaap_ContractWithCustomerLiability_c4124dc8-5402-4611-b066-cc8f82b9e9aa" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/AcquisitionNarrativeDetails" xlink:type="simple" xlink:href="rock-20240930.xsd#AcquisitionNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/AcquisitionNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_9939d826-7e46-42f3-9c30-0ab3b0220fac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7b60afda-79b0-4e46-87bb-83d5ade3184e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9939d826-7e46-42f3-9c30-0ab3b0220fac" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7b60afda-79b0-4e46-87bb-83d5ade3184e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_bc672016-7842-4d2a-8289-13826b42d3eb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7b60afda-79b0-4e46-87bb-83d5ade3184e" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_bc672016-7842-4d2a-8289-13826b42d3eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bc672016-7842-4d2a-8289-13826b42d3eb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_bc672016-7842-4d2a-8289-13826b42d3eb" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bc672016-7842-4d2a-8289-13826b42d3eb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_12779793-f727-42de-90e4-816e8c6128e1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_bc672016-7842-4d2a-8289-13826b42d3eb" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_12779793-f727-42de-90e4-816e8c6128e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_PrivatelyHeldUtahBasedCompanyMember_a69ca2d3-91db-4c14-b0de-85792a7d5982" xlink:href="rock-20240930.xsd#rock_PrivatelyHeldUtahBasedCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_12779793-f727-42de-90e4-816e8c6128e1" xlink:to="loc_rock_PrivatelyHeldUtahBasedCompanyMember_a69ca2d3-91db-4c14-b0de-85792a7d5982" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_d6fa3262-59cc-4b9f-890f-980602fe62dc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9939d826-7e46-42f3-9c30-0ab3b0220fac" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_d6fa3262-59cc-4b9f-890f-980602fe62dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_738253af-ea0f-458b-8761-b0990b02a75f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9939d826-7e46-42f3-9c30-0ab3b0220fac" xlink:to="loc_us-gaap_Goodwill_738253af-ea0f-458b-8761-b0990b02a75f" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/AcquisitionScheduleofAllocationofthePurchasePriceConsiderationoftheFairValueofAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="simple" xlink:href="rock-20240930.xsd#AcquisitionScheduleofAllocationofthePurchasePriceConsiderationoftheFairValueofAssetsAcquiredandLiabilitiesAssumedDetails"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/AcquisitionScheduleofAllocationofthePurchasePriceConsiderationoftheFairValueofAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_48b0ce40-0dea-43dc-aa8e-784e7d1737e8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_06828ecb-4c11-4df4-a3b0-b08ec23cfc0b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_48b0ce40-0dea-43dc-aa8e-784e7d1737e8" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_06828ecb-4c11-4df4-a3b0-b08ec23cfc0b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_34d95de4-89a7-46ff-ac68-95098be597c7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_06828ecb-4c11-4df4-a3b0-b08ec23cfc0b" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_34d95de4-89a7-46ff-ac68-95098be597c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_34d95de4-89a7-46ff-ac68-95098be597c7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_34d95de4-89a7-46ff-ac68-95098be597c7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_34d95de4-89a7-46ff-ac68-95098be597c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6f41c55a-d6a0-4007-931f-e17b8bf64288" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_34d95de4-89a7-46ff-ac68-95098be597c7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6f41c55a-d6a0-4007-931f-e17b8bf64288" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_PrivatelyHeldUtahBasedCompanyMember_7650b8cf-1fd7-4463-ba9c-f5f8631593d6" xlink:href="rock-20240930.xsd#rock_PrivatelyHeldUtahBasedCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6f41c55a-d6a0-4007-931f-e17b8bf64288" xlink:to="loc_rock_PrivatelyHeldUtahBasedCompanyMember_7650b8cf-1fd7-4463-ba9c-f5f8631593d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedWorkingCapital_204d3034-43b7-4afe-a925-b255b14c29df" xlink:href="rock-20240930.xsd#rock_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedWorkingCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_48b0ce40-0dea-43dc-aa8e-784e7d1737e8" xlink:to="loc_rock_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedWorkingCapital_204d3034-43b7-4afe-a925-b255b14c29df" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_de1deb76-08be-4ae3-976c-21ecbc9e04a4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_48b0ce40-0dea-43dc-aa8e-784e7d1737e8" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_de1deb76-08be-4ae3-976c-21ecbc9e04a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_03d9518e-f5ca-4951-b6a2-95f836e0b27b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_48b0ce40-0dea-43dc-aa8e-784e7d1737e8" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_03d9518e-f5ca-4951-b6a2-95f836e0b27b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_436656c9-0db3-4bf5-912e-220e49b49196" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_48b0ce40-0dea-43dc-aa8e-784e7d1737e8" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_436656c9-0db3-4bf5-912e-220e49b49196" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_0416bb12-9d28-4d9d-9fe1-40a50a337c53" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_48b0ce40-0dea-43dc-aa8e-784e7d1737e8" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_0416bb12-9d28-4d9d-9fe1-40a50a337c53" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_26bc2f1b-f033-43d3-8dff-7fbe08db422a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_48b0ce40-0dea-43dc-aa8e-784e7d1737e8" xlink:to="loc_us-gaap_Goodwill_26bc2f1b-f033-43d3-8dff-7fbe08db422a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_0b72733d-4d1a-48d5-97ec-3e09f8ca5d48" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_48b0ce40-0dea-43dc-aa8e-784e7d1737e8" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_0b72733d-4d1a-48d5-97ec-3e09f8ca5d48" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/AcquisitionScheduleofAcquiredIntangibleAssetsDetails" xlink:type="simple" xlink:href="rock-20240930.xsd#AcquisitionScheduleofAcquiredIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/AcquisitionScheduleofAcquiredIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_b1e1016a-578a-46fe-aaca-cc2e8c7043bf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_26c6491e-53c9-4304-be82-17a5f0742803" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_b1e1016a-578a-46fe-aaca-cc2e8c7043bf" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_26c6491e-53c9-4304-be82-17a5f0742803" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_29f59efa-ed14-44b6-a93f-1c322c66862f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_26c6491e-53c9-4304-be82-17a5f0742803" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_29f59efa-ed14-44b6-a93f-1c322c66862f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_29f59efa-ed14-44b6-a93f-1c322c66862f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_29f59efa-ed14-44b6-a93f-1c322c66862f" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_29f59efa-ed14-44b6-a93f-1c322c66862f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b715c8fb-3e8e-4457-9482-081e7dc7fdc1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_29f59efa-ed14-44b6-a93f-1c322c66862f" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b715c8fb-3e8e-4457-9482-081e7dc7fdc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_PrivatelyHeldUtahBasedCompanyMember_26cfc6f7-214e-452b-ba64-7ba5b0155042" xlink:href="rock-20240930.xsd#rock_PrivatelyHeldUtahBasedCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b715c8fb-3e8e-4457-9482-081e7dc7fdc1" xlink:to="loc_rock_PrivatelyHeldUtahBasedCompanyMember_26cfc6f7-214e-452b-ba64-7ba5b0155042" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_9b4f1b34-48ed-404a-ba26-ebd9d8ca5950" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_26c6491e-53c9-4304-be82-17a5f0742803" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_9b4f1b34-48ed-404a-ba26-ebd9d8ca5950" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9b4f1b34-48ed-404a-ba26-ebd9d8ca5950_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_9b4f1b34-48ed-404a-ba26-ebd9d8ca5950" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9b4f1b34-48ed-404a-ba26-ebd9d8ca5950_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a9508c39-f269-46d3-8d8b-994b86a4e5d1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_9b4f1b34-48ed-404a-ba26-ebd9d8ca5950" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a9508c39-f269-46d3-8d8b-994b86a4e5d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksMember_4cd74fd4-3cdb-4ca4-9015-4ca27789995c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TrademarksMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a9508c39-f269-46d3-8d8b-994b86a4e5d1" xlink:to="loc_us-gaap_TrademarksMember_4cd74fd4-3cdb-4ca4-9015-4ca27789995c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_b5558f2f-058c-4efd-b3cd-8cf663019a0e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a9508c39-f269-46d3-8d8b-994b86a4e5d1" xlink:to="loc_us-gaap_CustomerRelationshipsMember_b5558f2f-058c-4efd-b3cd-8cf663019a0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_650b8750-2386-4f03-b0a9-72875a51ac7d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_26c6491e-53c9-4304-be82-17a5f0742803" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_650b8750-2386-4f03-b0a9-72875a51ac7d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_650b8750-2386-4f03-b0a9-72875a51ac7d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_650b8750-2386-4f03-b0a9-72875a51ac7d" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_650b8750-2386-4f03-b0a9-72875a51ac7d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_c0bc4b2a-68a5-4aed-8624-0c8dd1476e43" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_650b8750-2386-4f03-b0a9-72875a51ac7d" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_c0bc4b2a-68a5-4aed-8624-0c8dd1476e43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksMember_b67ab273-cd7c-4bdd-b6d0-9420caeebadb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TrademarksMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_c0bc4b2a-68a5-4aed-8624-0c8dd1476e43" xlink:to="loc_us-gaap_TrademarksMember_b67ab273-cd7c-4bdd-b6d0-9420caeebadb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_24b08a40-46cc-453f-8797-53eaa28376f1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_b1e1016a-578a-46fe-aaca-cc2e8c7043bf" xlink:to="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_24b08a40-46cc-453f-8797-53eaa28376f1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_9131892f-3670-426b-8bb4-de7e4aa26e44" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_b1e1016a-578a-46fe-aaca-cc2e8c7043bf" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_9131892f-3670-426b-8bb4-de7e4aa26e44" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/GoodwillandRelatedIntangibleAssetsScheduleofChangesinCarryingAmountofGoodwillDetails" xlink:type="simple" xlink:href="rock-20240930.xsd#GoodwillandRelatedIntangibleAssetsScheduleofChangesinCarryingAmountofGoodwillDetails"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/GoodwillandRelatedIntangibleAssetsScheduleofChangesinCarryingAmountofGoodwillDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_14667dea-7f58-4101-a1d0-44e2d234ae47" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_8874bf80-faf1-4d8f-acf6-fb15b9502030" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_14667dea-7f58-4101-a1d0-44e2d234ae47" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_8874bf80-faf1-4d8f-acf6-fb15b9502030" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_d1fad5f4-5164-4d05-a62b-496e664d9a07" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_8874bf80-faf1-4d8f-acf6-fb15b9502030" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_d1fad5f4-5164-4d05-a62b-496e664d9a07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_d1fad5f4-5164-4d05-a62b-496e664d9a07_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_d1fad5f4-5164-4d05-a62b-496e664d9a07" xlink:to="loc_us-gaap_SegmentDomain_d1fad5f4-5164-4d05-a62b-496e664d9a07_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_a5427975-862a-40c6-861e-6941660c2f75" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_d1fad5f4-5164-4d05-a62b-496e664d9a07" xlink:to="loc_us-gaap_SegmentDomain_a5427975-862a-40c6-861e-6941660c2f75" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_ResidentialProductsMember_17eb4846-028a-405d-a4c1-8eb45bcb5cec" xlink:href="rock-20240930.xsd#rock_ResidentialProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_a5427975-862a-40c6-861e-6941660c2f75" xlink:to="loc_rock_ResidentialProductsMember_17eb4846-028a-405d-a4c1-8eb45bcb5cec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_RenewableEnergyandConservationMember_67559f4c-dc80-4f68-9c00-b166c9ecccbb" xlink:href="rock-20240930.xsd#rock_RenewableEnergyandConservationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_a5427975-862a-40c6-861e-6941660c2f75" xlink:to="loc_rock_RenewableEnergyandConservationMember_67559f4c-dc80-4f68-9c00-b166c9ecccbb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_AgtechMember_b53666d0-2b82-4cf6-8734-3452d9fb4242" xlink:href="rock-20240930.xsd#rock_AgtechMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_a5427975-862a-40c6-861e-6941660c2f75" xlink:to="loc_rock_AgtechMember_b53666d0-2b82-4cf6-8734-3452d9fb4242" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_InfrastructureMember_3052bd44-26fd-4646-b1dc-6db115f2a23e" xlink:href="rock-20240930.xsd#rock_InfrastructureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_a5427975-862a-40c6-861e-6941660c2f75" xlink:to="loc_rock_InfrastructureMember_3052bd44-26fd-4646-b1dc-6db115f2a23e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillRollForward_0a596447-db2c-4b08-99f9-98a5e5055e1f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GoodwillRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_14667dea-7f58-4101-a1d0-44e2d234ae47" xlink:to="loc_us-gaap_GoodwillRollForward_0a596447-db2c-4b08-99f9-98a5e5055e1f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_ebb4ed56-7150-446b-948e-361683813d0c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_0a596447-db2c-4b08-99f9-98a5e5055e1f" xlink:to="loc_us-gaap_Goodwill_ebb4ed56-7150-446b-948e-361683813d0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillPurchaseAccountingAdjustments_826780d8-1e13-4054-8601-b585082d88c2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GoodwillPurchaseAccountingAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_0a596447-db2c-4b08-99f9-98a5e5055e1f" xlink:to="loc_us-gaap_GoodwillPurchaseAccountingAdjustments_826780d8-1e13-4054-8601-b585082d88c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_9902d24f-af74-4eaa-bff1-cf6bbfdcec65" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_0a596447-db2c-4b08-99f9-98a5e5055e1f" xlink:to="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_9902d24f-af74-4eaa-bff1-cf6bbfdcec65" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_59dd6386-f5cd-403f-a815-720ff8cca001" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/GoodwillandRelatedIntangibleAssetsScheduleofAcquiredIntangibleAssetsDetails" xlink:type="simple" xlink:href="rock-20240930.xsd#GoodwillandRelatedIntangibleAssetsScheduleofAcquiredIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/GoodwillandRelatedIntangibleAssetsScheduleofAcquiredIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_81d5a4c3-3e90-437b-8f78-c069107259d2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_4ed4eeb3-a2ba-4ade-b57a-1c4fbb2b5c7c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_81d5a4c3-3e90-437b-8f78-c069107259d2" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_4ed4eeb3-a2ba-4ade-b57a-1c4fbb2b5c7c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_7326124d-df97-47b3-83d8-c1028cd70050" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_4ed4eeb3-a2ba-4ade-b57a-1c4fbb2b5c7c" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_7326124d-df97-47b3-83d8-c1028cd70050" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_7326124d-df97-47b3-83d8-c1028cd70050_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_7326124d-df97-47b3-83d8-c1028cd70050" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_7326124d-df97-47b3-83d8-c1028cd70050_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_99013cb7-7503-4a95-835b-8378da52459c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_7326124d-df97-47b3-83d8-c1028cd70050" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_99013cb7-7503-4a95-835b-8378da52459c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksMember_0769b343-18c2-4a01-ac0e-3e41958eb7b1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TrademarksMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_99013cb7-7503-4a95-835b-8378da52459c" xlink:to="loc_us-gaap_TrademarksMember_0769b343-18c2-4a01-ac0e-3e41958eb7b1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_68138d8b-5be1-4a7f-94f7-15cd69b32590" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_4ed4eeb3-a2ba-4ade-b57a-1c4fbb2b5c7c" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_68138d8b-5be1-4a7f-94f7-15cd69b32590" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_68138d8b-5be1-4a7f-94f7-15cd69b32590_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_68138d8b-5be1-4a7f-94f7-15cd69b32590" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_68138d8b-5be1-4a7f-94f7-15cd69b32590_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c1b2664c-a95d-4b03-af02-cf324a8798af" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_68138d8b-5be1-4a7f-94f7-15cd69b32590" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c1b2664c-a95d-4b03-af02-cf324a8798af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksMember_7b6978ff-06b8-41f3-8e45-09fd7f8c1d5f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TrademarksMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c1b2664c-a95d-4b03-af02-cf324a8798af" xlink:to="loc_us-gaap_TrademarksMember_7b6978ff-06b8-41f3-8e45-09fd7f8c1d5f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnpatentedTechnologyMember_a99fbe27-044d-47e2-9281-a0f6690c6dfc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_UnpatentedTechnologyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c1b2664c-a95d-4b03-af02-cf324a8798af" xlink:to="loc_us-gaap_UnpatentedTechnologyMember_a99fbe27-044d-47e2-9281-a0f6690c6dfc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_a60d1cd1-7fc2-417b-ba90-7ef94905f860" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c1b2664c-a95d-4b03-af02-cf324a8798af" xlink:to="loc_us-gaap_CustomerRelationshipsMember_a60d1cd1-7fc2-417b-ba90-7ef94905f860" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncompeteAgreementsMember_0b8f9abd-eb39-4d52-9938-1cde13102597" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NoncompeteAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c1b2664c-a95d-4b03-af02-cf324a8798af" xlink:to="loc_us-gaap_NoncompeteAgreementsMember_0b8f9abd-eb39-4d52-9938-1cde13102597" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_383d3c90-887b-46cd-bbc9-83bffd432ec6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_81d5a4c3-3e90-437b-8f78-c069107259d2" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_383d3c90-887b-46cd-bbc9-83bffd432ec6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_990c3d20-93f1-4428-ae92-bd6dd4bca0f8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_81d5a4c3-3e90-437b-8f78-c069107259d2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_990c3d20-93f1-4428-ae92-bd6dd4bca0f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_AcquiredIntangibleAssetsTotal_ea58c178-fd7f-4e78-949a-da05fc794f12" xlink:href="rock-20240930.xsd#rock_AcquiredIntangibleAssetsTotal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_81d5a4c3-3e90-437b-8f78-c069107259d2" xlink:to="loc_rock_AcquiredIntangibleAssetsTotal_ea58c178-fd7f-4e78-949a-da05fc794f12" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_IndefiniteLivedAccumulatedAmortization_63b9faf1-9f14-44bf-9235-1b39625209b3" xlink:href="rock-20240930.xsd#rock_IndefiniteLivedAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_81d5a4c3-3e90-437b-8f78-c069107259d2" xlink:to="loc_rock_IndefiniteLivedAccumulatedAmortization_63b9faf1-9f14-44bf-9235-1b39625209b3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_0e830f82-785e-4de8-88f3-5b2a95541d96" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_81d5a4c3-3e90-437b-8f78-c069107259d2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_0e830f82-785e-4de8-88f3-5b2a95541d96" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_TotalAcquiredIntangibleAssetsAccumulatedAmortization_1fe479c0-17d4-4e39-82e0-2e4e50b92c19" xlink:href="rock-20240930.xsd#rock_TotalAcquiredIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_81d5a4c3-3e90-437b-8f78-c069107259d2" xlink:to="loc_rock_TotalAcquiredIntangibleAssetsAccumulatedAmortization_1fe479c0-17d4-4e39-82e0-2e4e50b92c19" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/LongTermDebtNarrativeDetails" xlink:type="simple" xlink:href="rock-20240930.xsd#LongTermDebtNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/LongTermDebtNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_51411812-d49e-43ec-b8cf-840e99def566" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_a1527d5b-24bb-4fc2-a949-a726fbaf6961" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_51411812-d49e-43ec-b8cf-840e99def566" xlink:to="loc_us-gaap_DebtInstrumentTable_a1527d5b-24bb-4fc2-a949-a726fbaf6961" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_8e47ccd5-7e2d-41bd-9d46-7c354671eaac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_a1527d5b-24bb-4fc2-a949-a726fbaf6961" xlink:to="loc_us-gaap_DebtInstrumentAxis_8e47ccd5-7e2d-41bd-9d46-7c354671eaac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_8e47ccd5-7e2d-41bd-9d46-7c354671eaac_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_8e47ccd5-7e2d-41bd-9d46-7c354671eaac" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_8e47ccd5-7e2d-41bd-9d46-7c354671eaac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_965cced8-0fe7-4b8b-ba91-6969a9d826a8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_8e47ccd5-7e2d-41bd-9d46-7c354671eaac" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_965cced8-0fe7-4b8b-ba91-6969a9d826a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_A2022SeniorCreditAgreementMember_a9e2ad71-485f-4115-8cf0-06c7ec181383" xlink:href="rock-20240930.xsd#rock_A2022SeniorCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_965cced8-0fe7-4b8b-ba91-6969a9d826a8" xlink:to="loc_rock_A2022SeniorCreditAgreementMember_a9e2ad71-485f-4115-8cf0-06c7ec181383" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_A2019SeniorCreditAgreementMember_df368494-bb19-46f6-ac1a-087510f18567" xlink:href="rock-20240930.xsd#rock_A2019SeniorCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_965cced8-0fe7-4b8b-ba91-6969a9d826a8" xlink:to="loc_rock_A2019SeniorCreditAgreementMember_df368494-bb19-46f6-ac1a-087510f18567" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_SeniorCreditAgreementMember_affa3a90-b34c-4327-836b-b879b6e1ac4e" xlink:href="rock-20240930.xsd#rock_SeniorCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_965cced8-0fe7-4b8b-ba91-6969a9d826a8" xlink:to="loc_rock_SeniorCreditAgreementMember_affa3a90-b34c-4327-836b-b879b6e1ac4e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_8fc8a417-a556-4064-be1f-443d60177067" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_a1527d5b-24bb-4fc2-a949-a726fbaf6961" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_8fc8a417-a556-4064-be1f-443d60177067" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_8fc8a417-a556-4064-be1f-443d60177067_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_8fc8a417-a556-4064-be1f-443d60177067" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_8fc8a417-a556-4064-be1f-443d60177067_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_6fda01a4-a281-4a73-bc33-92df33215de6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_8fc8a417-a556-4064-be1f-443d60177067" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_6fda01a4-a281-4a73-bc33-92df33215de6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_30ffbd96-340d-4655-a07b-ae6557386d7d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_6fda01a4-a281-4a73-bc33-92df33215de6" xlink:to="loc_us-gaap_LineOfCreditMember_30ffbd96-340d-4655-a07b-ae6557386d7d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MediumTermNotesMember_105ae533-62b6-4ff6-b755-dc5d71c3597e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MediumTermNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_6fda01a4-a281-4a73-bc33-92df33215de6" xlink:to="loc_us-gaap_MediumTermNotesMember_105ae533-62b6-4ff6-b755-dc5d71c3597e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_DebtInstrumentApplicableRatePeriodAxis_42c5557d-1c72-4f2d-b153-f327f7de4d44" xlink:href="rock-20240930.xsd#rock_DebtInstrumentApplicableRatePeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_a1527d5b-24bb-4fc2-a949-a726fbaf6961" xlink:to="loc_rock_DebtInstrumentApplicableRatePeriodAxis_42c5557d-1c72-4f2d-b153-f327f7de4d44" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_DebtInstrumentApplicableRatePeriodDomain_42c5557d-1c72-4f2d-b153-f327f7de4d44_default" xlink:href="rock-20240930.xsd#rock_DebtInstrumentApplicableRatePeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_rock_DebtInstrumentApplicableRatePeriodAxis_42c5557d-1c72-4f2d-b153-f327f7de4d44" xlink:to="loc_rock_DebtInstrumentApplicableRatePeriodDomain_42c5557d-1c72-4f2d-b153-f327f7de4d44_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_DebtInstrumentApplicableRatePeriodDomain_2196d5b6-548f-44ad-967b-2e5970101b66" xlink:href="rock-20240930.xsd#rock_DebtInstrumentApplicableRatePeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_rock_DebtInstrumentApplicableRatePeriodAxis_42c5557d-1c72-4f2d-b153-f327f7de4d44" xlink:to="loc_rock_DebtInstrumentApplicableRatePeriodDomain_2196d5b6-548f-44ad-967b-2e5970101b66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_ApplicableRatePeriod1Member_6f2c67a6-b2bc-4367-86c4-4b0b907933c8" xlink:href="rock-20240930.xsd#rock_ApplicableRatePeriod1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_rock_DebtInstrumentApplicableRatePeriodDomain_2196d5b6-548f-44ad-967b-2e5970101b66" xlink:to="loc_rock_ApplicableRatePeriod1Member_6f2c67a6-b2bc-4367-86c4-4b0b907933c8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_ApplicableRatePeriod2Member_cfe46e83-2c7a-4ac2-a028-5a2d8aeaa113" xlink:href="rock-20240930.xsd#rock_ApplicableRatePeriod2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_rock_DebtInstrumentApplicableRatePeriodDomain_2196d5b6-548f-44ad-967b-2e5970101b66" xlink:to="loc_rock_ApplicableRatePeriod2Member_cfe46e83-2c7a-4ac2-a028-5a2d8aeaa113" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_541a6677-3e02-4639-baff-9dde681bce38" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_a1527d5b-24bb-4fc2-a949-a726fbaf6961" xlink:to="loc_us-gaap_VariableRateAxis_541a6677-3e02-4639-baff-9dde681bce38" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_541a6677-3e02-4639-baff-9dde681bce38_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_541a6677-3e02-4639-baff-9dde681bce38" xlink:to="loc_us-gaap_VariableRateDomain_541a6677-3e02-4639-baff-9dde681bce38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_031e03df-cbf5-4109-a2ce-216d6458f4e5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_541a6677-3e02-4639-baff-9dde681bce38" xlink:to="loc_us-gaap_VariableRateDomain_031e03df-cbf5-4109-a2ce-216d6458f4e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_f0192da2-2c6f-4678-b329-040bbabc7e0f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_031e03df-cbf5-4109-a2ce-216d6458f4e5" xlink:to="loc_us-gaap_BaseRateMember_f0192da2-2c6f-4678-b329-040bbabc7e0f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_edbee824-c928-4570-aaba-8fdaa9caaf5e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuredOvernightFinancingRateSofrMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_031e03df-cbf5-4109-a2ce-216d6458f4e5" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_edbee824-c928-4570-aaba-8fdaa9caaf5e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_LondonInterbankOfferedRateLIBOR1Member_081ff8f8-1cc0-4cc4-82f4-80abc1d2f9ce" xlink:href="rock-20240930.xsd#rock_LondonInterbankOfferedRateLIBOR1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_031e03df-cbf5-4109-a2ce-216d6458f4e5" xlink:to="loc_rock_LondonInterbankOfferedRateLIBOR1Member_081ff8f8-1cc0-4cc4-82f4-80abc1d2f9ce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_ForeignCurrencyRateFloorMember_d50607a1-1381-404b-ba31-8ec262bfb07f" xlink:href="rock-20240930.xsd#rock_ForeignCurrencyRateFloorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_031e03df-cbf5-4109-a2ce-216d6458f4e5" xlink:to="loc_rock_ForeignCurrencyRateFloorMember_d50607a1-1381-404b-ba31-8ec262bfb07f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_c262d37e-dcb5-4e4f-821f-05b025a84f31" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_a1527d5b-24bb-4fc2-a949-a726fbaf6961" xlink:to="loc_us-gaap_CreditFacilityAxis_c262d37e-dcb5-4e4f-821f-05b025a84f31" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_c262d37e-dcb5-4e4f-821f-05b025a84f31_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_c262d37e-dcb5-4e4f-821f-05b025a84f31" xlink:to="loc_us-gaap_CreditFacilityDomain_c262d37e-dcb5-4e4f-821f-05b025a84f31_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_494666bc-f664-4d20-aca8-ac0728bf9400" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_c262d37e-dcb5-4e4f-821f-05b025a84f31" xlink:to="loc_us-gaap_CreditFacilityDomain_494666bc-f664-4d20-aca8-ac0728bf9400" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandbyLettersOfCreditMember_252013f2-9c41-40ef-9cb5-07c056bc75d2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StandbyLettersOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_494666bc-f664-4d20-aca8-ac0728bf9400" xlink:to="loc_us-gaap_StandbyLettersOfCreditMember_252013f2-9c41-40ef-9cb5-07c056bc75d2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_60eb5e3e-6a14-4331-9b61-4f1ffb1b85ef" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_494666bc-f664-4d20-aca8-ac0728bf9400" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_60eb5e3e-6a14-4331-9b61-4f1ffb1b85ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_61e86d4c-6aed-42be-960c-c996c746c543" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_a1527d5b-24bb-4fc2-a949-a726fbaf6961" xlink:to="loc_srt_RangeAxis_61e86d4c-6aed-42be-960c-c996c746c543" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_61e86d4c-6aed-42be-960c-c996c746c543_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_61e86d4c-6aed-42be-960c-c996c746c543" xlink:to="loc_srt_RangeMember_61e86d4c-6aed-42be-960c-c996c746c543_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_eacfc717-9d67-4f64-9c5a-3ce43808aba9" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_61e86d4c-6aed-42be-960c-c996c746c543" xlink:to="loc_srt_RangeMember_eacfc717-9d67-4f64-9c5a-3ce43808aba9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_6b18087f-d338-49d8-9113-b470415e81b8" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_eacfc717-9d67-4f64-9c5a-3ce43808aba9" xlink:to="loc_srt_MinimumMember_6b18087f-d338-49d8-9113-b470415e81b8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_ce3844ae-55a3-48c4-be46-c493f4e65818" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_eacfc717-9d67-4f64-9c5a-3ce43808aba9" xlink:to="loc_srt_MaximumMember_ce3844ae-55a3-48c4-be46-c493f4e65818" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_511ecd74-ab3e-46fa-9470-e1d380bafe39" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_51411812-d49e-43ec-b8cf-840e99def566" xlink:to="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_511ecd74-ab3e-46fa-9470-e1d380bafe39" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_312937b3-3ab5-4034-833a-2146d9dcf36a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_51411812-d49e-43ec-b8cf-840e99def566" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_312937b3-3ab5-4034-833a-2146d9dcf36a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_b66771d8-dd0a-43a5-8697-ee96d701948e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_51411812-d49e-43ec-b8cf-840e99def566" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_b66771d8-dd0a-43a5-8697-ee96d701948e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_DebtInstrumentNumberOfDebtCovenants_de19cdee-80fa-496c-b261-6f52b4c9a801" xlink:href="rock-20240930.xsd#rock_DebtInstrumentNumberOfDebtCovenants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_51411812-d49e-43ec-b8cf-840e99def566" xlink:to="loc_rock_DebtInstrumentNumberOfDebtCovenants_de19cdee-80fa-496c-b261-6f52b4c9a801" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_f938703d-3251-4fec-aea4-c2d6f291b843" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_51411812-d49e-43ec-b8cf-840e99def566" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_f938703d-3251-4fec-aea4-c2d6f291b843" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_581822ce-b531-47ed-839c-15adf45ee0e5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_51411812-d49e-43ec-b8cf-840e99def566" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_581822ce-b531-47ed-839c-15adf45ee0e5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_199f5cd8-5bdd-4a74-bbde-9105aec957ef" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_51411812-d49e-43ec-b8cf-840e99def566" xlink:to="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_199f5cd8-5bdd-4a74-bbde-9105aec957ef" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_e74b7022-ca52-4a68-ad81-417f7346c87c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_51411812-d49e-43ec-b8cf-840e99def566" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_e74b7022-ca52-4a68-ad81-417f7346c87c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_d308bd34-670e-4eb4-9320-56caa7e63fc8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_51411812-d49e-43ec-b8cf-840e99def566" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_d308bd34-670e-4eb4-9320-56caa7e63fc8" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_8f8308b1-09fd-4c8b-9cd3-c27dc70dd56c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_51411812-d49e-43ec-b8cf-840e99def566" xlink:to="loc_us-gaap_LongTermDebt_8f8308b1-09fd-4c8b-9cd3-c27dc70dd56c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_b09d8c4d-3298-43f1-9992-1d0250b4de78" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_51411812-d49e-43ec-b8cf-840e99def566" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_b09d8c4d-3298-43f1-9992-1d0250b4de78" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/EquityBasedCompensationIncentivePlanDetails" xlink:type="simple" xlink:href="rock-20240930.xsd#EquityBasedCompensationIncentivePlanDetails"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/EquityBasedCompensationIncentivePlanDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1e5d14ae-b3e2-4ba4-bc1f-10298f6bc12a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f9bfd0bf-2a84-4538-9b6b-cdb11b0f096a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1e5d14ae-b3e2-4ba4-bc1f-10298f6bc12a" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f9bfd0bf-2a84-4538-9b6b-cdb11b0f096a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_2fb5d912-6822-4e34-86bf-e90e30f1cc8e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f9bfd0bf-2a84-4538-9b6b-cdb11b0f096a" xlink:to="loc_us-gaap_PlanNameAxis_2fb5d912-6822-4e34-86bf-e90e30f1cc8e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_2fb5d912-6822-4e34-86bf-e90e30f1cc8e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_2fb5d912-6822-4e34-86bf-e90e30f1cc8e" xlink:to="loc_us-gaap_PlanNameDomain_2fb5d912-6822-4e34-86bf-e90e30f1cc8e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_6ba4549b-c1cf-4a06-94d4-f645ce646777" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_2fb5d912-6822-4e34-86bf-e90e30f1cc8e" xlink:to="loc_us-gaap_PlanNameDomain_6ba4549b-c1cf-4a06-94d4-f645ce646777" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_Amended2018PlanMember_f7ff8975-b5e4-4c28-b11b-85313f8b8218" xlink:href="rock-20240930.xsd#rock_Amended2018PlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_6ba4549b-c1cf-4a06-94d4-f645ce646777" xlink:to="loc_rock_Amended2018PlanMember_f7ff8975-b5e4-4c28-b11b-85313f8b8218" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_NonEmployeeDirectorsPlanMember_862f2585-ec22-4c33-adcb-30c132eb06aa" xlink:href="rock-20240930.xsd#rock_NonEmployeeDirectorsPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_6ba4549b-c1cf-4a06-94d4-f645ce646777" xlink:to="loc_rock_NonEmployeeDirectorsPlanMember_862f2585-ec22-4c33-adcb-30c132eb06aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_01be2d5a-a33d-487a-a389-64a2a1399f18" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f9bfd0bf-2a84-4538-9b6b-cdb11b0f096a" xlink:to="loc_us-gaap_AwardTypeAxis_01be2d5a-a33d-487a-a389-64a2a1399f18" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01be2d5a-a33d-487a-a389-64a2a1399f18_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_01be2d5a-a33d-487a-a389-64a2a1399f18" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01be2d5a-a33d-487a-a389-64a2a1399f18_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_44da7666-c7b5-4c96-b4a0-44d717932848" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_01be2d5a-a33d-487a-a389-64a2a1399f18" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_44da7666-c7b5-4c96-b4a0-44d717932848" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_348e63ae-9f55-4a83-89b9-64881b6eccce" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_44da7666-c7b5-4c96-b4a0-44d717932848" xlink:to="loc_us-gaap_CommonStockMember_348e63ae-9f55-4a83-89b9-64881b6eccce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_bacd4d5e-6e1c-4b00-8a4f-1f2d88f0f862" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1e5d14ae-b3e2-4ba4-bc1f-10298f6bc12a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_bacd4d5e-6e1c-4b00-8a4f-1f2d88f0f862" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/EquityBasedCompensationScheduleofNumberofAwardsandWeightedAverageGrantDateFairValueDetails" xlink:type="simple" xlink:href="rock-20240930.xsd#EquityBasedCompensationScheduleofNumberofAwardsandWeightedAverageGrantDateFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/EquityBasedCompensationScheduleofNumberofAwardsandWeightedAverageGrantDateFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d7923595-99c9-4e34-8db0-9e2fdd8c17d2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b5e9750d-b592-4ac4-a388-9d1d7ce6e33e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d7923595-99c9-4e34-8db0-9e2fdd8c17d2" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b5e9750d-b592-4ac4-a388-9d1d7ce6e33e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_22f9fad1-8b0f-4ba5-aa2f-f59b60f9802c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b5e9750d-b592-4ac4-a388-9d1d7ce6e33e" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_22f9fad1-8b0f-4ba5-aa2f-f59b60f9802c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_22f9fad1-8b0f-4ba5-aa2f-f59b60f9802c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_22f9fad1-8b0f-4ba5-aa2f-f59b60f9802c" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_22f9fad1-8b0f-4ba5-aa2f-f59b60f9802c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_2cb39a2f-d1ba-41e9-978d-e212c86d11a4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_22f9fad1-8b0f-4ba5-aa2f-f59b60f9802c" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_2cb39a2f-d1ba-41e9-978d-e212c86d11a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_SharebasedCompensationMeasurementReturnOnInvestedCapitalMember_be13740c-3fdb-4556-b520-696ba668105a" xlink:href="rock-20240930.xsd#rock_SharebasedCompensationMeasurementReturnOnInvestedCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_2cb39a2f-d1ba-41e9-978d-e212c86d11a4" xlink:to="loc_rock_SharebasedCompensationMeasurementReturnOnInvestedCapitalMember_be13740c-3fdb-4556-b520-696ba668105a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_66490490-9a71-44a6-b040-fa2e7570a48e" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b5e9750d-b592-4ac4-a388-9d1d7ce6e33e" xlink:to="loc_srt_RangeAxis_66490490-9a71-44a6-b040-fa2e7570a48e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_66490490-9a71-44a6-b040-fa2e7570a48e_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_66490490-9a71-44a6-b040-fa2e7570a48e" xlink:to="loc_srt_RangeMember_66490490-9a71-44a6-b040-fa2e7570a48e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_2b6a950c-100a-4f3c-b11b-c3650a9a92a3" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_66490490-9a71-44a6-b040-fa2e7570a48e" xlink:to="loc_srt_RangeMember_2b6a950c-100a-4f3c-b11b-c3650a9a92a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_b7b8e34c-9ce6-47db-b2f7-addae463cb62" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_2b6a950c-100a-4f3c-b11b-c3650a9a92a3" xlink:to="loc_srt_MinimumMember_b7b8e34c-9ce6-47db-b2f7-addae463cb62" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_4ae288a4-8c41-40ec-948c-e86e70528951" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_2b6a950c-100a-4f3c-b11b-c3650a9a92a3" xlink:to="loc_srt_MaximumMember_4ae288a4-8c41-40ec-948c-e86e70528951" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_79cabb32-82f2-4702-b582-a893ad79247b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b5e9750d-b592-4ac4-a388-9d1d7ce6e33e" xlink:to="loc_us-gaap_PlanNameAxis_79cabb32-82f2-4702-b582-a893ad79247b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_79cabb32-82f2-4702-b582-a893ad79247b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_79cabb32-82f2-4702-b582-a893ad79247b" xlink:to="loc_us-gaap_PlanNameDomain_79cabb32-82f2-4702-b582-a893ad79247b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_1b81819d-038e-487f-91ad-2cd2c1286fd3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_79cabb32-82f2-4702-b582-a893ad79247b" xlink:to="loc_us-gaap_PlanNameDomain_1b81819d-038e-487f-91ad-2cd2c1286fd3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_A2018PlanMember_170e50bb-9dc6-4026-9f31-e9fccd8ad477" xlink:href="rock-20240930.xsd#rock_A2018PlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_1b81819d-038e-487f-91ad-2cd2c1286fd3" xlink:to="loc_rock_A2018PlanMember_170e50bb-9dc6-4026-9f31-e9fccd8ad477" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_3636a7f0-0cef-4f5d-9c54-329df10ae149" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b5e9750d-b592-4ac4-a388-9d1d7ce6e33e" xlink:to="loc_us-gaap_AwardTypeAxis_3636a7f0-0cef-4f5d-9c54-329df10ae149" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3636a7f0-0cef-4f5d-9c54-329df10ae149_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_3636a7f0-0cef-4f5d-9c54-329df10ae149" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3636a7f0-0cef-4f5d-9c54-329df10ae149_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1853960d-9831-4499-99d5-d9d9c4fe983c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_3636a7f0-0cef-4f5d-9c54-329df10ae149" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1853960d-9831-4499-99d5-d9d9c4fe983c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_72112b89-bc4c-486e-a729-0d88eee5bd9f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1853960d-9831-4499-99d5-d9d9c4fe983c" xlink:to="loc_us-gaap_PerformanceSharesMember_72112b89-bc4c-486e-a729-0d88eee5bd9f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_c2ab1080-9aac-4898-a858-bd17b052858f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1853960d-9831-4499-99d5-d9d9c4fe983c" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_c2ab1080-9aac-4898-a858-bd17b052858f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_DeferredStockUnitsMember_80d5654b-ebbc-4f84-b713-33a7d2d32b4d" xlink:href="rock-20240930.xsd#rock_DeferredStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1853960d-9831-4499-99d5-d9d9c4fe983c" xlink:to="loc_rock_DeferredStockUnitsMember_80d5654b-ebbc-4f84-b713-33a7d2d32b4d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_a15e9fbe-106b-4cfa-90fd-1fec6cf88ab0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1853960d-9831-4499-99d5-d9d9c4fe983c" xlink:to="loc_us-gaap_RestrictedStockMember_a15e9fbe-106b-4cfa-90fd-1fec6cf88ab0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_ba3b9021-39c1-42b0-942e-ca8a0cb16925" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d7923595-99c9-4e34-8db0-9e2fdd8c17d2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_ba3b9021-39c1-42b0-942e-ca8a0cb16925" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_efc5f1b6-6804-4357-b139-7448d0b4929f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d7923595-99c9-4e34-8db0-9e2fdd8c17d2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_efc5f1b6-6804-4357-b139-7448d0b4929f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsBasedOnTargetedThresholdsPercent_b9a0308c-c7f6-4c7f-9340-1c70e129ab7d" xlink:href="rock-20240930.xsd#rock_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsBasedOnTargetedThresholdsPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d7923595-99c9-4e34-8db0-9e2fdd8c17d2" xlink:to="loc_rock_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsBasedOnTargetedThresholdsPercent_b9a0308c-c7f6-4c7f-9340-1c70e129ab7d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_SharebasedCompensationArrangementbySharebasedPaymentAwardAwardPerformancePeriod_6e6e0a25-a72e-40bf-9bb6-60d99c30297b" xlink:href="rock-20240930.xsd#rock_SharebasedCompensationArrangementbySharebasedPaymentAwardAwardPerformancePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d7923595-99c9-4e34-8db0-9e2fdd8c17d2" xlink:to="loc_rock_SharebasedCompensationArrangementbySharebasedPaymentAwardAwardPerformancePeriod_6e6e0a25-a72e-40bf-9bb6-60d99c30297b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_c979b4fc-4496-4702-bbd0-8e44daddd1ff" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d7923595-99c9-4e34-8db0-9e2fdd8c17d2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_c979b4fc-4496-4702-bbd0-8e44daddd1ff" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsToBeConverted_48460ead-659d-4151-a8a5-a2ba68106e09" xlink:href="rock-20240930.xsd#rock_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsToBeConverted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d7923595-99c9-4e34-8db0-9e2fdd8c17d2" xlink:to="loc_rock_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsToBeConverted_48460ead-659d-4151-a8a5-a2ba68106e09" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsUnitsToBeConvertedPercentageOfTargetAmount_7923dc23-525e-4bf8-81cd-fed57f3991d9" xlink:href="rock-20240930.xsd#rock_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsUnitsToBeConvertedPercentageOfTargetAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d7923595-99c9-4e34-8db0-9e2fdd8c17d2" xlink:to="loc_rock_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsUnitsToBeConvertedPercentageOfTargetAmount_7923dc23-525e-4bf8-81cd-fed57f3991d9" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/EquityBasedCompensationEquityBasedAwardsSettledinCashDetails" xlink:type="simple" xlink:href="rock-20240930.xsd#EquityBasedCompensationEquityBasedAwardsSettledinCashDetails"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/EquityBasedCompensationEquityBasedAwardsSettledinCashDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_927a24a9-7ca3-4a99-906b-a68a14a85214" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_687c721a-e66d-49ef-8c0c-8089a8d4968d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_927a24a9-7ca3-4a99-906b-a68a14a85214" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_687c721a-e66d-49ef-8c0c-8089a8d4968d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_c0596725-a1cb-48dc-952b-5bfd57504942" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_687c721a-e66d-49ef-8c0c-8089a8d4968d" xlink:to="loc_us-gaap_PlanNameAxis_c0596725-a1cb-48dc-952b-5bfd57504942" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_c0596725-a1cb-48dc-952b-5bfd57504942_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_c0596725-a1cb-48dc-952b-5bfd57504942" xlink:to="loc_us-gaap_PlanNameDomain_c0596725-a1cb-48dc-952b-5bfd57504942_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_ff76874b-2907-44ab-8897-6f8f67110992" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_c0596725-a1cb-48dc-952b-5bfd57504942" xlink:to="loc_us-gaap_PlanNameDomain_ff76874b-2907-44ab-8897-6f8f67110992" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_ManagementStockPurchasePlanMember_9fedc204-5b99-4fad-b9dd-1ad6745dc748" xlink:href="rock-20240930.xsd#rock_ManagementStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_ff76874b-2907-44ab-8897-6f8f67110992" xlink:to="loc_rock_ManagementStockPurchasePlanMember_9fedc204-5b99-4fad-b9dd-1ad6745dc748" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_5082af7f-e2f3-4cd2-8d80-cd21690f5e2f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_687c721a-e66d-49ef-8c0c-8089a8d4968d" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_5082af7f-e2f3-4cd2-8d80-cd21690f5e2f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_5082af7f-e2f3-4cd2-8d80-cd21690f5e2f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_5082af7f-e2f3-4cd2-8d80-cd21690f5e2f" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_5082af7f-e2f3-4cd2-8d80-cd21690f5e2f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_cfb55ec2-6baa-4b36-9572-7db7f867e0b7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_5082af7f-e2f3-4cd2-8d80-cd21690f5e2f" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_cfb55ec2-6baa-4b36-9572-7db7f867e0b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_NonCurrentLiabilitiesMember_a7f718fb-a516-4d99-9e4d-df6e6ebde20f" xlink:href="rock-20240930.xsd#rock_NonCurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_cfb55ec2-6baa-4b36-9572-7db7f867e0b7" xlink:to="loc_rock_NonCurrentLiabilitiesMember_a7f718fb-a516-4d99-9e4d-df6e6ebde20f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_AccruedExpensesCurrentMember_4263ca45-2edb-4713-80bd-041e20a7be22" xlink:href="rock-20240930.xsd#rock_AccruedExpensesCurrentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_cfb55ec2-6baa-4b36-9572-7db7f867e0b7" xlink:to="loc_rock_AccruedExpensesCurrentMember_4263ca45-2edb-4713-80bd-041e20a7be22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_355c63ee-0231-452c-af24-bf02ef45b979" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_687c721a-e66d-49ef-8c0c-8089a8d4968d" xlink:to="loc_us-gaap_AwardTypeAxis_355c63ee-0231-452c-af24-bf02ef45b979" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_355c63ee-0231-452c-af24-bf02ef45b979_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_355c63ee-0231-452c-af24-bf02ef45b979" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_355c63ee-0231-452c-af24-bf02ef45b979_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_53e0a4bd-6725-4305-a7f6-79bc4df41351" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_355c63ee-0231-452c-af24-bf02ef45b979" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_53e0a4bd-6725-4305-a7f6-79bc4df41351" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_c1baceb1-8dd6-4d36-b851-706f333b98aa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_53e0a4bd-6725-4305-a7f6-79bc4df41351" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_c1baceb1-8dd6-4d36-b851-706f333b98aa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_AccruedEquityBasedCompensation_5c8f0292-63d6-44ed-9f4b-68d9f8083d9a" xlink:href="rock-20240930.xsd#rock_AccruedEquityBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_927a24a9-7ca3-4a99-906b-a68a14a85214" xlink:to="loc_rock_AccruedEquityBasedCompensation_5c8f0292-63d6-44ed-9f4b-68d9f8083d9a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_SharebasedCompensationArrangementBySharebasedPaymentAwardAverageCompanyStockPriceMeasurementPeriod_8c10ebc9-2c72-4cef-894d-3f9fab6bab56" xlink:href="rock-20240930.xsd#rock_SharebasedCompensationArrangementBySharebasedPaymentAwardAverageCompanyStockPriceMeasurementPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_927a24a9-7ca3-4a99-906b-a68a14a85214" xlink:to="loc_rock_SharebasedCompensationArrangementBySharebasedPaymentAwardAverageCompanyStockPriceMeasurementPeriod_8c10ebc9-2c72-4cef-894d-3f9fab6bab56" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_b2ab6d9d-b415-4245-9590-8121bc443269" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_927a24a9-7ca3-4a99-906b-a68a14a85214" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_b2ab6d9d-b415-4245-9590-8121bc443269" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareBasedLiabilitiesPaid_0598f08d-406e-4929-9324-4c02aee10ece" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareBasedLiabilitiesPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_927a24a9-7ca3-4a99-906b-a68a14a85214" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareBasedLiabilitiesPaid_0598f08d-406e-4929-9324-4c02aee10ece" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/ExitActivityCostsandAssetImpairmentsSummaryofExitActivityCostsandAssetImpairmentsbySegmentDetails" xlink:type="simple" xlink:href="rock-20240930.xsd#ExitActivityCostsandAssetImpairmentsSummaryofExitActivityCostsandAssetImpairmentsbySegmentDetails"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/ExitActivityCostsandAssetImpairmentsSummaryofExitActivityCostsandAssetImpairmentsbySegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_b3b195ca-9b05-4e0f-b716-3147aa90bc45" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_788c8cd1-3a06-4736-b721-22ab54804576" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_b3b195ca-9b05-4e0f-b716-3147aa90bc45" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_788c8cd1-3a06-4736-b721-22ab54804576" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_ef871563-6dc5-4445-8b3e-9afbbddb84ce" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_788c8cd1-3a06-4736-b721-22ab54804576" xlink:to="loc_srt_ConsolidationItemsAxis_ef871563-6dc5-4445-8b3e-9afbbddb84ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_ef871563-6dc5-4445-8b3e-9afbbddb84ce_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_ef871563-6dc5-4445-8b3e-9afbbddb84ce" xlink:to="loc_srt_ConsolidationItemsDomain_ef871563-6dc5-4445-8b3e-9afbbddb84ce_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_0655559c-5e3e-4c2f-ba01-9c837cba7aa0" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_ef871563-6dc5-4445-8b3e-9afbbddb84ce" xlink:to="loc_srt_ConsolidationItemsDomain_0655559c-5e3e-4c2f-ba01-9c837cba7aa0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_3ab2d726-b2ec-4cdd-93d1-75b3bcba00b6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_0655559c-5e3e-4c2f-ba01-9c837cba7aa0" xlink:to="loc_us-gaap_OperatingSegmentsMember_3ab2d726-b2ec-4cdd-93d1-75b3bcba00b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_59ea3e43-183f-432a-9411-da408dd6bcba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_0655559c-5e3e-4c2f-ba01-9c837cba7aa0" xlink:to="loc_us-gaap_CorporateNonSegmentMember_59ea3e43-183f-432a-9411-da408dd6bcba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_1b7dafec-97b7-4970-9c7b-4ced2d5819ed" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_788c8cd1-3a06-4736-b721-22ab54804576" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_1b7dafec-97b7-4970-9c7b-4ced2d5819ed" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_1b7dafec-97b7-4970-9c7b-4ced2d5819ed_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_1b7dafec-97b7-4970-9c7b-4ced2d5819ed" xlink:to="loc_us-gaap_SegmentDomain_1b7dafec-97b7-4970-9c7b-4ced2d5819ed_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_5d54c099-4eda-4edc-adda-b16d51b67fa5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_1b7dafec-97b7-4970-9c7b-4ced2d5819ed" xlink:to="loc_us-gaap_SegmentDomain_5d54c099-4eda-4edc-adda-b16d51b67fa5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_ResidentialProductsMember_bde3572d-4916-486f-b9a1-c89adbcb6b50" xlink:href="rock-20240930.xsd#rock_ResidentialProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_5d54c099-4eda-4edc-adda-b16d51b67fa5" xlink:to="loc_rock_ResidentialProductsMember_bde3572d-4916-486f-b9a1-c89adbcb6b50" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_RenewableEnergyandConservationMember_18ca1ab1-ef01-45ba-8a1e-c48263946ab4" xlink:href="rock-20240930.xsd#rock_RenewableEnergyandConservationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_5d54c099-4eda-4edc-adda-b16d51b67fa5" xlink:to="loc_rock_RenewableEnergyandConservationMember_18ca1ab1-ef01-45ba-8a1e-c48263946ab4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_AgtechMember_68e625b3-323f-4214-ab71-f4cccffaf27a" xlink:href="rock-20240930.xsd#rock_AgtechMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_5d54c099-4eda-4edc-adda-b16d51b67fa5" xlink:to="loc_rock_AgtechMember_68e625b3-323f-4214-ab71-f4cccffaf27a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_InfrastructureMember_370cb8b9-c262-41dc-9342-d9a6ee3340a5" xlink:href="rock-20240930.xsd#rock_InfrastructureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_5d54c099-4eda-4edc-adda-b16d51b67fa5" xlink:to="loc_rock_InfrastructureMember_370cb8b9-c262-41dc-9342-d9a6ee3340a5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessExitCosts1_4e05767a-94c5-41dc-8a99-5be242d8adc7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessExitCosts1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_b3b195ca-9b05-4e0f-b716-3147aa90bc45" xlink:to="loc_us-gaap_BusinessExitCosts1_4e05767a-94c5-41dc-8a99-5be242d8adc7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_BusinessExitCostsRecoveries_db3854e6-14cf-4e36-9e60-465d8bb51a74" xlink:href="rock-20240930.xsd#rock_BusinessExitCostsRecoveries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_b3b195ca-9b05-4e0f-b716-3147aa90bc45" xlink:to="loc_rock_BusinessExitCostsRecoveries_db3854e6-14cf-4e36-9e60-465d8bb51a74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringSettlementAndImpairmentProvisions_d8edcd9f-696e-41b6-8c6a-2b5cd17a0c93" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestructuringSettlementAndImpairmentProvisions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_b3b195ca-9b05-4e0f-b716-3147aa90bc45" xlink:to="loc_us-gaap_RestructuringSettlementAndImpairmentProvisions_d8edcd9f-696e-41b6-8c6a-2b5cd17a0c93" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_RestructuringSettlementAndImpairmentProvisionsRecovery_37fec861-00d0-4285-8073-d56ec2a92f69" xlink:href="rock-20240930.xsd#rock_RestructuringSettlementAndImpairmentProvisionsRecovery"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_b3b195ca-9b05-4e0f-b716-3147aa90bc45" xlink:to="loc_rock_RestructuringSettlementAndImpairmentProvisionsRecovery_37fec861-00d0-4285-8073-d56ec2a92f69" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_13e55520-4f74-4616-82d8-58d5741109f0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_b3b195ca-9b05-4e0f-b716-3147aa90bc45" xlink:to="loc_us-gaap_RestructuringCharges_13e55520-4f74-4616-82d8-58d5741109f0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_RestructuringChargesRecoveries_6b015246-1ce0-4dc9-92f0-e23d37a28528" xlink:href="rock-20240930.xsd#rock_RestructuringChargesRecoveries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_b3b195ca-9b05-4e0f-b716-3147aa90bc45" xlink:to="loc_rock_RestructuringChargesRecoveries_6b015246-1ce0-4dc9-92f0-e23d37a28528" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/ExitActivityCostsandAssetImpairmentsSummaryofExitActivityCostsandAssetImpairmentsDetails" xlink:type="simple" xlink:href="rock-20240930.xsd#ExitActivityCostsandAssetImpairmentsSummaryofExitActivityCostsandAssetImpairmentsDetails"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/ExitActivityCostsandAssetImpairmentsSummaryofExitActivityCostsandAssetImpairmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_3135ba68-d828-4f13-b382-36b6073cb564" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_42836229-9ba0-45da-8f86-60d32b3bc6a7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_3135ba68-d828-4f13-b382-36b6073cb564" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_42836229-9ba0-45da-8f86-60d32b3bc6a7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_ebaa5e86-6667-4dde-aa7a-c9ed59b44c74" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_42836229-9ba0-45da-8f86-60d32b3bc6a7" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_ebaa5e86-6667-4dde-aa7a-c9ed59b44c74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_ebaa5e86-6667-4dde-aa7a-c9ed59b44c74_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_ebaa5e86-6667-4dde-aa7a-c9ed59b44c74" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_ebaa5e86-6667-4dde-aa7a-c9ed59b44c74_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_13475261-b36c-4212-8920-0676eaeb31df" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_ebaa5e86-6667-4dde-aa7a-c9ed59b44c74" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_13475261-b36c-4212-8920-0676eaeb31df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_c915bf2a-b2f4-4975-b829-820c1c5aaf3b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_13475261-b36c-4212-8920-0676eaeb31df" xlink:to="loc_us-gaap_CostOfSalesMember_c915bf2a-b2f4-4975-b829-820c1c5aaf3b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_SellingGeneralAndAdministrativeExpenseMember_93242e43-2df8-40ed-930d-75a4ce30cd68" xlink:href="rock-20240930.xsd#rock_SellingGeneralAndAdministrativeExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_13475261-b36c-4212-8920-0676eaeb31df" xlink:to="loc_rock_SellingGeneralAndAdministrativeExpenseMember_93242e43-2df8-40ed-930d-75a4ce30cd68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_cfaf199c-bef3-4bfb-951b-8b8e081552ee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_3135ba68-d828-4f13-b382-36b6073cb564" xlink:to="loc_us-gaap_RestructuringCharges_cfaf199c-bef3-4bfb-951b-8b8e081552ee" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/EarningsperShareDetails" xlink:type="simple" xlink:href="rock-20240930.xsd#EarningsperShareDetails"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/EarningsperShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_3377fde6-a8a2-4d41-b8da-53ed32df633b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1ddf7e91-60ae-4163-ac9f-a405d25f708f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_3377fde6-a8a2-4d41-b8da-53ed32df633b" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1ddf7e91-60ae-4163-ac9f-a405d25f708f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_236c6132-971c-4ddf-b5c9-fc9a17088726" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1ddf7e91-60ae-4163-ac9f-a405d25f708f" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_236c6132-971c-4ddf-b5c9-fc9a17088726" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_236c6132-971c-4ddf-b5c9-fc9a17088726_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_236c6132-971c-4ddf-b5c9-fc9a17088726" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_236c6132-971c-4ddf-b5c9-fc9a17088726_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_6b8144f2-95b9-4398-91bd-3d08f165ede4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_236c6132-971c-4ddf-b5c9-fc9a17088726" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_6b8144f2-95b9-4398-91bd-3d08f165ede4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_01199e30-58ee-48e1-b2fa-594f83a22277" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_6b8144f2-95b9-4398-91bd-3d08f165ede4" xlink:to="loc_us-gaap_CommonStockMember_01199e30-58ee-48e1-b2fa-594f83a22277" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_415dfeca-86ca-4962-bce7-a9ae890cc286" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_3377fde6-a8a2-4d41-b8da-53ed32df633b" xlink:to="loc_us-gaap_NetIncomeLoss_415dfeca-86ca-4962-bce7-a9ae890cc286" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_e3a00e31-5f1f-4942-9583-d8507c1d8104" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_3377fde6-a8a2-4d41-b8da-53ed32df633b" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_e3a00e31-5f1f-4942-9583-d8507c1d8104" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_f4d22635-31f3-4a8b-af80-3f29f9decccb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_3377fde6-a8a2-4d41-b8da-53ed32df633b" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_f4d22635-31f3-4a8b-af80-3f29f9decccb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_86514c51-ba14-4cd7-b6f8-40ba68ce7f26" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_3377fde6-a8a2-4d41-b8da-53ed32df633b" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_86514c51-ba14-4cd7-b6f8-40ba68ce7f26" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_4eb488db-a1e0-4731-bc9d-9b292a81aa66" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_3377fde6-a8a2-4d41-b8da-53ed32df633b" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_4eb488db-a1e0-4731-bc9d-9b292a81aa66" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/SegmentInformationDetails" xlink:type="simple" xlink:href="rock-20240930.xsd#SegmentInformationDetails"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/SegmentInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems_ad49b731-667c-4815-a4af-d236d9306258" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable_85435321-e191-4681-9800-6a64bce5d5b8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems_ad49b731-667c-4815-a4af-d236d9306258" xlink:to="loc_us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable_85435321-e191-4681-9800-6a64bce5d5b8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_3fa27491-684f-4ba5-8930-6d7286b98de9" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable_85435321-e191-4681-9800-6a64bce5d5b8" xlink:to="loc_srt_ConsolidationItemsAxis_3fa27491-684f-4ba5-8930-6d7286b98de9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_3fa27491-684f-4ba5-8930-6d7286b98de9_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_3fa27491-684f-4ba5-8930-6d7286b98de9" xlink:to="loc_srt_ConsolidationItemsDomain_3fa27491-684f-4ba5-8930-6d7286b98de9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_9f021e69-d5c4-48b3-ad63-247a3ab1b0b6" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_3fa27491-684f-4ba5-8930-6d7286b98de9" xlink:to="loc_srt_ConsolidationItemsDomain_9f021e69-d5c4-48b3-ad63-247a3ab1b0b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_c689285f-c935-4ee0-8ed3-a6d65c52d66a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_9f021e69-d5c4-48b3-ad63-247a3ab1b0b6" xlink:to="loc_us-gaap_OperatingSegmentsMember_c689285f-c935-4ee0-8ed3-a6d65c52d66a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_5466bffe-ea17-4e85-ab78-f022db742bea" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_9f021e69-d5c4-48b3-ad63-247a3ab1b0b6" xlink:to="loc_us-gaap_CorporateNonSegmentMember_5466bffe-ea17-4e85-ab78-f022db742bea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_aeb6008a-d2a6-4c9a-a567-aeb2d5ff7848" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfOtherSignificantReconcilingItemsFromSegmentsToConsolidatedTable_85435321-e191-4681-9800-6a64bce5d5b8" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_aeb6008a-d2a6-4c9a-a567-aeb2d5ff7848" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_aeb6008a-d2a6-4c9a-a567-aeb2d5ff7848_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_aeb6008a-d2a6-4c9a-a567-aeb2d5ff7848" xlink:to="loc_us-gaap_SegmentDomain_aeb6008a-d2a6-4c9a-a567-aeb2d5ff7848_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_f7ae1f23-01ce-4a12-971e-4659de259669" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_aeb6008a-d2a6-4c9a-a567-aeb2d5ff7848" xlink:to="loc_us-gaap_SegmentDomain_f7ae1f23-01ce-4a12-971e-4659de259669" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_ResidentialProductsMember_c97730c3-58d6-4613-85ff-0721820fdcfa" xlink:href="rock-20240930.xsd#rock_ResidentialProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_f7ae1f23-01ce-4a12-971e-4659de259669" xlink:to="loc_rock_ResidentialProductsMember_c97730c3-58d6-4613-85ff-0721820fdcfa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_RenewablesMember_b7eb670a-3326-4207-b638-88eda6e60db8" xlink:href="rock-20240930.xsd#rock_RenewablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_f7ae1f23-01ce-4a12-971e-4659de259669" xlink:to="loc_rock_RenewablesMember_b7eb670a-3326-4207-b638-88eda6e60db8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_AgtechMember_c4a137cb-4713-4ebc-94fb-7a03fd1c702a" xlink:href="rock-20240930.xsd#rock_AgtechMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_f7ae1f23-01ce-4a12-971e-4659de259669" xlink:to="loc_rock_AgtechMember_c4a137cb-4713-4ebc-94fb-7a03fd1c702a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_InfrastructureMember_02804068-b4ac-4448-8ed8-e10634e6ba9d" xlink:href="rock-20240930.xsd#rock_InfrastructureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_f7ae1f23-01ce-4a12-971e-4659de259669" xlink:to="loc_rock_InfrastructureMember_02804068-b4ac-4448-8ed8-e10634e6ba9d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_d6fe2cc6-dd20-4765-872b-932e879940e8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems_ad49b731-667c-4815-a4af-d236d9306258" xlink:to="loc_us-gaap_NumberOfReportableSegments_d6fe2cc6-dd20-4765-872b-932e879940e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_072819f5-96ce-4112-8a29-f67275b60463" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems_ad49b731-667c-4815-a4af-d236d9306258" xlink:to="loc_us-gaap_Revenues_072819f5-96ce-4112-8a29-f67275b60463" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_43e9c785-0620-4149-8d7c-dd8ebfe1dffc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems_ad49b731-667c-4815-a4af-d236d9306258" xlink:to="loc_us-gaap_OperatingIncomeLoss_43e9c785-0620-4149-8d7c-dd8ebfe1dffc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_40cf4280-2912-4e92-b932-cc7b1dded301" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemLineItems_ad49b731-667c-4815-a4af-d236d9306258" xlink:to="loc_us-gaap_Assets_40cf4280-2912-4e92-b932-cc7b1dded301" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.gibraltar1.com/role/SegmentInformationDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="rock-20240930.xsd#SegmentInformationDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.gibraltar1.com/role/SegmentInformationDisaggregationofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_7901f36c-0d1d-4189-9cb8-8949a7c1a0c4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_c46b835c-3098-485e-834d-ffddf466fa1f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_7901f36c-0d1d-4189-9cb8-8949a7c1a0c4" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_c46b835c-3098-485e-834d-ffddf466fa1f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_c1c7aefd-df3d-43f2-a642-5c6032395cd0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimingOfTransferOfGoodOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_c46b835c-3098-485e-834d-ffddf466fa1f" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_c1c7aefd-df3d-43f2-a642-5c6032395cd0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_c1c7aefd-df3d-43f2-a642-5c6032395cd0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_c1c7aefd-df3d-43f2-a642-5c6032395cd0" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_c1c7aefd-df3d-43f2-a642-5c6032395cd0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_92b4a214-2adb-4f27-b538-e04b8ef380fa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_c1c7aefd-df3d-43f2-a642-5c6032395cd0" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_92b4a214-2adb-4f27-b538-e04b8ef380fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferredAtPointInTimeMember_1206537b-23bc-4ea4-a5c6-26c74a5f19c6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransferredAtPointInTimeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_92b4a214-2adb-4f27-b538-e04b8ef380fa" xlink:to="loc_us-gaap_TransferredAtPointInTimeMember_1206537b-23bc-4ea4-a5c6-26c74a5f19c6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferredOverTimeMember_55ef99d0-6953-4ac3-a7c0-386910c58450" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransferredOverTimeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_92b4a214-2adb-4f27-b538-e04b8ef380fa" xlink:to="loc_us-gaap_TransferredOverTimeMember_55ef99d0-6953-4ac3-a7c0-386910c58450" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_e9497ec0-fb87-495c-a558-7cbb8c574c46" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_c46b835c-3098-485e-834d-ffddf466fa1f" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_e9497ec0-fb87-495c-a558-7cbb8c574c46" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_e9497ec0-fb87-495c-a558-7cbb8c574c46_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_e9497ec0-fb87-495c-a558-7cbb8c574c46" xlink:to="loc_us-gaap_SegmentDomain_e9497ec0-fb87-495c-a558-7cbb8c574c46_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_766d2b3e-95ad-44ca-8a82-cf29c5180155" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_e9497ec0-fb87-495c-a558-7cbb8c574c46" xlink:to="loc_us-gaap_SegmentDomain_766d2b3e-95ad-44ca-8a82-cf29c5180155" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_ResidentialProductsMember_3388a930-1c13-427b-b3b7-780efd816165" xlink:href="rock-20240930.xsd#rock_ResidentialProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_766d2b3e-95ad-44ca-8a82-cf29c5180155" xlink:to="loc_rock_ResidentialProductsMember_3388a930-1c13-427b-b3b7-780efd816165" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_RenewablesMember_6889062e-6b54-4a15-8838-9b0de541998a" xlink:href="rock-20240930.xsd#rock_RenewablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_766d2b3e-95ad-44ca-8a82-cf29c5180155" xlink:to="loc_rock_RenewablesMember_6889062e-6b54-4a15-8838-9b0de541998a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_AgtechMember_6d62b38d-1da9-41f0-93a9-d853c5ac8f9e" xlink:href="rock-20240930.xsd#rock_AgtechMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_766d2b3e-95ad-44ca-8a82-cf29c5180155" xlink:to="loc_rock_AgtechMember_6d62b38d-1da9-41f0-93a9-d853c5ac8f9e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_rock_InfrastructureMember_8b16b2fc-c149-41b1-9a86-b00fab595c7f" xlink:href="rock-20240930.xsd#rock_InfrastructureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_766d2b3e-95ad-44ca-8a82-cf29c5180155" xlink:to="loc_rock_InfrastructureMember_8b16b2fc-c149-41b1-9a86-b00fab595c7f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_9ff6d3f2-3b2f-4c63-bfb7-f61b6a9df065" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_7901f36c-0d1d-4189-9cb8-8949a7c1a0c4" xlink:to="loc_us-gaap_Revenues_9ff6d3f2-3b2f-4c63-bfb7-f61b6a9df065" xlink:type="arc" order="0"/>
  </link:definitionLink>
</link:linkbase>
