<SEC-DOCUMENT>0001666138-20-000166.txt : 20201201
<SEC-HEADER>0001666138-20-000166.hdr.sgml : 20201201
<ACCEPTANCE-DATETIME>20201201185439
ACCESSION NUMBER:		0001666138-20-000166
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20201127
FILED AS OF DATE:		20201201
DATE AS OF CHANGE:		20201201

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Lariviere Peter J
		CENTRAL INDEX KEY:			0001674832

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-37793
		FILM NUMBER:		201362007

	MAIL ADDRESS:	
		STREET 1:		16100 SOUTH LATHROP AVENUE
		CITY:			HARVEY
		STATE:			IL
		ZIP:			60426

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Atkore International Group Inc.
		CENTRAL INDEX KEY:			0001666138
		STANDARD INDUSTRIAL CLASSIFICATION:	MISCELLANEOUS ELECTRICAL MACHINERY, EQUIPMENT & SUPPLIES [3690]
		IRS NUMBER:				900631463
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0930

	BUSINESS ADDRESS:	
		STREET 1:		16100 SOUTH LATHROP AVENUE
		CITY:			HARVEY
		STATE:			IL
		ZIP:			60426
		BUSINESS PHONE:		7083391610

	MAIL ADDRESS:	
		STREET 1:		16100 SOUTH LATHROP AVENUE
		CITY:			HARVEY
		STATE:			IL
		ZIP:			60426
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_160686686477100.xml
<DESCRIPTION>FORM 4
<TEXT>
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    <periodOfReport>2020-11-27</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001666138</issuerCik>
        <issuerName>Atkore International Group Inc.</issuerName>
        <issuerTradingSymbol>ATKR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001674832</rptOwnerCik>
            <rptOwnerName>Lariviere Peter J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>16100 SOUTH LATHROP AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>HARVEY</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60426</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President, Cable Solutions</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

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                <value>Common Stock</value>
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                <value>2020-11-27</value>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
                    <value>1063</value>
                    <footnoteId id="F1"/>
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                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
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                </directOrIndirectOwnership>
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            <securityTitle>
                <value>Common Stock</value>
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                <transactionCode>F</transactionCode>
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                    <footnoteId id="F3"/>
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                <transactionAcquiredDisposedCode>
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                </sharesOwnedFollowingTransaction>
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                    <value>D</value>
                </directOrIndirectOwnership>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-11-30</value>
            </transactionDate>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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                <transactionShares>
                    <value>12828</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>39.4484</value>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>37230</value>
                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Securities withheld to pay withholding taxes on vested restricted stock units exempt under Rule 16b-3.</footnote>
        <footnote id="F2">Each performance restricted stock unit (&quot;PSU&quot;) was granted on November 28, 2017 under the Atkore International Group, Inc. 2016 Omnibus Incentive Plan (the &quot;2016 Plan&quot;). The PSUs vested on November 28, 2020 upon the achievement of performance criteria established at the time of grant.</footnote>
        <footnote id="F3">Represents PSUs withheld to satisfy tax withholding obligations in connection with the vesting of PSUs described in footnote 2 above, exempt under Rule 16b-3.</footnote>
        <footnote id="F4">This price represents the approximate weighted average price per share of common stock (each a &quot;Share&quot;) of Atkore International Group Inc. (the &quot;Issuer&quot;) of sales that were executed at prices ranging from $39.06 to $39.61 per Share.  The Reporting Person undertakes to provide, upon request by the Securities and Exchange Commission staff, the Issuer or a security holder of the issuer, full information regarding the number of Shares sold at each price.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Daniel S. Kelly, Attorney-in-Fact for Peter J. Lariviere</signatureName>
        <signatureDate>2020-12-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
