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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 lbvbsZtwMuyyheTMS94Cpg==

<SEC-DOCUMENT>0001179110-09-007706.txt : 20090513
<SEC-HEADER>0001179110-09-007706.hdr.sgml : 20090513
<ACCEPTANCE-DATETIME>20090513124514
ACCESSION NUMBER:		0001179110-09-007706
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090511
FILED AS OF DATE:		20090513
DATE AS OF CHANGE:		20090513

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Grace David R
		CENTRAL INDEX KEY:			0001302538

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-50924
		FILM NUMBER:		09821380

	MAIL ADDRESS:	
		STREET 1:		BEACON ROOFING SUPPLY, INC.
		STREET 2:		1 LAKELAND PARK DRIVE
		CITY:			PEABODY
		STATE:			MA
		ZIP:			01960

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			BEACON ROOFING SUPPLY INC
		CENTRAL INDEX KEY:			0001124941
		STANDARD INDUSTRIAL CLASSIFICATION:	WHOLESALE-LUMBER & OTHER CONSTRUCTION MATERIALS [5030]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0930

	BUSINESS ADDRESS:	
		STREET 1:		ONE LAKELAND PARK DRIVE
		CITY:			PEABODY
		STATE:			MA
		ZIP:			01960
		BUSINESS PHONE:		978-535-7668

	MAIL ADDRESS:	
		STREET 1:		ONE LAKELAND PARK DRIVE
		CITY:			PEABODY
		STATE:			MA
		ZIP:			01960
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-05-11</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001124941</issuerCik>
        <issuerName>BEACON ROOFING SUPPLY INC</issuerName>
        <issuerTradingSymbol>BECN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001302538</rptOwnerCik>
            <rptOwnerName>Grace David R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ONE LAKELAND PARK DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>PEABODY</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>01960</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CFO, Treasurer &amp; SVP-Finance</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $.01 par value</value>
            </securityTitle>
            <transactionDate>
                <value>2009-05-11</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>48422</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>15.611</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>225842</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $.01 par value</value>
            </securityTitle>
            <transactionDate>
                <value>2009-05-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>11578</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>15.01</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>214264</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, $.01 par value</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5128</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See note 3</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">This sales price represents a weighted average sales price. Sales were made on this date at prices ranging from $15.50 to $15.755. The undersigned undertakes to provide to the staff of the Securities and Exchange Commission, the issuer and any securityholder of the issuer upon request the number of shares sold at each separate price.</footnote>
        <footnote id="F2">This sales price represents a weighted average sales price. Sales were made on this date at prices ranging from $15.00 to $15.04. The undersigned undertakes to provide to the staff of the Securities and Exchange Commission, the issuer and any securityholder of the issuer upon request the number of shares sold at each separate price.</footnote>
        <footnote id="F3">These shares are held by Mr. Grace's wife individually and as custodian for their son. Mr. Grace's son owns 4,528 shares and his wife owns 600 shares. Mr. Grace disclaims beneficial ownership of these shares.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>David R. Grace</signatureName>
        <signatureDate>2009-05-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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