-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 IvCR1hemTFMv6/RDCmJdqGq0/NbiYH3U5rx/zOrZiEE1HsqWMqHCw5J9FumkA3ps
 xfP/oqimN7//4T7U0Wnn0w==

<SEC-DOCUMENT>0001264385-04-000092.txt : 20040510
<SEC-HEADER>0001264385-04-000092.hdr.sgml : 20040510
<ACCEPTANCE-DATETIME>20040510121030
ACCESSION NUMBER:		0001264385-04-000092
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040507
FILED AS OF DATE:		20040510

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			REDFERN JOHN D
		CENTRAL INDEX KEY:			0001241952

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-08584
		FILM NUMBER:		04791745

	MAIL ADDRESS:	
		STREET 1:		606 CATHCART 8TH FLOOR
		CITY:			MONTREAL
		STATE:			A8
		ZIP:			H3B 1L7

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			LAFARGE NORTH AMERICA INC
		CENTRAL INDEX KEY:			0000716783
		STANDARD INDUSTRIAL CLASSIFICATION:	CEMENT, HYDRAULIC [3241]
		IRS NUMBER:				581290226
		STATE OF INCORPORATION:			MD
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		12950 WORLDGATE DR. SUITE 500
		CITY:			HERNDON
		STATE:			VA
		ZIP:			20170
		BUSINESS PHONE:		7034803600

	MAIL ADDRESS:	
		STREET 1:		12950 WORLDGATE DR. SUITE 500
		CITY:			HERNDON
		STATE:			VA
		ZIP:			20170
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-05-07</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000716783</issuerCik>
        <issuerName>LAFARGE NORTH AMERICA INC</issuerName>
        <issuerTradingSymbol>LAF</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001241952</rptOwnerCik>
            <rptOwnerName>REDFERN JOHN D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>12950 WORLDGATE DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 500</rptOwnerStreet2>
            <rptOwnerCity>HERNDON</rptOwnerCity>
            <rptOwnerState>VA</rptOwnerState>
            <rptOwnerZipCode>20170</rptOwnerZipCode>
            <rptOwnerStateDescription>QUEBEC, CANADA</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-05-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3268</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>42.858</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1732</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>55</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By wife</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <ownerSignature>
        <signatureName>William G. Miller, signed pursuant to authorization previous</signatureName>
        <signatureDate>2004-05-10</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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