<SEC-DOCUMENT>0000920371-18-000044.txt : 20180223
<SEC-HEADER>0000920371-18-000044.hdr.sgml : 20180223
<ACCEPTANCE-DATETIME>20180223112550
ACCESSION NUMBER:		0000920371-18-000044
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20180215
FILED AS OF DATE:		20180223
DATE AS OF CHANGE:		20180223

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Swartzendruber Kevin Lee
		CENTRAL INDEX KEY:			0001732479

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-13429
		FILM NUMBER:		18635227

	MAIL ADDRESS:	
		STREET 1:		5956 W. LAS POSITAS BLVD.
		CITY:			PLEASANTON
		STATE:			CA
		ZIP:			94588

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SIMPSON MANUFACTURING CO INC /CA/
		CENTRAL INDEX KEY:			0000920371
		STANDARD INDUSTRIAL CLASSIFICATION:	CUTLERY, HANDTOOLS & GENERAL HARDWARE [3420]
		IRS NUMBER:				943196943
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		5956 W LAS POSITAS BLVD
		CITY:			PLEASANTON
		STATE:			CA
		ZIP:			94588
		BUSINESS PHONE:		9255609000

	MAIL ADDRESS:	
		STREET 1:		5956 W LAS POSITAS BLVD
		CITY:			PLEASANTON
		STATE:			CA
		ZIP:			94588
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>wf-form3_151940313331809.xml
<DESCRIPTION>FORM 3
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2018-02-15</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000920371</issuerCik>
        <issuerName>SIMPSON MANUFACTURING CO INC /CA/</issuerName>
        <issuerTradingSymbol>SSD</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001732479</rptOwnerCik>
            <rptOwnerName>Swartzendruber Kevin Lee</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>5956 W LAS POSITAS BLVD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>PLEASANTON</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94588</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior VP of Finance</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Restricted stock units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.0</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>609.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Amount includes 609 shares of restricted stock units (RSUs) awarded on February 15, 2018. Twenty percent of RSUs vest on February 15, 2019, forty percent on February 17, 2020 and February 15, 2021.Granted RSUs do not have exercise dates or an expiration date.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Kevin L Swartzendruber</signatureName>
        <signatureDate>2018-02-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
