<SEC-DOCUMENT>0000920371-18-000046.txt : 20180223
<SEC-HEADER>0000920371-18-000046.hdr.sgml : 20180223
<ACCEPTANCE-DATETIME>20180223191948
ACCESSION NUMBER:		0000920371-18-000046
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20180221
FILED AS OF DATE:		20180223
DATE AS OF CHANGE:		20180223

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SIMPSON SHARON H
		CENTRAL INDEX KEY:			0001627636

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-13429
		FILM NUMBER:		18638204

	MAIL ADDRESS:	
		STREET 1:		21C ORINDA WAY
		STREET 2:		SUITE 358
		CITY:			ORINDA
		STATE:			CA
		ZIP:			94563

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>4
<SEQUENCE>1
<FILENAME>wf-form4_151943157244957.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-02-21</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001627636</rptOwnerCik>
            <rptOwnerName>SIMPSON SHARON H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>21C ORINDA WAY</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ORINDA</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94563</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-02-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>29107</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>57.769</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4335902</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-02-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1267</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>57.939</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4334635</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The shares are owned by Sharon H. Simpson, Trustee of the Barclay and Sharon Simpson 2007 Trust, dated May 25, 2007.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/By Sunny H. Leung, as
Attorney-in-fact for Sharon H. Simpson</signatureName>
        <signatureDate>2018-02-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
