<SEC-DOCUMENT>0001415889-24-020708.txt : 20240805
<SEC-HEADER>0001415889-24-020708.hdr.sgml : 20240805
<ACCEPTANCE-DATETIME>20240805101621
ACCESSION NUMBER:		0001415889-24-020708
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20240801
FILED AS OF DATE:		20240805
DATE AS OF CHANGE:		20240805

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Kapoor Gaurav
		CENTRAL INDEX KEY:			0001693758
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-13011
		FILM NUMBER:		241173420

	MAIL ADDRESS:	
		STREET 1:		C/O AECOM
		STREET 2:		1999 AVENUE OF THE STARS, SUITE 2600
		CITY:			LOS ANGELES
		STATE:			CA
		ZIP:			90210

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			COMFORT SYSTEMS USA INC
		CENTRAL INDEX KEY:			0001035983
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRICAL WORK [1731]
		ORGANIZATION NAME:           	05 Real Estate & Construction
		IRS NUMBER:				760526487
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		675 BERING DRIVE
		STREET 2:		SUITE 400
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77057
		BUSINESS PHONE:		7138309600

	MAIL ADDRESS:	
		STREET 1:		675 BERING DRIVE
		STREET 2:		SUITE 400
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77057
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form4-08052024_020818.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2024-08-01</periodOfReport>

    <issuer>
        <issuerCik>0001035983</issuerCik>
        <issuerName>COMFORT SYSTEMS USA INC</issuerName>
        <issuerTradingSymbol>FIX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001693758</rptOwnerCik>
            <rptOwnerName>Kapoor Gaurav</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>675 BERING DRIVE, SUITE 400</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77057</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>false</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2024-08-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>385</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>385</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Trust</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Shares granted pursuant to the 2017 Omnibus Incentive Plan as approved by stockholders on May 23, 2017. Non-employee directors are given an annual grant of Comfort Systems USA Common Stock following election or reelection at the Company's annual stockholders' meeting. Mr. Kapoor's term of service commenced August 1, 2024, and Mr. Kapoor received a pro rated grant. This grant is equal to $126,684.93, as rounded down to the nearest whole share, based on the average of the high and low price of the Company's Common Stock on August 1, 2024, the date the pro rated grant was effective in accordance with Mr. Kapoor's appointment date.</footnote>
        <footnote id="F2">Held by Kapoor Family Trust, dated August 20, 2023, for which the Reporting Person and his spouse are trustees.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Rachel R. Eslicker, Attorney-in-Fact</signatureName>
        <signatureDate>2024-08-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
