<SEC-DOCUMENT>0001179110-19-003603.txt : 20190308
<SEC-HEADER>0001179110-19-003603.hdr.sgml : 20190308
<ACCEPTANCE-DATETIME>20190308160259
ACCESSION NUMBER:		0001179110-19-003603
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20190306
FILED AS OF DATE:		20190308
DATE AS OF CHANGE:		20190308

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Shaeff Julie
		CENTRAL INDEX KEY:			0001319782

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-13011
		FILM NUMBER:		19669095

	MAIL ADDRESS:	
		STREET 1:		COMFORT SYSTEMS USA, INC.
		STREET 2:		675 BERING DRIVE, SUITE 400
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77057

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			COMFORT SYSTEMS USA INC
		CENTRAL INDEX KEY:			0001035983
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRICAL WORK [1731]
		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>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-03-06</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001319782</rptOwnerCik>
            <rptOwnerName>Shaeff Julie</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O COMFORT SYSTEMS USA, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>675 BERING DR. SUITE 400</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77057</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Accounting Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-03-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2286</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>27876</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-03-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2677</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>30553</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-03-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1022</value>
                    <footnoteId id="F3"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>52.04</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>29531</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Each restricted stock unit granted on March 6, 2019 represents a right to receive one share of common stock and will vest in equal installments over a three-year vesting schedule.</footnote>
        <footnote id="F2">Reflects dollar-denominated performance restricted stock units granted on March 23, 2016 that vested on March 6, 2019. These units vested as a result of the Company's 2016-2018 relative Total Shareholder Return and 2016-2018 Company average EPS - the applicable performance metrics.</footnote>
        <footnote id="F3">Forfeited shares are related to dollar-denominated performance restricted stock units that vested on March 6, 2019 and were priced based on the closing price of the Company's common stock on March 6, 2019.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Laura F. Howell, by power of attorney</signatureName>
        <signatureDate>2019-03-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>ex24shaeff.txt
<TEXT>
Limited Power of Attorney for Section 16 Reporting Obligations

The undersigned hereby makes, constitutes, and appoints Laura F. Howell and
Rachel J. Reagor, each acting individually, as the undersigned's true and
lawful attorney-in-fact, with full power and authority as hereinafter
described on behalf of and in the name, place, and stead of the
undersigned to:

     1) prepare, execute, acknowledge, deliver, and file Forms 3, 4, and 5
(including any amendments thereto) with respect to the securities of
Comfort Systems USA, Inc., a Delaware corporation (the "Company"), with the
United States Securities and Exchange Commission, any national securities
exchanges, and the Company, as considered necessary or advisable under
Section 16(a) of the Securities Exchange Act of 1934 and the rules and
regulations promulgated thereunder, as amended from time to time (the
"Exchange Act");

     2) seek or obtain, as the undersigned's representative and on the
undersigned's behalf, information on transactions in the Company's securities
from any third party, including brokers, employee benefit plan administrators,
and trustees, and the undersigned hereby authorizes any such person to release
any such information to the attorney-in-fact and approves and ratifies any such
release of information; and

      3) perform any and all other acts that, in the discretion of such
attorney-in-fact, are necessary or desirable for and on behalf of the
undersigned in connection with the foregoing.

The undersigned acknowledges that:

     1) this Power of Attorney authorizes, but does not require, such
attorney-in-fact to act in his or her discretion on information provided to
such attorney-in-fact without independent verification of such information;

     2) any documents prepared and/or executed by such attorney-in-fact on
behalf of the undersigned pursuant to this Power of Attorney will be in such
form and will contain such information and disclosure as such attorney-in-fact,
in his or her discretion, deems necessary or desirable;

     3) neither the Company nor such attorney-in-fact assumes (i) any liability
for the undersigned's responsibility to comply with the requirement of the
Exchange Act, (ii) any liability of the undersigned for any failure to comply
with such requirements, or (iii) any obligation or liability of the undersigned
for profit disgorgement under Section 16(b) of the Exchange Act; and

     4) this Power of Attorney does not relieve the undersigned from
responsibility for compliance with the undersigned's obligations under the
Exchange Act, including without limitation the reporting requirements under
Section 16 of the Exchange Act.

The undersigned hereby gives and grants the foregoing attorney-in-fact full
power and authority to do and perform all and every act and thing whatsoever
requisite, necessary, or appropriate to be done in and about the foregoing
matters as fully to all intents and purposes as the undersigned might or could
do if present, hereby ratifying all that such attorney-in-fact of, for, or on
behalf of the undersigned, shall lawfully do or cause to be done by virtue of
this Limited Power of Attorney.

This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4, and 5 with respect to
the undersigned's holdings of and transactions in securities issued by the
Company, unless earlier revoked by the undersigned in a signed writing
delivered to the foregoing attorney-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to
be executed in Harris County, Texas as of this 6th date of March, 2019.

/s/ Julie S. Shaeff__________________________
Julie S. Shaeff
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
