FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * Zambanini Adam Dante   2. Issuer Name and Ticker or Trading Symbol TREX CO INC [TREX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Vice President, Marketing (Last) (First) (Middle) 160 EXETER DRIVE 3. Date of Earliest Transaction (Month/Day/Year) 09/06/2016 (Street) WINCHESTER, VA 22603 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 09/06/2016   M(1)   3,710 A $ 13.1 34,396 D   Common Stock 09/06/2016   M(1)   4,282 A $ 12.78 38,678 D   Common Stock 09/06/2016   M(1)   3,482 A $ 21.94 42,160 D   Common Stock 09/06/2016   D   2,906 D $ 61.84 39,254 D   Common Stock 09/06/2016   F(2)   2,838 D $ 61.84 36,416 D   Common Stock 09/07/2016   S(3)   1,956 D $ 61.6058 (4) 34,460 D   Common Stock 09/07/2016   S(3)   2,272 D $ 61.6145 (5) 32,188 D   Common Stock 09/07/2016   S(3)   1,502 D $ 61.5965 (4) 30,686 D

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Stock Appreciation Right

$ 13.1

09/06/2016

M(1)

3,710

02/16/2012

02/16/2022

Common Stock

3,710

$ 0

0

D

Stock Appreciation Right

$ 12.78

09/06/2016

M(1)

4,282

02/15/2013

02/15/2022

Common Stock

4,282

$ 0

4,282

D

Stock Appreciation Right

$ 21.94

09/06/2016

M(1)

3,482

02/12/2014

02/12/2023

Common Stock

3,482

$ 0

6,960

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Zambanini Adam Dante 160 EXETER DRIVE WINCHESTER, VA 22603			Vice President, Marketing

Signatures

/s/ William R. Gupp by power of attorney		09/07/2016
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Stock Appreciation Rights are being exercised pursuant to a Rule 10b5-1 Sales Plan adopted by the reporting person on June 1, 2016.
(2)	2,838 shares are being surrendered as allowed by the Company's 2014 Stock Incentive Plan to cover the payment of taxes currently due on the exercise of SARs.
(3)	The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 Sales Plan adopted by the reporting person on June 1, 2016.
(4)	The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $61.40 to $61.85, inclusive. The reporting person undertakes to provide Trex Company, Inc., any security holder of Trex Company, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in Footnote (4) to this Form 4.
(5)	The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $61.27 to $61.85, inclusive. The reporting person undertakes to provide Trex Company, Inc., any security holder of Trex Company, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in Footnote (5) to this Form 4.

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