Ownership Submission
FORM 3
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF 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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(Print or Type Responses)
1. Name and Address of Reporting Person *
  Cox James Mitchell
2. Date of Event Requiring Statement (Month/Day/Year)
05/07/2009
3. Issuer Name and Ticker or Trading Symbol
TREX CO INC [TWP]
(Last)
(First)
(Middle)
C/O TREX COMPANY, INC, 160 EXETER DRIVE
4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
Vice President, Sales
5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

WINCHESTER, VA 22603-8605
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 Beneficially Owned
1.Title of Security
(Instr. 4)
2. Amount of Securities Beneficially Owned
(Instr. 4)
3. Ownership Form: Direct (D) or Indirect (I)
(Instr. 5)
4. Nature of Indirect Beneficial Ownership
(Instr. 5)
Common Stock (1) 6,667
D
 
Common Stock (2) 5,213
D
 
Common Stock (3) 26,666
D
 
Common Stock (4) 10,696
D
 
Common Stock (5) 1,477
D
 
Common Stock (6) 15,728
D
 
Common Stock 62,808
D
 
Common Stock 3,983
D
 

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 4)
2. Date Exercisable and Expiration Date
(Month/Day/Year)
3. Title and Amount of Securities Underlying Derivative Security
(Instr. 4)
4. Conversion or Exercise Price of Derivative Security 5. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 5)
6. Nature of Indirect Beneficial Ownership
(Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares
Stock Appreciation Right (7) 02/18/2010 02/18/2019 Common Stock 21,519 $ 13.44 D  
Stock Appreciation Right 05/07/2009 02/21/2017 Common Stock 6,825 $ 25.37 D  
Stock Appreciation Right (8) 02/21/2010 02/21/2017 Common Stock 3,413 $ 25.37 D  
Stock Appreciation Right (9) 05/07/2009 02/08/2016 Common Stock 9,700 $ 24.17 D  
Stock Appreciation Right (10) 05/07/2011 05/07/2018 Common Stock 37,049 $ 9.14 D  

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
Cox James Mitchell
C/O TREX COMPANY, INC
160 EXETER DRIVE
WINCHESTER, VA 22603-8605
      Vice President, Sales  

Signatures

/s/ William R. Gupp by power of attorney 05/11/2009
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 5(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) This restricted stock award vests on January 12, 2011.
(2) This restricted stock award vests on January 8, 2010.
(3) This restricted stock award vests in approximately two equal installments on January 8, 2010 and January 8, 2011.
(4) This restricted stock award vests over a three-year period in approximately three equal installments beginning on the first anniversary of the February 18, 2009 grant date.
(5) This restricted stock award vests on February 21, 2010.
(6) This restricted award vests over a three-year period in approximately three equal installments beginning on the first anniversary of the May 7, 2008 grant date.
(7) This stock appreciation right becomes exercisable in approximately three equal installments beginning on the first anniversary of the February 18, 2009 grant date.
(8) This stock appreciation right becomes execisable on February 21, 2010.
(9) This stock appreciation right is fully exercisable.
(10) This stock appreciation right becomes exercisable in approximately three equal annual installments beginning on the first anniversary of the May 7, 2008 grant date.

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