TREX CO INC — Director's Dealing 2012

May 3, 2012

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: TREX CO INC (TREX)
CIK: 0001069878
Period of Report: 2012-05-01

Reporting Person: Gupp William R. (CAO, Gen. Counsel & Secretary)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2012-05-01	Common Stock	M	1418	$9.14	Acquired	35926	Direct
2012-05-01	Common Stock	D	408	$31.78	Disposed	35518	Direct
2012-05-01	Common Stock	F	427	$31.78	Disposed	35091	Direct
2012-05-01	Common Stock	S	300	$31.93	Disposed	34791	Direct
2012-05-01	Common Stock	S	450	$31.96	Disposed	34341	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2012-05-01	Stock Appreciation Right	$9.14	M	1418	Disposed	2018-05-07	Common Stock (1418)	Direct

Footnotes

F1: 1,418 Stock Appreciation Rights (SARs) are being exercised pursuant to Rule 10b5-1 trading plan adopted by the reporting person on November 14, 2011.

F2: The stock appreciation right becomes exerciseable in three equal installments beginning on the first anniversary date of the transaction date.

F3: 427 shares are being surrendered as allowed by the Company's 2005 Stock Incentive Plan to cover payment of taxes currently due on the exercise of SARs.

F4: The sales reported in this Form 4 were effected pursuant to Rule 10b5-1 trading plan adopted by the reporting person on November 14, 2011.