TREX CO INC — Director's Dealing 2011

May 4, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: TREX CO INC (TREX)
CIK: 0001069878
Period of Report: 2011-05-02

Reporting Person: KAPLAN RONALD W (Director, President and CEO)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-05-02	Common Stock	M	16175	$8.80	Acquired	133633	Direct
2011-05-02	Common Stock	D	4606	$30.90	Disposed	129027	Direct
2011-05-02	Common Stock	F	4884	$30.90	Disposed	124143	Direct
2011-05-02	Common Stock	S	300	$31.10	Disposed	123843	Direct
2011-05-02	Common Stock	S	917	$31.16	Disposed	122926	Direct
2011-05-04	Common Stock	S	385	$29.00	Disposed	122541	Direct
2011-05-04	Common Stock	S	100	$29.007	Disposed	122441	Direct
2011-05-04	Common Stock	S	100	$29.017	Disposed	122341	Direct
2011-05-04	Common Stock	S	100	$29.024	Disposed	122241	Direct
2011-05-04	Common Stock	S	100	$29.04	Disposed	122141	Direct
2011-05-04	Common Stock	S	200	$29.046	Disposed	121941	Direct
2011-05-04	Common Stock	S	100	$29.05	Disposed	121841	Direct
2011-05-04	Common Stock	S	100	$29.054	Disposed	121741	Direct
2011-05-04	Common Stock	S	100	$29.056	Disposed	121641	Direct
2011-05-04	Common Stock	S	200	$29.06	Disposed	121441	Direct
2011-05-04	Common Stock	S	100	$29.062	Disposed	121341	Direct
2011-05-04	Common Stock	S	100	$29.065	Disposed	121241	Direct
2011-05-04	Common Stock	S	600	$29.07	Disposed	120641	Direct
2011-05-04	Common Stock	S	100	$29.071	Disposed	120541	Direct
2011-05-04	Common Stock	S	200	$29.072	Disposed	120341	Direct
2011-05-04	Common Stock	S	100	$29.075	Disposed	120241	Direct
2011-05-04	Common Stock	S	100	$29.076	Disposed	120141	Direct
2011-05-04	Common Stock	S	100	$29.08	Disposed	120041	Direct
2011-05-04	Common Stock	S	100	$29.085	Disposed	119941	Direct
2011-05-04	Common Stock	S	100	$29.0875	Disposed	119841	Direct
2011-05-04	Common Stock	S	100	$29.09	Disposed	119741	Direct
2011-05-04	Common Stock	S	400	$29.10	Disposed	119341	Direct
2011-05-04	Common Stock	S	100	$29.11	Disposed	119241	Direct
2011-05-04	Common Stock	S	100	$29.116	Disposed	119141	Direct
2011-05-04	Common Stock	S	200	$29.12	Disposed	118941	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2011-05-02	Stock Appreciation Right	$8.80	M	16175	Disposed	2018-01-07	Common Stock (16175)	Direct

Footnotes

F1: 16,175 Stock Appreciation Rights (SARs) are being exercised pursuant to Rule 10b5-1 trading plan adopted by the reporting person on November 3, 2010.

F2: 4,884 shares are being surrendered as allowed by the Company's 2005 Stock Incentive Plan to cover the payment of taxes currently due on the exercise of SARs.

F3: The stock appreciation right becomes exerciseable in three equal installments beginning on the first anniversary date of the transaction date.

F4: The sales reported in this Form 4 were effected pursuant to Rule 10b5-1 trading plan adopted by the reporting person on November 3, 2010.