X0303 4 2011-02-18 0001069878 TREX CO INC TREX 0001201351 KAPLAN RONALD W C/O TREX COMPANY, INC. 160 EXETER DRIVE WINCHESTER VA 22603-8605 1 1 President and CEO Common Stock 2011-02-18 4 S 0 200 26.64 D 147809 D Common Stock 2011-02-18 4 S 0 178 26.635 D 147631 D Common Stock 2011-02-18 4 S 0 2300 26.62 D 145331 D Common Stock 2011-02-18 4 S 0 1122 26.61 D 144209 D Common Stock 2011-02-18 4 S 0 3489 26.60 D 140720 D Common Stock 2011-02-18 4 S 0 200 26.595 D 140520 D Common Stock 2011-02-18 4 S 0 806 26.59 D 139714 D Common Stock 2011-02-18 4 S 0 2200 26.58 D 137514 D Common Stock 2011-02-18 4 S 0 1705 26.57 D 135809 D Common Stock 2011-02-18 4 S 0 689 26.56 D 135120 D Common Stock 2011-02-22 4 S 0 500 26.15 D 134620 D Common Stock 2011-02-22 4 S 0 6 26.145 D 134614 D Common Stock 2011-02-22 4 S 0 500 26.12 D 134114 D Common Stock 2011-02-22 4 S 0 600 26.11 D 133514 D Common Stock 2011-02-22 4 S 0 200 26.10 D 133314 D Common Stock 2011-02-22 4 S 0 700 26.09 D 132614 D Common Stock 2011-02-22 4 S 0 190 26.085 D 132424 D Common Stock 2011-02-22 4 S 0 2835 26.08 D 129589 D Common Stock 2011-02-22 4 S 0 1359 25.61 D 128230 D Common Stock 2011-02-22 4 S 0 100 25.605 D 128130 D Common Stock 2011-02-22 4 S 0 7000 25.50 D 121130 D The sales reported in this Form 4 were effected pursuant to Rule 10b5-1 trading plan adopted by the reporting person on May 10, 2010. /s/ William R. Gupp by power of attorney 2011-02-23