X0306 5 2012-12-31 1 0 1 0001069878 TREX CO INC TREX 0001463613 Cox James Mitchell C/O TREX COMPANY, INC 160 EXETER DRIVE WINCHESTER VA 22603-8605 1 Vice President, Sales Common Stock 2012-08-16 4 M 0 L 9700 24.17 A 129047 D Common Stock 2012-08-16 4 M 0 L 6825 25.37 A 135872 D Common Stock 2012-08-16 4 M 0 L 3413 25.37 A 139285 D Common Stock 2012-08-16 4 M 0 L 37049 9.14 A 176334 D Common Stock 2012-08-16 4 M 0 L 21519 13.44 A 197853 D Common Stock 2012-08-16 4 M 0 L 9948 17.41 A 207801 D Common Stock 2012-08-16 4 M 0 L 3515 26.20 A 211316 D Common Stock 2012-08-16 4 D 0 L 47172 29.41 D 164144 D Common Stock 2012-08-16 4 F 0 L 18810 29.41 D 145334 D Common Stock 2012-08-16 4 S 0 L 16909 29.51 D 128425 D Common Stock 2012-08-16 4 S 0 L 10000 29.61 D 118425 D Common Stock 2012-08-17 4 S 0 L 35862 29.97 D 82563 D Common Stock 2012-08-28 4 S 0 L 4044 30.14 D 78519 D Common Stock 2012-08-29 4 S 0 L 3185 30.14 D 75334 D Common Stock 2012-08-29 4 S 0 L 7553 30.29 D 67781 D Common Stock 2012-08-31 4 S 0 L 12447 30.29 D 55334 D Common Stock 2012-08-31 4 S 0 L 20000 30.77 D 35334 D Common Stock 2012-09-13 4 S 0 L 6419 33.26 D 28915 D Common Stock 2012-09-13 4 S 0 L 10000 33.04 D 18915 D Common Stock 2012-09-13 4 S 0 L 359 33.50 D 18556 D Common Stock 2012-09-13 4 S 0 L 18556 33.50 D 0 D Stock Appreciation Right 24.17 2012-08-16 4 M 0 L 9700 0 D 2009-05-07 2016-02-08 Common Stock 9700 0 D Stock Appreciation Right 25.37 2012-08-16 4 M 0 L 6825 0 D 2009-05-07 2017-02-21 Common Stock 6825 0 D Stock Appreciation Right 25.37 2012-08-16 4 M 0 L 3413 0 D 2010-02-21 2017-02-21 Common Stock 3413 0 D Stock Appreciation Right 9.14 2012-08-16 4 M 0 L 37049 0 D 2011-05-07 2018-05-07 Common Stock 37049 0 D Stock Appreciation Right 13.44 2012-08-16 4 M 0 L 21519 0 D 2010-02-18 2019-02-18 Common Stock 21519 0 D Stock Appreciation Right 17.41 2012-08-16 4 M 0 L 9948 0 D 2011-02-17 2020-02-17 Common Stock 9948 4972 D Stock Appreciation Right 26.20 2012-08-16 4 M 0 L 3515 0 D 2012-02-16 2022-02-16 Common Stock 3515 7029 D 18,810 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. This stock appreciation right is fully exercisable. This stock appreciation right becomes exercisable in three equal annual installments beginning on the first anniversary of the grant date. /s/ William R. Gupp by power of attorney 2012-11-26