TREX CO INC

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

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2500 Trex Way

Winchester, Virginia 22601

Notice of Annual Meeting of Stockholders

April 28, 2026

To our stockholders:

Notice is hereby given that the 2026 annual meeting of stockholders of Trex Company, Inc. will be held at Trex University, 331 Apple Valley Road, Winchester, Virginia, on Tuesday, April 28, 2026, at 9:00 a.m., local time, for the following purposes:

to elect four directors of Trex Company, Inc.;

to approve, on a non-binding advisory basis, the compensation of our named executive officers;

to ratify the appointment of Ernst & Young LLP as Trex Company’s independent registered public accounting firm for the 2026 fiscal year; and

to transact such other business as may properly come before the annual meeting or any adjournment or postponement thereof.

Only stockholders of record at the close of business on March 06, 2026 will be entitled to notice of and to vote at the annual meeting or any adjournment or postponement thereof.

All stockholders are cordially invited to attend this meeting.

We have elected to adopt the U.S. Securities and Exchange Commission rule that allows companies to furnish their proxy materials over the Internet. As a result, we are mailing a Notice Regarding the Availability of Proxy Materials (the “Notice of Availability”) to our stockholders instead of a paper copy of this Proxy Statement and our 2025 Annual Report. The Notice of Availability contains instructions on how to access and review those documents over the Internet. We believe that this process will allow us to provide our stockholders with the information they need in a timelier manner, while reducing the environmental impact and lowering the costs of printing and distributing our proxy materials. Stockholders who receive a Notice of Availability by mail and would like to receive a printed copy of our proxy materials should follow the instructions for requesting such materials included on the Notice of Availability.

Your vote is very important to us. Whether or not you plan to attend the meeting in person, your shares should be represented and voted. To vote, please complete and return your proxy card, or vote by telephone or via the Internet by following the instructions on your Notice of Availability. Returning a proxy card or otherwise submitting your proxy does not deprive you of your right to attend the annual meeting and vote in person.

By Order of the Board of Directors,

Amy M. Fernandez

Senior Vice President, Chief Legal Officer

Secretary and Chief Sustainability Officer

Dated: March 16, 2026

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