Fred;

I am a representative of Trex and would like to answer your question.

Trex has not been tested for use as flooring for a trailer, but it cannot handle heavy loads, as it is not a structural product. This would also be an application that would not be covered under our warranty. If you chose to use Trex, it would have to be fully supported with no span.
Please contact us at 800-BUY-TREX or [email protected] if you have any further questions.

Pat M - Trex