Should I Use Trex Decking at Ground Level?

We used Trex decking on our previous deck that was approx 3 feet above ground. We really liked working with the Trex.

In our new place we are replacing the ground level deck and would like to use Trex again.

We were told that it is not advised to use Trex on ground level because it can get very hot and there is no circulation around the boards to cool them. Our deck is South - Southwest facing from a walk-out basement.

It will be in an enclosed area due to the upstairs deck right over the top.

I have been trying to read up on the Trex decking and can find no reference to ground using it at ground level.

Comments for Should I Use Trex Decking at Ground Level?

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Mar 24, 2010
by: Craig

I would not recommend using Trex. They have had a lot of problems with their product. It has mold issues and I have seen it fall apart after only two years. They are having big warranty claims on their decking.

I would recommend using Correct Deck, it has a protective layer of plastic over the top and mildew inhibitors.

Apex Carpentry Inc.

Feb 19, 2010
7 Months in to this Project
by: Scott

I went ahead and installed Lowe's version of Trex.

It is 12 inches off the ground and installed over 3/4 inch treated plywood. I needed a way to cover this area which had bad drainage and where nothing would grow.

I left it open to North and South to catch the prevailing winds. I also coated the piers and decking with a professional mildew preventer (I forget the name).

I also had gutters installed to further divert rain.

So far so good. Everything is still level and plumb but this stuff does stain easily. Color leaching off of leaves and bird poop have made spots that will need to be scrubbed or power washed this Spring.

I will let you know what happens in the future.

Feb 18, 2010
No Way
by: Dennis

I wouldn't recommend composite decking on ground level decks under 36".

It is real simple. There is no air to circulate, and moisture from the ground is at a stand still.
Trex is known for mold, especially if your deck is not on the sunny side of the house. Unless you like cleaning it every month.

No offense, but I would be a little skeptical of the Trex salesman.

They know how to sell. I have been building custom Trex decks for more than 15 years. And I stand behind my work for 8 years.

So I frequently go back and speak with homeowners and their concerns. Mold is a serious issue for ground level decks.

At least that is my experience in Colorado and Iowa.

Aug 18, 2009
Straight Answer Wanted
by: Scott

I called and still couldn't get a good answer. Just talk of air circulation and moisture.

So once more, what's the worst that can happen? Warpage? Decomposition? Mildew?

Aug 10, 2009
Trex at Ground Level
by: Deck Guy

I would be cautious when installing Trex at ground level.

The lower a deck is to the ground, the less air flow there is to dry it out when it gets wet. This could lead to a potential for mould or mildew with the Trex board.

I would recommend a solid PVC based decking product such as Veka, Azek, or Endeck - they will stand up in those conditions much better.

Aug 04, 2009
Trex on Solid Surface
by: Scott

Simply, what happens when Trex is attached to a solid surface such as a subfloor?

May 18, 2009
Should I use Trex Decking at Ground Level
by: Pat M

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

Trex needs a 3 1/2" airspace or a sleeper system. A sleeper system is a buffer between the solid surface and Trex. Trex should never be attached to a solid or water tight surface when used as decking.

If you have any further questions, please contact me at 800-BUY-TREX or

Pat M
Trex Company

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