My front porch has some treads and the bottom riser are rotting out.

I'd like to replace the surface with Trex if possible. Is it as simple as removing treads and risers and replacing with Trex boards?

  • It would help to see pictures. Hard to answer this question without knowing how it's constructed now. – gregmac Aug 17 '10 at 23:39
  • Without starting to tear it off, I could only know that it's wood stringers, risers, and treads. – hometoast Aug 18 '10 at 17:09
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    One thing to consider about composite decking -- it gets hot in the summer time. If you're used to hanging out on your deck in bare feet, it might not be the best choice. (I'm not sure if all have this problem, or just the couple of ones I've walked on). – Joe Aug 19 '10 at 0:28

It should be just that simple, yes. I don't know if I would recommend the Trex brand though. They've had lots of problems in the past with mold issues. Not sure if those are still a concern or not, but you might want to think about another brand of composite decking.

  • Thanks for the heads-up on the Trex brand. I usually consider other brands when shopping, but not sure what to call Trex other than "composite decking" and it doesn't quite roll of the tongue. – hometoast Aug 18 '10 at 17:08
  • Did some more research and the only thing to be concerned with is that I will likely have to add more stringers to support it better to prevent it from sagging. – hometoast Sep 28 '10 at 16:27

Composite decking isn't stiff, so you probably need to add more support underneath. Every manufacturer has a data sheet. For example, Trex recommends a 10.5" span underneath steps, and 12"-16" under a deck.


Trex or other plastic woods will be more expensive, you will need more support (as already mentioned) and you will need to use special screws (for Trex) to prevent "mushrooming" (the Trex will squash up around the screwhead) or drill and countersink the holes.

Also, Trex (and other plastic woods) don't have the tensile strength of wood, so fasteners located near the edges may cause the edge/corner of the plank to rip off. In my area, the city built bus stop benches with Trex(like) seat planks, and half of them broke at the corners after a year or so of use. (The upshot here is Trex is not structural. It's just a decking.)

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