Any downside to trex decking?

it’s very expensive
It can be slippery when wet
you have to trim any cut ends that show
but, it won’t rot and you don’t need to stain or seal it

yes I like 12” centers under it. If it’s going on a deck that already is on 16” centers it’s likely going to be fine but adding one at 8” isn’t that hard to do

Go Timbertech PVC. It is solid, no need to cut returns on stairs. It’s all we do now on raised properties

It is HOT!!!

Space them well. My dad and I replaced boards on an old deck with it, and I know with pressure treated deck boards they will shrink and leave a gap. I didn't think you needed as much of a gap with the Trex other than drainage, but they will swell and shrink with heat and rain. Some of ours warped a bit and I had to take them up and put them back down. Also they do fine with a light pressure washing. Just don't get the tip too close and use the fan spray pattern. I pressure washed it about every couple of years. We have a ton of pines that drop needles, and that will stain them some. Also the fasteners look to be improved. Our required drilling pilot holes and using the square bit screws. When you're doing that a thousand times it gets old and your bit gets worn out quickly. But it was solid for about a dozen years before we ended up doing a demo and replacement deck.

There is an art to installing it correctly. Also, make sure it’s not in the sun prior to installing; this is what causes the shrinkage and buckling. We are putting one in now in Pass Christian.

They aren’t joking about getting hot, if your deck is fully exposed to afternoon sun you really want to think twice or add shade if you like to be barefoot. Also if you have little kids around it that me be crawling or playing. It’s fantastic outside of that if put down properly.