1. Build Your Trex Deck Above Building Code
Trex Composite decking is three times the weight of western red cedar and is much more pliable. So what does this mean when building your deck?
Because of the sheer weight and the fact that Trex will follow your joists over time we recommend going above building code. First, we recommend always building your deck with joists a minimum 12 inch on centre. Second, depending on your beam spans it is worth adding an addition ply (i.e. from 2-ply to 3ply) or increasing the size of your lumber (i.e. 2×8 to 2×10)
Yes, this does add cost to your substructure but it will be worth it 10 years down the road when your deck has little to no sag.
2. Waterproof your Trex Deck Substructure.
Trex has a 25 year warranty and may in fact last even longer than that. We recommend improving the longevity of the joists , blocking and beams with joist tape to ensure it lasts as long as your Trex Decking.
3. Toe nail your Trex Decking Mitres
Trex Composite Decking tends to expand and contract more than wood this means that in winter months your mitres can pull apart and look horrible. An easy solution is to add additional toe nail to all.