So you have an old deck. You want a new deck. You've heard about composite. Here you are...
You've probably been researching Trex and Azek deck products. Both are similar, both lead the market. The information to follow should apply to both manufacturers.
Your old deck is probably pretty tired looking. You've been putting this off for a while. After all composite decking is lifetime so you pay the price up front never to return again. Assess the old deck, not the decking the framing. In the case of the deck pictured, a good shove took the railing and rim joist off giving us a good look at the structure itself.
Look for Rot
Rot presents itself in pressure treated wood as dark almost black staining. If you see a lot of black staining poke it with a screw driver. If it's soft it needs to be replaced. In the case of this deck we were able to reinforce the old structure to add strength and living space.
If you need a lesson on deck framing it's best to hire a professional. Composite decking doesn't have the structure or strength of wood, especially when heated from the sun. You will use more pressure treated framing lumber with a composite deck than with a traditional wood deck.
Once you're properly framed and blocked you're ready to lay decking. It's important to start from the outside and work in. Decide how much overhang you want and fasten your outer most edge board. The longer deck boards the better. Cuts or joints in the deck are prone to cupping upward in the sun and require extra fasteners. With this deck we used 20' deck boards. Lay the boards longs and scribe your end cut with your edge board. Its common that a deck isn't square. It's even more common that composite decking isn't straight or consistent in it's spacing.
Once you have your field laid and fastened it's time to scribe the end to your edge board with equal spacing and cut. We used the Trex hidden fasteners in the field with grooved deck boards but on the edge boards and any place needed an extra fastener we used Cortex plug fasteners. In the ends you'll see two holes where we drilled Cortex in at an angle to the rim joist. This is where the boards will want to curl up on hot days. On all other cuts, miters, notches etc. leave plenty of room for expansion. At least an eighth of an inch but color and exposure will vary expansion.
Railing systems are tricky. They're packaged and labeled like IKEA furniture. If you're savvy at assembly IKEA, you may just be an ace with composite railing systems. We did a cocktail rail here. Trex suggests leaving the ends of the deck board cut but the inside of Trex is different from the outside. We miter cut and returned the rail so the finish would be consistent.
This deck has been covered with Trex composite decking and railing and wrapped with Kleer PVC facia. The only maintenance it will need is an annual cleaning.