This article may be geared towards do it your selfers more than someone looking to hire a contractor, but its good to share the knowledge nonetheless.
Before a discussion about composite decking fasteners can be started, we need to cover the characteristics of composite that make it unique. The primary difference to be considered when installing a composite deck is that composite and pure PVC decking expand and contract length wise with the change in temperatures.
This fact needs to be noted both in the design of the deck itself and the choice/ installation of fasteners. For this reason it is also highly recommended that you hire a licensed contractor if you want to have a composite deck built.
This is a picture of a composite deck that was built by an unlicensed contractor, it shows just how bad things can go wrong.
Because of this movement there is a risk that traditional through the face fastening can lead to the screws breaking over time. For this reason, stainless steel fasteners are recommended as they are the strongest type of screw. There are non-stainless screws on the market but they are less strong in the long run and we don’t recommend them.
If you are building a deck yourself, it is better to pre drill the holes for composite, although this isn’t necessary for PVC decking. Pre drilling gives the screw more space which makes it less likely to break and also leaves less mushrooming on the surface of the deck. PVC decking has a different cell structure with more “give” so to speak and just doesn’t require the same technique.
If you are buying screws at a home improvement store or even a local lumber store, we don’t recommend using any screw that has a, “V” shaped head.
These screws are more likely to mushroom the decking and are more of an eye sore than the better looking trim head type screws. These screws have a smaller head that is flat on the bottom and top with rounded edges.
We have found the Dexxter stainless steel 3″ screw to be the best bet for composite. We had issues with the Splitstop screws breaking during installation through pre drilled decking, and hardly any problem with the Dexxter.
You may be tempted to get the 2.5″ screw instead of the 3″ but don’t do it. The 3″ screw grabs more of the framing below for a more secure connection. With all of that said however, the most attractive and best structurally speaking fastener of all is Timbertech’s Concealock hidden fasteners. They are made specifically to be used with Timbertech’s grooved decking, are stainless steel, are virtually invisible, and allow for more expansion and contraction without breaking any screws.
Hopefully this has been informative for anyone looking to choose the right fastener for their deck. Here at Deck Masters, llc we recommend you give us a call if you are in the Portland metro area, but if you choose to do it yourself, good luck!