Every great outdoor living space starts with a good plan and a solid foundation—which is what our decking series is all about. In this series, we sit down with our good friend Kevin Kunka of Trex Company to cover some of the ins and outs of executing a successful decking project. Trex is the world’s largest manufacturer of wood-alternative decking products and a veteran in the outdoor living industry. Over the years, the Trex name has become synonymous with quality manufactured decking.
In today’s episode, we talk about two methods for installing manufactured fascia and various best practices to keep in mind as you plan and install your deck. Watch our conversation above or read a summary of the discussion below.
Best practice 1: Install fascia boards properly
Successful fascia installation is all about understanding the dynamic between the deck surface, rim joists, and fascia. Because rim joists are treated lumber and manufactured fascia boards are typically capped-composite or PVC, the two materials will expand and contract at different rates. To avoid unwanted tension and warping over time, it’s critical to account for movement in your installation.
When using either of the methods described below, remember always to consult your product’s installation manual.
Fascia screw system
Fascia screws are designed to allow the joists and fascia boards to move naturally. The screws, which are smooth at the top, get countersunk into a hole slightly larger than the screw itself. This extra room allows the boards to move around without issue. For a 12” fascia board, Kevin recommends installing three fascia screws every 18” laterally.
If you decide to go this route, we recommend using a fascia screw system that is approved by the manufacturer of your fascia board.
Instead of keeping things loose and flexible, this method aims to fasten the fascia snugly to keep it from moving. Here, fascia screws are swapped out for decking fasteners and an exterior-grade construction adhesive is applied to the rim board before installation.
With this approach, the decking fasteners are screwed in tightly to keep the boards from moving against each other. You’ll also want fasteners closer together: one-by-eight fascia boards get two screws every 12” laterally (rather than every 18”), while one-by-twelve fascia boards get three screws every 12”.
Best practice 2: Overhang deck boards
Rather than running the decking boards into the fascia, Kevin recommends running the deck boards over the top, creating an overhang. There are two reasons for doing this: First, having an overhang eliminates a gap between the decking and the fascia that could accumulate debris, which can cause challenges over time. Additionally, that overhang method will allow the deck boards to expand and contract over time without pushing the fascia out of place and creating gaps and warping.
Best practice 3: Leave gaps in butt joints and corners
This best practice is a bit counterintuitive: While you’d think installing tight joints and corners would be the goal, you actually want to leave a gap between boards to allow them to expand and contract without creating unwanted tension. In this video, Kevin mentions a 1/8" gap for the Trex brand products. Make sure you reference your installation manual for the specific brand of manufactured fascia you use.
Contractors have come up with several creative solutions to achieve joints and corners that look clean while leaving enough room for boards to move. One solution is to cut the groove off both edges on the back side of a short piece of deck board. With the fascia boards spaced appropriately, the modified deck board can provide a clean look at the joint while allowing the fascia boards to move as needed. When going this route, Kevin recommends planning the fascia board layout so that these joints fall directly below railing posts to create a cleaner, more intentional look.
To create a clean aesthetic with corner joints, one method is to cut the groove off one edge on the back side of two pieces of deck boards. Then cut a 45-degree angle on the other edge of the two boards to form a 90-degree corner. Using glue and a screw and plug method works well to fasten the two pieces together. With the fascia boards positioned properly, this corner piece will cover any gaps while allowing things to move as needed. With either of these methods, planning is essential.
We’re lucky to have friends in the industry like Kevin who can provide key insights and best practices that will help you build a deck that will serve you for years to come, whether you're a contractor or homeowner. For more manufactured decking best practices, check out Kevin’s recommendations for fastening options for manufactured decking and his best practices for pre-planning with manufactured decking.