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.
Stairs can often become an afterthought in the deck-planning process—but whether they’re a focal point of the overall design or not, deck stairs require thoughtful planning to ensure they’re strong, safe, and up to code.
In today’s episode, Kevin shares his best practices for installing stair stringers, treads, and code-compliant handrails with manufactured decking. Watch our discussion in the video above or read the highlights below.
Spacing stair stringers
Deck joists are typically spaced at 16” on-center, but that doesn’t always carry over to stair stringers—that’s because building codes typically require stairs to support twice as much load (in pounds per square foot) than the deck surface.
With manufactured decking products, you often need to install additional stringers off of the deck’s rim joist; for example, Trex’s Transcend line requires stringers every 12 inches, while their Select line requires stringers every nine inches. Always refer to your product’s installation manual to find specific stringer requirements.
Fastening stair treads
Stairs are subject to much more wear and tear than the rest of a deck. When it comes to choosing a fastening system for stair treads, Kevin recommends going with whatever type of fastener will give you the tightest connection—in other words, hidden fasteners may not be the strongest choice. Instead, color-matched screws that fasten through the surface and joists are a great option, as are screw-and-plug systems.
Securing bottom railing posts
Deck stair posts are notorious for growing wobbly. To avoid this—and to avoid getting dinged during inspection—install railing posts that can withstand a large lateral force. There are several techniques out there for installing rock-solid bottom stair posts that will withstand both weight and moisture.
Installing ADA-compliant handrails
While different municipalities have different handrail requirements, it’s becoming more and more common that code requires handrails to be ADA compliant (meaning the handrail is continuously graspable). Not all railing systems meet ADA requirements, so Kevin recommends opting for an ADA-approved system, whether or not your project requires it.
For more tips for building safe and secure decks, check out our guide to installing code-compliant guardrail post connections and these pro tips for installing safe and code-compliant connection points.