Building a deck is a big project, and whether you decide to take it on yourself or enlist the help of a professional, knowing what a decking project entails is essential to a successful install.
In part two of our decking series, we’re going to share just that. We’re joined by one of the greater Seattle area’s premier deck builders: former co-founder of West Coast Decks, Joel Skillingstead. Joel has been building decks in the Pacific Northwest since 1990. With more than 30 years of experience building, overseeing, and waterproofing deck projects large and small, Joel is one of the best resources out there.
In this episode, I ask Joel about building low-level decks and things to be aware of throughout the construction process. Watch our discussion in the video above or read below for a recap.
What should you consider when building a low-level deck?
The most important consideration when building a low-level deck in the Pacific Northwest is ventilation. Because the deck surface will be so close to the ground, you need to construct a frame that will allow adequate airflow to avoid moisture build-up.
The decking product you’re using will determine the amount of ventilation needed—different products require different levels of circulation. PVC products need less ventilation, so you can build reasonably close to the ground. Capped-composite decking products (composite material with a polymer cap) typically require more ventilation, so you’ll need to reference the manufacturer's recommendation for spacing and airflow.
How do you frame a low-level deck?
Traditional deck framing consists of a layer of post, beam, joist, then deck board on top. This yields a minimum surface height of 12" to 15". To lower the finished deck surface further, the joists need to run (hang) in between the beams (instead of laying on top of the beams).
Another option is to double-up the joists on either end, having them function as your beam. If building a longer deck, you may consider building multiple “box” frames that blend together. No matter what approach you choose, pay close attention to the height of your framing members to ensure they're perfectly flush (or as close to perfect as possible). Even the slightest difference in joist or beam height can create a visible imperfection in the deck's surface (especially with manufactured decking products) and is not easily corrected.
What’s the best way to build around foundation vents?
Newer homes have more foundation vents than older homes, and if you’re planning a low-level deck in an area with vents, you need to make sure those vents have adequate space to allow for airflow.
There are several ways to do this. Joel’s approach is to frame around the vent by removing the siding and installing a vapor barrier, flashing, and running the ledger up to either side of the vent. Then, install the joists on either side of the vent, leaving about 30” of spacing between the joists, (depending on your framing and the width of the vent). Next, install a "header" running between the two joists, creating a place for the missing joist to be attached to. The width of your decking material will dictate how much space to leave between the vent and the header.
Should you treat the ground underneath the deck before building?
If you aren’t installing your deck over an existing patio, you’ll want to think about how to treat the ground underneath, so you don’t have issues with things growing up through the deck.
To avoid this situation, make sure you (or your contractor) remove vegetation below the deck footprint. Then, put down a ground cover cloth after the deck is framed. The cloth will allow moisture to pass through but prevent vegetation from growing up.
How do you ensure proper drainage?
Most patios slope away from the home to promote drainage and keep water from pooling against the house. In some cases, however, a patio can have a reverse slope—which you’ll want to look out for at the project's onset. A reverse slope can happen when sections of the patio settle in a way that leads water towards the home rather than away. When this happens, you will want to break up that section of the patio (and possibly remove it) to allow for proper drainage. If you don't have a patio but your ground still has a reverse slope, you’ll need to level out the soil before framing your deck.
Low-level decks can be elegant additions to a home, but they require a slightly different thought process than a traditional deck. Joel is one of the best decking resources in the Pacific Northwest, and we hope today’s insights help you find success on your next project.
For more on decking, check out our discussion on how to decide whether to resurface or rebuild a deck and how to choose a deck surface.