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, we discuss what to consider when building a deck on sloped terrain. Whether you’re dealing with a gentle, consistent slope or a significant fall-off, building on sloped terrain affects a number of variables, especially permitting, designing, and additional support or materials required for the actual construction. Watch the video above or keep reading for a detailed recap.
Determining project viability
There are many things to consider before you begin any decking project—this post containing questions to ask yourself during the planning process is a must-read at the start of any decking endeavor. Sloped terrain, however, plays a particularly significant role in a deck’s design and viability.
If you’re working with a sloped landscape, you want to begin by finding your city’s “critical area map” that shows old, active, and potential slide areas, and where there's unstable soil. These maps will help you determine the potential risks in your area and offer an idea of how your terrain may affect the cost of your deck, or if you can even build—some slopes are impossible to build on. You can often find this information on your municipality’s website or by contacting your city.
Find out what building codes you’re working with before you go too far; it will make a huge difference in the cost and viability of your project.
Design considerations for building a deck on sloped ground
Sloping terrain increases the variables you need to consider for a decking project. Every site's slope, soil, design and municipality building requirements can vary significantly, and you’ll want professional help to guide you through the process. Depending on the degree of your slope, you may need to bring in a geotechnical engineer, or “geo tech,” along with your designer and structural engineer. They’ll research your site, including potentially visiting your site and digging some holes, to determine what’s necessary to support the deck.
There are a variety of solutions to build a deck on sloped terrain, such as using pin footings. Pin footings are forged steel pipes that can be driven into the ground until they simply won’t go any deeper. Depending on the slope and soil, however, that depth could be six feet or 60 feet, which can greatly affect the materials needed, and cost.
Permit requirements for building a deck on sloped ground
Permits are almost always required for decks built on sloped ground. Municipalities will have permitting requirements on their websites, and your building department team will guide you through the process. If you have an existing deck that you’d like to rebuild, you may still need a permit, but you’ll likely be able to build something similar to what currently exists. However, if the existing structure was built without a permit, you'll need to go through a more thorough permitting process.
Pricing considerations for building a deck on sloped ground
As with everything else we covered above, there are many pricing variables for building a deck on a slope, too. One important factor is the slope’s grade and soil quality—the deeper you need to drive foundation footings into the ground, the higher the cost. When building a deck high in the air, your builder will also need to spend more time and resources making it safe and possible for workers to haul up materials and get high enough to build, including potentially building a framework and temporary deck to be better positioned to build the permanent structure.
Your engineer or contractor should be able to give you a project bid that covers many of these variables, but they may include clauses where the final project cost may increase due to having to go deeper into the ground, soil issues, or needing additional equipment.
Looking for more decking support? Check out the Dunn Solutions library—it’s filled with decking videos and trusted decking resources, like our recent video on multi-level deck precautions.
