Framing a Deck on the Side of a Hill

Building a deck in your backyard involves many steps and considerations if you want a structure that will be safe for use and last many years.

Benefits

One end of a hillside deck may be several feet above the ground.One end of a hillside deck may be several feet above the ground.
Deck construction is even more complicated when your yard includes a hill. While much about building a deck on the side of a hill is the same as building one on level ground, special care and planning are required during the framing process.

You may choose to build a deck on the side of a hill for many reasons. Besides the benefits that come with any type of deck, including more usable outdoor space, a deck on a hill will ensure that water collecting around and below the deck drains away from your home. It also allows you to build a deck where it makes the most sense for your home without moving large amounts of earth to grade the landscape.

Challenges

Framing a deck on a hillside is more challenging than it is for a deck on flat or slightly graded ground. This is because the deck, which still needs a level surface, will have a vertical support structure that consists of support posts of many different heights. Each support post must be cut to the precise length before installation. Longer posts also require special bracing to ensure that they can support the weight of the deck above.

Framing Techniques

For a deck on the side of a hill, use temporary lumber supports to place the deck rim in its correct position before you install any support posts. This will ensure that the rim is level and the deck surface is square. Depending on the distance between the ground and the deck rim at the low end of the hill, you may need to use reinforced concrete posts instead of concrete footers with pressure-treated lumber posts. Cross braces can also strengthen wooden posts without the need for additional concrete pouring.

Additional Building

A deck that you build on the side of a hill may require additional structures to make it useful. For example, if you want to be able to access the deck from your yard, you'll need to build a stairway. This can be a stairway set into the side of the hill, or a wooden stairway that attaches to the deck's rim and connects it to the ground below. For this type of stairway, your deck rim must be able to support more weight. It also means you should incorporate a stair railing into your design.