How to Build a Deck on a Hill; Hillside Deck Building Tips

How to Build a Deck on a Hill; Hillside Deck Building Tips


Building a deck is a complicated project, especially when that deck extends over an incline.  Hillside deck building requires careful planning. Hopefully, this blog will help you start this difficult project.  However, there are different building codes, and you may need more information in your deck’s construction.  Or, you might need more information about a process because this information is only intended to help you plan.


Mark the Location for Hillside Deck Building:

Lay out the location for your deck posts with batter boards.  Put the boards at least a foot away from the deck’s outline.  Finally, tie strings from the edge of your house to the batter board to outline the deck.


hillside deck building. deck foundation on a slope.

Foundation Options:

In warmer climates with stable soil conditions, pre-cast concrete pier blocks are great.  However, in freezing winter conditions, it is necessary to install foundation beneath the frost level.  To install foundation beneath the frost level, dig down beneath the frost level.  After that, pour concrete in a pillar that extends into the ground and above the grade.  To pour the concrete, you cut a cardboard tube the length of the pillar that you need.  Next, wrap that tube in polyethylene so that soil does not bond to the tube in cold months.  After that, fill the tube with concrete.  Finally, let the concrete begin to set, and then plant an anchor in the top of the pillar.


Beginning Construction:

With the location of your deck outlined by batter boards, you can begin to dig out the locations you need for your foundation and your deck frame and install those posts.  Next, mark the areas of your house’s siding you need to remove to attach the deck and remove that siding.  Now you can attach flashing, a galvanized piece of sheet metal that helps keep water out of the house.  Attach the ledger and make sure to securely fashion the ledger as it helps support the deck.  Mark the locations for the joist and attach the joist to the ledge with a joist hanger and joist hanger nails.  When you attach the joist hanger, make sure to nail through all the holes.


Constructing the Deck:

To start construction, you need to install your posts.  To install the posts, hold a deck post in place and measure out from the house.  Mark on the post where you need to cut to make your deck level, and cut the deck post.  Now, you can attach the post to the anchor.  Attach the post to the anchor with the factory-treated end down because this end will experience wear from rain and mud.  The treatment will protect it and ensure that it lasts longer.

With your posts down, you can attach the beam to your posts, but keep in mind that lumber usually has a crown or an arch.  Put the crown arched up so that the weight of the deck will straighten the beam.  Install the joists, and attach the bracket to the beam and the posts.  If your deck needs bracing, now is the time to attach the bracing.


Laying the Decking:

To reduce work, when you lay the deck, lay the wood first and let it hang over the edge.  After you finish, you can cut all the wood at the edge at the same time.  It is important to lay the decking with a small crack between the boards so water can drain.  Hardware stores carry commercially made spacers, but you can make a spacer by driving a nail through a small piece of wood and using the nail as a spacer.  For attaching the boards to your deck, your options include a hammer and nails, a nail gun, screws, and deck clips.  Each of these options has positives and negatives.  When you cut the decking, allow an inch overhang.


The Last Steps:

The last steps you of hillside deck building are the stairs. Once the stairs are complete, you can build a railing and stain the wood.   If you make stairs, make sure where you attach the stairs to the ground is level.  To decide how many stairs you need, find the length from the deck to the ground and divide that by an even number of risers.  To make a railing, start by installing the posts.  You notch the post to fit around the edge of the deck and use bolts to attach the post to the frame of the deck.  Construct the fence between the posts.  Last, apply finish if you decide to do so.


For more information on hillside deck building, watch this video