How to Build a Custom Shed or Playhouse

Just prior to the cold weather season, I was recently contacted by a customer interested in building a custom 12' x 12' shed on a sloped piece of property in his back yard.

While the backyard was expansive, there was simply no way to transport a pre-fabricated shed to the area he wanted it. Additionally, the shed needed to be placed on a hillside with a 7' drop from front to back.

With these conditions, the only option was to build the shed from scratch. In this blog article I will walk you through the process of building a custom shed on a sloped piece of property.

Foundation

My first step in constructing the shed was to spend some time laying out the foundation. Most sheds can be placed onto a tightly packed bed of gravel, and then set on pre-fabricated masonry foundation blocks. As you can see from the picture below, that approach was not going to work for this custom built shed.

If you are from Pittsburgh, you know it is rare to find a flat piece of ground! Therefore, this shed called for a more involved foundation.

With orange lay-out spray paint I carefully measured and marked where my 4x6” foundation posts would go.

After laying out the 12’ x 12’ structure, it was time to dig.

With a post hole digger, I dug nine foundation holes at a depth of 40” deep. The depth of the foundation is important because you want it to be below the frost line. In Pittsburgh our frost line is 36”.

After digging I placed a 4” layer of crushed gravel in the bottom of the foundation holes. This gravel helps keep the foundation from sinking deeper into the earth.

Finally I cemented the 4x6” pressure treated foundation posts into the ground. The key to this step is ensuring that the top of each post is level with each other post. To do this, I placed a spare 4x4” on the top of each post, then placed a 6’ level on top of the 4x4”. When the 4x4” was level, I knew the top of each post was level with the others.

After letting the cement cure, I installed pressure treated 4x4”’s over the foundation posts to form my floor joists. Using 12” stainless steel brackets, I secured the floor joists to the foundation posts.

Lastly, I installed 45 degree 4x4's between the floor joists and foundation posts. This last step helps distribute weight throughout the foundation structure.

Framing

For the flooring of the shed, my customer chose to go with pressure treated decking boards. While this is a bit more expensive then regular plywood flooring, it will last much longer then plywood, and resist water damage.

After laying the floor, I framed in the exterior walls. Wall Studs should be 16” apart from on another. While drafting my plans, I came across this helpful link that automatically lays out your stud measurements for you.

Once the walls were erected I drove 6” lag screws with retention washers through the bottom 2x6” and into the floor joists.

Now it was time to install the roof trusses. After much research, I decided to go with a simple “King” Truss.

To install the trusses I first installed a temporary 12ft 2x4” in the middle of the front and rear walls of the shed. With these 2x4’s in place I was then able to hang the main 2x6” roof joist 3’ above the top of the sheds walls.

With the 2x6 roof joist in place I installed the rest of the roof trusses and removed the temporary 2x4’s from the front and rear walls.

Roof

After installing 7/16” OSB onto the roof joists and 1x6" trim boards to the eves, I installed 1” drip edge around the perimeter of the roof. Drip edge helps keep water from backing up under the shingles and causing the roof to rot.

Next I covered the entire roof in weatherproofing ice-guard. This materials also helps to ensure that ice will not back up under the eves, rotting the roof.

After installing the architectural type shingles I cut a 4” wide vent into the ridge of the shed and installed a plastic ridge vent to help hot air escape from the shed and keep the roof’s shingles cool in the summer time.

Lastly I capped the vent and roof peak with double layered cap shingles.

Siding and Trim

For siding my customer chose a pressure treated T111 that will eventually be stained for added weather protection.

After installing the T111 I ran trim boards around the corners of the shed, doors, and window for aesthetic appeal.

As you can see from the pictures, and per the customers request, I installed a 20” x 20” window in the gable area of the shed. Fearing the windows may get bumped with lawn tools or storage hanging in the trusses, I went with a clear Lexan Polycarbonate material for the window. This material is as clear as glass, but carries the impact resistance of an engineering grade PC.