DIY Playhouse Plans: A Backyard Playhouse with a Covered Porch

Build the Deck Frame

The deck is the foundation of the whole playhouse, so take your time here. Seven 2×6 joists go 16″ on center between two 96″ rim joists, all pressure-treated, with two 3″ exterior screws at every joint. The three 30″ 4×4 porch posts stand flush with the bottom of the joists, screwed in from two sides, with a 2×6 block beside the middle post. Two 96″ 4×4 skids go underneath, their bottom corners cut off at 45 degrees. Before any decking goes on, measure corner to corner both ways. When the two diagonals match, the frame is square, and every wall that follows will be too.

Install the Decking

The deck boards are 5/4 x 6 x 96″ pressure-treated decking, fourteen of them, spaced with a nail and fastened with 2-1/2″ exterior screws at every joist. Three boards need a notch to fit around the posts: hold each one in place, trace around the post and cut it out with a jigsaw.

And pre-drill near the ends. Here’s where I thought I was better than pre-drilling. I wasn’t: the board cracked, and it took a little wood glue to save it. Learn from me.

Frame the Side Walls

The walls are ordinary 2×4 studs. Frame each one flat on the deck: screw a straight board down along one edge and build tight against it, and the plates stay straight. Each side wall is a 68″ bottom plate, a 90-1/8″ top plate and 45″ studs. The top plate runs long, past the front of the house, so it can carry the porch roof without a post in the way. The window is framed between two studs with a 25-1/8″ sill and header and short cripples above and below. Build two: the second is the mirror of the first.

Frame the Back Wall

The back wall is the simple one: two 72″ plates and six 45″ studs, no openings. Mark both plates together so the studs line up, then drive two 3″ screws through the plates into every stud end.

Frame the Front Wall

The front wall has the door and the third window. The bottom plate is two pieces with the 24″ door opening between them, and there’s no door header: the 72″ top plate does that job. The window is framed just like the ones in the side walls.

Stand the Walls

Stand the walls with a helper and tack a scrap diagonally across each one to hold it plumb until its neighbor is on. Screw the bottom plates down into the deck. Then join the corners from inside the house: a 3″ screw driven from outside can’t reach through a stud lying on its side. To check that the walls are square, use a 3-4-5 triangle. Mark 3 feet along one wall and 4 feet along the other, and the diagonal between the marks should be exactly 5 feet.

Side the Walls and Cut the Openings

The walls might seem a little flimsy at this stage, but the siding locks everything into place. It’s 3/8″ exterior paneling, one sheet per wall laid on its side, screwed on with 1-1/4″ exterior screws. Then cut out the windows and the door: drill a hole in each corner from inside, mark the lines on the outside, and cut along the framing. I used a reciprocating saw; a jigsaw works too.

One honest note on the paneling. What I used in 2016 was an inexpensive pressed fiberboard panel with a nice wood grain look, and it soaked up a ton of paint. That one isn’t sold anymore. Today the closest match is a 3/8″ LP SmartSide panel, or 11/32″ Ply-Bead plywood if you want to save a little. Either way, prime it.

Set the Ridge and Wall Plates

Now the roof. Screw a full 8′ 2×4 wall plate onto each side wall’s top plate, flush at the porch end and 5-7/8″ past the back wall for an eave. The ridge is a full 8′ 2×6. Screw two temporary 2×4 supports to it 9-3/8″ in from each end, flush with its top, then stand it on the deck centered between the side walls.

One good tip: mark where your rafters go on the ridge and the wall plates before the ridge goes up. It’s a lot easier on the ground than in the air.

Cut and Install the Rafters

The rafters are 2x4s cut at 48 degrees, the pitch of the roof, with a birdsmouth notch where they sit on the wall plate. Mark the two points, pivot a speed square on the first one and draw the line out, then cut the birdsmouth with a circular saw and finish it with a jigsaw. Test that first rafter on the ridge and the wall plate, then use it to trace the rest. Here’s the birdsmouth layout in the video.

There are twelve rafters, six a side. (The 2016 drawing says “x 10″; it draws six a side, and twelve is right.) Set the end pairs first, toe-screw each one into the ridge and the wall plate with 3” screws, then take the temporary supports down.

Install the Gable Studs

The gable studs fill in under the end rafters and give the gable siding something to grab: two 22″ and two 38″ 2x4s on each end, mitered at 48 degrees across the top. I installed mine with pocket hole screws on the outside face, so the siding hides them. No jig? Toe-screw them with 3″ screws.

Side the Gables

Now comes the fun part. Fitting the gable siding takes a few trips: hold the sheet up, mark it, bring it down, cut it, try again. My shortcut is to hold the sheet against the end rafters from inside and trace along their tops. It beats measuring angles in the air. Notch it around the wall plates and the ridge, then screw it on with 1-1/4″ screws.

Sheath the Roof

The roof deck is 19/32″ OSB, full 4×8 sheets running 1″ past the end rafters, so the shingles have something to nail into. (I used plywood in 2016; OSB does the same job for about half the price.) If the sheets won’t line up at the ends, your rafters are a little out of square: screw one side down first, then pull the other side into place before you fasten it. Rip the last sheet into strips to finish both sides at the ridge.

Roofing, Trim and the Porch Railing

Drip cap goes around the edges, then the felt, then the shingles from the eaves up. I chose 3-tab shingles instead of architectural shingles so I didn’t have to buy a whole package of ridge caps for a few feet of ridge. Then case the windows and door with 1x4s over 1×5 jamb liners and add the corner boards.

Last is the porch railing. The plan uses 2×4 rails pocket-screwed between the posts and capped with 5/4 decking. On ours, I drilled through the top and bottom rails, ran 3/8″ rope through and crossed it in the middle to make an X, then capped it with another 5/4 x 6 deck board. Either way, round over every corner little hands can reach.