Convertible Backyard A-frame Fort From a Swing Set.

We turned our old swing set into a new A-frame fort. Our kids stopped using the swing set and it was getting a little rickety as they got bigger. This new A-frame fort gets a lot more use and is usable year-round. In the warmer months, they even sleep in it. It also makes a good adult place to hang out in the shade and read a book.

Step 1: The Swing Set.

The swing set I built a few years ago out of 5 4"x4" 10' posts. The top of the 4x4's are notched to allow the ridge beam to sit in the top pocket. The footprint of the swing set is 10' x 10'. If your swing set is a different size it should still work but you will just need to adjust the calculations. Before you get started I would recommend that the swing set is sitting level and square.

Step 2: Add Cross Bracing

I used (7) 2x4 12'. Four of them evenly spaced on the backside with one at the top and the bottom. On the front side, there is one at the top and one on the bottom with one 3/4 of the way up. Make sure they are level and well secured. Now would also be a good time to make sure it is sitting where you want it. It is going to get heavy once the metal is on it.

Step 3: Add the Roofing.

Since the 4x4's are 10' long you will need ten-foot lengths of metal roofing. I bought 10' lengths of metal roofing and didn't have to cut any metal which was nice. I screwed the roofing down with sheet metal roofing screws. Start at one end and continue to work towards the other end. Overlap the sheets on a rib. Check for level on each sheet added to keep the roof square. If your frame isn't square or level you will start to notice now.

If you wanted, you could side with plywood and shingle it later.

Step 4: Frame the Ends.

To frame the ends, I just used 2x4 and mitered the ends and screwed them in horizontally between the 4x4's. Then for the vertical framing for the window and the door, I ran a 2x4 on edge between the horizontal 2x4's and screwed them together. On one end I installed a window and on the other end a door. I got the window and the door from the local home recycling yard. I would recommend getting the door and the window first so you can decide how to frame them. For the sheathing, I used OSB and then painted it. I know OSB isn't rated for exterior siding but I live in a pretty dry climate and it was so much cheaper than normal siding that I took my chances.

Step 5: The Lifting Wall!

This part took a lot of problem-solving. I started with the fact that the plexi roofing sheets are 8' long. I didn't want to cut them so I designed the lifting wall to be 8' long. I screwed on a header board at a height that would leave 8' of opening for the lifting wall. Next, I attached the hinged board parallel, below it with 4 hinges. The horizontal boards are wider than the opening and this stops them from falling into the opening. They rest on the 4x4's.

Next two 2x4's are run vertically next to the 4x4's. They are notched at each end and in the middle to go around the horizontal 2x4's. They are glued and screwed to the horizontal 2x4's because they will take a lot of torque as they swing. You might even want to think about using some cross braces but I was banking on the shear strength of the panels to keep it rigid.

Step 6: The Gap and the Ridge Cover.

Before you put the plexi panels on I would deal with the two-foot gap and the ridge cover. Once you put the plexi panels on it is much harder to access the ridge with a ladder. I used more OSB to cover the opening. I was planning on putting some shingles over it but that didn't happen. The ridge cap is just a 10' ridge cap from the lumber yard that I screwed down. I also used the gap OSB to mount my solar panel.

Step 7: Mount the Plexi Panels.

I bought 8' sections of Suntuf polycarbonate panels. I also bought the corrugated closure strips that go with the panels. I used roofing screws to mount the panels to the wall frame. I screwed the panels to the ridges of the closure strips because the closure strips are not quite the same profile as the panels and it was causing a lot of warping to screw into the valleys where the screw holes should be. I also used a piece of webbing to create a handle to help lift the wall.

Step 8: The Wall Supports

I used two 2x4's to create the side supports to hold the wall up. It is fairly heavy so I wanted to make sure that the wall was safely supported. I didn't want a gust of wind to blow the wall closed and crush anyone. The top corners are attached with a single bolt and nut so that they can pivot. I rounded the corners so that it doesn't catch on the frame while it pivots. For the bottom corner, I added a 2x4 block spacer so the support would be in line with the top mounting. Next, I drilled a hole through the 4x4 and the spacer support. This allows me to put a long bolt from the outside through the support and attach a washer and nut. I don't screw it down tight it is just to assure that the bolt doesn't come out if someone bumps the support. When the wall is closed the supports are detached from the bottom and slid into the fort as the wall closes.

Step 9: Add Joint Cover.

Since I wanted the fort to be pretty weatherproof, I needed to protect the gap where the wall hinges. To do this I needed a flexible material to lay over the gap. While I was at the home recycling center I saw some rubber lawn edging. ( At least that is what I think it was.) It came in a tube shape that was flattened. I cut the tube open along the crease and that allowed it to open up and be the size I needed. As an added benefit it started to curl after a few weeks in the sun but this made for a perfect gutter. I attached it under the OSB with roofing screws.

Step 10: Solar System.

I had a solar panel laying around so I decided this would be a great use for it. I attached it to the south-facing roof and ran the wires through the end. I attached it to two SLA batteries and a charge controller. It outputs to a cigarette lighter plug so that it can run any mobile 12V devices. It is also connected to an RGB LED strip that provides lighting at night.

Step 11: Furnish

We didn't put a floor in ours and just used the rock chips that were in the swing set area. You could put in an area rug or my kids like to put down blankets when they are playing Legos. We recently acquired a free futon that has made a good addition as a place to sit and sleep. We also added anchors for a hammock by recycling the anchors that were used for hanging the swings in the swing set.

Enjoy!