Treehouse Bed

My son’s treehouse bed is possibly the largest, most complex project I have attempted. It took over a year to complete. After planning and partially building this project, I discovered the finished pieces wouldn’t fit out the door. This set me back several months as I tried to figure out how to salvage the bed. Many months later I came up with a new design and finally finished it. I wish I would have taken more pictures of the building process, but I was more concerned with getting this behemoth out of my shop than documenting the construction. I also put off writing this post for so long that I had to go back and examine the bed to try and remember what I did. Here’s what I was able to piece together.

Let’s go back to the beginning. One day my wife went to Pottery Barn and found a treehouse bed for my son. Since the bed was ridiculously expensive, she suggested that maybe I build one for him. After a little searching I found a person who designed a similar bed made with 4 sections that was designed to be easily taken apart. So I decided to make my bed in four sections: two identical sides, a front, and a back. Each section would have a 2×4 on both sides, when the bed was bolted together the 2×4’s would form the 4×4 posts for supporting the bed.

My design constraints were as follows. I designed the bed for a standard size twin mattress (75″ x 38″) with about an inch around the perimeter to have room to get the sheets on and off. I also wanted 40″ of head room underneath the bed and the total height could be no taller than 95″ to fit into the room. I shot for 92″ total height because I didn’t wan’t it to touch the ceiling. 

After calculating the total number of 2x4s, 1x6s, 1x4s, 1x3s, and 1x2s I would need to build the bed, I purchased all the dimensional lumber to build the frame. I sorted through piles of boards to find the best wood, but it was clear that to make this a furniture grade piece I had my work cut out for me. It took me about a month to sand all the pieces to be smooth and splinter free. 

Once I was satisfied, I built the sides first. The 1×3 slats are captured by 3/4″ routed grooves in the upper and lower rails. I made 3/4″ square filler pieces to space the slats and hide the exposed part of the groove. Neither the spacers or slats are glued to allow them to move with changes in the season. Hopefully the spacers won’t fall out, they are just friction fit! If it becomes a problem I can just drive a single nail through the center to keep them in place while still allowing them a little wiggle room. The upper and lower rails are held in place by 3-1/2″ screws through the uprights. The angle braces are held in place with pocket screws. Neither the rails or the braces are glued either, I didn’t see much point since I would be trying to glue end-grain.

The front and back were supposed to have 2×4’s running the entire length of the sides. The cross-member to which the bed rail was supposed to attach was going to be fastened to those sides forming an H. I started laying out the roof line and calculating the angle I would need to make the roof meet the sides at 70″, which turned out to be 23.70°. I was screwing the frame for the front together when I had that ohh-shit moment…how was I going to get the front and back out of my shop. They would be 92″ tall and most doors are much shorter than that even on the diagonal.

Many months later after I recovered, I came up with a new plan. The front and back would sit on 40″ short 2×4’s attached to the sides. This would make them a more manageable 52″ tall. Rather than have a cross-member, the bed rail would be the bottom sill of the front and back. It would be a 2×4 with notches out of each side so it could sit on the short 40″ 2x4s. To give it enough strength to support the weight of the mattress, my son, and about 5 friends, I glued and screwed a 1×6 to this rail forming a 1/2 I-beam. The 1×6 is set back about 3/4″ from the front so it can also serve as a place to screw in the car-siding.

Of course before starting to assemble the front and back, I did remember to drill the holes for the carriage bolts through the 2x4s that would become the sides. I didn’t want measure for the holes and hope I didn’t screw up, or worse yet have to drill the holes while trying to hold the heavy front and side together when I was assembling them. 

One I had the front and back frames built, I calculated the amount of siding I would need and purchased it when it was on sale. Since it was in much better shape than the dimensional lumber, I did not have to spend nearly as much time sanding the siding. I sided the back first since it had no openings to worry about. Each piece of siding received two drywall screws top and bottom. So that all the screws lined up nicely, I had a combo square set to the distance I wanted the screws from the edge of the board. I did not use glue and I spaced the boards so there was about a 1/8 to 1/4″ inch gap in the tongue and groove for expansion.

On the front I needed openings for two windows and one door. Rather than side over the front completely and then cut out the openings, I laid out the openings and cut the siding while I was installing it. I planned on doing it that way to save money on siding; it didn’t prove to be much more difficult than siding the back.

The last real construction part on the tree house itself was framing in the windows and the door. The windows are just square 1×2 frames mitered in the corners and reinforced by a pocket screw in each corner. I routed dadoes in the middle of the back of the frames to hold the muntins. The muntins were ripped from the edges of 1x stock and the middle was dadoed where they crossed.

I created a sill for the bottom of the door, because I wanted something smooth and flat so my son (or me) didn’t hurt himself every time he got in and out of bed. The frame of the door is just mitered 1x2s with the same pocket hole to reinforce the joint.

The last thing I needed to build was a ladder to climb into the tree house. The ladder is made from 1x6s with 2×2 blocks connecting the sides to the steps with a 20° slant. I thought this would be much simpler and stronger than trying to cut angled dadoes in the sides for the steps to fit into. At the top of the ladder, I cut the sides so they would lay flat against the front of the tree house and I added a 1×4 in case I ever wanted to secure the ladder to the tree house bed. Everything is screwed and glued.

After all these pieces were built, I put the entire bed together inside my shop. As you can see in the first picture it barely fit. I wanted to make sure it was sturdy enough and didn’t need any more bracing. It surpassed my expectations, I figured it’d support a small car if it was lowered onto it. From my research I found with beds of this type the mattress rests on slats which in turn rest on the bed rails. The slats used are 1x4s I cut to fit between the sides of the bed while resting on the rails. To keep them from wandering all over the place when my son jumps and wiggles, I stapled nylon strapping from some old ratchet straps.

I did a lot of research to figure out the right finish to use. I wanted to use an exterior stain, but by experience with exterior stains is that they get powdery over time and I didn’t want that to happen to the tree house bed. After consulting with my dad, he said that stain only gets that powdery residue after long exposure to the sun. I also wanted a finish that wouldn’t telegraph every imperfection. I spent a lot of time preparing the wood, but there were still swirl marks from the random orbit sander. I didn’t want to emphasize them.

Finally I decided to use a water-based solid stain: Cabot Solid Acrylic Decking Stain in Chestnut Brown. This was my first experience using a water based stain and I was really impressed at how well it covered and of course the ease of cleanup. I was able to finish most of the bed with just one coat, only touching up a few spots afterwards.

The bed is complete and my son loves it. My wife made me secure the ladder to the bed because she was afraid of it falling while my son was climbing it. I used two hook and eyes, one on either side of the ladder. This way the ladder can still be easily detached when we need to vacuum his room.