I Built a Treehouse

After we moved into our new house last month, my kids started asking for a treehouse. I told them I’d need to see some plans before I could get started, and the next morning, I found this on my workbench:

Fair enough. The previous owners said that there had previously been a tree fort built in these trees, and some of the detritus was still visible:

These trees didn’t look so hardy, but there is no shortage of other trees to choose from on our property.

We settled on this one. V-shaped, about 200 feet from the house, and with good views in all directions.

The most important thing to consider when building a treehouse is that the tree will move, especially in a strong wind. To account for this, the main supports should have slots where the bolts attach the beams to the tree so that a swaying tree doesn’t tear apart the entire structure. (You can also use special hardware like Garnier Limbs or treehouse attachment bolts.) I used 2×12 treated lumber and started by drilling holes about 5″ apart.

Then I removed the wood between the holes to create a slot for the bolt to slide in.

The bolt holes need to be pre-drilled, otherwise you’ll never get them in all the way. I drilled 9/16″ holes for the 3/4″ bolts.

As long as you only put a few holes into the tree, it should be able to survive. It’s actually worse to put a bunch of small holes in a tree by using nails or screws than a few big holes for bolts, since many small holes may cause the tree to compartment that entire area, causing the wood between the small holes to rot.

Here’s the first beam attached with two of the 10″ long 3/4″ bolts. It’s about 5′ off the ground on the left side, 8′ off the ground on the right.

I put up the other beam and attached the joists above them to support the treehouse floor. Here’s a side-view that shows better the shape of the tree and the main support V.

The ladder on the ground means “Kids, don’t try and climb up there yet.”

At this point, I was able to put in the floor boards. There’s nothing complicated about this; just leave space around the trunks so that the tree has room to grow.

With this kind of support system, the platform will be wobbly without additional support, so I added the first of two corner supports and bolted them to the trunk near the ground.

The kids brought up some tools to help out.

I started on the railing and added a second vertical V support.

A view from behind the treehouse, looking down the hill.

I added a ladder, built out of 2x6s. It’s steeper than a stairway but shallower than a vertical ladder.

I trimmed off most of the floorboards, but the kids asked me to leave this one long.

I don’t know if their original intention was to mount the disembodied head of Vader on it, but that’s what they did.

To avoid too much weight and too much work, I went with a canopy roof. If I had planned ahead, I wouldn’t have had to replace the railing posts on both sides with taller ones to support the roof, but I did not. I was able to reuse the shorter posts anyway, so the only thing I lost was a bunch of time and energy.

I used a big PVC pipe as the peak of the roof, and I think that was probably dumb. I wanted to avoid using something that would wear out the tarp if it rubbed against it, but a sanded 2×4 probably would have been fine, and stronger too. Oh well.

The canopy is tied down using horn cleats. This worked well, but I should have planned their spacing a little better to get the roof as taut as possible.