Tree House Plans

I built a tree house, or more correctly as house on stilts, for my children. Here are the plans and a few instructions how to build one.

COPYLEFT If you use this plan please feel free to modify it. If you modify it please post it with a comment like "this is a modified version of N. Shirtcliffe's tree house, the original can be found here" with a link back to here.

I am in the process of writing this, sorry.

The plan is for a 2x1.8m wooden building on a 2x2.4m platform. Ours is at a height of 2m from ground level. The reason for having a larger platform is that otherwise the door of the building would be a site of many accidents, either falling off the ladder or out of the door. A trapdoor is an alternative, but also difficult to keep safe. As the idea was to have children playing with only half an eye on them it has to be reasonably safe. Also the whole fun of a treehouse is that it is high, so making it safe by making it low would defeat the purpose.

Tools

Spade

Concrete bucket

Drill (I used a corded one with a slow speed for screwdriving)

Wood drill bits 25 mm (I used a flat one but does not matter) 8mm, 6 mm long (must go through the beams), 3mm.

Socket set (can do without, but saves a lot of effort)

Screwdrivers

Circular saw

Hand saw (crosscut)

Paintbrushes

Hammer

Allen Keys

Spirit Level

Parts list

For the stand

4 Legs, 90mm square the height desired (I have 2m to the platform plus the front two the height of the balcony (0.8m), the back two the height of the hut (I have 1.5m at the back for legal reasons). It depends, however, on the shape of your ground.

The front vertical posts of the house (see diagram), I used 3 70mm square posts 1.8m long. It would have been easier if one of the sides of these was 90 mm, but smaller is cheaper. With thinner ones you will need spacers.

6 horizontal supports, I used metric 4”x2”, which is something like 120x50mm as I am in Germany. Normal 4x2 would be fine. They were all 2.4m long.

Foot stands, galvanized steel for 90 mm. (4)

Coach bolts 16 at10mm 25-30mm long for feet, 24 at

The big advantage of a stilt house is that the ground does not need to be level, and is in fact better when it is far from level.

The four posts making up the stand are 90mm square treated pine and are bolted to galvanized H pieces concreted into the ground. I set these up and allowed the concrete two weeks to set. The holes are about 2 feet deep and 1 foot round (70 by 40 cm) but depending upon your ground you might need more.

The posts were then bolted on using 10 mm coach bolts set vertically with the spirit level. I attached the first four horizontals as soon as possible to keep them steady. I used sash clamps to hold the shorter crosspieces on while drilling holes. I started the holes with the 25 mm bit, in the crosspieces, only cutting down about 15mm. Then I used the 6mm to drill through the horizontal piece into the vertical post. I then widened the hole in the horizontal post to 8mm before screwing an 8 mm coach bolt in with the socket wrench. Without a socket wrench it will be difficult to sink the heads like this.

As you can see the two bolts are set diagonally so that neither piece of wood is likely to split.

As an afterthought I added a middle front post for a climbing wall. This is 70 mm square and concreted straight into the ground. I hung this from the frame into a hole and then poured concrete in. If you are planning this you can put this post in with the others.

The Diagonal supports are necessary at this point otherwise fixing the floor needs good sea legs. These are short sections of 70mm square post screwed to the faces of the legs and the square frame of the floor.

The next two beams support the rest of the floor, these run under the centre of the floor and sit on the lower horizontal beam shown above. I used joist hangers to fix these in place as they are protected from rain by the floor. These particular ones are just angles.

The nest step is to fix three longer verticals where the front of the house will be. I did not do this, but it would have saved some effort later and would be a better solution. They would be screwed onto the sides of the horizontal beams, two on the outside and one in the middle to make the doorpost. Take care to use spacers if you use thinner than 90mm posts so that the house is square. I fixed these instead to the floor to avoid this.

The next step is to deck the whole thing. Here in Germany decking comes in multiples of 1m so 2m sections are easy to buy or cut from 4m lengths. I left gaps as suggested by the instructions, but this seems to be a bad idea, my house was moist and I had to caulk the gaps. If doing this again I would leave narrower gaps.

Once fully decked, you can start to build the house. I levelled the frame pieces by cutting them with an electric chainsaw.