How to build a treehouse?

[kitfriendesq]

My son keeps asking when we're going to build him a 'proper treehouse' to expand his cubby on stilts in the garden so I figured the xmas break is a good time to start planning. I did stilt based job in the UK so some experience but this one feels like a proper tree-based job is in order, and the kids are noticably bigger now so something chunkier is in order!

Our old UK treehouse: 

The tree next to our cubby here is pretty beefy and there's a handy junction for the branches at about the right height so I'm thinking:

- Platform sitting in the notch of the branches, 1-2 "beams" in the notch, and then 1 either side of the tree

- Some 'knee brace' diagonals 

- Perhaps a horizontal tie to the cubby, not sure it'll really add much stability as the tree is so thick already

Most of the 101s seem to be American but essentially have chunky beams with slimmer joists on top: https://www.thisoldhouse.com/yards/21017559/how-to-build-a-tree-fort 

Questions I've got already and would love some thoughts on!:

- The US tutorials all seem to have crazy amounts of proprietary tree bolts and brackets. Our tree is mature so I'm not anticipating huge growth, for bolting the beams and braces to the trunk what sort of lag bolts might be usable?

- Economic timber options for the beams, braces and joists 

[Jason]

Hi @kitfriendesq,

Sounds like a fun project. I'm sure our resident Bunnings D.I.Y. experts will be happy to assist as soon as possible to you build the treehouse safely.

Let me also tag some other members who have taken on treehouse projects: @Dan_M, @mjkworldwide, @Jerry1, @Holdent    

Check out @Dan_M's Building a treehouse discussion for some excellent techniques. And our collection of clever cubby house designs might also provide some inspiration. 

Jason

[kitfriendesq]

Yes I saw @Dan_M's treehouse post and was very inspired!

[EricL]

Hello @kitfriendesq 

I propose doing some measurements and drawing your framing plan on paper. From there you'll be able to see where you'll need to put the lag bolts. The store does carry some Everhang M12 x 120mm Zinc Plated Hanger Bolts, but if you are after something bigger you could use coach screws. The size of the bolts also depends on the size of the timber pieces you'll be using. I propose looking at 90 x45 H3 for your framing and 70x35 for the house walls and roofing.

If you have any other questions we can help with, please let us know.

Eric