I see most treehouse's have knee braces to support the frame of their treehouse. I'm trying to find an alternative, if any, and also ask if my 2x4x12 frame will be strong enough.

Here are pictures of where I am in my current treehouse build.

enter image description here

I have 2 2x10x12's for my main lower support held into tree with 3/4" x 10" Lag bolts. I have 2 more 2x10x12's on top of those for my base support. they are also fastened to tree with 3/4" x 10" Lag bolts. Them frame and joist are made up of 2x4x12's and held secured with joist hangers and rafter ties.

I offset the platform to get more room on the left side. The only weight that will be on this platform will be the 1x4 flooring and railing. There will not be any structure built on it or heavy furniture.

My original plan was to set 2 4x4's in concrete and support the longest stretch of 2x10's. Here is a mockup i did to illustrate.

enter image description here

However, after walking on the corners I am realizing that is not going to be enough support. My first idea was to place 2 more 4x4's in those corners to left and right of the ladder. But I wanted this platform to be as independent from the ground as possible. But i am quickly realizing that might not be possible.

So here are my questions: 1) Would the 2 4x4's for the ladder and 2 4x4's in corner to left/right of ladder be sufficient?

2) Is there another way to do support those corners without using the ground?

3) Are the 2x4x12's I used in the frame good enough to support the platform? should I have used 2x6's?

Here is a mockup of what the deck will look like once completed

enter image description here

  • 3
    The trouble you have is obviously twisting, and the challenge is supporting the entire perimeter. Since you've gone with a cross-shaped stiffback arrangement, the outer corners are left unsupported. Are you opposed to cables angling upward to the tree? My last treehouse was cable-supported and really worked out well.
    – isherwood
    Commented Sep 20, 2017 at 14:36
  • My concern with knee bracing is attachment. You'd have to bolt some cleats to the trunk near the ground and push out from there. It'll end up being a somewhat inelegant structure when you're done.
    – isherwood
    Commented Sep 20, 2017 at 14:39
  • That is a possibility. Could you show me an example of what that would look like?
    – Bignadad
    Commented Sep 20, 2017 at 14:40
  • I understand your concern with knee bracing. would the 4x4's in the corner be sufficient if I had to go that way?
    – Bignadad
    Commented Sep 20, 2017 at 14:41
  • 1
    Sort of. You won't have much keeping the entire thing from swaying in a rotational manner unless you knee brace the posts. Ideally, though, a treehouse should be able to move with the tree.
    – isherwood
    Commented Sep 20, 2017 at 14:43

1 Answer 1


This is what we ended up doing. Took the center link brackets off of JD tractors and bolted them to the base of tree with lag bolts. Used 2x6's to brace the corners. Have had a large group of people up there and has no sag.

enter image description here

  • Thanks for answering your question! Please click the check-mark so that others know you've found a successful solution.
    – FreeMan
    Commented Jan 22, 2021 at 12:24

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.