I plan to build a tree house by bolting two (2) 2x6 on the side of this 12-in diameter tree:

enter image description here

I don't know what tree it is and in the process of asking here:


The tree seems stable but I don't know how it will behave during strong wind. We don't have extreme weather in Seattle but I could see the pine trees moving in strong winds.

So should I bold the platform of the tree house into this tree? Or it is better just to build 4 foot and support the play house and have this tree in the middle (make a hole for it)?



I "feel" a bit unsafe to rely on this tree. So I was thinking of doing this:

enter image description here

Basically the structure will have 4 legs. The tree is in the middle.

  • What kind of tree?
    – J Crosby
    Jul 23, 2019 at 22:50
  • Yeah I am trying to find out as well. I think it is a type of madrona?!
    – HP.
    Jul 23, 2019 at 22:51
  • the tree could be an Arbutus ... does it shed its bark?
    – jsotola
    Jul 24, 2019 at 1:17
  • I saw the skin peeling off a bit but not much...
    – HP.
    Jul 24, 2019 at 1:18
  • Don't stay in the tree during a windstorm. How much total weight do you want in the tree-house ? Jul 24, 2019 at 1:25

2 Answers 2


As requested, The reddish color makes me want to ask if it is madrone, does it shed it’s bark? ,Are the leaves mid size thick or leathery and almost feel waxy? If this is what it is I would not use it for support. Madrone is very hard and cracks and splits easily, it is a large one but I would verify the type before trying to use as it might work for now but the next storm in the PNW and the tree may break apart.


Bolting will work short term, but will kill the tree long term (a few years) The tree continues to grow. Your system needs to allow for the fasteners to be let out to not cut the sap flow.

The usual way to fasten a serious tree house to the trunk uses special hardware. Example here: https://www.nelsontreehouse.com/blog/2017/2/21/hardware-highlight-tab

Every tree house I did as a kid, or images of caches for wilderness living have used multiple trees, or a tree with heavy branches. A nailed plank on top of the branch will be pushed up by the growth of the tree. Similarly a nailed plank on the side of a tree can be pushed out (Non-ardox nail) However a few nails may not be enough to support the weight.

In your update photo, you are making a very low tree house. As a kid part of the thrill was being out of sight in the tree, with the ground a scary distance below. This is unsafe. But that was why it was fun.

If you are attaching to a single trunk at multiple points, your attachment points have to spread the load over something larger than a bolt shank, hence the large cylinders in the TAB system.

If you are attaching to multiple trunks, you need some method to allow the trees to sway out of sync. The easiest way to do this is to use something like TAB, and hang the support beams from short chains. This can make the treehouse a bit disconcerting in a wind, as platform will lift and shift in odd ways.

You also have to do this in ways that allow the stress of the weight moving about. Generally supporting a rigid object at more than 3 points at once is hard. (Think of getting all 4 legs of a table on an uneven floor.) Design the platform either to be rigid enough to be supported by any 3 of your set of support points, or design it to flex. Warning: Flexible systems can pinch.

You can compensate for a lot of this by using strong springs as part of the linkage between the tree and the platform. This makes the transition as the chains move much smoother.

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