Standard size lumber is a beautiful thing. As it happens, a lot of standard size lumber elements come in similar standard sizes. So when I decided to make my life a little easier by using stockade fence sections for the walls, they happened to also be the same length as the longest side of my tree house. So while I did have to cut down one side, the other could be used full size and was exactly the right length.
With the help of some very nice (and very strong) friends, I lifted each of the (very heavy) stockade fence sections into place and nailed/screwed them in. This secured the back and side walls which faced the neighbors. (I’m sure the neighbors don’t want my kids peeking out at them over the fence any more than I want the neighbors peeking in on my kids in their tree house.) Since the front sides would be just railings, the back walls had no need for windows.
For added stability, I cut one brace for the fourth side and secured it to the tree. It’s the only place where anything is attached to the tree. Because I didn’t want a fourth post interrupting the flow of my backyard, I opted for three posts and one bracket to the tree. It’s very sturdy!
This was also the time to make the ladder. It was pretty simple, just the vertical side pieces with horizontal steps braced by “L” brackets underneath. It’s also designed with hooks on the main landing of the tree house so that the ladder can be removed in the winter, or if the kids should not have access for some reason.