You should never use a flat roof for a treehouse.
How to roof a treehouse.
I used shingles cut in half to seal around the tree and shingled the rest of the roof like normal.
How to level a treehouse floor.
I have worked with tar and gravel shingles before but never wood.
To keep a large tree house stable center the load over the trunk and spread the weight among several branches.
The ideal roof is impervious to water but also needs to rapidly shed water so there is no chance of pools or damp patches building up.
For our hideaway we went simple and used a 6 12 pitch.
Which would put the center of our roof right at 7 feet.
The first decision we made when it came to the roof was how tall you want your treehouse.
This was quite challenging because i had to figure out how to properly attach them as well as work from a high and dangerous height.
A properly sloped or pitched roof is much superior.
Drive one hook into both trunks about 8 feet 2 4 m above the bottom of the platform.
Remember our walls are at 5 feet so we have a 2 rise a 6 12 pitch will give us a 26 5 degree slope on our roof.
Allow a two inch gap around the tree if it passes through the floor and a three inch gap if it passes through the roof see photo.
When your rafters are all on lay down the plywood for the roof an leave a good 2 and 1 2 space around the tree so it can sway in the wind without hitting the roof.
String a bungee cord between the two hooks and slip a tarp overhead.
Add a simple roof to your treehouse.
Building the roof was one of the most challenging parts of this treehouse build.
If your design calls for a flat roof try to introduce even a small slope of 3 5 so water cannot sit there.