How to Build a Tree House or Tree Fort

Video Transcript

Build a tree house of pressure-treated two-by-eights, four-by-four posts and other pressure-treated wood that will last and be kid-safe.

Construct this kid's tree house or fort and children will play there for hours. A perfect do‑it‑yourself project with neighbors, the tree house design uses the tree as one support post and straddles a wall to offer access to both families. Build by this plan and the tree house will be safe, won't damage the tree, and will last for years.

Position the First Frame Board for the Tree House Platform
Step 1

Position the First Frame Board for the Tree House Platform

Place the first two-by-eight pressure-treated frame board in the crotch of the tree to position the tree house platform and use the tree as the first support post

Position the Second Frame Board and Chalk-mark the Post Hole
Step 2

Position the Second Frame Board and Chalk-mark the Post Hole

Position the second frame board and brace it. Drop a plum bob from the board to the ground, marking the site for the first post hole. Chalk mark the perimeter and excavate with a post-hole digger to two feet.

Add a Gravel Base and Level the First Four-by-four Post
Step 3

Add a Gravel Base and Level the First Four-by-four Post

Pour in a 3-inch gravel base and drop in a four-by-four post. Use a post level to insure that the post is vertical. Clamp the post to the frame board to keep it from moving.

Set the Three Posts in Quick-Dry Concrete
Step 4

Set the Three Posts in Quick-Dry Concrete

Add dry-mix concrete within three inches from the top of the post hole. Add water and tap the wet mortar to help the water penetrate the dry mix and eliminate air pockets. Set the other two posts the same way.

Complete the Tree House Frame and Square the Corners
Step 5

Complete the Tree House Frame and Square the Corners

Add the remaining two frame boards to complete the 4-sided platform with "square" corners. Drive rust-proof screws through the corners to secure them.

Attach the Posts Permanently to the Tree House Frame
Step 6

Attach the Posts Permanently to the Tree House Frame

Pre-drill through each post and the frame and hammer in carriage bolts. Add a washer and nut and tighten the nut with a socket wrench. Trim the post tops flush with the top of the frame using a Japanese handsaw.