- 1). Find the right tree. You'll want something sturdy like an oak or a maple. Ideally, you want a tree that has three large branches comeing off the main trunk. That allows you the maximum building opportunity. For the matter of this fort, assume you have three prongs to build on.
- 2). Start with the base. Cut 2 x 4s to make a floor for the fort. Generally, speaking you'll want to build a fort that is at least 6 feet wide and 6 feet across, but smaller and larger forts are fine. Attach support beams between the three tree prongs, and nail a floor onto them.
- 3). Build supports. Attach 4 support beams going vertically from the floor. Then nail 4 support beams to them to build a roof structure.
- 4). Prepare for a pitched roof. You will want to have some angle on the roof to keep water and leaves from accumulating up there. Take a set of 2 x 4s and cut them so they make an angle coming off parallel sides of the roof.
- 5). Decide what kind of walls you want. The easy thing to do is buy some strong plywood and nail those around the support beams for walls. Two layers of plywood will make it more sturdy. Make a plywood roof as well.
- 6). Add a door and some windows by cutting throught the plywood.
- 7). Touch up the outside. Consider adding faux logs to the plywood to give it a "cabin look."
- 8). Make a ladder leading up to the front door by drilling some planks into the tree.
- 9). Hang the rope and the tire from a nearby branch to have a swing.
Source...