How to Build a Tree House With 2x4s

Cut four of the 2-by-4 boards into 8-foot lengths. These will serve as the cross-beams for the structure.

Drill a 1/4-inch hole through each of the cross-beams. The hole should be located in the center, 4 feet from either end and 2 inches from either side.

Measure 7 feet from the ground and drill two holes on opposite sides of the tree. The tree should be at least 20 feet tall with no branches below 14 feet. Its diameter should be no less than 2 feet.

Place a cross-beam horizontally so the hole in the beam is over one of the holes in the tree. Insert the lag screw and tighten it with the ratchet. As it comes close to tightening completely, use the level to check that the cross beam is level. Repeat the process for the second cross beam, with the second beam going over the other hole.

Place the third cross beam on top of the two cross beams, forming 90-degree angles, placing it flush against the tree. Drill a hole through the hole in the beam and into the tree. Insert a lag screw and tighten it with the ratchet. Repeat the process on the opposite side, for the fourth cross beam. You will now have four cross-beams fixed to the tree, forming a cross, with one set of cross beams on top of the other set.

Cut two more pieces of lumber, 8 feet, 4 inches long each. Align both pieces on their 2-inch sides and place them on top of the edges of the lower cross beams, parallel with the upper cross beams. Attach these pieces to the ends of the lower beams by inserting wood screws through the newest beams and into the lower beams at 45-degree angles. Use one wood screw for each lower beam. You'll now have four upper cross beams.

Cut two beams, 7 feet, 8 inches long each. Place the beams between the 8-foot-4-inch beams so the face of each beam is flat against the end of the 8-foot beams. This will create a square surrounding the tree, creating the frame for your platform. Secure the 7-foot-8 beams with the wood screws. Insert two screws through the 7-foot-8 beams and into each end of the 8-foot beam, and insert two screws through the 8-foot-4-inch beam and into each end of the 7-foot-8 beams.

Measure the circumference of the tree directly above the platform.

Lay two pieces of plywood on the ground so they form an 8-foot-by-8-foot surface. Draw a circle in the center of the plywood with a circumference that's approximately 30 percent greater than the tree's circumference. Cut the circle out of the plywood using the reciprocating saw. Repeat this process with two more pieces of plywood and set them aside.

Place two pieces of plywood over the platform, then attach them to the platform with wood screws. The outer edges of the platform are flush with the outer parts of the frame. Use one screw for every foot of beam.

Cut eight 2-by-4 beams, each 4 feet long. Attach two beams vertically to each corner of the platform -- with one on each side. You should have two beams on each end of each side, reaching upward to form the wall posts. Attach them using two screws per beam, through the cross beam and into the vertical beam.

Cut four more beams, two 8 feet long and two 7 feet, 8 inches long. Attach them to the tops of the upright posts, parallel to the beams of the same size on the lower frame. Assemble them in the same manner as you did the lower frame.

Place the pieces of plywood that you set aside in Step 9 on the top of the roof platform, parallel with the floor. Attach them just as you attached the plywood to the lower frame.

Place an 8-foot-by-4-foot piece of plywood on the inside of three of the walls. Attach them using the wood screws, placed every 4 inches. Leave one side open as an entranceway.