Things You'll Need
Instructions
Decide where you want the fort. There should be enough room for kids to get in and out of it easily. Also take into consideration issues such as rocky ground or slopes that might make level construction difficult.
Start by laying two of the 2-by-4 beams flat on the ground about 5 feet apart. Lay one 2-by-12 board flat on top of them. Take the hammer and nail the 2-by-12 board onto the beams. Use two nails on each side so the board is securely fastened to the beams. Continue to nail 2-by-12 boards to the beams until you reach the end of the beams. This is the back wall of your fort.
Turn the wall over so the beams are facing up now. These are going to be the back corners of your fort. Keep the back wall flat on the ground and begin constructing the sides of the fort by nailing one of the 2-by-12 boards to the end of one of the beams, standing vertically. Nail a second 2-by-12 board to the end of the other beam, also standing vertically. You should now have two boards sticking straight up in the air, both on the same end of the back wall. This is the bottom of your fort, and you have just created the bottom of your side walls.
Pick the wall up so you can work with the fort standing upright.
Nail the other two 2-by-4 beams to the free end of the two new boards. You should now have four corners, a full back wall, and two boards on the bottom of your side walls. Finish the sides of the fort by nailing the remaining 2-by-12 boards to the 2-by-4 beams all the way to the top.
Construct your roof. Cut two of your 1-by-3 lumber sticks at a 45-degree angle and hold them on top of the sides of your fort to check their fit. Make minor adjustments to your stick length and angle as needed until they fit together and form a good triangular frame for your roof. Nail the sticks together at the top point, then nail the triangle to the top of the front wall. Repeat the process for the back wall.
Place a sheet of waterproof plywood over the top of each side of your triangles and nail it down. Trim the length of the plywood sheets once you get the roof on and nailed down.
Construct a door frame by cutting the remaining 2-by-4 in half and positioning the boards between the floor of the front wall and the base of the front roof triangle. Then, nail extra 2-by-12 boards to your corner beams to create a front wall. To add a door (optional), cut a piece of the leftover plywood to fit and affix it with inexpensive door hinges.