An outhouse brings a bit of nostalgia and whimsy to the backyard. Today outhouses are used more as decoration than as functioning buildings. However, if you want to build a working outhouse, it's not difficult. Just remember to place it 50 to 150 feet from the house, and at least 50 feet from any water source.
Building the Box Structure
Determine the location of the outhouse. Dig a trench 3 feet square and 5 feet deep.
Construct the base from 2-by-4s, making a 4-foot square box. Nail plywood over the box to make a floor. Place it over the trench.
Add 2-by-4 posts at each corner.
Cut one sheet of plywood 4 feet wide by 7 feet high. Cut one sheet 4 feet wide by 6 feet high. Cut two sheets 4 feet wide, but angle the top side to run from 7 feet down to 6 feet. Run a pencil line connecting the 7-foot side to the 6-foot side. Cut the angle with a circular saw.
Nail up the pre-cut sheets of plywood, placing the 7-foot piece at the front of the outhouse, the 6-foot piece on the back and the two angled pieces on the sides.
Build a 5-foot square box from 2-by-4s. Attach the 5-foot square of tin. Nail this roof onto the plywood walls, allowing for a 6-inch overhang on all sides.
Finishing the Outhouse
Cut a hole in the 7-foot side of the box for a door. Using the cut piece, or using a regular door, attach it on hinges to the outhouse structure. If using plywood, construct a Z-bar frame from 2-by-4s for extra sturdiness, and nail to the door.
Build a seat box, 2 feet high by the width of the interior. Nail onto the back wall and the floor. Cover the box with plywood, cut to size.
Cut an oblong hole about 10 to 12 inches wide and 15 inches long, using a drill to start a hole, then using a hand saw. Attach a toilet seat to cover this opening, using the accompanying hardware.
Add screens at the top of the rear wall for ventilation, or run a 4-inch vent pipe through the roof. Cut a hole in the door for extra ventilation.
Paint the interior with a mixture of 1 tablespoon calcium hypochlorite and water. This anti-bacterial agent acts like household bleach to disinfect the interior, and also is a deterrent to insects and other pests.