Four-poster beds are similar to canopy beds. They have a tall post at each corner of the bed, and the tops of the posts are connected with smaller boards. The boards that connect the posts on the top are sometimes left uncovered, but often have some type of fabric draped over the top of them for decoration, privacy, or to keep out light. Building a four-poster bed can be done inexpensively with construction lumber and basic hardware.
Lay two 84-inch boards flat, parallel and 53 inches apart. Lay a 60-inch board perpendicularly on top of the two 84-inch boards so the ends are flush with the sides of the 84-inch boards. The 60-inch board should be 15 inches away from the ends of the two boards. Screw the board to the 84-inch boards in this position. Use six screws for this task and repeat this process with the remaining 84-inch boards. The 84-inch boards are your bed posts.
Stand the two pairs of 84-inch boards upright so the 60-inch boards are parallel, 15 inches above the floor and 80 inches apart. You may need an extra person to help you do this. Screw a 90-inch board to the 84-inch boards. The ends of the 90-inch boards should be flush with the sides of the 84-inch boards, and the top edges should be flush with the top edges of the 60-inch boards. This is your bed frame. There should a 90-inch board on both sides to complete the frame. Use 12 screws for this task.
Position a 60-inch board perpendicularly between the 90-inch boards and 15 inches away from one of the 60-inch boards on the frame. The 6-inch wide surface of the board should be flush with the bottom edge of the 90-inch boards. Screw through the 90-inch boards into the 60-inch board. Use six screws. Screw the last 60-inch board to the frame in the same manner, but 15 inches away from the opposite 60-inch board. These boards hold your box springs.
Cut the ends of all the stock lumber at a 45-degree angle. Do not alter the length of the boards. When they lay flat they should look like a trapezoid.
Lay a 60-inch piece of stock lumber on a pair of 84-inch boards that are 60 inches apart. The angled cuts should be angled toward the centre of the bed. The 60-inch edge of the stock lumber should be flush with the outsides of the 84-inch boards. The ends of the stock lumber also should be flush with the sides of the 84-inch boards. Screw the stock lumber to the top of the boards in this position. Use two screws and repeat this process on the opposite side of the bed frame.
Lay the 90-inch stock lumber on top of the 84-inch boards so the angled cuts are tight against the angled cuts on the 60-inch stock. There should be one on each side of the bed. Screw the stock lumber to the boards just as you did in the previous step.
Place your box springs inside the frame so it rests on the two 60-inch boards. Lay your mattress on top of the box springs and the bed is ready to be made.
Subtract six inches from the 60-inch boards and five inches from the 80-inch boards to make this bed frame for a full-size mattress. Subtract the same values on the corresponding stock lumber (the stock that is directly above the board on the frame) as well. Add 16 inches to the 60-inch boards and the corresponding stock lumber to make the frame suitable for a king-size mattress.