It’s something like a cave and something like a bunk bed, but it’s goes beyond that. A loft offers a modern bed with more than just storage underneath — there’s room for a study area, large bookcases, built-in shelves or drawers, or a small love seat perfect for watching television. While you can purchase a loft, you can’t customize it the way you can when you build it yourself. It’s also much cheaper and not much more work than assembling one you buy.
Find the floor to ceiling height in the room in which you will place the completed bed. Measure the thickness of the mattress you will place in the loft as well. Record these figures. Measure and cut a sheet of 3/4- to 1-inch thick plywood to the size of 55 inches wide and 76 inches long. This is your bottom bed frame board and the mattress will rest on it. A normal full size bed is 54 inches by 75 inches, but adding an extra inch allows the mattress a little extra wiggle room. This makes using and making the bed easier.
Cut four posts from the 4-by-4-inch boards. Use the height of your room to guide you in cutting the posts. For standard ceiling heights of 8 feet, make the posts 72 inches, or 6 feet, long. With taller ceilings, such as those 9 or 10 feet high, extend the posts another foot or two. Safety requirements dictate a minimum of 30 inches head room between the mattress and ceiling, so the height of your room minus 30 inches is highest your mattress may rest. Posts should extend past the mattress at least 6 inches.
Lay the posts, side by side with the ends flush, in the middle of the room. Measure on the outside posts up to a minimum of 52 inches, and mark a straight line across to indicate the bottom of the mattress frame.
Adjust the mattress frame mark as necessary: increase the height 12 inches for every foot over 8 feet high your ceilings measure, or decrease by 1 inch for every inch your mattress measures thicker than 13 inches. For instance, if you have 9 foot ceilings, make this mark at 64 inches. If you have 8 foot ceilings and an 18-inch-thick mattress, however, make the bed frame mark at 47 inches. Clearance under the bed should ideally be 52 inches for comfort, but this space plus the mattress thickness plus the headroom cannot exceed the ceiling height.
Measure and cut two 2-by-12-inch boards to 79 inches in length. Make two more 58 inches long. These are the mattress frame boards. They are slightly longer than the width and length of the bed to account for the 1 inch extra mattress room plus the thickness of the boards, which is 1 1/2 inches. Cut four ledger strips to the same dimensions using 2-by-2-inch boards. These will nail flush with the bottom of the completed frame, holding the plywood bottom-up in place inside the frame. This allows your mattress to sit recessed in the frame, instead of on top of it.
Align a ledger board along the bottom edge of each frame board. Drill a hole through the frame board, into the ledger board, every 6 to 8 inches. Insert drywall screws into the holes and tighten to secure. Attach the frame boards, with ledgers pointing inward, in a box-shaped construction. Place the ends of the short boards inside the ends of the long boards to create a butt joint. Check for clearance of 75 inches by 54 inches inside the frame before securing. Drill three holes through the outer board at each corner. Insert drywall screws and tighten. The mattress frame is complete.
Tilt the bed frame on its side. Join the posts, one at a time, carefully aligning the bed frame mark on the post with the bottom of the bed frame. Flip the frame as necessary to access each side. Drill, from the inside of the frame outward, through the frame and into the post three times per side of the post -- a total of six times per post -- and insert a 3/8 inch carriage bolt. Tighten well.
Divide the height between the bottom of the post and the top of the frame by eight. Take the result, rounded up or down to a whole number, and cut that number of 2-by-4-inch boards. Make the boards as long as the width between the posts on the ends of the loft.
Space the boards equally far apart, between the posts at the ends of the loft, with the wide edge horizontal. Attach by either drilling through the posts into the board ends or driving screws at an angle -- called toenailing -- through the boards into the post from above and below the board. These boards help stabilize the loft, provide structural support if you hang shelves or build anything below the loft, or serve as possible stairs.
Tilt the loft up into position. Sand all blunt, exposed edges and stain, paint or finish as desired. Lift the plywood bed frame bottom up and slide it into the bed frame, allowing it to come to rest on top of the ledger boards to complete.