How to Build a Loft Bed. Nothing makes a small bedroom more spacious than a loft bed. Loft beds create extra space by building the bed upward and allowing the space below it to be reused. Many people place dressers, shelves or an extra bed under their loft beds. In some cases it's easier to build a loft bed than to find one that exactly meets the specifications of the bedroom.
Place a twin mattress on the floor or work area as a guide. Build a box that fits the mattress, leaving a little room around the edges for linens. Build the box over the mattress, with 2 x 6 wood pieces making up the sides and a piece of plywood covering it and forming the base of the box.
Use drywall screws at two-foot intervals to connect the plywood bottom to the rest of the wooden box.
Choose a height for the loft. Cut 4 x 4 boards to make posts that will hold the loft bed in the air. Set the posts in the position they will occupy under the bed box. Get a few people to lift the box and set it on top of the 4 x 4s.
Attach the posts to the box with lag bolts.
Make a ladder for the loft bed using one-inch thick wood slats. Place each slat 10 inches to one foot apart. Keep the slope at 60 degrees. Attach the ladder to the loft bed with screws to make sure that the ladder will not disconnect and leave someone stranded in the bed.