Lofted full beds are often best built even because there are very few commercially available loft beds, and most are built for two mattresses. Whether you want a bigger loft bed for your child or an adult-sized loft bed for a vacation home, a full or double size loft bed is a project that can save you a lot of floor space in your room in exchange for cheap supplies and an afternoon labor. Cut wood load to fit bed dimensions. If you do not have an electrical case, the sawmill or home improvement center will usually cut it for you cheaply. Sand all the faces to the load.
Paint or stain wood, if you want. If you choose to add this step, the rest of the project will take an extra day as you wait overnight for the cover to dry. Place your four beams on the floor in a rectangle. Adjust the shorter beams with the ends in longer beams. Drill through the front of the longer beam and into the center of the end of the shortest beam, with the two screws stacked vertically about an inch apart. Place plywood sheets on top of your rectangular frame with all edges of the sheet flush with all edges of the frame.
Screw the sheet into place with a screw in each corner, drilled down through the plywood into the beam below. Reinforce with a screw on the center for each edge of the mattress frame. Drill this screw down through the plywood and into the beam below. For best results, run this screw for about 3/4 inches from the outside edge of the plywood. Place the frame at the end so that you can access both the plywood side and the beam side. Put a 6-inch with 6-inch post in the corner, well placed in the angle formed by two beams. Screw it into place with three wooden screws along the diagonal of the square formed at the end of the post. Screw through the plywood and into the end of the post.