Full-size loft beds are often best built yourself because there are very few commercially available loft beds, and most are built for twin mattresses. Whether you want a larger 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 inexpensive supplies and an afternoon's labour
Cut lumber to fit bed dimensions. If you don't have a power saw, your lumber yard or home improvement centre will usually cut it for you inexpensively.
Sand all faces of your lumber.
Paint or stain the lumber, if you want to. If you choose to add this step, the rest of the project will take an additional day as you wait overnight for your cover to dry.
Set your four beams on the floor in a rectangle. Set the shorter beams with the ends inside the longer beams. Position all beams so the narrowest side (the 2-inch side) is on the floor (the beams will be taller than they are wide.)
Screw the beams together with two wood screws per corner. Drill through the face of the longer beam and into the centre of the end of the shorter beam, with the two screws stacked vertically about an inch apart.
Lay the plywood sheet on top of your rectangular frame with all edges of the sheet flush with all edges of the frame.
Screw the sheet in place with one screw at each corner, drilled down through the plywood into the beam beneath.
Reinforce with one screw on centre for each edge of the mattress frame. Drill this screw down through the plywood and into the beam beneath. For best results, drive this screw in approximately 3/4 inches from the outside edge of the plywood.
Set your frame on end so that you can access both the plywood side and the beam side.
Set one 6-inch by 6-inch post in the corner, nestled into the angle formed by two beams. Screw it in place with three wood screws along the diagonal of the square formed by the end of the post. Screw through the plywood and into the end of the post.
Reinforce by drilling one screw through the shorter beam into the side of the post. Further reinforce by drilling one screw through the longer beam into the other side of the posts.
Repeat steps two and three to add the other three posts, forming the legs of the platform bed.
Connect two support posts along one long end of the frame by attaching a 72-inch plank. Set the plank so that the top edge is 2 1/2 feet below the bottom of the beams. Screw it in place with three screws on the diagonal for each beam. Drill these screws through the plank and into the side of the beam.
Attach the second 72-inch plank directly opposite the one you just mounted. Screw it in place in the same fashion.
Connect two support posts along one short end of the frame by attaching a 50-inch plank. Set the plank so that the top edge is flush with the bottom of the 72-inch planks you've already attached. Screw it in place with three screws on the diagonal for each beam.
Attach the second 50-inch plank directly opposite the one you just mounted. Screw it in place in the same fashion.
Repeat steps seven and eight to add support planks to the opposite short end.
Slide the frame into position in its assigned bedroom, long side with the planks against the wall. This leaves the open side facing the room, allowing easy access to the space beneath the bed.
Hoist up your full size mattress and put it in place on top of the platform.
Some people find it easier to make loft beds if they take the mattress down and add the fitted sheet on the floor, then put the bed back into position.