Floating shelves conceal their support structure within a hollow in the shelf itself. This makes for a storage space with clean, modern lines. It seems like the same concept could be applied to a bed, making a modern-looking addition to the bedroom. Unfortunately, even a twin bed with a child will strain the structural support of a classic floating shelf. However, by adding removable support chains you can keep the shape of a floating shelf while adding stability when somebody actually sleeps on the floating bed.
Cut your 4 x 4 beam to the right length using your power saw.
Drill two parallel lines of five holes each through your 4 x 4 beam. Set each line 1 inch from either edge of the beam. Drill the holes 5, 21, 37, 53 and 69 inches from one end of the beam. Use a drill bit the same diameter as the shafts of your lag bolts.
Drill two parallel, level lines of holes in your wall at the height at which you want the floating bed. Space them as you did the holes in your beam. With each hole 16 inches apart, you should be able to set them all in a wall stud.
Install a lag nut in each of the holes in your wall, anchoring them into the wall studs.
Set the 4 x 4 beam in place. Bolt it in place by running a lag bolt through each hole and into the lag nut behind.
Drive one eye screw each into the wall studs attached to the outermost two lag bolts. Set each screw 36 inches above the beam.
Hook a carabiner through each of the eye screws you just mounted.
Arrange one 39-inch beam and one 76-inch beam into an L-shape, with the end of the longer beam abutting the face of the shorter. Screw them together with two wood screws.
Attach the remaining 39-inch beam to the other end of the 76-inch beam, forming a C-shape. Screw it in place with two wood screws.
Slide the remaining 76-inch beam on centre between the two 39-inch beams. Screw it to each beam with two screws.
Place one plywood sheet on top of the frame, its edges flush with the frame. Screw it in place with one wood screw per corner.
Flip the frame over. Install the other plywood sheet on the underside just as you did the first.
Drive one eye screw each into two corners along one long side of the bed frame. Attach a carabiner to each eye screw.
Sand and paint all outside faces of your platform. Let dry.
Slide the open face of your platform over the beam mounted to the wall.
Screw the platform to the beam using two parallel lines of five screws each. Drive the screws through the underside of the platform and into the beam above.
Reinforce with two screws each at each end of the platform, driven through the beam and into the wall mount behind.
Further reinforce with one line of five screws driven through the top of the platform and into the beam beneath.
Cover over the heads of the edge and top screws with painter’s putty. Allow putty to dry.
Sand off excess putty. Paint over the putty and any dings in the paint from mounting the platform.
Run one chain between the eye bolts on each end of the bed. You can remove these chains when the platform carries a light load, if the appearance bothers you.