Building the Loft
Step 1
Arrange two each of the 75-inch and 36-inch beams into a rectangle with the short beams inside the long beams. Screw the rectangle together with two wood screws at each corner.
Step 2
Set one of the plywood sheets on top of the frame and attach it with a screw at each corner: insert two evenly spaced screws along each long side and a single screw in the center of the short side.
Step 3
Place a 66-inch post on end in one corner of the frame, nestled in the angle formed by the beams. Screw it in place, drilling through the plywood and into the end of the post. Use four screws set in a square.
Step 4
Repeat Step 3 to attach the other three 66-inch posts.
Step 5
Set the bed frame upright, standing on the four legs you've built. Be careful while turning as the legs don't yet have enough lateral strength to handle sideways pressure.
Step 6
Use one of the 66-inch planks to connect two planks along the long side of your bed nearest the wall. Place them approximately 3 feet from the floor. Screw the plank in place with three screws spaced diagonally at each point of connection.
Step 7
Attach the second 66-inch plank directly opposite the first, screwing it place in the same way, using a total of six screws.
Step 8
Reinforce each short end with two 33-inch planks per side. Place the planks so the top edge of the plank butts against the bottom edges of the longer planks you've already put in position. Use three screws per point of connection, just as you did with the longer planks.
Building the Shorter Bed
Step 1
Arrange two each of the 75-inch and 36-inch beams into a rectangle with the short beams inside the long beams. Screw the rectangle together with two wood screws at each corner.
Step 2
Set one of the plywood sheets on top of the frame and attach it with a screw at each corner, two evenly spaced screws along each long side and a single screw in the center of the short side.
Step 3
Attach the 12-inch posts in the corners of this frame as you did the 66-inch posts for the loft.
Step 4
Slide the bottom bunk into position at a right angle to the upper bunk.