Transform a spare room or media room into a guest bedroom with addition of a Murphy bunk bed that holds two twin mattresses.
About This Project
Maximize space by placing a custom side-fold Murphy bunk bed in an unused closet or odd-sized nook in a room. To further customize this bed, the bottom can be used as an area for arts and crafts, playing board games or creating artwork.
Gather your supplies before you start this project.
Hand-held drill and bit driver set
7 1/4" circular saw or table saw
Pocket screw jig
Band saw or hacksaw with metal blade
Household clothes iron
15 ga. finish gun
Wrench and socket set
7/8" paddle or Forstner bit
5 sheets of prefinished birch plywood 3/4"
3/4" birch edge banding
8 bronze flanged-sleeve bearings for 5/8" shaft diameter, 7/8" OD, 1/2" length
4 alloy steel shoulder bolts, 5/8" shoulder dia., 1 1/2" Shoulder, 1/2"-13 thread
4 steel coupling nut, 1/2"-13 thread size, 1 1/4" length
4 fully threaded hex head cap bolts, 1/2"-13 thread, 1/2" length
16 flat washers, 1/2" hole size, 1 1/4" OD
1 heavy-duty piano hinge with holes, unfinished, .042" thick, 1 1/16" Width, 2' length
24' of 1x4 poplar
60 pocket screws
100 15 ga. 1 1/4" finish nails
2 5" bunk mattresses
2 gate latches
1 dual-spring-enclosed trailer ramp spring and cable set (approx. 76" wide)
64 1.25" wood screws
Step 1: Determine Location
Could an existing nook in a room be used? Generally, closets in bedrooms should not be used as this may reduce the number of counted bedrooms when a house is resold. For a side-folding twin-sized mattress, a space at least 80.5" wide x 83.5" tall x 12" deep will be required.
Step 2: Measure and Cut Materials
A standard twin-sized mattress is 39" x 75" with bunk mattresses available as shallow as 5" deep. If a deeper space is available, modify these instructions for a standard-depth mattress. Start by cutting a sheet of 3/4" prefinished plywood into 5" strips with a fine-toothed blade. Rip eight 5" rows out of one sheet. Then trim the strips to create the following pieces: four 76.5" x 5" and four 39" x 5". Next cut two 40.5" x 76.5" pieces out of two more sheets of plywood. These will form the box bottoms.
Step 3: Drill Screw Holes
Assemble the boxes with pocket screws. Drill pocket screw holes 16" on center on one side of each long edge of each piece. Drill two pocket screw holes on one side of each short edge of the short 39" pieces only (four holes total). Be sure to set the depth of the jig for joining two 3/4" pieces of material.
Step 4: Assemble Sides
Using a bit driver and a framing square, assemble the box sides onto the box bottom starting with the long pieces first. They will be flush with the box bottom whereas the short sides will be inset 3/4” on each side. Once all sides are attached to the bottom fasten the corners of the short pieces (to the long pieces), ensuring the corner remains square and flush along the outside edge.
Step 5: Edge Band Exposed End Cuts
Set a clothes iron to medium heat and allow to fully warm. Start the edge band at one end and slowly heat it while moving along the piece. Be sure to run the banding straight; go back, reheat and rework any off-track sections. Cut the banding flush at each end and then use a banding trimmer to remove any excess once the piece has cooled. Lightly sand each edge to knock the sharpness off.
Step 6: Build Frame
The frame will be constructed out of 3/4" plywood and needs to be sized as deep as the space it is installed in. The total dimensions in this case will be 77" wide x 84" tall x 14" deep (clear). If the space is larger, infill frame to 80.5" wide x 83.5" tall for the bed frame to have room for shims against the framing. Cut two 14" x 82.5" sides and one 14" x 80" top out of a piece of plywood. Cut two 40.5" x 5" pieces out of scrap plywood. Arrange these on one of the 14" x 82.5" sides to determine the correct pivot point. Both sides should be able to open and close without hitting each other. Position them so that the bottom face is 3/4" proud of the frame when closed. Be sure to space them vertically so that equal space is present between the floor, the bed frames and the top frame. Use a small nail or screw to temporarily test the pivot points. The closer to the center of the mattress the better the balance will be. In this case, the depth was limited so the pivot point is biased to the back of the mattress.
Step 7: Screw Frame Sides and Top Together
Once the pivot point is established, pocket-screw the concealed outside edges of the frame sides and top together. Use spare strips of plywood across the back top and bottom to help keep the frame square. Cut four approximately 4" x 80" pieces of plywood and laminate both sides of the outer face of the vertical frame legs with 1.25" wood screws. Transfer the pivot points and drill the vertical frame legs with a 5/8" bit. Epoxy the coupling nut in this hole.
Step 8: Finish Frame
Drill the mattress frame at the pivot point with a 7/8" bit and epoxy a flange bearing in each side. Once the epoxy dries, install one 1/2" cap bolt with washer in the outer face of the coupling nut with a thread locker.
Step 9: Install Outer Frame
Install the outer frame into opening. Align the frame so that it is flush with the existing wall covering less trim. Plumb each side with a level and shim as required. Fasten with 15 ga. finish nails (at least 2" long) through the inner face of the plywood frame and into the opening framing at each shim. Make sure to secure this frame as it carries half of the total bed weight. Trim the perimeter of the plywood frame to the wall with 1x4 poplar (or trim to match the existing space).
Step 8: Install Upper and Lower Mattress Frames
With an assistant, install the lower mattress frame in the opening, passing one shoulder bolt threaded with four washers through the flange bearings threaded on the back side with three washers into the coupling nut. Tighten shoulder bolts with a thread locker. Temporarily secure the mattress frame by leaning it against the back wall. Following the same steps, install the upper mattress frame.
Step 9: Trim Out Bottom Face
Trim out the bottom face (visible when closed) with 1x4 poplar with a 1" overlap on the outer frame trim that was already installed. Since this trim creates the outer parallel pivot point for the mattresses, fasten it with pocket screws from the back. Two vertical legs and two horizontal pieces will cover the 0.25" gap between the mattresses and the outer frame. The vertical legs will not be full-length as they form the front leg supporting the mattress. Cut four pieces of piano hinge at 3.5" and fasten them to the bottom edge of the mattress frames behind the floating outer trim. Fasten the floating trim to the piano hinge.
Step 10: Install Gate Latch
Install one gate latch at the mid-span point of the floating trim (at the bottom frame piano hinge point) to the outer fixed trim on the wall. This is only to hold the frame closed, not to support the weight. Lastly, there will be one piece of 1x4 trim fixed to the outer frame (below the floating portion that forms the mattress leg). It may be necessary to back-cut the floating leg so that these two pieces do not contact on opening.
Step 11: Finish Up
The final steps include installation of a ladder, a safety rail to the upper bunk and a spring counter-balance system. The simplest spring balance system is a double-drum-enclosed trailer ramp spring and cable set. These are available both locally at trailer vendors as well as online. The spring set will install across the interior head of the outer frame. Follow the manufacturer's instructions for installation and tension-setting, and connect the cable to the outer edge of the upper bed frame. The spring-load tension should be set so that the bed has a slight upward movement when released near the closed position. This step is very important as the bed can cause a hazard to young children that attempt to open it.
A ladder can be constructed out of a variety of fun and innovative materials to match the bunk bottoms. In this case, a simple ladder was made from 2x4s to match the “billboard” art sign painted on the bottom of the bunks. The ladder should mount directly to the floating trim to hinge with the bed. Make sure the ladder feet touch the floor when the bed is open to fully support its own weight. The upper bunk also needs safety rails installed on both sides. The interior side should have a rail installed across the entire length. The exterior side should have a rail starting at the ladder edge and both should be at least 5" above the mattress. If in doubt, be sure to contact the local health department, a licensed contractor and online resources such as the CPSC.