How to Build Your Own Kids Murphy Bed

Measure the length, width and depth of the child's mattress.

Cut the required pieces of 1-inch thick medium-density fiberboard, or MDF, with a circular saw: you'll need two pieces that match the measurement for width-by-depth, and two pieces to match the length-by-depth measurement.

Arrange these pieces to form a rectangle, apply glue to the connecting ends to further strengthen the structure, and screw them together at each corner using three 2-inch wood screws for each corner.

Measure the length and width of the box and cut a piece of 1/2-inch thick MDF to cover the box; this will be the exposed, bottom of the Murphy bed.

Apply wood glue around the edges of the rectangle, lay the MDF piece on top and screw it into place with 2-inch wood screws spaced every 6 inches. When the glue is dry, put the mattress inside the box and set the unit aside while you work on the wall frame.

Build a second box that is approximately 1 1/4-inch bigger on all sides than the mattress box you previously built; adjust measurements as necessary to ensure the mattress box fits inside with just enough room to move easily. This box is set inside the wall and the Murphy bed box folds up inside it.

Hold the larger box up against the wall in the desired location for the bed, then trace the outline of the box onto the wall. If you plan to add legs to the end of the bed, hold the box up higher on the wall, equal to the height of the legs you intend to use. If possible, line one or both sides of the box up with 2-by-4 studs inside the wall, using a stud finder to locate the studs.

Cut out the section of the wall along the lines with a drywall saw, circular saw or reciprocating saw. Plaster walls are more difficult to cut, so a circular saw or reciprocating saw is necessary.

Cut out the 2-by-4 studs within the area of the hole to allow the bed to fit inside the wall. Cut the boards only as high up as the height of the wall bed.

Install new 2-by-4 studs to either side of the hole in the wall, to provide a frame in which to secure the bed box. Drive 6d nails in at an angle to go through the bottom of the board into the sole plate of the wall frame and through the top of the board into the top plate of the wall frame.

Connect the 2-by-4s on the side with a 2-by-4 header at the top of the hole in the wall, providing a stable anchor for the top of the bed. Measure from the header to the top plate and nail one or two 2-by-4 cripple boards in place to increase stability. Repeat this step with the bottom of the hole if the bed will have legs; in this case, it is called a saddle and supports the headboard of the bed.

Set the second, larger box into the wall and secure to the studs, headers and saddle, if applicable, with 3-inch wood screws spaced no more than 6 inches apart. If a saddle is not used, then screw the box into the sole plate of the existing wall frame.

Fit the mattress box inside the larger box and install a large piano hinge to the bottom of the head of the bed and the floor, or saddle, of the wall frame, depending on if you plan to use legs. Open and close the bed carefully to ensure it works properly.

Install your choice of legs, if desired, to the foot of the bed. If you choose to use legs, they will be visible when the bed is closed. Options for legs may be as simple as a piece of 4-by-4-inch lumber cut to the width of the bed and screwed into the mattress box, or you might use hinged metal legs, which work like the legs of fold-out tables.

Close the bed and hold it up in position. Install three sliding bolts to secure the bed, ensuring that the pieces of the sliding bolts line up on the wall frame and the bed box.

Cover the rough edges of the cut drywall with trim molding to complete the built-in look of the bed.