How to Make a Staircase Bunk Bed

Measure the mattresses you will use to begin the basic framework design. Plan a twin bed over a twin bed, or design a twin bed over a full bed, for example. Purchase a bunk bed construction plan, as one option. Count on a twin mattress measuring close to 3 1/2 feet wide by 6 1/2 feet long. Draw the bed design by planning stairs leading up at one end that will measure 24 inches wide with 1 foot between stair treads.

Build the basic framework for applying plywood as a platform under each mattress. Cut two boards, each 2 by 6 inches, with a circular saw. Make them 88 inches long, for example. Cut two boards, each 2 by 6 inches, that are 48 inches long as well. Do not miter the corners because corners will need bulk for strength.

Fit all four boards together in a rectangle whereby the framing will stand on its 2-inch sides. Bolt all corners with two carriage bolts each.

Repeat Steps 3 and 4 to construct an identical frame for the second twin bed in the bunk bed unit.

Secure each rectangular box with four separate 1-by-6-inch crosswise boards that are 44 inches long. Bridge the longer two sides together with these shorter boards, which must be cut to fit inside the framing box. Screw these connecting boards into place 3 inches down from the top and 3 inches up from the bottom.

Cut 3/4-inch plywood to form a mattress platform. Fit the plywood to rest on the crosswise boards. Screw the plywood into place, making room for a slightly smaller mattress to rest a couple of insides inside the framework.

Cut 4-inch square post material to fit the bed corners. Attach the bed framing to the posts with carriage bolts.

Build a staircase at the end of the bed. Make the stairwell by constructing stair stringers from sheets of 3/4-inch thick plywood. Design and cut the stairs so that the finished tread is 24 inches wide. Cut stringers so steps will measure 12 inches from the top of one tread to top of the next tread. Allow five steps total, not counting the top bunk's final landing -- the last stepping place before climbing into the top bunk.

Nail the risers and treads over the stringers, so the staircase is a stand-alone unit leading up to the top bunk.Construct a stairwell to surround the stairs before you bolt the stair unit to the bed unit with carriage bolts. Build the stairwell of 3/4-inch thick plywood as well.

Attach all railings for safety on one or both sides of each mattress. Predrill holes and bolt these safety rails to the bed's mattress platform or larger posts at the four corners.