Older mattresses have a tendency to sag, and that can cause you to wake up with a backache or--perhaps worse--make it difficult for you to get any sleep. But there is a solution that does not involve buying a pricey new mattress. Making a back board for your bed is an inexpensive and simple way to solve the problem.
Measure the length and width of your mattress. Measure and mark a sheet of plywood 2 inches shorter than the length of your mattress. Measure and mark the sheet 2 inches shorter than the width of your mattress. You want the plywood smaller than your mattress so that it does not stick out and catch on sheets and blankets.
Cut the plywood along the marked lines. Sand the edges of the plywood to prevent splinters.
Place the board on your box springs. Make sure that the plywood is centred, so that no edges hang over. To keep it from slipping, drill and insert several wood screws through the plywood and into the wooden frame of the box springs.
Place the mattress on top of the secured back board.
Measure the length and width of your mattress. Since full-size and larger mattresses are wider than a sheet of plywood, you must use two pieces to support the mattress.
Measure and mark the plywood to cover the width of the bed, minus 2 inches. Cut the plywood with circular saw. Repeat this procedure with a second sheet of plywood.
Lay the cut pieces of plywood side by side, as they will fit on your bed. Run the length of each piece of plywood across the width of the bed to avoid the joint where the two pieces meet from getting too much direct pressure when the mattress is in use. Measure and mark the length of your bed from the top of the plywood. Cut the lower piece along the marked line. Sand edges to prevent splinters.
Remove the mattress from your bed and place the pieces of plywood on the box springs. Make sure the plywood does not hang over the edge. To keep it from slipping, drill and insert several wood screws through the plywood and into the wooden frame of the box springs.
Place your mattress on top of the secured back board.
Particle board may be used instead of plywood.
Wear safety glasses when using a circular saw.