When the hitch in your giddy-up starts the minute you get out of bed -- you wake with a crick in your neck, your back or both -- it's time to think about ways to fix that sagging mattress. It might be an old bed, and your budget won't support shelling out for a new one. Even brand new mattresses can sag in just a few months' time. You have several inexpensive methods of fixing that sagging mattress.
Measure the length and width of the mattress with a measuring tape.
Transfer the measurements to the plywood sheets and cut them lengthwise to fit atop the box spring. Full plywood sheets come in 4-by-8 foot dimensions, so you will need two sheets of plywood for a double, queen- or king-size bed. Sand any rough spots on the plywood where you made the cuts.
Pull the mattress from the bed after removing the bed clothes.
Lay the plywood sheets atop the box spring, with the sanded cut sides to the outside. This allows you to butt the uncut edges of the plywood together in the middle of the box spring.
Place a sheet of vinyl or plastic atop the plywood sheets to protect the mattress and eliminate any concern that you may have about children's accidents or moisture retention in the wood.
Place the mattress on top of the vinyl-covered plywood and arrange it to fit as necessary.
Bed Support Products
Find the product that fits your bed and budget to support your sagging mattress. For instance, you can choose a plastic board with an uplifted center that fits between the mattress and foundation across the width of the bed. Or you can use heavy-duty baffled-sewn polyurethane foam under-mattress support sandwiched between the box spring and the mattress. Some online sites also offer foldable bed boards in various widths made of fiber ply-board covered in vinyl. The boards go between the foundation and mattress to keep the mattress from sagging.
Slide the plastic support product between the foundation and the mattress centered in the middle width of the bed, if you chose that product.
Remove the mattress from the foundation to lay out the foldable bed-board or to position the heavy-duty baffled polyurethane foam. Center the support product in the middle of the foundation based on its size. If you chose the foam product, you will need to center two foam units underneath where each person sleeps for a two-person bed.
Replace the mattress on top of the sag-mitigating support.
Remove the mattress from the box-spring foundation and set it aside.
Fold several thick blankets and set them atop the foundation where the mattress typically sags, generally the middle of the bed.
Arrange a pillow or pillows atop the blankets to provide added lift for a mattress that sags in the middle.
Reposition the mattress and verify it doesn't sag. If it still sags a bit, remove the mattress and continue building up the areas that sag with a combination of folded blankets and pillows.