Repairing and Preventing Sagging Mattresses

old folded over mattress

A saggy mattress that sinks in various spots isn’t just an indicator that your mattress is old or in need of repair. A sinking mattress also means that you’re in for a world of discomfort, back pain, and sleep problems.

To be clear, the best option is to replace a mattress that sags with a new one. However, if you don't want to buy a brand new mattress on the sole basis of a little sagging on your otherwise usable one, you can repair it instead.

Even though traditional mattresses require more complex repair than something like an air mattress, which you can buy repair kits for, there are still ways you can check your current mattress and make small fixes to breathe some life back in to it.

Underneath the Mattress

When tackling issues that may cause a mattress to sag, check for the following situations under your mattress. In many cases, adding a new piece or simply replacing an old piece can fix sunken in mattresses.

Box Springs

If the mattress set you have includes box springs, check them. Many times, if the box springs are worn out, replacing them will fix the sag in the top mattress. Buying replacement box springs is less expensive than buying a whole mattress set.

A Layer of Plywood

Measure the mattress and cut a sheet of ½ inch thick plywood the same size. You may have to use two pieces, depending on the size of the mattress. Place the plywood between the box spring and the mattress, assuming you have a box spring.

Replacing Slats

Check the slats in the frame under the box springs. Replace them if they are warped. Add one or two more for extra support, especially where the sag is. You might consider replacing 1x4s, the usual width of bed slats, with 1x6s or 1x8s to provide even more support.

Memory Foam

Put a piece of memory foam between the mattress and the box springs where the mattress dips.


There is also a type of bladder, or inflatable pouch, available that pumps up like an air mattress that can be placed between the mattress and box springs where the sag is. These bladders come in different sizes for different sized beds.

On Top of the Mattress

There are several types of mattress toppers that can help with a sagging mattress. Some are less expensive than replacing a whole mattress set. Options include: a memory foam mattress topper, air mattresses, or down mattress toppers, which can be up to 3 inches thick. Keep in mind prices will vary depending on the thread count of the cotton, the amount of stuffing in the topper, and its size.

Something else you can use above the mattress to make an impact are body pillows that are filled with down or polyester. They contour to your body and provide extra support for any sleep position.

Preventing Mattress Dips and Sagging

As with most things, prevention is easier than the cure. Here are some things you can do to help prevent your mattress from sagging in the first place.

Turning Your Mattress

Unless you have a no-turn mattress, shift the mattress in three cycles on a regular basis. The first cycle entails rotating the mattress (without flipping it over) so that you swap the position of the head of the bed and the foot of the bed. The second cycle is flipping the mattress over, but don’t do any rotating this time. The third cycle is rotating the head to the foot again, but this one differs from the first cycle since this time it will be on the opposite side of the mattress.

Regular Checking and Maintenance

Check both the box springs and the slats of the frame on a regular basis to make sure everything is still in good shape. The springs should have a fair amount of give but still be springy and the slats should not show signs of warping. Maintaining this strong foundation prevents sagging in the top mattress.