How To Fix A Sagging Mattress with Plywood?

A sagging mattress that tends to sink at the center or in several spots can be a sign that your mattress is getting old. A sinking mattress forms the basis of pain in pressure points, general sleep discomforts and groggy mornings characterized by mild or intense headaches. It may also interfere with your sleep schedule and end up leaving you with a huge sleep debt. Because there’s no mattress that guarantees too many years of longevity, it’s highly likely that at some point in time, your mattress will sag.

Ideally, the best and most recommended option for such a situation is to replace the old mattress with a new one. But considering how expensive investing in sleep equipment can be, you may consider finding a temporary solution to allow you more time to raise as much money as you may need for a good mattress. The primary goal should be how to fix a sagging mattress to extend its lifespan while keeping it fresh.

What Causes a Mattress to Sag?

There’s a wide variety of mattresses on the market today. Additionally, there’s endless controversy on what constitutes a good mattress based on the several types including traditional mattresses, spring mattresses, latex mattresses, memory foam mattresses and complete multilayered bedding systems. Among such types you mostly need to know how to fix a sagging memory foam or pillow top mattress. In fact, these are few types people tend to use much.

As compared to the past when people had fewer options to choose from with a limited set of criteria to refer to when choosing their mattresses, there’s a huge pool of sleep equipment being advertised daily.

Given the availability of traditional mattresses as the auxiliary recourse, it used to be that the only way you could gauge the longevity of a mattress was on the basis of their thickness. This implied that the thicker the foam was, the longer it was likely to survive – the reverse might have been true.

However, with evolving changes, new technologies have been developed and incorporated into mattresses thus diversifying the options and creating more check boxes for prospective buyers. Nonetheless, all these types of mattresses are bound to sag for either one of the following reasons:

1. Poor Quality

Unfortunately with the many different kinds of mattresses, it can be pretty hard to find a perfect one. It is important that the mattress you go for is of excellent quality.

As compared to lower quality options, high-grade mattresses are usually made with an ideal ratio of components that helps to withstand sinking and sagging, meaning that you won’t have to worry about disintegration and aging of the foam.


The materials used in the construction of mattresses are different and may vary from one type or brand to the other but they have to be incorporated in perfect proportions for effectiveness. A good way to determine the quality is to read through customer reviews to assess their experience with the mattress based on the materials used in its construction.

2. Old Box Springs

One of the common reasons for sagging mattresses that may often go unnoticed is aged box springs. While the mattress may be in perfect condition and capable of withstanding a longer period of use, the box springs are likely to break, get old or damaged thus causing it to sag.

Therefore, it’s necessary that box springs are replaced every few decades or checked regularly for damages. Box springs are significantly cheaper than a new mattress, thus replacing old or damaged ones is generally regarded as not such a huge cost.

3. Poor Maintenance

Typically, eight years is the possible maximum comfort life for good-quality mattresses. However, it is recommended that a mattress be flipped and rotated every once or twice every month in order to extend this lifespan. This also helps to even out the wear on the mattress thus preventing sagging and excessive dipping.

Sagging is likely to occur from deep body impression particularly when a mattress is not properly rotated. Without rotation, any quality mattress is susceptible to sagging.

4. Frequent Usage

The most obvious and most common cause of a sagging mattress is frequent usage. Old mattresses are definitely bound to sag. There are countless debates on how often a mattress needs to be replaced.

Essentially, it’s important to replace an old one every 8 years. But before you even think of replacing your old mattress, there is the option of remedying the sagging using plywood.

How Do You Fix a Sagging Mattress Using Plywood?

A layer of plywood cut to the dimensions of your bed can be the ultimate way to fix sagging mattress either temporarily or as a means to completely restore it to its original comfort level.

Depending on the size of the mattress, you might need to use two pieces.


If you have a box spring bed, the plywood can be placed between the mattress and the box spring but if yours is a slat-based bed, you can lace the slats with the plywood sheet. Here’s how you can go about it:

Step 1

The first step is to determine the type of the mattress. The underlying factor for sagging of a mattress could be more predominantly based on its type. This helps to determine whether or not using plywood would help to fix the sagging. Plywood is an effective option for most types of mattresses but it may not be as useful in innerspring, waterbed and air mattresses. Using it on a wrong type of the mattress will be ineffective as the effect of the support is more or less absorbed than it is transferred.

Step 2

Measure the depth of the sag to determine the ideal thickness that will reverse the sagging. This you can do using a tape measure and yardstick positioned perpendicularly. Knowing the depth of the sag forms the basis of the desired overall thickness of the sleeping surface once plywood is fitted onto the bed.

Step 3

Using a saw, cut a piece of plywood. Make it smaller than the dimensions of your bed and mattress by an inch. Place the plywood between the box spring and the mattress. If the sagging is as a result of lack of support, plywood will provide the mattress with a firm base. For a bed with a slat base, lay the sheet of plywood on the slats of the bed frame and place the mattress on top of it. This should be able to support the mattress from beneath and prevent it from sagging.


If the underlying cause of sagging is frequent use, plywood may only help as a temporary solution. What you need to do is cut a piece of plywood that matches the shape and size of the sagging area and place it under the mattress in the soft spot. This should push up on the mattress from the problem area and make it feel firmer and more like the rest of the mattress.


Much as using plywood is a great way to fix sagging and make a mattress firm, it does have some drawbacks. Basically, since the bottom of the mattress rests flat against the wood, air circulation around it is limited therefore increasing the risk of the growth of mildew at the bottom of the mattress, more so if you live in a particularly humid area. This means that the plywood will be able to help to an extent but for a certain period of time after which the mattress becomes less comfortable.


Plywood is an excellent choice if you are looking for a short-term solution to remedy sagging before taking up a long-term fix either by purchasing a new mattress or replacing an old box spring. There are a couple of practices that can be implemented to prevent sagging altogether. This may include flipping or rotating the mattress regularly to expose the unused portions of the mattress while providing better internal support as well as a firmer place to sleep without the need for plywood. Placing the mattress on the floor might also help keep it flat while acting as a stop-gap solution.

Ending Thoughts

Investing in a new mattress may not be in the cards quite yet for you despite the fact you may have been using the same mattress for more than 8 years without replacing. And it’s possible your mattress has worn out and in the process sagged leaving you with sleepless nights. A bad night’s sleep is the perfect recipe for short term effects on health like headaches and drowsiness that may develop into long term effects such as sleep apnea, a weakened immune system, weight and respiratory complications. Due to this indentation, back and neck pain are also guaranteed consequences of sleeping on a sagging mattress.

You might want to use plywood to ease up on the sagging while still saving up to replace your old mattress. Of course all mattresses eventually fail, wear out or lose comfort but with proper care, a good box spring and plywood support beneath the mattress and the right metal frame, your investment can be protected for sure.

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