How to fix a sagging mattress with plywood (5 steps)

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We know how annoying it is to sleep on a sagging mattress. From difficulty falling asleep at night to waking up with neck and back pain, it’s a complete nightmare. But, did you know that you can use something as simple as a piece of plywood to fix this? In this article, we give you a step-by-step guide on how to fix a sagging mattress with plywood support.

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Steps for fixing a sagging mattress with plywood

Follow these steps to fix your sagging mattress with plywood:

1. Gather your tools
2. Measure your bed
3. Measure the part of your mattress that is sagging
4. Cut the plywood
5. Add plywood underneath the sagging part

It’s normal for a mattress to start sagging in certain areas as time goes by. However, this could happen much sooner if you’re using an unsupportive bed frame or foundation. More on that later.

Plywood is an easy and effective way of fixing a sagging mattress. That said, plywood is not a permanent solution but it can prolong the lifespan of your mattress by at least a year or two.

Since it’s such a substantial investment, I’m sure you would prefer to make sure your mattress doesn’t sag for as long as possible.

So without further ado, here is our detailed guide on how to fix a sagging mattress using plywood.

Step 1: Gather your tools

You need to prepare the following tools and materials before you start:

• Measuring tape
• Jigsaw
• AB or BC softwood plywood

Although you can also use medium-density fiberboard (MDF), it’s not as durable and supportive as AB or BC plywood. We recommend getting a plywood sheet or planks that are at least 3/4 of an inch thick. Anything thinner than this will not provide adequate mattress support, especially if you have a mattress that’s on the thicker side.

Step 2: Measure your bed

Once you’ve gathered all the tools, use the tape measure to get the exact dimensions of your bed base. This is a crucial step to ensure that you get the correct plywood size.

If the plywood sheet is too big, it won’t fit properly on the bed frame and it could stick out from under the side of your mattress. Most hardware stores and home improvement stores provide different sizes of pre-cut plywood but if you’re handy with a saw, then by all means do the cutting but please be careful.

Step 3: Measure the part of your mattress that is sagging

Next, you’re going to measure the sagging area on your mattress. This step is optional. Do this if you only want to add plywood underneath a certain sagging spot on your mattress instead of the entire bed base.

Step 4: Cut the plywood

Use the jigsaw to cut the plywood to size whether you want to place it underneath the whole mattress or just on a specific saggy area. If you don’t have a jigsaw, you can go to the nearest home improvement center or woodworking store and have the plywood cut to size there, as mentioned previously.

You can cut the plywood into one solid board to cover the entire bed base. Or, you can also cut the it into slats. Both options are great for adding support and combating sagging, but slats will allow for airflow while a solid board will have no ventilation.

Step 5: Add plywood underneath the sagging part

The final step is to simply add the plywood underneath your mattress. Remove your mattress from the bed frame first so you can place the plywood on the base of the bed. If you’re using planks/slats, make sure they’re evenly placed and that they are no more than 3 inches apart.

You might be wondering – how about those of us who use box springs as foundations? In that case, just place the plywood board on top of the box spring. Make sure that it fits properly and try putting the mattress on top and testing it out.

Listen for any bending or creaking sounds from your mattress. If there’s none, then you did everything right. You should notice the added support on your mattress immediately.

Again, this isn’t a permanent fix so don’t expect your mattress to be as good as new. What you can expect is sturdier support and an extended lifespan for your mattress.

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How to tell if plywood support is right for your mattress

These are the signs that you need a plywood support board for your mattress:

• Your mattress is visibly sagging
• The mattress feels too thin in some areas
• Parts of your mattress are too soft

Let me delve deeper on each of these signs below.

Your mattress is visibly sagging

It doesn’t matter if you have an innerspring mattress or a springless mattress such as a memory foam model. All types of mattresses will begin to sag eventually.

If you notice visible dips or indentations on your mattress, you should consider reinforcing it with plywood or a bunkie board.

The mattress feels too thin in some areas

This next sign is closely related to the first one but instead of seeing it, you can feel the sagging areas on your mattress. If your mattress feels too thin that you’re starting to feel the box spring or bed frame below it, it’s time to take action.

Aside from adding a plywood sheet under your mattress for support, you can also place a mattress topper on top of it. A mattress topper is great for extra support, comfort, and for prolonging your mattress’ lifespan.

Parts of your mattress are too soft

If there are certain spots in your mattress that aren’t as firm and supportive as it used to be, this means it has started sagging. The earlier you notice this, the better so you can add plywood support immediately.

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Benefits of placing plywood underneath your mattress

You should place plywood underneath your sagging mattress because:

• It’s an easy solution
• Plywood is durable
• It extends the lifespan of your mattress

Is plywood any good for enhancing mattress support? The short answer is – yes. The following are the benefits of placing plywood underneath your mattress:

It’s an easy solution

Placing plywood under a mattress is extremely easy and you can do it with minimal tools. Plywood is also affordable and readily available in home improvement centers and lumber distributors.

Plywood is durable

AB or BC plywood is more durable than the commonly used medium-density fiberboard (MDF). It’s made of several layers rather than one solid piece of wood which makes it sturdier and more supportive overall. Just make sure that you use thick plywood to carry the load of your mattress and your body weight.

It extends the lifespan of your mattress

Lastly, the support that plywood provides can extend the lifespan of your mattress. It can help combat wear-and-tear and it will help you feel well-supported when you sleep.

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Causes of a sagging mattress

Most mattress manufacturers and brands might market their products as immune to sagging. That simply isn’t true. Even the most durable and most expensive latex or hybrid mattresses are bound to sag after many years of continued use.

The following are the most common causes of a sagging mattress:

Sleeping in the same spot

Sleeping on the same spot for several years has a high chance of creating dips and body indentations. But, it also depends on your body weight. The heavier the load is on the mattress, the quicker it starts sagging.

That’s why we always recommend getting a mattress that’s suitable for your body type and weight. Light to average weight individuals can do well on an all-foam mattress, whereas heavier people should opt for a hybrid mattress that combines supportive coils and foam. We also recommend rotating your mattress every 3-6 months, which we get more into below.

Poor mattress maintenance

It’s common for people to forget about maintaining their mattress. If you’re one of these people, then you should start taking care of your mattress today.

The first thing you can do is rotate your mattress 180 degrees every 3-6 months. This prevents you from sleeping in the same spot all year-round. This way, the load will be evenly distributed throughout the mattress surface.

Next, you should regularly wash your sheets and other bedding. Sweat and dead skin cells can accumulate over time and slowly weaken the layers of your mattress. That’s why keeping your mattress clean and fresh is very important.

The last thing we can recommend is adding a mattress protector for your mattress. Most good-quality models are waterproof and are great for protection against accidental spills and stains.

Old, worn-out mattress

The average high-quality mattress can last at least 7-10 years, while some models can last up to 20 years. Of course, this is assuming the mattress is properly maintained and kept clean on a regular basis.

If your mattress is severely sagging and worn-out, it has reached the inevitable end of its lifespan. No amount of plywood support can fix it at this point and your left with only one option – replacing the mattress with a new model.

If this is your situation and your mattress is completely worn-out and old, we recommend taking a look at our best mattresses list for the top five brands this year.

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FAQs

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Conclusion

Finally, you can get a good night’s sleep again now that your sagging mattress has been fixed. Plywood boards and planks provide sturdy support to prevent further sagging and to extend the lifespan of your mattress. From now on, make sure to take care of your mattress by cleaning it and rotating it regularly to combat wear-and-tear.

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Next step: Read our Bear Elite mattress review. If your mattress is so worn-out that it’s impossible to stop it from sagging, then it’s time to get a new one. We like the Bear Hybrid because its supportive coil base helps prevent indentations so it never sags.

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Psst… the sleep review industry is full of liars, sharks, and thieves. It’s a modern-day version of getting ripped off at your local mattress store. So, why should you trust us?