Quick Answer: Can You Fix a Sagging Mattress?
Sometimes. A mattress topper can add support if the sag is minor (under 1 inch). Rotating or flipping your mattress may help even out wear. But if the sag is deeper than 1.5 inches, the internal structure has likely failed, and no topper will fix that. At that point, you need a new mattress.
Why Mattresses Sag in the First Place
Every mattress will eventually sag. It's not a design flaw. It's physics.
Your body puts the most pressure in the same spots night after night. Hips and shoulders bear the most weight. Over time, the foam compresses and the springs fatigue in those areas.
Some mattresses hold up better than others. Higher density foams and individually wrapped coils tend to last longer. Budget mattresses often use lower density materials that break down faster.
What Causes Mattress Sagging
- Body impressions: Repeated pressure in the same spots compresses the materials
- Foam breakdown: Lower density foams lose their resilience after 3-5 years
- Spring fatigue: Metal coils weaken over time, especially in high-pressure areas
- Foundation problems: A bad foundation or box spring can cause uneven support
- Age: Most mattresses are designed to last 7-10 years
Fixes That Actually Work
1. Add a Mattress Topper
If your sag is less than 1 inch deep, a firm mattress topper (3-4 inches thick) can fill in the depression and restore a flatter sleep surface. Memory foam or latex toppers work better than thin fiber toppers.
Here is the honest part: a topper does not fix the mattress. It masks the problem. You are adding a band-aid, not a cure. But it can buy you another year or two of comfortable sleep.
2. Rotate Your Mattress
Most people sleep in the same position every night. Rotating your mattress 180 degrees every 3-6 months distributes wear more evenly. The spot where your hips were is now where your feet go.
This works better as prevention than as a fix. Once the damage is done, rotating will not undo it.
3. Flip Your Mattress (If It's Flippable)
Most modern mattresses are one-sided and cannot be flipped. But if you have a two-sided mattress, flipping it gives you a fresh sleep surface while the worn side recovers underneath.
We carry flippable mattresses at Mattress Miracle specifically because they last longer. Twice the surface area means twice the lifespan.
4. Check Your Foundation
Sometimes the mattress is fine. The foundation is the problem. Slats that are too far apart, a broken box spring, or a frame that has shifted can all cause the mattress to sag in the middle.
Put your mattress on the floor for a week. If the sag disappears, your foundation needs attention, not your mattress.
5. Use Plywood Under the Mattress
A sheet of 3/4 inch plywood between your mattress and foundation creates a solid, flat surface. This prevents the mattress from dipping into gaps between slats.
Fair warning: this makes the bed firmer. If you already find your mattress too firm, this fix will make it worse.
When Fixing Is Not Worth It
If your mattress is more than 8 years old and the sag is deeper than 1.5 inches, you are fighting a losing battle. The internal support structure has failed. A topper might help for a few months, but you will be back to the same problem. At that point, the money you spend on temporary fixes would be better put toward a new mattress.
Fixes That Do Not Work
We have heard them all. Here is what does not help:
- Putting books or boards under the sagging spot: Creates an uneven surface that is worse than the sag
- Vacuuming the mattress: Good for dust mites, useless for structural support
- Letting the mattress sit in the sun: May help with odors, does nothing for sagging
- Flipping a one-sided mattress: You will be sleeping on materials not designed for sleeping
Mattress Help in Brantford
If you are not sure whether your mattress can be saved, bring in some photos. We will tell you honestly if a topper will help or if you need to start shopping. No pressure either way. We have been doing this since 1987, and we would rather give you good advice than sell you something you do not need.
When to Replace Instead of Fix
Replace your mattress if:
- The sag is deeper than 1.5 inches
- You wake up with back or hip pain that goes away during the day
- You sleep better in hotels than at home
- The mattress is more than 10 years old
- You can feel springs poking through
A good mattress is not cheap. But neither is chronic back pain. In our experience, people who wait too long to replace a failing mattress spend more on toppers, chiropractor visits, and pain medication than they would have spent on a new mattress.
Frequently Asked Questions
Can a mattress topper fix a sagging mattress?
For minor sags under 1 inch, yes. A 3-4 inch firm topper can fill in the depression and create a flatter surface. For deeper sags, a topper helps temporarily but will not solve the underlying problem. The mattress structure has failed and will continue to worsen.
How deep of a sag is too much?
Most mattress warranties consider 1.5 inches to be the threshold for defective sagging. At that depth, the internal support has failed and cannot be repaired. If your sag is less than 1 inch, you have more options. Between 1-1.5 inches, a topper may help but expect limited results.
Does rotating a mattress prevent sagging?
It helps distribute wear more evenly. Rotating your mattress 180 degrees every 3-6 months means your heaviest pressure points (hips and shoulders) are not always in the same spot. This slows down sagging but does not prevent it entirely. All mattresses will eventually develop some body impressions.
Why does my mattress sag in the middle?
Two reasons. First, if you sleep with a partner, your combined weight compresses the center where you both roll toward. Second, your foundation may be the problem. Slats that are too far apart or a worn-out box spring cannot support the mattress properly in the center. Try putting the mattress on the floor to test if the foundation is causing the issue.
How long should a mattress last before sagging?
Quality mattresses should maintain their support for 7-10 years. Lower-cost mattresses with less dense foams may start sagging after 3-5 years. Flippable mattresses tend to last longer because you can use both sides. If your mattress is sagging significantly before 5 years, it was either poor quality or the foundation is not providing proper support.
Questions About Your Mattress?
Not sure if your mattress can be saved? Stop by and we will take a look. We have toppers if you need a temporary fix, and mattresses if you need a long-term solution. Either way, we will give you an honest answer.
Mattress Miracle
441 1/2 West Street, Brantford, Ontario
519-770-0001
Family owned since 1987