Quick Answer: If your mattress feels too soft, the most effective fixes are adding a firm latex or high-density foam topper, placing a plywood board between the mattress and base, upgrading to a solid platform foundation, and rotating or flipping if the model supports it. These changes can significantly improve support before replacing the mattress.
In This Guide
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Why Mattresses Go Soft Over Time
Every mattress softens with use. This is normal. Foam compresses under repeated weight, fibre fills settle, and spring tension reduces gradually. The real question is whether the softening has gone beyond what is comfortable and supportive, or whether the mattress was simply wrong for you from the start.
A mattress is generally considered too soft when it no longer keeps your spine in a neutral alignment during sleep. Side sleepers need some softness at the shoulders and hips, but even for them, the spine should stay roughly level from neck to tailbone. If you are sinking deeply enough that your hips drop lower than your shoulders, the mattress is too soft for your weight and sleep position.
Softness, Support, and Back Pain
A landmark randomised controlled trial published in The Lancet (Kovacs et al., 2003) found that patients with chronic low back pain reported better outcomes on medium-firm mattresses than on firm ones. However, research in Applied Ergonomics (Verhaert et al., 2011) found that personalised body-contour support is more important than firmness alone. The takeaway for most people: excessively soft mattresses that allow spinal misalignment are a problem, but very firm mattresses are not universally better. The goal is support with appropriate pressure relief for your body type and sleep position.
8 min read
6 Ways to Make a Mattress Firmer
1. Add a Firm Mattress Topper
A firm topper placed on top of your existing mattress is the most effective non-structural fix. Look for:
- Latex toppers (Dunlop latex, 3-4 inches): Natural latex has a resilient, supportive feel that resists permanent compression. Dunlop process latex is denser and firmer than Talalay. A 3-inch Dunlop latex topper in ILD 28-36 will make most soft mattresses feel noticeably firmer.
- High-density foam toppers (4-6 lb density): High-density polyurethane foam holds its shape and adds surface support. Avoid memory foam for this purpose since it conforms to your body shape and adds softness, not firmness.
At Mattress Miracle, we carry toppers and can advise on which will provide the firmness increase you need. Call us at (519) 770-0001 before buying.
2. Check and Upgrade Your Foundation
A soft or worn-out foundation transfers softness up through your mattress. Slats that flex, a sagging box spring, or a foundation with gaps wider than 3 inches allow foam and springs to sink into the gap. This alone can make a mattress feel 20 to 30% softer than its design.
Check your foundation by pressing down across the surface. If you feel it flex, it needs replacing or reinforcement. Options:
- A solid platform base or bunkie board provides a completely flat surface
- A slatted foundation with slats no more than 3 inches apart
- A firm box spring (not a motion-isolating soft foundation)
Brad, Owner since 1987: "Half the calls I get from people saying their mattress is too soft turn out to be a foundation issue. The mattress is fine, but the slats are bowing or the box spring has given out. It is worth checking the base first before spending on a new mattress or topper."
3. Place Plywood Between the Mattress and Base
A simple and inexpensive fix. A sheet of 3/4-inch plywood cut to the size of your mattress creates a completely solid base. This works well for mattresses on slatted frames or where the foundation is slightly soft or uneven.
Cost is typically $30 to $60 for a queen-size sheet. Drill a few ventilation holes if you are concerned about moisture build-up underneath the mattress. This is a temporary or medium-term fix, not an elegant long-term solution, but it works.
4. Rotate the Mattress (and Flip If Applicable)
Rotating a mattress 180 degrees (head to foot) redistributes wear so that the area where your hips and midsection rest is not always in the same spot. Most manufacturers recommend rotating every three to six months.
If your mattress is double-sided, flipping it puts the less-compressed side on top. One of the reasons we recommend Restonic and our Sleep In flippable mattresses is specifically this longevity benefit. Many customers who buy a flippable mattress report that it feels new again after the first flip, which typically happens at six months.
Flippable Mattresses at Mattress Miracle
Our Sleep In flippable mattresses are Canadian-made and designed to be used on both sides. They are harder to find in Brantford than single-sided models, but they tend to last significantly longer because wear is distributed across two surfaces. If longevity and firmness retention matter to you, a flippable model is worth considering. Come in to our West Street showroom to feel the difference.
5. Adjust Room Temperature
Memory foam mattresses soften noticeably in warm rooms. The viscoelastic material responds to body heat and ambient temperature. If your bedroom runs above 20°C, your memory foam mattress will feel softer than it did in a cooler environment. In Ontario winters, some customers notice their mattress feels firmer, and in summer it softens.
Lowering the thermostat slightly, using a ceiling fan, or improving bedroom ventilation can firm up a memory foam mattress by a perceptible degree without any cost.
6. Evaluate Whether a Replacement Is Needed
If your mattress is more than eight to ten years old and none of the above fixes restore adequate support, it is likely at the end of its useful life. Foam that has permanently compressed does not recover. Coil systems with broken or fatigued springs cannot be restored.
In this case, the most cost-effective long-term solution is replacing the mattress with one suited to your current weight, sleep position, and preference. The fixes above work best when the mattress has some remaining life left in it.
When Firming-Up Is Not Enough
Some signs that the mattress needs replacing rather than firming up:
- Visible sagging of 1.5 inches or more in your sleeping area
- You wake with back, hip, or shoulder pain that clears after getting up
- Your partner's movements wake you more than before (worn foam or springs reduce motion isolation)
- The mattress is over ten years old and was not a high-quality model to begin with
- The springs are audible when you move
The Case for Choosing a Flippable Mattress Next Time
If you are replacing a mattress that has gone soft, consider a flippable double-sided model for your next purchase. The main advantage is simple: when one side softens, you flip and start fresh on the other side. This typically doubles the useful life of the mattress.
We carry flippable mattresses from Sleep In (Canadian-made) and select Restonic models at our Brantford store. Dorothy, our sleep specialist, can walk you through which models are currently in stock and what the firmness difference is between sides on each model.
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Find Your Perfect Mattress at Mattress Miracle
We are a family-owned mattress store in Brantford, helping our community sleep better since 1987. Come try mattresses in person and get honest, no-pressure advice.
441 1/2 West Street, Brantford, Ontario
Call 519-770-0001Frequently Asked Questions
Can I make my memory foam mattress firmer?
You can improve the support on a memory foam mattress by checking the foundation (slats too wide or bowing will make any mattress soft), placing plywood beneath it, and keeping the bedroom cooler. A firm latex topper on top of memory foam can add surface firmness. However, if the foam has permanently compressed, no fix will fully restore the original feel.
Does a plywood board under a mattress actually work?
Yes, it is effective and inexpensive. A 3/4-inch plywood sheet placed between the mattress and a slatted frame creates a solid, even base that eliminates sag caused by gaps between slats. Many people are surprised by how much of a difference a solid base makes. Drill a few ventilation holes to prevent moisture build-up.
What firmness topper should I get for a soft mattress?
For adding firmness, use a Dunlop latex topper in ILD 28 or higher, or a high-density polyurethane foam topper (4 lb per cubic foot or greater). Avoid memory foam toppers as they add contouring and softness rather than firmness. A 3-inch topper is usually enough to notice a meaningful difference.
How do I know if my mattress is too soft or just broken down?
Look for visible sagging. If there is a body impression of 1.5 inches or more in your sleep area, the mattress has broken down. If the surface appears flat but feels soft overall, the mattress may have been too soft for your body weight from the start. In the first case, a topper or plywood may offer temporary relief. In the second case, a new mattress is the proper fix.
Is a soft mattress bad for your back?
A mattress that is too soft for your body weight can allow your hips to sink lower than your shoulders, creating a lateral curve in the spine. Over time this can contribute to low back pain. However, very firm mattresses are not always better. The goal is a mattress that keeps your spine neutral while providing enough pressure relief for your sleep position. Medium-firm is the best starting point for most adults.
Visit Our Brantford Showroom
We are located at 441½ West Street in downtown Brantford. Free parking available. Our team does not work on commission, so you get honest advice based on your needs.
Mattress Miracle , 441½ West Street, Brantford, ON · (519) 770-0001
Hours: Monday–Wednesday 10am–6pm, Thursday–Friday 10am–7pm, Saturday 10am–5pm, Sunday 12pm–4pm.