Memory Foam Explained: Types, Densities and Off-Gassing UK
Memory foam mattresses are made from viscoelastic polyurethane foam that moulds to the body under heat and pressure before slowly returning to shape. UK mattress buyers should understand the different memory foam densities, cooling technologies, and potential VOC off-gassing to select a product that balances pressure relief, support and indoor air quality.
What Is Memory Foam?
Memory foam, also called viscoelastic foam, was originally developed by NASA in the 1960s for aircraft seating. It reacts to body heat and weight, contouring closely to reduce pressure points. In UK beds this material is used in mattresses from small single up to super king. Open-cell and gel-infused versions have been introduced to address the traditional drawback of heat retention. Always check the exact product specifications on the page before purchase.
Types of Memory Foam
Standard memory foam offers classic slow recovery. Gel memory foam incorporates cooling gel beads or infusions to dissipate heat. Plant-based memory foam replaces a proportion of petroleum-based polyols with natural oils such as soy or castor. Hybrid memory foam layers the foam with pocket springs for improved breathability and edge support. For children, softer formulations are used in dedicated kids memory foam mattresses.
Shop the full range of Memory Foam Mattresses or view Kids' Memory Foam Mattresses if buying for younger family members.
Plant-Based and Eco Memory Foam
Brands such as SOLACE+CO use plant-derived ingredients to reduce reliance on fossil fuels while maintaining viscoelastic properties. These foams often meet the same UK fire-safety standards (BS 7177) as conventional versions. They typically produce lower VOC emissions during initial off-gassing.
Memory Foam Densities Explained
Density is measured in kilograms per cubic metre (kg/m³) and indicates durability and feel. Lower-density foam feels softer, responds more quickly and is lighter to turn. Medium-density foam offers a balance of contouring and support for most sleepers. High-density foam provides firmer support, resists body impressions longer and usually costs more.
Use this quick checklist when comparing densities:
- Measure your current mattress depth in cm and compare recovery speed.
- For side sleepers, test 55kg/m³ or higher to avoid shoulder sinkage.
- Check the maximum mattress depth allowed by any bunk bed; top bunks must comply with BS EN 747 and require at least 16cm clearance above the mattress to the guard rail.
- Consider room temperature: higher-density foam retains more heat unless gel or open-cell technology is used.
Cooling Properties of Memory Foam
Traditional memory foam can sleep warm because it conforms so closely that airflow is restricted. Modern cooling memory foam uses gel particles, graphite, or phase-change materials to draw heat away. Open-cell structures improve ventilation compared with closed-cell designs. Pairing a memory foam mattress with a breathable Mattress Protector helps wick moisture and maintain surface temperature. For hotter sleepers, consider switching to a Latex Mattress which naturally promotes airflow without the slow-sink feel of memory foam.
Off-Gassing and VOC Concerns in the UK
Off-gassing is the release of volatile organic compounds (VOCs) from new polyurethane foam. Most memory foam mattresses emit a slight chemical odour for a few hours to several days. UK regulations under the Furniture and Furnishings (Fire) (Safety) Regulations 1988 require all mattresses to meet BS 7177 fire resistance; this does not directly control VOC levels but reputable makers minimise them. To reduce exposure, unroll the mattress in a well-ventilated room, ideally outdoors or with windows open for 24-48 hours before use. Sensitive individuals or households with children may prefer plant-based foams with lower VOC profiles. A simple decision rule: if the odour persists beyond one week, contact the retailer.
Choosing the Right Memory Foam Mattress
Match density to body weight and sleeping position. Heavier adults usually need higher density to prevent bottoming out. Lighter sleepers or those who change position frequently may prefer lower density. Check whether the mattress is single-sided or dual-sided for rotation. Always verify the stated maximum mattress depth on children’s beds or bunk beds to maintain the required 16cm guard-rail clearance above the sleep surface for safety. Consider adding a thin Mattress Topper if you want to adjust firmness without replacing the entire bed.
Recommended brands include Flair, Solace+Co, Maxitex, Recoil and Noomi. Look for their names when comparing specifications on individual product pages.
| Density (kg/m³) | Typical Feel | Best For | Durability Expectation |
|---|---|---|---|
| 40-50 | Soft, quick response | Light sleepers, children | 4-6 years |
| 50-65 | Balanced contouring | Most adults, side and back sleepers | 6-8 years |
| 65-80 | Firmer support | Heavier adults, stomach sleepers | 8+ years |
Practical checklist before buying:
- Confirm the mattress size matches your bed frame.
- Decide on cooling needs and check for gel or open-cell wording in the product name.
- Review the maximum mattress depth allowed if using with bunk beds or cot beds.
- Choose plant-based options where VOC sensitivity is a concern.
- Compare at least three similar densities across different brands.
Our picks for this guide
- SOLACE+CO Plant Based Eco Memory Foam Mattress – Uses plant-based memory foam with lower VOC off-gassing while delivering classic pressure-relieving contouring suitable for most UK sleepers.
- Maxitex Fresh Ortho Cool Memory Mattress – Features cooling technology in a medium-to-high density memory foam layer to reduce heat retention, ideal for hot sleepers concerned about traditional memory foam warmth.
- Maxitex Kids Magic Memory Foam Mattress – Specifically formulated lower-density memory foam for children, meeting UK safety standards with reduced sink and easier off-gassing management.
- Noomi Waterproof Eco Foam Mattress Single – Eco foam construction with waterproof protection offers a practical low-VOC choice for single-bed setups and households prioritising air quality.
Frequently asked questions
How long does memory foam off-gassing last?
Most memory foam mattresses stop smelling after 24-72 hours when unrolled in a well-ventilated room. Stronger odours may linger up to two weeks. Place the mattress in a spare bedroom with windows open or outdoors under cover. Plant-based foams such as the SOLACE+CO range generally off-gas less. If the smell remains after 14 days, return the product.
Is memory foam safe for children in the UK?
Memory foam is safe when it meets BS 7177 fire regulations. For bunk beds the top-bunk guard rail must sit at least 16cm above the mattress surface; always use the maximum depth stated by the manufacturer. Children under 6 should not sleep in a top bunk. Consider dedicated kids memory foam mattresses designed with lower density and reduced VOC formulations.
Does higher density memory foam sleep cooler?
Higher-density foam (65kg/m³ and above) usually retains more heat because it conforms more tightly. Cooling is improved by gel infusions, open-cell structures or graphite rather than density alone. Pairing with a breathable mattress protector helps. Many UK buyers choose hybrid designs that combine memory foam with pocket springs for better airflow.
Can you wash a memory foam mattress?
Memory foam cannot be immersed in water. Use a waterproof mattress protector to guard against spills and dust mites. Spot-clean surface stains with mild detergent and a damp cloth; never soak. Rotate or flip the mattress according to the care label to extend its life. Protectors are available in various sizes to fit UK single through super king mattresses.
What density memory foam is best for side sleepers?
Side sleepers usually benefit from 50-60kg/m³ memory foam to cradle the shoulder and hip without excessive sink. Too low and you may bottom out; too high and pressure relief decreases. Test several options in store if possible. Adding a thin memory foam topper can fine-tune firmness on an existing mattress.
Related guides
- Should You Turn a Memory Foam Mattress?
- Memory Foam vs Pocket Sprung Mattress: Which Is Best?
- Memory Foam Mattress Pros and Cons: Benefits and Drawbacks
- Mattress Type Quiz: Memory Foam, Pocket Sprung or Hybrid?
- Mattress Construction Types Explained – UK Guide
- Latex vs Memory Foam Mattress: Pros, Cons and Which to Buy