Sofa Bed Mattress Foam: How to Fix an Uncomfortable Fold-Out Bed
Sofa Bed Mattress Foam: How to Fix an Uncomfortable Fold-Out Bed
If your sofa bed isn’t comfortable to sleep on, the foam inside it is very likely the problem rather than the sofa bed itself. Most sofa beds come from the factory with thin, low-cost foam fitted purely to keep costs down, and that foam is usually the first thing to go flat, lumpy or uncomfortable, often within a couple of years. Replacing it with proper cut-to-size foam is a straightforward, affordable way to fix an uncomfortable sofa bed without buying a new one.
- Sofa bed mattresses are made thinner than standard bed mattresses, usually 5cm or 10cm deep, so they fold away inside the mechanism.
- Getting the depth right matters more than usual: too deep and the sofa bed will not close properly.
- Foam density matters more at shallow depths: a firmer grade suits a 5cm sofa bed, a medium grade suits a 10cm one, with memory foam best used as an optional comfort topper rather than the whole mattress.
- Foam is cut to your exact measurements, so it works with any make of sofa bed, not just specific brands.
Why Sofa Bed Mattresses Are Different
A standard mattress can be as deep as you like, but a sofa bed mattress has to fold away inside the frame when the sofa is folded back up for daytime use. That means the foam has to be shallower than a normal mattress, and it has to bend cleanly at the fold lines without cracking or losing its shape over time. Sofa bed mattresses are typically available in two depths, 5cm or 10cm, and ordering the wrong depth is a common mistake, since a mattress that is too deep will stop the mechanism closing properly. Always measure your existing foam or the gap in the mechanism before ordering a replacement, rather than assuming a standard depth will fit.
Choosing the Right Foam Grade
Foam density matters more here than in a normal mattress, because there is less material to provide support. If your sofa bed uses the shallower 5cm depth, a firmer, higher density grade helps stop the foam bottoming out under weight. At 10cm, a supportive medium-firm grade works well. Pure memory foam on its own can feel too soft and warm for this application, so it works best as a thin comfort layer on top of a firmer base rather than the entire mattress.
If you would like a memory foam topper on top, add it to your order as a second foam item alongside your base foam, and let us know in the notes that you’d like the two pieces bonded together when we cut them.
| Grade | Best For | Notes |
|---|---|---|
| GB 39H (Luxury Firm) | Sofa beds needing 5cm depth | At this shallow depth there is less foam to provide support, so a firmer, higher density grade helps stop it bottoming out under weight. |
| GB 41M (Luxury Medium) | Sofa beds needing 10cm depth | A supportive, high density medium-firm foam suited to seating and mattress use at 10cm and above. |
| GB 33M (Average Medium) | Sofa beds needing 12.7cm depth or more | A more affordable option where you have a little extra depth to work with. |
| GB 55M (Memory Foam) | Optional comfort topper | Not recommended as a standalone mattress. Order this as a separate item alongside your base foam and add a note asking us to bond the two together. |
How to Measure Your Sofa Bed Mattress
Getting an accurate measurement is the most important step, particularly for depth. Measure the length and width of your existing foam or the mattress space when the bed is folded out, and measure the depth of the space available when the bed is folded away, not just the depth of your current foam if it has already gone flat or thin. If you are at all unsure, get in touch and our team will talk you through it.
How to Order Your Replacement Foam
Select the Foam Cube / Rectangle shape, which is the correct shape for a sofa bed mattress insert.
Measure and enter your size in mm, cm or inches, using your existing foam or the folded mechanism gap as your guide.
Select your foam grade. GB 39H suits a shallow 5cm-deep sofa bed, while GB 41M or GB 33M suit a 10cm depth.
Choose any additions, such as a dacron or stockinette wrap to help the new foam slide into your existing cover. Want a memory foam topper too? Add it as a second foam item and let us know in the notes that you’d like the two bonded together.
Place your order. Orders placed before 11am are despatched for next working day delivery as standard.
Frequently Asked Questions
What depth of foam do I need for a sofa bed mattress?
Most sofa beds use either a 5cm or 10cm deep mattress, but this depends on your specific mechanism. Measure your existing foam or the folded gap in the frame before ordering, rather than assuming a standard depth.
Can I use memory foam for a sofa bed mattress?
Memory foam works well as a comfort topper, but is not recommended as the entire mattress, since it can feel too soft and retain too much heat for this use. Order a base grade suited to your depth (a firmer grade for 5cm, a medium grade for 10cm) and a memory foam layer as a separate item, then add a note asking us to bond the two together when we cut your order.
Will new foam damage or affect the sofa bed mechanism?
No. The foam is only the sleep surface. It does not attach to or affect the frame, springs or mechanism underneath, provided you order the correct depth so the bed still folds away properly.
Can this fit any make of sofa bed?
Yes. Because the foam is cut to your exact measurements rather than sold as a fixed size, it will fit any manufacturer’s sofa bed, not just specific brands.
Speak to Our Experts
If you are not sure which grade or depth is right for your sofa bed, our team is happy to help. Call 01494 441177 or visit our contact page, and we will help you get the measurements and grade right before you order.
Cameron has emerged as a key marketing expert since joining GB Foam Ltd in 2017. A graduate of the University of Winchester, with a professional background in Public Relations; he has combined his content writing and brand awareness expertise with an in-depth knowledge of foam products and foam conversion technology to enhance the company’s marketing strategies and industry presence. Cameron has led numerous marketing campaigns, in both B2B and B2C segments, to further brand recognition and open up new business avenues worldwide.