Medium Firm Sofa Cushion Foam Sheet 35M — 35kg/m³ High Density, Crib 5 (V36F / RX36/125)
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£44.49
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A medium-firm, high density upholstery foam sheet — the standard choice for replacing collapsed sofa and chair seat cushions. 35 kg/m³ density, 125 Newton firmness, Crib 5 fire rated, cut in the UK.
This is the grade most people want when a sofa cushion has gone soft and you can start to feel the frame beneath you. It is especially suited to replacing fibre-filled cushions, which flatten quickly and do not recover their shape. It gives a supportive sit without feeling hard.
Specifications
| Foam grade | 35M (V36F – RX36/125) |
|---|---|
| Density | 35 kg/m³ (high density) |
| Firmness | 125 Newtons (ILD at 40% compression) — medium feel |
| Fire behaviour | Crib 5 (BS 5852 Ignition Source 5) |
| Colour | Beige white |
| Material | Polyurethane foam |
| Sheet sizes | 230 x 200cm (90.5" x 78.7") · 230 x 100cm (90.5" x 39.3") |
| Thicknesses | 1/2", 1", 1.5", 2", 3", 4" |
| Manufactured | United Kingdom |
What this foam is for
- Sofa seat cushions — the most common use. Medium firmness suits everyday sitting.
- Chair and armchair cushions
- Replacing fibre-filled cushions — fibre flattens and stays flat; foam recovers.
- Window seats and bench pads
Want a firmer sit? See the 33H (190N) or 39H (200N). Want the same medium feel but longer-lasting? See the Luxury 41M (41 kg/m³, 150N).
Questions about this foam
Does 35 kg/m³ mean this foam is firm?
No — density and firmness are different things. Density (kg/m³) tells you how much material is in the foam, which predicts how long it lasts. Firmness (Newtons) tells you how it feels to sit on. This foam is 35 kg/m³ and 125N. Our 39S is denser at 39 kg/m³ but softer at 120N. Higher density does not mean firmer.
How thick should my sofa cushion foam be?
Measure the internal depth of the existing cushion cover, not the old collapsed foam — a worn cushion has compressed and will under-measure. Sofa and chair seat cushions are typically 4"–6".
What does Crib 5 mean?
Crib 5 is BS 5852 Ignition Source 5 — the UK furniture fire test required for contract and commercial seating. It is a different standard from Class 0, which is a building regulations rating for walls and ceilings, not furniture. Note that BS 5852 is a composite test: certification applies to the foam and cover fabric together, so the finished cushion’s compliance also depends on the fabric you use with it.
For the full explanation of density, firmness and fire ratings, see our foam FAQs. To compare every grade side by side, see our foam grade comparison.
Cut to order in our own UK factory. Next working day delivery is available to most of the UK — see our delivery page for timings to your area.