Firm Upholstery Foam Sheet 33H — 33kg/m³, 190N Hard, Crib 5 (V33H / RX33/190)
Regular price
£44.49
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A firm, high density upholstery foam sheet — 33 kg/m³ density, 190 Newton firmness, Crib 5 fire rated, cut in the UK. One of the two most widely used upholstery grades in the UK.
This is the grade to choose when you want a firm, supportive sit rather than a soft one. It is used for high-quality furniture, and for seating and mattresses in caravans, boats, yachts and camper vans, where a firm foam holds its shape under repeated use in a confined space.
Specifications
| Foam grade | 33H (V33H – RX33/190) |
|---|---|
| Density | 33 kg/m³ (high density) |
| Firmness | 190 Newtons (ILD at 40% compression) — hard feel |
| Fire behaviour | Crib 5 (BS 5852 Ignition Source 5) |
| Colour | Blue |
| 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
- Firm seat cushions for sofas and chairs
- Caravan, motorhome and campervan seating and bed bases
- Boat and yacht cushions and mattresses (interior, dry use)
- Mattresses where a firm support layer is wanted
- Dining chairs and upright seating
For a softer sit, see the 35M (125N, medium). For the same firm feel in a longer-lasting grade, see the Luxury 39H (39 kg/m³, 200N) or the Superior 42H (42 kg/m³, 240N).
Questions about this foam
This is 33 kg/m³ — is it less durable than your 39 kg/m³ soft foam?
Density does predict durability, so a 39 kg/m³ foam will generally outlast a 33 kg/m³ one used the same way. But note the two are not alternatives for each other: our 39S is softer (120N) despite being denser. If you want firm and longer-lasting, the right upgrade is the 39H or 42H — both hard grades at higher density.
Is this foam suitable for boat cushions?
Yes, for interior use in a dry environment. It is not suitable for cushions that will get wet or sit outdoors in the weather — polyurethane foam absorbs water and stays wet. For anything exposed to water, use our reticulated foam, which is designed to let water drain straight through.
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.