Upholstery foam, feather and fibre: what to specify

At a glance

Descriptions of the fills, not performance claims. Density and hardness are left out of this table on purpose: see the data sheet table. Fire statements follow the FIRA and British Furniture Confederation guide (2010, updated 2011).

Density and hardness are two different numbers

Density is the mass of foam in a cubic metre, in kg/m3. It is measured to ISO 845 and is the usual shorthand for how much polymer is in the seat. Hardness is how firmly the foam resists being pressed, measured in newtons to ISO 2439 by indenting a test piece by a set percentage. The two are measured separately, and a foam data sheet should give both.

Neither number alone tells you how long a cushion will keep its shape. The standard for load-bearing polyurethane foam (BS EN ISO 5999:2013) grades foam by its type, by how it performs in a fatigue test and by an indentation hardness index, and the fatigue test (ISO 3385) measures the loss of thickness and hardness after repeated loading. So ask for fatigue evidence as well as density and hardness.

The drawing shows where each kind of evidence applies in the seat: the foam data sheet describes the foam alone, while the fire test treats cover, interliner and filling together.

What published data sheets report

These are the figures on five foam grades whose data sheets we read on 5 November 2026, from one UK foam supplier and one European foam maker. They are shown to illustrate how a data sheet is laid out, not as a band to specify, and not as the grades our partner workshops use.

• The grade name is not the measured density. On the European maker's sheets, CMHR 28 lists 25 ± 1 kg/m3 and CMHR 30 lists 30 ± 1 kg/m3. Specify by the measured figure and its tolerance, not the grade number.
• Hardness is reported in different ways. Method A of ISO 2439 gives one point at 40%; method B records several points. One maker gives 25%, 40% and 65%, and the UK sheets give a single range without the indentation. Ask which.
• A grade is more than a density. The sheets also carry compression set, fatigue classification and a fire statement. Read them together.
• Check the edition on the fire line. A sheet from a second UK foam supplier, not in the table, cites BS 5852 Part 2 of 1982, while the FIRA guide cites the 2006 edition of BS 5852. Ask for the edition on the certificate.

Published guidance on density bands for contract seating varies from source to source, including between pages we have read. That is why this sheet quotes no band: state the grade, the measured density with tolerance and the hardness with its method, and let the workshop's data sheet be the evidence.

Properties and test standards at a glance

Foam and the fire certificate

The Furniture and Furnishings (Fire) (Safety) Regulations 1988 define the furniture they cover as furniture ordinarily intended for private use in a dwelling. For non-domestic furniture the FIRA and British Furniture Confederation guide (2010, updated 2011) says there is no direct furniture legislation and that fire safety is regulated indirectly through the Regulatory Reform (Fire Safety) Order 2005. Under that Order the Responsible Person for the premises assesses the risk and so sets the level; BS 7176 puts premises such as restaurants, public houses and bars, and hotel bedrooms, in its Medium Hazard category as typical examples.

• The foam has its own test. The guide says a foam producer shows compliance by testing to Schedule 1 Part 1 of the 1988 Regulations or to the relevant annex of BS 7176, and that only foam passing that test is considered compliant. It expects foam suppliers to provide certification, normally no more than a year old.
• The seat is tested as a composite. BS 7176 requires each different composite, the combination of cover, interliner and filling, to be tested, and a seat, back and arms with different fillings are separate composites. The foam passing its own test does not give the seat a certificate.
• A change of filling is a new model. The same guide says a change of filling, of cover other than a simple colour change, or of component supplier needs re-testing, and that enforcement authorities normally expect a UKAS accredited test certificate less than a year old.
• A fabric certificate may not cover your build. The guide says fabric suppliers routinely test over a 35 kg/m3 combustion modified foam, and advises direct tests where the foam is of lower density, uses a different flame-retardant chemical, comes from a different producer, or is a distinctly different filling type, such as a feather or fibre wrap over foam, where it says the behaviour is difficult to equate.

This sheet states no pass level of its own. Ask for the certificate for the exact build, naming the hazard category the Responsible Person has set.

Feather, down and fibre

Wraps change the surface of a seat more than its support. A polyester fibre wrap softens the edge and first touch without feather. A feather and down wrap gives a softer, more relaxed surface and needs plumping. Down is the softest and least supportive; feather adds structure, which is why blends are common. A down-proof ticking holds the fill in so that quills do not come through the cover.

• Labelling. EN 12934:2025 is the labelling standard for the composition of processed feathers and down used as the sole filling material; it replaces the earlier edition. Ask the workshop what the fill is and how its composition is declared.
• Fire. A feather or fibre wrap is part of the filling in the composite and has to sit inside the tested build. Do not assume a certificate for a foam-only seat carries over to a wrapped one.
• Care. Feather and down wraps need regular plumping to keep their shape; fibre settles over time; foam-only seats need the least. Say who will do the plumping when you choose the wrap.

Comfort versus formality in the build

As a simple ladder, the more layers sit on the foam and the softer they are, the more relaxed the seat feels and the more care it needs. In order from the most formal to the most relaxed: firm foam alone; firm foam with a thin fibre wrap; a foam core with a feather or fibre wrap; a deep feather and down wrap. Geometry, suspension and the cover tightness change the feel as much as the fill does, which is why we set them out together in the formal versus relaxed seating matrix.

What to ask the workshop to put in writing

• The foam grade for each layer and the manufacturer's data sheet for it.
• Measured density with tolerance (ISO 845) and hardness with the method and % indentation (ISO 2439).
• Fatigue evidence (ISO 3385 or the classification in BS EN ISO 5999) for the seat foam.
• The foam's own fire certificate, with its date and the edition of the test cited.
• The composite certificate for the finished build: cover, interliner, wrap and foam, to the hazard category the Responsible Person set, from a UKAS accredited laboratory and dated within a year.
• A build-up drawing with the thickness of every layer, and the wrap and ticking named.
• For feather and down, the composition declaration and the care instructions.
• A full-size mock-up approved by sit test before production.

Seat foam: [CMHR] polyurethane foam, density [ ] kg/m3 (tolerance [ ]) to ISO 845, hardness [ ] N at [40] % indentation to ISO 2439 [method A], fatigue classification [ ] to ISO 3385. State grade, density and hardness for each foam layer. Supply the data sheet and a foam ignition certificate (Schedule 1 Part 1 of the 1988 Regulations, or BS 7176 Annex A) dated within [12] months with the shop drawings.

Build-up from the top: cover [ ]; interliner [as the fire certificate requires]; wrap [polyester fibre, or feather and down in down-proof ticking]; comfort foam [ ] mm; core foam [ ] mm; suspension [ ]. Show each layer's thickness on the build-up drawing. Declare feather and down composition [to EN 12934:2025]. Approve a full-size mock-up by sit test before production.

Upholstery to comply with BS 7176 [Medium] Hazard, tested as a composite for each different cover, interliner and filling build (seat, back and arms separately where they differ), and labelled. Provide a UKAS accredited certificate for the build as supplied, dated within [12] months. Re-test any change of filling, interliner, wrap or cover (other than colour) before supply.

Standards and sources

• FIRA and the British Furniture Confederation, Fire safety of furniture and furnishings in the contract and non-domestic sectors (2010, updated 2011): composites, foam certificate, re-testing.
• Furniture and Furnishings (Fire) (Safety) Regulations 1988, SI 1988/1324: regulation 3 and Schedule 1; revised version read 5 November 2026.
• BS 7176:2007+A1:2011 and BS 5852:2006: as described in the FIRA guide; not read.
• ISO 845:2006, ISO 2439:2008, ISO 3386-1:2025, ISO 3385:2014, BS EN ISO 5999:2013: foam test and specification standards; catalogue records only.
• BS EN 12934:2025: feather and down labelling; catalogue record only.

Questions we are asked

What is the difference between foam density and hardness?

Density is the mass of foam per cubic metre (kg/m3, ISO 845). Hardness is how firmly it resists being pressed, in newtons (ISO 2439). They are measured separately, so a data sheet should state both, along with fatigue evidence.

What does CMHR foam mean?

Combustion modified high resilience: a high-resilience polyurethane foam formulated to resist ignition. The FIRA guide describes combustion modified foam as the UK's main way of slowing fire development in furniture. The foam is tested on its own, and the finished seat is then tested as a composite.

What foam density should I specify for restaurant or hotel seating?

Published figures disagree, so we do not quote a single band. State the foam grade, the measured density with tolerance and the hardness with its test method, and ask the workshop for the data sheet for the grade they will use, plus fatigue evidence and the fire certificates.

Does fire-retarded foam make a seat fire compliant?

No. BS 7176 tests the cover, interliner and filling together as a composite, so the seat needs its own certificate for the exact build. A change of filling or of cover, other than colour, means a new test.

Is feather or foam better for comfort?

They give different characters. Firm foam supports at once and needs no daily care; a feather and down wrap is softer and more relaxed but needs plumping; a foam core with a wrap is the usual middle route. See the formal versus relaxed seating matrix.