Interliners and flame-retardant upholstery: three routes

At a glance

Section numbers are from the FIRA and British Furniture Confederation guide (2010) read on 7 November 2026. The effects on handle, shape and cleaning are questions to put to the supplier, not findings: no source read gives figures.

Three routes, one test of the whole stack

The guide defines an upholstery composite as the combination of cover and filling, made up of layers such as fabric, interliner and filling, and an interliner as an extra layer of fire-retardant material between the exterior cover and the filling. The fire test is made on the composite, not on one layer. So a flame-retardant interliner does not make a seat pass by itself, and a cover with an inherent flame-retardant yarn does not either: the report has to describe the stack the seat will have.

There are three ways to build a composite that passes. A: the cover is flame retardant in the fibre. B: a treatment, such as a back-coating, is applied to the finished cover. C: an interliner is added. Many seats combine them, for example a treated cover over an interliner. Whatever the route, the supplier should name it in writing.

What the guide says about each route

• Treatments and the water soak. Where a flame-retardant treatment has been applied to the outer cover or to the fire barrier material, it is soaked for thirty minutes before conditioning and testing. The soak applies to treatments, back-coating included, on covers that are finished in all other respects (guide, A1.2).
• Inherent flame retardancy. A cover produced from materials formulated to be, or inherently, flame retardant, for example fabric woven from flame-retarded yarns, needs no water soak provided no additional treatment is applied. If it is not known whether the cover is treated, it is soaked and dried (A1.2).
• Cleaning. The guide says treatments may deteriorate in dry cleaning and in washing, and strongly recommends cleaning cycles before testing for covers marked as washable or dry-cleanable (BS 5651 is named): A1.1 and A1.2.
• A cover supplier’s result is guidance. Fabric suppliers commonly test over a 35 kg/m³ combustion-modified foam. The manufacturer must judge whether that result applies to the real filling, and distinctly different fillings are difficult to equate (7.2.2).
• What the domestic regime does with interliners. Schedule 3 of the Furniture and Furnishings (Fire) (Safety) Regulations 1988 is an ignition resistance test for an interliner: a chemically treated interliner fabric is first soaked, then tested under a specified polyester cover and a non-fire-retardant polyurethane foam of 20 to 22 kg/m³, using ignition source 5. That is the domestic test for the interliner as a component, and it is not the contract test: for contract and non-domestic furniture the level is the Responsible Person’s (see our domestic or contract fire regulations sheet).

A change of component changes the answer. The guide lists what makes a new model that has to be re-tested:

Effect on handle, shape and cleaning: ask, and see it in the sample

None of the sources we read puts a number on how a route changes the feel of a cloth or the shape of a seat. So treat these as questions for the partner upholsterer and as things to judge on the approved sample, not as facts.

• Handle and drape. A back-coating sits on the reverse of the cloth and an interliner is a further layer under it. Either can change how a cloth bends, pleats and holds a pattern. Ask for a sample of the cloth as it will be supplied, with the route applied, not the loose cloth.
• Shape. An interliner adds a layer between cover and filling. On a tailored or tufted seat, ask the upholsterer to show it on the mock-up: our mock-up approval sheet covers how.
• Cleaning. Ask whether the cover is washable, dry-cleanable or spot-clean only, whether the test included the cleaning cycles the guide recommends, and whether the treatment can be renewed after cleaning, and by whom. We found no source on re-treatment.
• Colour and pile. A treatment can in principle affect shade or pile on some cloths; ask for it to be shown on the actual sample and for the report to name the same colourway family. A change of colour alone is not a new model under the guide (A1.3).

Our fabric performance tests sheet covers abrasion, light and colour fastness; the questions above sit beside those.

What the certificate and report must name

Ask the supplier to state the route in writing, then check the report names it. The report should describe the cover, any treatment or back-coating, any interliner, the filling for each part of the seat, and the level, and it should be from a laboratory accredited for the tests. Our sheet on reading a test report goes through those lines against a build sheet, and our hazard category sheet draws the ladder of levels. A report for a cloth alone, or for a foam alone, does not cover the finished composite.

The guide says the water soak is part of the standards (BS EN 1021-1, BS EN 1021-2 and BS 5852, in the 2006 editions it cites). The editions currently listed on BSI Knowledge are in the notes to this sheet and on our report sheet.

Chemistry and the supplier’s declaration

Routes B and C usually involve a chemical flame retardant somewhere in the build, and the rules on some of those chemicals have been changing. FIRA publishes guidance on REACH for upholstery; we did not open it for this sheet, so we do not state what is restricted. What a specifier can do is ask the supplier to say in writing whether any chemical flame-retardant treatment is used in the cover, the interliner or the filling, and to supply its current compliance declaration. Do not accept, and do not make, a claim that a material is free of a named substance without a certificate.

Each upholstered item achieves [BS 7176:2007+A1:2011 / current edition] [Medium] Hazard by route [A inherent / B treated or back-coated / C interliner / combination]. [Supplier] states the route per item in the composite record: cover [ref], treatment [none / back-coating, supplier], interliner [none / ref, supplier], filling [type, grade] for the seat, back and arms.

[Supplier] provides, before production, a test report for each composite from a laboratory accredited for the methods used, dated within [12] months, whose specimen description is identical to the composite record. Where the cover or interliner is treated, the report records the water soak. Reports for the cloth alone, the foam alone or the interliner alone are not accepted.

The approved sample and mock-up are made with the production composite, route applied. [Designer] approves handle, drape, colour and seat shape on that sample. [Supplier] states the cleaning method permitted for the cover, whether it was included in the test, and whether the treatment can be renewed after cleaning and by whom.

A change of cover (other than colour), pattern or construction, filling, interliner, treatment or component supplier after approval is a new model: [supplier] notifies [designer] in writing before the change and provides a new test report before it is used.

Standards and sources

• FIRA and British Furniture Confederation guide (2010): 48-page PDF read 7 Nov 2026: definitions, 7.1.1, 7.2.2, Appendix 1 A1.1 to A1.3.
• Furniture and Furnishings (Fire) (Safety) Regulations 1988, Schedule 3: revised text read 7 Nov 2026: interliner test; amended 1 Oct 2010.
• BS 7176; BS 5852; BS EN 1021-1 and -2; BS 5651: not read; statuses on our report sheet (BSI listings read 5 Nov 2026). Confirm against current editions.

Questions we are asked

Is an interliner always needed?

No. It is one of three routes. Whether a seat needs one depends on the cover, the filling and the level, and the answer is the test report for the finished composite. Do not accept a statement that a cloth passes untreated without a report that names the filling it was tested over.

Is an inherently flame-retardant cloth better than a back-coated one?

They are different routes. The guide says a cover made from flame-retarded yarn needs no water soak if nothing further is applied, while a back-coating or other treatment is soaked before the test. Which suits a job depends on look, handle, cleaning and the test result for the composite, so ask for the report.

Does a flame-retardant back-coating change the handle of a cloth?

It can, but no source we read quantifies it. Judge it on a sample of the cloth with the coating applied, as it will be supplied.

Can a back-coated cloth be dry cleaned or washed?

The guide says treatments may deteriorate in dry cleaning and washing and strongly recommends cleaning cycles before testing for covers marked as cleanable. Ask the supplier whether the test included them. Whether a treatment can be renewed after cleaning is a question for the supplier; we found no source.

Does the domestic test for interliners apply to my hotel seating?

No. Schedule 3 of the 1988 Regulations is the domestic ignition test for an interliner as a component. For contract and non-domestic furniture the Responsible Person sets the level and the composite is tested to it: see our domestic or contract fire regulations sheet.