The Building Safety Act 2022 and Fabric Specification: What Interior Designers Need to Know

What the Act introduced: A Principal Designer role with legal duties to ensure all design work — including material specification — complies with Building Regulations. Operative from 1 October 2023 for all projects requiring building control approval.
Higher-risk buildings: Residential buildings 18 metres or more in height, or seven or more storeys. Additional, more stringent duties apply to all design work on these buildings.
What this means for fabric specification: Any designer specifying materials in a higher-risk building must be able to demonstrate competence in fire safety compliance. Every fabric specification decision that affects fire safety must be documented and retained as part of the building’s safety case.
Who this applies to: Interior designers, architects, and design-and-build contractors involved in any project requiring building control approval in England.

The Building Safety Act 2022 is the most significant change to the regulation of building design and construction in England since the 1980s. It was enacted in response to the Grenfell Tower disaster and introduced a comprehensive new duty-holder framework, new competence requirements, and a new regulatory body — the Building Safety Regulator (BSR) — with powers to scrutinise and approve higher-risk building work. Interior designers and fabric specifiers are affected by the Act in ways that are not always clearly communicated. This guide explains what the Act requires, what it means for fabric specification decisions, and how to document compliance.

What the Building Safety Act 2022 Does

The Act creates a new regulatory regime for all building work requiring building control approval in England, with additional and more stringent requirements for higher-risk buildings. It does three things relevant to interior designers and fabric specifiers.

First, it introduces a mandatory Principal Designer role for any project with more than one contractor, operative from 1 October 2023. The Principal Designer is responsible for planning, managing, monitoring, and coordinating the design work to ensure compliance with Building Regulations — including fire safety. This is a distinct role from the Principal Designer under CDM Regulations 2015, although the same person or organisation may hold both roles if competent to do so.

Second, it places a duty of competence on anyone carrying out design work. Section 35 of the Act defines competence as having the necessary skills, knowledge, experience, and behaviours. A designer who specifies materials — including fabrics and soft furnishings — in a building subject to the Act must be able to demonstrate that their specification decisions comply with the applicable Building Regulations fire safety requirements.

Third, it introduces a golden thread of information — a continuous, maintained record of design decisions relating to fire safety and structural integrity — that must be created during the design phase, updated through construction, and retained for the life of the building. For higher-risk buildings this is a formal legal requirement. For other buildings the principle of maintaining clear documentation of safety-related design decisions is strongly recommended and increasingly expected by the insurance market.

Higher-Risk Buildings: What They Are and Why They Matter

A higher-risk building (HRB) is defined under the Act as a building of at least 18 metres in height or at least seven storeys, containing at least two residential units. Most tall residential apartment buildings in England meet this definition. Many hotel developments, residential care buildings, and mixed-use developments with residential components also qualify.

For HRB projects, the Building Safety Regulator must approve the design before construction begins at Gateway 2. The Principal Designer must submit a detailed compliance statement demonstrating that the design meets Building Regulations requirements. All duty holders — including designers — must operate a mandatory occurrence reporting system and report any safety occurrence to the BSR.

A safety occurrence is defined as any aspect of the design relating to the structural integrity or fire safety of a higher-risk building that, if built, would present a significant risk of death or serious injury. A fabric specification that does not meet the applicable fire standard — or that uses a topical FR treatment that has degraded without replacement — could in principle constitute a safety occurrence in an HRB context. This is not a theoretical risk. It is the kind of documentation failure that the golden thread requirement is specifically designed to prevent.

What This Means for Fabric Specification

For most interior design projects, the Building Safety Act’s practical impact on fabric specification is not a change in the fire standards that apply — Crib 5, BS 7176, BS 5867 were the applicable standards before the Act and remain so — but a change in the documentation and accountability requirements around compliance with those standards.

Before the Act, a designer who specified a Crib 5-certified fabric for a hotel project was meeting the applicable fire standard. After the Act, that same designer must also be able to demonstrate: that they understood the applicable standard and specified correctly against it; that they obtained a valid test certificate from a UKAS-accredited laboratory; that they documented the specification decision and retained the certificate; and, if the project involves an HRB, that the fabric specification was included in the golden thread information provided to the Principal Designer and ultimately to the building owner.

The practical implication is that fabric specification documentation must be more systematic than it often has been. A verbal instruction to the upholsterer or a purchase order without fire certification reference is no longer adequate for projects subject to the Act. The fire test certificate must be obtained before installation, referenced in the specification document, and retained as part of the project file.

For full guidance on obtaining fire test certificates and what they must cover, see our Crib 5 guide, our hotel fabric specification guide, and our FR treatment guide.

The Principal Designer Role and Interior Design Services

The RIBA/BIID professional services contracts — updated in their 2024 amendments — include an expanded schedule of services that now explicitly references the Principal Designer role under Part 2A of the Building Regulations. An interior designer or architect carrying interior design services within their scope on a qualifying project may be asked to act as, or contribute to the duties of, the Principal Designer.

The 2024 amendment to the RIBA/BIID contracts draws specific attention to the requirement for the designer to assess their competency to undertake the Principal Designer role before accepting it. Interior designers whose practice includes projects in higher-risk buildings should assess whether their competence in fire safety, structural safety, and the golden thread documentation requirements meets the standard required by PAS 8671, the publicly available specification setting out the minimum competence requirements for Principal Designers.

The Golden Thread and Fabric Documentation

The golden thread is a digitally maintained record of design decisions relating to fire safety and structural integrity. For fabric specification in a higher-risk building, it should contain the following for each fire-safety-relevant fabric decision. The fabric description — supplier, range name, colourway, width, and fibre composition. The fire standard the fabric is certified against — BS 7176 Medium or High Hazard, BS 5867 Part 2 Type B or C, or equivalent. The test certificate reference number and the name of the UKAS-accredited laboratory that issued it. The filling and interliner specified with the fabric, as the certificate covers the assembly rather than the face fabric alone. The date of installation and the location within the building. Any re-treatment or re-certification requirement and the recommended review date.

Building this documentation into the fabric specification process at Stage 3 of the RIBA Plan of Work — when specific fabrics are selected and technical data sheets are obtained — adds minimal time and significantly strengthens both legal compliance and the designer’s professional liability position. For guidance on fabric decisions at each RIBA stage, see our RIBA Plan of Work fabric guide.

Liability and the 30-Year Limitation Period

A 2025 Supreme Court ruling in URS Corporation Ltd v BDW Trading Ltd interpreted section 135(3) of the Building Safety Act to extend the limitation period for negligence claims relating to building safety from six to thirty years, including retrospective claims. This means that design decisions made today — including fabric specification decisions that affect fire safety in higher-risk buildings — could be subject to legal challenge for up to thirty years.

The practical implication for fabric specifiers is that the documentation of fire compliance at the time of specification — the fire test certificate, the specification schedule, the installation record — is evidence of due diligence that may need to be relied upon many years after practical completion. Maintaining systematic records of fire certification for all higher-risk building fabric specification decisions is strongly advisable.

What Interior Designers Should Do

Review your specification documentation process and confirm that it captures fire test certificate references, UKAS-accredited laboratory names, and filling and interliner details for every fabric specified in a fire-safety-relevant position. This applies to all contract projects, not only those classified as higher-risk buildings.

For any project that may involve an HRB — a residential building of seven or more storeys or 18 metres or more in height — seek advice from the Principal Designer appointed on the project about what fabric documentation is required as part of the golden thread. If you are the party being asked to act as Principal Designer, assess your competence against PAS 8671 before accepting the role.

Ensure your professional indemnity insurance covers the scope of design services you are providing on BSA-affected projects. The Act has introduced new and more extensive liabilities for designers, and cover that was adequate before 1 October 2023 may need to be reviewed.

When specifying fabric for fire-safety-relevant positions in higher-risk buildings, prefer inherently fire-resistant fabrics over those requiring topical FR treatment. Inherent fire resistance does not degrade with cleaning or over time and does not require re-certification during the building’s life. See our FR treatment and fibre compatibility guide for guidance on which fabrics carry inherent certification.

Frequently Asked Questions

Does the Building Safety Act apply to all interior design projects?

The duty-holder framework applies to all projects requiring building control approval in England where there is more than one contractor, from 1 October 2023. The additional and most stringent requirements apply to higher-risk buildings — residential buildings of at least 18 metres in height or at least seven storeys containing two or more residential units. Most interior refurbishment projects of individual apartments do not require building control approval and are not directly caught by the Act. Commercial fit-outs, whole-building refurbishments, and new build projects with residential use at seven or more storeys are more likely to be affected.

What fire standards apply to fabric in higher-risk buildings?

The Building Safety Act does not introduce new fire standards for fabrics. The applicable standards remain BS 7176 for upholstered seating, BS 5867 for curtains, and the Regulatory Reform (Fire Safety) Order 2005 for the responsible person’s ongoing fire safety obligations. What the Act changes is the documentation and accountability requirements around compliance with those standards — specifically the requirement to maintain a golden thread of fire safety design decisions for higher-risk buildings.

What is the golden thread and what fabric information does it need to contain?

The golden thread is a digitally maintained record of design decisions relating to fire safety and structural integrity. For fabric specification in a higher-risk building, it should contain the fabric description, the fire certification standard and certificate reference, the UKAS-accredited laboratory name, the filling and interliner details, the date and location of installation, and any re-treatment requirements. This information must be maintained for the life of the building.

Can an interior designer be the Principal Designer under the Building Safety Act?

Yes, if they have the necessary competence as defined by PAS 8671. An interior designer appointed as lead designer on a project with more than one contractor must assess whether their competence in fire safety, structural safety, and documentation management meets the standard required. For HRB projects, the competence requirements are more demanding and formal competence assessment against PAS 8671 is advisable before accepting the appointment.

For fire certification standards and test certificates, see our Crib 5 guide. For fabric documentation at each RIBA Plan of Work stage, see our RIBA Plan of Work fabric guide. For FR treatment and inherent fire resistance, see our FR treatment and fibre compatibility guide.

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How FR Treatment Works: A Plain-English Guide for Interior Designers

How FR Treatment Works: A Plain-English Guide for Interior Designers

What FR treatment does: It slows or prevents the ignition and spread of flame by interfering with the chemistry of combustion at the surface of the fabric.
The two main methods: Back-coating (paste applied to the reverse — standard for upholstery Crib 5) and wet padding (chemical solution applied to the whole fabric — standard for curtain treatment).
Inherent vs topical: Inherent fire resistance is a permanent property of the fibre itself. Topical treatment is applied after weaving and can degrade over time, through cleaning, or through interaction with certain dyes.
Who can certify: Only a UKAS-accredited testing laboratory. No fabric company, designer, or treatment provider can self-certify.

Most interior designers who specify FR-treated fabrics regularly have never seen the treatment process and have only a general idea of how it works. This guide explains the chemistry and process in plain language — not to make designers into treatment specialists, but to give them enough understanding to ask the right questions, spot specification risks before they become problems, and explain FR compliance confidently to clients and contractors.

For which fibres can be treated, see our FR treatment and fibre compatibility guide. For dye types and their interaction with treatment, see our dye types and FR treatment guide. For the fire standards that require treatment, see our Crib 5 guide.

Why Fabrics Need FR Treatment

All organic fibres will burn if exposed to sufficient heat and ignition energy. The chemistry of combustion in textiles follows a consistent pattern. When a fibre is heated, its polymer structure begins to break down — a process called pyrolysis. This produces flammable gases. The gases mix with oxygen from the atmosphere and ignite, producing a flame. The flame generates further heat, which causes more pyrolysis, which produces more flammable gas, which sustains and spreads the fire. This self-reinforcing cycle is what makes unprotected upholstery and curtains a serious fire hazard in public buildings.

FR treatment breaks this cycle at one or more points. Depending on the type of FR compound used, it may prevent or delay pyrolysis, reduce the quantity or flammability of the gases produced, cause the fabric to form a carbonaceous char layer that insulates the underlying structure from the heat source, or dilute the flammable gases with inert gases that cannot sustain combustion. The goal in all cases is the same: to prevent the fabric from sustaining ignition and propagating flame when exposed to the ignition sources defined in the test standard.

The Two Main Treatment Methods

Back-coating. The standard method for upholstery Crib 5 treatment. The fabric is passed through a machine that applies a paste or emulsion of FR chemicals to the reverse face of the fabric. The paste is then dried and cured to fix the compound to the backing structure. The treatment sits on the back face and does not penetrate the face yarns. This is why back-coating, when correctly applied, does not alter the appearance or handle of the face fabric.

The FR compounds used in back-coating are typically phosphorus-based or halogenated compounds — most commonly brominated flame retardants applied in a paste that also contains a binder to hold the compound to the fabric. The phosphorus compounds work primarily in the solid phase: when heated, they decompose to form phosphoric acid, which causes the polymer to char rather than produce flammable gases. The halogenated compounds work primarily in the gas phase: they release halogen radicals that interrupt the chain reactions sustaining the flame.

Back-coating adds weight to the fabric — typically a few grams per square metre — and gives the reverse a firmer, slightly stiffer character. This can be an advantage in upholstery construction because the stiffer back helps the fabric behave consistently during cutting and making-up. It does not affect the face pile character of velvet or the handle of the woven face.

Wet padding. The standard method for curtain FR treatment and some lighter upholstery fabrics. The fabric is fed through a padder — a bath of FR chemical solution followed by rollers that squeeze the solution into the fabric structure under controlled pressure — and then dried and cured. The wet pickup is controlled to achieve the required chemical loading. Because the solution penetrates the whole fabric including the face yarns, wet padding can affect handle and, critically, can interact with certain dye types. See the dye types and FR treatment guide for the specific risks.

The FR compounds used in curtain wet padding are typically water-soluble inorganic salts — ammonium phosphate or ammonium sulphate compounds — applied in aqueous solution. These are effective for cellulosic fibres and work primarily by releasing inert gases when heated that dilute the flammable gas mixture around the burning fabric. They are less suitable for upholstery because they are water-soluble and would wash out in cleaning. Back-coating compounds are insoluble and more durable.

Inherent Fire Resistance vs Topical Treatment

The distinction between inherent and topical fire resistance is commercially significant and frequently misunderstood.

Inherent fire resistance is a permanent property of the fibre itself, arising from its chemical structure. Wool and mohair have inherent fire resistance because they are protein fibres with high nitrogen and sulphur content. These elements make the fibre self-extinguishing — when the ignition source is removed, the fibre stops burning. No chemical treatment is required and no treatment can be washed away. The fire resistance is permanent for the life of the fabric.

Trevira CS is an inherently flame-retardant synthetic fibre. The flame-retardant chemical is incorporated into the polyester polymer during fibre production, not applied to the surface afterwards. Like mohair, the fire resistance is permanent and survives cleaning.

Topical treatment applies FR chemicals to the fabric after it has been woven or knitted. The chemicals are not part of the fibre structure — they sit on or within the fabric surface. This means they can potentially be degraded by cleaning, by mechanical abrasion over time, or by interaction with atmospheric pollutants or incompatible dyes. The degree to which this happens depends on the specific FR compound, the fabric construction, and the cleaning regime.

Back-coated fabrics retain their FR properties well under normal contract cleaning conditions because the back-coating compound is insoluble and mechanically fixed to the backing structure. The relevant risk is the dye interaction problem in wet-padded fabrics described in the dye types guide rather than the physical removal of the compound.

For contract environments where cleaning frequency is high — healthcare, transport seating, hotel restaurants — the distinction between inherent and topical certification carries practical weight. A fabric whose fire resistance survives aggressive cleaning without needing re-treatment or re-certification is operationally simpler and more reliably compliant over its full service life.

The Testing and Certification Process

FR treatment produces a claim of compliance. The claim must be verified by an independent test before it has any legal or commercial standing.

The test is conducted by a UKAS-accredited testing laboratory. The fabric and, for composite tests such as BS 7176, the filling material as well, are prepared and tested against the relevant ignition sources. For BS 5852 Crib 5, the ignition source is a wooden crib of defined dimensions and mass placed at the junction between a test seat and back assembly made from the fabric and a standard filling. The assembly must show no sustained flaming or progressive smouldering after the crib has burned out.

If the assembly passes, the laboratory issues a test certificate. The certificate identifies the fabric by name or reference, the filling used in the test, the standard tested against, and the test result. This certificate is the document that a designer must obtain from the fabric supplier and retain as evidence of compliance for the project.

A fabric supplier’s claim that a fabric is Crib 5 compliant without a certificate from a UKAS-accredited laboratory is not sufficient for contract specification. The Regulatory Reform (Fire Safety) Order 2005 requires the responsible person for a building to be able to demonstrate that furnishings comply with the applicable standard. A verbal assurance or a product description are not adequate evidence. The test certificate is.

What FR Treatment Cannot Do

Understanding the limits of FR treatment is as important as understanding what it achieves.

FR treatment cannot make a fabric fireproof. No textile can be made completely non-combustible by topical treatment. FR treatment reduces ignitability and slows flame spread sufficiently to meet the defined test standard. In a real fire involving sustained heat and ignition energy beyond the test conditions, treated fabric will eventually burn.

FR treatment cannot compensate for incorrect installation. A Crib 5-certified fabric used without the foam specified in the test certificate does not maintain its certification. The certificate is issued for the specific fabric and filling combination tested. Substituting a different foam invalidates the certificate for that assembly.

FR treatment does not substitute for structural fire safety. The fire resistance of the building fabric — walls, floors, doors, compartmentation — is a separate matter from the fire safety of soft furnishings. FR upholstery fabric is one element of a fire safety strategy, not a substitute for the rest of it.

FR treatment does not make a fabric immune to cleaning degradation permanently. Back-coated fabrics are durable under normal cleaning conditions, but cleaning with inappropriate chemicals — very high pH alkaline cleaners, solvents incompatible with the binder system — can over time affect the integrity of the coating. The cleaning code on the fabric data sheet should be followed.

What Happens When a Treated Fabric Is Cleaned

The question designers are most frequently asked by clients is whether the FR treatment survives cleaning. The answer depends on the treatment method and the cleaning agent.

Back-coated upholstery fabrics coded S (solvent clean only) should not be cleaned with water-based products. The binder system holding the back-coating to the fabric may be water-sensitive. Repeated water-based cleaning of an S-coded back-coated fabric can progressively weaken the adhesion of the coating. The FR compound may remain present but its mechanical adhesion to the fabric is reduced.

Back-coated fabrics coded W or WS can be spot-cleaned with water-based products without significant effect on the back-coating, provided the products are not strongly alkaline. Hotel-grade alkaline cleaners applied repeatedly can over time affect the coating. This is one of the reasons to prefer inherently fire-resistant fabrics for hotel environments with high-frequency professional cleaning. See our hotel fabric specification guide for practical guidance on this.

Wet-padded curtain fabrics treated with water-soluble inorganic salt compounds are water-sensitive by nature. The standard BS 5867 Part 2 Type B test includes a water-soak stage precisely to assess whether the treatment survives cleaning. A fabric that passes this stage has demonstrated that its treatment survives a defined level of water exposure. This does not mean the treatment is permanent under repeated laundering. For healthcare curtain applications requiring Type C certification, a more rigorous laundering pre-conditioning is included in the test.

The Treatment Supply Chain

Understanding who is responsible for what in the FR treatment supply chain helps designers avoid the most common specification failures.

The fabric supplier is responsible for knowing whether their fabric can be treated, which treatment method is appropriate, and which treatment providers have successfully treated their fabric before. A good fabric supplier maintains this information and can advise the designer before the fabric is ordered.

The treatment provider applies the FR compound and, in most cases, arranges testing through a UKAS-accredited laboratory. The treatment provider issues the test certificate. They are responsible for the quality and consistency of the treatment and for ensuring the treated fabric meets the specified standard.

The designer is responsible for specifying the correct standard for the project, confirming that the fabric supplier and treatment provider can meet it, and obtaining the test certificate before the fabric is installed. The designer cannot certify compliance — only the testing laboratory can do that — but the designer is responsible for ensuring the certified fabric is what is installed.

The contractor or upholsterer is responsible for installing the certified fabric with the certified filling. Substituting materials without re-testing invalidates the certificate. The contractor should be briefed on this before work begins.

Frequently Asked Questions

Does FR treatment change how a fabric looks or feels?

Back-coating, correctly applied to the reverse of an upholstery fabric, does not alter the appearance or handle of the face. The back will feel slightly firmer and heavier but the face pile character and surface quality are unchanged. Wet padding for curtain treatment can affect the handle of lightweight or delicate fabrics — sheers in particular may feel slightly stiffer after treatment. Any fabric where handle or appearance change would be commercially significant should be sample-treated and approved before committing to the full order.

How long does FR treatment last?

Inherent fire resistance is permanent. Topical back-coating is durable under normal contract conditions and will typically remain effective for the life of the fabric provided it is cleaned according to the cleaning code and not subjected to chemicals that attack the binder system. Wet-padded treatments are less durable and may require re-treatment after intensive cleaning or after a defined number of years in high-frequency cleaning environments. For healthcare curtains under BS 5867 Type C, re-treatment after a defined number of wash cycles is standard practice.

Can a fabric be re-treated after cleaning?

Yes, in most cases. Back-coated upholstery fabrics that have been in service for many years can typically be re-treated if the original treatment has degraded, though this requires removing the fabric from the furniture. Wet-padded curtain fabrics can be re-treated when they are laundered if the treatment has been removed. The re-treated fabric must be re-tested if a new certificate is required. Contact the original treatment provider for advice on re-treatment for specific fabrics.

What is the difference between Crib 5 and BS 7176?

BS 5852 Crib 5 is the test method — the specific ignition source and test procedure. BS 7176 is the specification standard for non-domestic upholstered seating that references Crib 5 and additionally includes the cigarette and match tests, a water-soak stage, and documentation of the specific hazard category and filling used. For hotel and contract upholstery, BS 7176 Medium Hazard is the correct standard to specify because it produces a more complete and defensible certificate than Crib 5 alone. See our Crib 5 guide and hotel fabric specification guide for full detail.

Can I self-certify that a fabric is fire retardant?

No. Only a UKAS-accredited testing laboratory can issue a valid fire test certificate. A fabric supplier, designer, treatment provider, or contractor cannot self-certify FR compliance. Under the Regulatory Reform (Fire Safety) Order 2005, the responsible person for a commercial building must be able to produce evidence of compliance. A test certificate from a UKAS-accredited laboratory is that evidence. A verbal assurance, a product description, or a supplier’s own claim of compliance are not.

For the fire standards requiring treatment, see our Crib 5 guide. For which fibres can be treated, see our FR treatment and fibre compatibility guide. For dye types and their FR interaction, see our dye types and FR treatment guide.

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Which Fabrics and Fibres Can Be FR Treated: A Guide for Designers

Which Fabrics and Fibres Can Be FR Treated: A Guide for Interior Designers

Fibres that can generally be treated: Cotton, linen, wool, mohair, silk, viscose, polyester (with conditions), nylon, modacrylic
Fibres to avoid for FR treatment: Acrylic, polypropylene, polyethylene, pure acetate or triacetate
Exempt fibres (domestic upholstery): Cotton, linen, wool, silk, viscose — do not require match test treatment if at least 75% natural fibre by weight with a Schedule 3 interliner
The single most important rule: Fibre type is a guide, not a guarantee. The specific fabric construction, dye type, and finish all affect treatability. Always confirm with the treatment provider before ordering.

A fabric that cannot be successfully FR treated is a fabric that cannot be legally used in a contract environment without an alternative compliance route. Discovering this after the fabric has been specified, ordered, and delivered is a significant problem. This guide explains which fibres and fabric types are treatable for the UK standards most commonly required in contract interiors, which should be avoided, and what the exemption rules mean for domestic upholstery.

For the fire standards that require treatment, see our Crib 5 guide and our hotel fabric specification guide. For how dye type affects FR treatment, see our dye types and FR treatment compatibility guide.

How Treatability Works

FR treatment works by introducing a chemical compound — typically phosphorus-based or halogenated — into or onto the fabric structure. For the treatment to be effective, the compound must be able to penetrate and adhere to the fabric in sufficient quantity to inhibit combustion. The fibre type determines whether this is chemically and physically possible.

Natural protein fibres — wool, mohair, silk — have an inherently higher resistance to ignition than cellulosic and synthetic fibres, which reduces the amount of chemical treatment required to achieve compliance. This is one reason protein fibre fabrics can often be treated successfully even at relatively low chemical loadings.

Cellulosic fibres — cotton, linen, viscose — ignite readily and require more chemical treatment to achieve compliance. They can generally be treated successfully, but the dye type carried on the fabric affects whether the treatment can be applied without causing colour change. See the dye types and FR treatment guide for detail on this.

Synthetic fibres present a different challenge. Some — polyester, nylon — can be treated. Others — acrylic, polypropylene, polyethylene — melt and flow when exposed to heat rather than forming a char, which FR chemicals cannot effectively prevent. Fabrics containing significant proportions of these fibres cannot be reliably FR treated.

Fibre by Fibre: Treatability for UK Contract Standards

Cotton. Can be treated for both Crib 5 upholstery and BS 5867 Part 2 Type B curtains. Cotton is one of the most commonly treated fibres in the UK contract market. Back-coating is the standard method for upholstery Crib 5. Wet padding is used for curtain treatment. Dye type matters: reactive-dyed cotton carries a risk of post-treatment colour change and should be confirmed with the treatment provider before committing to an order. In domestic upholstery, cotton is an exempt fibre — fabric of at least 75% cotton by weight does not require match test treatment if used with a Schedule 3 fire-retardant interliner.

Linen. Can be treated for Crib 5 and BS 5867. Linen is an exempt fibre for domestic upholstery at 75% or above by weight with a Schedule 3 interliner. For contract use, treatment is required and linen takes FR chemical treatment well when correctly applied. The same reactive dye caution applies as for cotton.

Wool. Can be treated. Wool is a protein fibre with natural fire resistance arising from its high nitrogen and sulphur content. It is an exempt fibre for domestic upholstery. For contract upholstery requiring Crib 5, wool can be back-coated. The treatment chemical loading required is typically lower than for cotton because of wool’s inherent resistance. Wool treated with FR chemicals retains its handle well compared to some other fibres. An exempt fibre for domestic use.

Mohair. Can be treated, and Kothea’s active ranges carry independently certified Crib 5 passes achieved without topical treatment on the tested ranges, meaning treatment is not required. Where a mohair velvet does not carry an inherent certification, it can be back-coated. Mohair is not listed as an exempt fibre for domestic upholstery under the Furniture and Furnishings (Fire) (Safety) Regulations, which means it does not qualify for the Schedule 3 interliner route at any fibre content level. It requires treatment for domestic match test compliance unless it passes the test inherently.

Silk. Can be treated with care. Silk is an exempt fibre for domestic upholstery. For contract use, silk can be back-coated for Crib 5 but the treatment process must be managed carefully — silk is a delicate fibre and incorrect application can alter handle and appearance. Silk velvet in particular is sensitive to any wet process and should be approached with specialist advice before treatment is specified. The low Martindale rub count of silk velvet means it is unlikely to be specified for most contract upholstery applications regardless of fire treatment status.

Viscose and modal. Can be treated. Viscose (also called rayon) is a regenerated cellulose fibre and behaves similarly to cotton in FR treatment. It is an exempt fibre for domestic upholstery. For contract use it can be back-coated or wet-padded. Viscose is prone to shrinkage in wet processes and the treatment must be applied with appropriate tension control. Modal (polynosic) is a modified viscose and is also generally treatable.

Cuprammonium (cupro). Can be treated but is not an exempt fibre. Less commonly encountered in upholstery specification but treatable by similar methods to other regenerated cellulosics.

Acetate and triacetate. Problematic. Acetate and triacetate are cellulose acetate fibres with thermoplastic properties — they melt and drip when heated. This makes effective FR treatment very difficult. Treatment is only practically viable when acetate or triacetate are present as minor components in a blend with natural fibres. Fabrics with significant acetate or triacetate content should be avoided for contract applications requiring FR treatment. Not exempt fibres for domestic use.

Polyester. Can be treated when blended with natural fibres. Pure polyester is a thermoplastic fibre — it melts rather than chars — and standard FR back-coating compounds are less effective on pure polyester than on natural fibres. However, polyester blended with natural fibres at significant proportions can be treated. Trevira CS is a permanently flame-retardant polyester fibre whose fire resistance is inherent to the polymer and does not require topical treatment. Standard polyester in blend with cotton or wool at 50% or above natural fibre content is typically treatable by back-coating. Confirm the specific blend and proposed treatment method with the treatment provider.

Nylon (polyamide). Can be treated when blended with natural fibres. Similar position to polyester — thermoplastic in its pure form, more treatable in natural fibre blends. Nylon 6,6 blended with wool or cotton at significant proportions can generally be back-coated for Crib 5.

Modacrylic. Can be treated. Modacrylic is a modified acrylic fibre with significantly better inherent fire resistance than standard acrylic. It is treatable for both upholstery and curtain standards and behaves well in FR treatment processes.

Acrylic. Avoid. Standard acrylic (at least 85% acrylonitrile) is thermoplastic and melts and drips when exposed to heat. FR chemicals cannot effectively prevent this behaviour. Acrylic should not be specified for contract applications requiring FR treatment. This applies to both upholstery and curtain use. Not an exempt fibre.

Polypropylene. Avoid. Polypropylene burns readily and melts at low temperatures. It cannot be reliably FR treated to UK contract standards. Not an exempt fibre.

Polyethylene. Avoid. Same position as polypropylene — melts and burns without forming a char. Not treatable. Not an exempt fibre.

The Domestic Exemption: What It Means in Practice

The Furniture and Furnishings (Fire) (Safety) Regulations define a category of exempt fibres for domestic upholstery. A fabric composed of at least 75% by weight of exempt fibres — alone or in combination — does not require treatment for the match test (BS 5852 Source 1), provided it is used with a fire-retardant Schedule 3 interliner. It must still pass the cigarette test (BS 5852 Source 0).

The exempt fibres are: cotton, linen (flax), wool, silk, viscose (rayon), modal (polynosic). Mohair is not on the exempt list despite being a natural protein fibre with good inherent fire resistance. A fabric of 100% mohair does not qualify for the Schedule 3 interliner route and must pass the match test by another means — either inherently or through topical treatment.

The exemption applies to domestic upholstery only. It does not apply to contract upholstery, where Crib 5 or BS 7176 certification is required regardless of fibre content. A fabric of 100% cotton used on a domestic sofa with a Schedule 3 interliner is compliant for domestic sale. The same fabric on a hotel chair requires Crib 5 certification.

The Schedule 3 interliner must itself be fire retardant to the required standard. It cannot be a standard curtain interlining or a general-purpose backing fabric. The interliner supplier should provide confirmation that the product meets the Schedule 3 requirement.

Fabric Construction and Finishes That Affect Treatability

Fibre type is the primary determinant of treatability but not the only one. The following fabric characteristics can affect whether a treatment will be effective or practical.

Pile fabrics. Velvet and other pile fabrics present additional considerations for FR treatment. The pile surface increases the volume of combustible material at the surface relative to a flat-woven fabric of the same fibre and weight. A pile fabric may require a higher chemical loading to achieve compliance than a flat-woven fabric of the same fibre. The pile structure also means that any visible effect of treatment — colour change, handle alteration — is more noticeable than on a plain fabric. Treatment must be applied from the back only, without penetrating the pile face.

Coated or laminated fabrics. Fabrics with a polymer coating or laminate backing may not be treatable by standard back-coating methods because the existing coating prevents adhesion of the FR compound. Faux leather and coated technical fabrics typically achieve their fire performance through the inherent properties of the coating compound rather than topical FR treatment.

Water-repellent or stain-resistant finishes. Some fabrics carry a Teflon, Scotchgard, or similar fluorocarbon finish for stain resistance. These finishes can reduce the penetration of FR chemicals into the fabric structure, potentially reducing treatment effectiveness. Confirm with the treatment provider whether the specific finish is compatible with the proposed treatment method before ordering.

Very lightweight fabrics. Sheer curtain fabrics and extremely lightweight upholstery fabrics may be difficult to treat without visible handle change or shrinkage, regardless of fibre type. The chemical loading required for compliance may be a higher proportion of the fabric weight than for a heavier cloth, making the treated fabric noticeably different in handle from the untreated original.

What to Ask Before Specifying a Fabric for FR Treatment

Before specifying a fabric that will require topical FR treatment for contract use, confirm the following with the fabric supplier and with the proposed treatment provider.

What is the full fibre composition by percentage? The fibre content label gives this, but confirm with the supplier whether any blend components are thermoplastic — polyester, nylon, acrylic — and at what proportion.

Does the fabric carry any surface finish — stain resistance, water repellency, or coating — that might affect FR treatment penetration?

What is the dye class? See the dye types and FR treatment guide for why this matters.

Has this specific fabric been successfully FR treated before, and to which standard? Treatment providers keep records and can often advise whether a specific fabric has been through their process previously.

Is the treatment provider UKAS-accredited to issue the certificate required for the project? For contract upholstery the certificate must be issued by a UKAS-accredited laboratory. No fabric company or designer can self-certify FR compliance.

Frequently Asked Questions

Can all fabrics be made fire retardant?

No. Fibres that melt rather than char when heated — acrylic, polypropylene, polyethylene, and pure acetate — cannot be reliably FR treated to UK contract standards. FR chemicals work by inhibiting combustion in fibres that burn; they cannot prevent the melt-and-drip behaviour of thermoplastic fibres. Fabrics containing significant proportions of these fibres should not be specified for contract applications requiring Crib 5 or BS 5867 compliance through topical treatment.

Can polyester be FR treated?

Pure polyester is thermoplastic and difficult to treat effectively by standard back-coating methods. Polyester blended with natural fibres at substantial proportions — typically 50% or more natural fibre — can generally be back-coated for Crib 5. Trevira CS is a permanently flame-retardant polyester fibre with inherent fire resistance that does not require topical treatment. Always confirm the specific blend composition and proposed treatment method with the treatment provider before specifying.

Does a fabric with 75% natural fibre content need FR treatment for contract use?

Yes. The 75% natural fibre exemption applies only to domestic upholstery under the Furniture and Furnishings (Fire) (Safety) Regulations, allowing the use of a Schedule 3 interliner in place of match test treatment. It does not apply to contract upholstery, where Crib 5 or BS 7176 certification is required regardless of fibre content. A hotel, restaurant, or other commercial environment requires certified FR compliance irrespective of whether the fabric is made from exempt fibres.

Can mohair velvet be FR treated?

Mohair velvet that does not carry an inherent Crib 5 certification can be back-coated for Crib 5. However, Kothea’s active mohair velvet ranges carry independently certified Crib 5 passes on the tested ranges without topical treatment, which removes the need for treatment entirely. Mohair is not an exempt fibre under the domestic regulations regardless of fibre content, so it requires Crib 5 compliance by inherent certification or topical treatment for all contract applications.

Will FR treatment change how my fabric looks or feels?

Back-coating applied correctly to upholstery fabric does not typically alter the appearance or handle of the face. Wet-padded curtain treatment can affect the handle of lightweight fabrics, particularly sheers. Pile fabrics treated from the back retain their face pile character if the treatment does not penetrate the face. Any fabric where colour or handle change would be commercially significant should be sample-treated and approved before committing to a full order.

Who can issue a Crib 5 certificate?

Only a UKAS-accredited testing laboratory can issue a Crib 5 certificate. A fabric supplier, treatment company, or interior designer cannot self-certify FR compliance. When specifying a fabric for contract use, request the test certificate from the supplier and confirm that the issuing laboratory is UKAS-accredited. For contract curtain treatment requiring BS 5867 Part 2 Type B, the same applies.

For how back-coating and wet padding work, see our how FR treatment works guide. For the fire standards requiring FR treatment, see our Crib 5 guide. For dye types and their interaction with FR treatment, see our dye types and FR treatment guide.

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6 April 20266 April 2026

Dye Types and FR Treatment Compatibility: What Interior Designers Need to Know

Dye Types and FR Treatment Compatibility: What Interior Designers Need to Know

The hidden risk: Reactive dyes — used on many cotton, linen, and silk fabrics — can cause progressive fading in the months after FR treatment. The fading is not visible at installation. It develops slowly and cannot be reversed.
The safest dye class for FR-treated fabrics: Vat dyes on cellulosic fibres; acid dyes on protein fibres (wool, mohair, silk). Both form strong bonds resistant to the chemical conditions of FR treatment.
Fibres to approach with caution: Cotton and linen with reactive dyes; fabrics with unknown dye composition.
The practical rule: Always ask the supplier which dye class was used before sending a fabric for FR treatment.

Fire retardant treatment is a routine requirement for contract upholstery and curtains in commercial interiors. What is less widely understood is that the chemical process of FR treatment can interact with certain dye types and cause colour change — sometimes immediately after treatment, and sometimes months later when the problem is much harder to diagnose and impossible to reverse. This guide explains how different dye types are used on the fabrics most relevant to interior designers, which dye types carry the highest risk in FR treatment, and what to confirm with suppliers before committing to treatment.

For how back-coating and wet padding work in plain language, see our how FR treatment works guide. For the fire certification standards that require FR treatment, see our complete guide to BS 5852 Crib 5. For guidance on which fabrics and fibres can be FR treated, see our guide to FR treatment and fibre compatibility. For colour fastness testing, see our colour fastness and crocking guide.

How FR Treatment Works and Why Dyes Matter

The two main methods of applying FR treatment to upholstery and curtain fabrics are back-coating and wet padding. Understanding the difference is essential to understanding the dye interaction risk.

Back-coating applies a chemical compound — typically a phosphorus or halogenated compound suspended in a paste — to the reverse of the fabric. The coating sits on the back face and does not penetrate the face yarns where the dye is located. Provided the back-coating is applied correctly and the fabric is not saturated, back-coating has minimal interaction with the face dyes. The majority of Crib 5 treatments for upholstery fabrics use this method.

Wet padding applies FR chemicals in solution to the whole fabric by running it through a padder — rollers that squeeze the chemical solution into the structure of the cloth. The fabric is then dried and cured. This process is used primarily for curtain fabrics and some lighter upholstery weights. Because the chemical solution penetrates the entire fabric including the face yarns, it comes into direct contact with the dye molecules. This is where dye-FR interaction can occur.

The pH of the FR solution used in wet padding is mildly acidic for phosphorus-based compounds. Certain dye classes are sensitive to acidic conditions. When an acid-sensitive dye is exposed to the mildly acidic FR solution during padding, the bond between the dye molecule and the fibre can be weakened. The weakening may not cause immediate visible colour change. Instead, the dye becomes more susceptible to subsequent degradation by atmospheric pollutants — oxides of nitrogen and sulphur from the environment — which produce acids on the surface of the fabric after treatment. Fading develops progressively over weeks and months. It is not visible at installation and cannot be detected by standard pre-treatment testing.

The Main Dye Classes and Their FR Compatibility

Reactive dyes. The highest-risk dye class for FR treatment. Reactive dyes are used extensively on cellulosic fibres — cotton, linen, viscose — and occasionally on wool and silk blends. They produce bright, vivid colours with good light fastness and excellent wash fastness under normal conditions. The dye molecule forms a covalent chemical bond with the fibre during dyeing. However, this bond is sensitive to acid. The mildly acidic conditions of some FR padding treatments can initiate the breakdown of the dye-fibre bond, making the dye vulnerable to subsequent fading from atmospheric pollutants.

The fading problem with reactive dyes is well documented in the FR treatment industry. It does not affect all reactive dyes equally — different reactive dye variants have different acid sensitivity — but a significant proportion of fading problems encountered by FR treatment companies involve reactive dyes. The problem is compounded by its delayed onset: a fabric that passes visual inspection immediately after treatment may show noticeable fading within three to six months. By the time the fading is visible, installation is complete and remediation is not possible.

The practical advice from experienced FR treatment houses is: where possible, avoid specifying fabrics with reactive dyes for wet-padded FR treatment. If you cannot avoid it — because the fabric is specified and cannot be changed — request that the treatment provider tests a sample and stores it for three to six months before treating the full order. This does not guarantee the full order will behave identically, but it provides the best available advance warning of a fading risk.

Acid dyes. Used on protein fibres — wool, mohair, silk, and some nylon. Acid dyes form strong bonds with protein fibres and are not sensitive to the mildly acidic conditions of FR treatment in the way that reactive dyes are. Back-coated wool and mohair velvets treated for Crib 5 using phosphorus or halogenated back-coating compounds do not typically show dye interaction problems. Acid-dyed silk is more cautious territory because silk is a delicate protein fibre and any chemical exposure requires care, but acid dye instability is not the primary risk for silk in FR treatment.

Vat dyes. The most stable dye class available and the least susceptible to FR treatment interaction. Vat dyes are used on cellulosic fibres — cotton and linen primarily — and produce colours with exceptional light fastness and wash fastness. The dye molecule is insoluble and is locked within the fibre structure rather than bonded chemically at the surface in the same way reactive dyes are. Vat dyes do not react with the acidic conditions of FR treatment and do not show the progressive fading associated with reactive dyes after treatment. Cotton and linen fabrics dyed with vat dyes are among the most FR-treatment-compatible cellulosic fabrics available. The limitation of vat dyes is a smaller colour range and higher dyeing cost compared to reactive dyes, which is why many fabric producers use reactive dyes as their default.

Disperse dyes. Used on polyester and acetate. Disperse dyes are forced into synthetic fibres under high heat and pressure. They are virtually insoluble in water and chemically stable. FR treatment of polyester fabrics, particularly Trevira CS which is inherently flame resistant, does not typically involve the same dye interaction risks as cellulosic FR treatment. Disperse-dyed polyester fabrics are generally low-risk for FR treatment. A known issue with disperse dyes is discolouration from oxides of nitrogen in the atmosphere — a separate problem from FR treatment interaction but worth noting for polyester fabrics in high-pollution urban environments.

Direct dyes. Used on cellulosics. Direct dyes have good substantivity for cotton and linen but moderate wash fastness — they are relatively water-soluble. The FR treatment interaction risk is lower than for reactive dyes because the dye-fibre bond mechanism is different, but direct-dyed fabrics should still be assessed for colour stability before FR treatment. Their water solubility means they are somewhat susceptible to the aqueous conditions of wet padding regardless of pH.

Sulphur dyes. Used on cellulosics, producing blacks, dark browns, and dark navies. Sulphur dyes have been associated with isolated fading problems after FR treatment — typically affecting specific yarn colours within a fabric rather than the entire cloth, making the problem appear as uneven colour change across the weave. This is relatively uncommon but has been observed.

Which Fabrics Carry the Highest Risk

Cotton curtain fabrics in saturated colours — particularly bright reds, coral, fuchsia, and vivid blues and greens — are most likely to be dyed with reactive dyes and carry the highest risk of post-treatment fading. Linen curtain fabrics in the same colour range carry comparable risk. The deeper and more saturated the colour, the more likely reactive dyes are involved.

Pale, muted, or neutral colours in cotton and linen are sometimes dyed with direct or vat dyes, which carry lower risk. However, the dye class cannot be determined from the colour alone. The only way to confirm the dye type is to ask the supplier.

Wool, mohair, and silk upholstery fabrics dyed with acid dyes and back-coated rather than wet-padded are the lowest-risk category for FR treatment colour interaction. This is one of the practical advantages of specifying mohair velvet with an inherent Crib 5 certification: the need for wet-padded FR treatment is eliminated entirely, removing the dye interaction risk from the specification chain.

Synthetic fabrics — polyester, Trevira CS, nylon — are generally low risk for dye interaction in FR treatment, with the specific disperse dye caveat noted above.

What to Ask Before Sending a Fabric for FR Treatment

Before sending any fabric to an FR treatment company for Crib 5 treatment, confirm the following with the fabric supplier.

Which dye class was used on this fabric? If the supplier cannot answer this question, treat the fabric as reactive-dyed and proceed with caution. Most reputable fabric suppliers can provide this information from their mill technical data sheet.

Has this fabric been FR treated before, and were any colour changes observed? A fabric that has been successfully FR treated and stored without fading gives some reassurance. A fabric that has not been treated before carries the full unknown risk.

Is the colour in the current batch produced by the same dyehouse as previous batches? Dye lot variation between batches extends to dye class selection in some mills, where the dyehouse may substitute a dye type if the standard dye is temporarily unavailable.

Once you have confirmed the dye class, convey this information to the FR treatment company before treatment begins. Experienced treatment companies maintain records of which fabrics and dye classes have caused problems and can advise whether a screen test — treating a small sample and storing it for an extended period before treating the full order — is warranted.

The FR Treatment Process and Colour Change: Timing and Detection

Immediate colour change visible at the point of treatment is typically caused by a direct chemical reaction between the FR compound and the dye. This type of problem is detectable during the treatment process and gives the treatment company an immediate opportunity to halt treatment and contact the specifier. It is the minority of dye-FR problems.

Progressive fading developing over weeks to months after treatment is caused by the mechanism described earlier — the FR treatment weakens the dye-fibre bond, making the dye susceptible to subsequent degradation by atmospheric pollutants. This type of problem is not detectable at the time of treatment and will not be evident at the point of installation. It develops after the fabric is in situ. By the time it is noticed, the treatment cannot be reversed and the fading cannot be corrected without replacing the fabric.

This is the most commercially damaging outcome of dye-FR interaction. It occurs after the project is complete, generates a complaint the designer cannot easily resolve, and involves a fault that originated in the specification chain before installation. The only effective mitigation is to avoid the risk at the specification stage by confirming the dye class before specifying the fabric for FR treatment.

Frequently Asked Questions

Can any fabric be FR treated without colour change risk?

No fabric carries zero risk, but the risk varies significantly by dye class and treatment method. Wool and mohair fabrics dyed with acid dyes and back-coated for Crib 5 carry the lowest practical risk of colour change from FR treatment. Cellulosic fabrics — cotton, linen — dyed with vat dyes and wet-padded carry low risk. Cellulosic fabrics dyed with reactive dyes and wet-padded carry the highest risk of progressive fading. Always confirm the dye class with the supplier before specifying a fabric for FR treatment.

What are reactive dyes and why are they a problem for FR treatment?

Reactive dyes are a dye class widely used on cotton, linen, and viscose that produce vivid colours with good light and wash fastness under normal conditions. The dye molecule forms a covalent chemical bond with the fibre during dyeing. This bond is sensitive to acidic conditions. The mildly acidic FR solutions used in some wet-padding treatments can weaken the bond, making the dye susceptible to progressive fading from atmospheric pollutants in the months after treatment. The fading is not visible at installation. Reactive dyes are the dye class most frequently associated with post-treatment fading problems documented by specialist FR treatment houses.

Does back-coating affect fabric colour?

Back-coating, applied to the reverse of the fabric, does not typically affect the face colour provided the treatment is applied correctly and the fabric is not saturated. It is the wet-padding process — where FR chemicals in solution are applied to the whole fabric — that carries the dye interaction risk. Back-coating is the standard method for upholstery fabric Crib 5 treatment and has minimal colour impact on the face dyes under normal application conditions.

How can I tell if a fabric has been dyed with reactive dyes?

You cannot determine the dye class from visual inspection or handling alone. The dye class must be confirmed with the fabric supplier, who should be able to provide this information from the mill technical data sheet. As a general guide, cotton and linen fabrics in saturated, vivid colours — bright reds, corals, vivid blues and greens — are more likely to be reactive-dyed. Pale and muted neutrals in the same fibres may use direct or vat dyes. This is a guide only and cannot substitute for direct confirmation.

What should I do if I cannot avoid specifying a reactive-dyed fabric for FR treatment?

Request that the FR treatment company treats a sample piece and stores it under normal conditions for three to six months before treating the full order. This does not guarantee that the full order will behave identically, but it provides the best available advance warning of a fading risk. Brief the client on the risk before treatment and document the briefing. If fading develops after installation, having documented the risk identification and mitigation steps provides important protection.

Is mohair velvet at risk from FR treatment colour change?

Mohair velvet that carries an independently certified Crib 5 pass achieved without topical treatment does not require FR treatment and therefore carries no dye-FR interaction risk. This is one of the practical advantages of specifying correctly certified mohair velvet for contract use: the treatment stage and its associated colour risks are removed from the specification chain entirely. Mohair velvet that requires topical treatment — because the specific range does not carry an inherent Crib 5 certification — is typically back-coated rather than wet-padded, which also carries low colour interaction risk as noted above.

For guidance on which fibres and fabric types can be FR treated, see our guide to FR treatment and fibre compatibility. For the fire certification standards that require treatment, see our Crib 5 guide.

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5 April 202611 April 2026

Velvet Types Compared: Mohair, Cotton, Silk, Linen and Synthetic

Velvet Types Compared: A Complete Specifier’s Guide for Interior Designers and Architects

Most durable natural velvet: Mohair — 80,000 to 100,000 Martindale rubs
Contract fire standard: BS 5852 Crib 5 — inherent in correctly certified mohair; topical treatment required for cotton, linen, and silk
Cleaning code: S (solvent only) for most natural velvets; W or WS for synthetic
Decorative use only: Silk velvet and cashmere velvet — not suitable for upholstery in regular use

Velvet is a construction method, not a fibre. A velvet fabric is produced by weaving two layers of cloth simultaneously with threads connecting them, then cutting those threads to create an upstanding pile. That pile can be made from almost any fibre, and the fibre is the primary determinant of specification performance — durability, fire rating, cleaning requirements, light fastness, and cost — alongside construction, pile density, and backing. Choosing between velvet types on aesthetic grounds alone is the most common specification error in interior design.

This guide compares the principal velvet types available to specifiers in the UK market across every dimension relevant to a professional specification. For background on the testing standards referenced throughout this guide, see our posts on the Martindale rub test, BS 5852 Crib 5 fire certification, light fastness and the Blue Wool Scale, and fabric care symbols and cleaning codes.

How Velvet Is Made

Understanding the construction helps explain why fibre choice matters so much in velvet. In warp pile velvet, the pile yarns run along the length of the fabric and are woven over wires or rods. When the rods are withdrawn and the loops cut, a cut pile is formed. In double-cloth velvet, two fabrics are woven face to face simultaneously, joined by pile threads that are then cut to separate them and create pile on both faces. The resulting fabric has a distinct face and back, with the pile standing perpendicular to the base cloth.

The density and height of the pile, the twist of the pile yarn, and the weight and construction of the base cloth all affect performance. But the most fundamental variable is the fibre from which the pile is made.

Mohair Velvet

Fibre origin: Hair of the Angora goat, primarily from South Africa and Turkey. South Africa produces more than half of the world’s mohair supply and is the global benchmark for quality. A long-staple, smooth, lustrous fibre with exceptional tensile strength. For background on South African mohair production and the Responsible Mohair Standard, see Mohair South Africa.

Martindale rub count: 80,000 to 100,000 and above, depending on construction and pile density. Mohair velvet achieves the highest rub counts of any natural-fibre velvet and is the most reliably suitable natural-fibre velvet for heavy contract use. Kothea’s mohair velvet ranges are independently tested and achieve between 80,000 and 100,000 Martindale rubs across the active collections.

Fire rating: Mohair fibre, like wool, has natural flame-resistant properties arising from its high protein content. A correctly woven and constructed mohair velvet can achieve a BS 5852 Crib 5 pass without topical chemical treatment, depending on construction and backing. This is not universal across all mohair velvets and must be confirmed by an independent test certificate for the specific range. Kothea’s active mohair velvet ranges carry independently certified Crib 5 passes without topical treatment. Where this is confirmed, the certification does not depend on chemical coatings, is unaffected by cleaning, and does not alter the handle or appearance of the fabric. This is the single most commercially significant advantage of a correctly certified mohair velvet over other natural-fibre velvets.

Cleaning code: S. Dry-cleaning solvent only. Water applied to mohair velvet can cause watermarks and pile matting. For minor fresh stains, a barely dampened lint-free cloth worked in the direction of the pile is acceptable as a first response. For full cleaning guidance see our post on cleaning and maintaining mohair velvet.

Light fastness: ISO 105-B02 grade 4 to 5 in light colourways and grade 5 to 6 in dark colourways. Suitable for most residential environments. For south-facing rooms, specify dark colourways or confirm the specific colourway grade with the supplier.

Pile appearance: High lustre with a characteristic directional sheen. The pile reflects light differently depending on viewing angle and pile direction, producing the depth of colour associated with luxury upholstery velvet. The sheen is a natural property of the mohair fibre and cannot be replicated by cotton or synthetic alternatives.

Suitable applications: Heavy contract upholstery including hotel seating, restaurant banquettes, theatre and hospitality seating, residential sofas and chairs, headboards, cushions, and curtains. The combination of inherent Crib 5 and high Martindale makes it the standard against which all other upholstery velvets are measured in the UK contract market.

Not recommended for: High-light environments without confirming the colourway grade. Outdoor or semi-outdoor use. Applications requiring machine washing.

Cost position: Premium. The Angora goat produces a limited annual clip, and the fibre must be woven to a high pile density to achieve the rub counts associated with contract performance. The cost is justified by the specification advantage of inherent Crib 5 and the durability of the fabric in use.

Cotton Velvet

Fibre origin: Cotton plant. A short-staple natural cellulose fibre, widely grown and relatively inexpensive.

Martindale rub count: 20,000 to 60,000 depending on construction, pile density, and backing. Cotton velvet varies enormously in quality. A well-constructed heavyweight cotton velvet can achieve sufficient durability for general domestic and light contract use. A thin, loosely woven cotton velvet intended for curtains or cushions may achieve 10,000 rubs or fewer. Always confirm the specific Martindale figure for the range you are specifying.

Fire rating: Topical treatment required. Cotton fibre does not pass BS 5852 Crib 5 inherently. A back-coating of flame-retardant chemicals must be applied before use in contract environments. The treatment process can affect the appearance and handle of the pile if not applied correctly, and specialist treatment houses experienced with velvet pile should be used. The Crib 5 certification achieved through topical treatment is subject to degradation through repeated cleaning. See our complete guide to Crib 5 for detail on inherent versus topical certification. For the risk of dye colour change after FR treatment, particularly on cotton with reactive dyes, see our dye types and FR treatment guide.

Cleaning code: S or WS depending on the specific range. Confirm the cleaning code on the fabric data sheet before specifying. Cotton velvet treated with a back-coating for Crib 5 may require solvent-only cleaning to avoid degrading the treatment.

Light fastness: Grade 4 to 5 typically with standard reactive dyes. Broadly comparable to mohair at equivalent price points. Cotton velvet takes dye well and can achieve good colour depth.

Pile appearance: Matte to semi-matte. Cotton pile lacks the lustre of mohair and does not produce the same directional sheen. The aesthetic is warmer and less formal than mohair, which suits some residential briefs.

Suitable applications: Domestic upholstery, cushions, curtains, and headboards. Suitable for general domestic and light contract use when correctly specified and treated. Not the first choice for heavy contract environments where the additional cost and complexity of topical treatment, re-treatment requirements, and lower Martindale thresholds make mohair velvet a more defensible specification.

Not recommended for: Heavy contract use without FR treatment and independent testing. High-humidity environments. Applications where the FR certification must survive repeated cleaning without re-treatment.

Cost position: Mid-range. Cotton velvet is typically less expensive than mohair at equivalent pile weights but requires the additional cost of FR treatment for contract use, which narrows the price difference in contract projects.

Silk Velvet

Fibre origin: Cocoon of the silkworm Bombyx mori. Silk is a continuous filament natural protein fibre of exceptional fineness and lustre.

Martindale rub count: Below 15,000 in most cases. Natural silk is the weakest of the natural-fibre velvets in abrasion terms. The fineness of the filament that produces silk’s extraordinary lustre is also the source of its vulnerability to mechanical wear. Silk velvet is decorative fabric, not upholstery fabric in the contract sense of the word.

Fire rating: Topical treatment is possible for domestic standards but silk velvet cannot reliably achieve a full Crib 5 pass for contract use. The coating process can damage the silk pile irreversibly. Silk velvet should not be specified for contract environments requiring BS 5852 Crib 5 certification unless the specific range has been independently tested and certified.

Cleaning code: S. Dry-clean only. Silk is highly water-sensitive. Water will cause permanent watermarking and potentially alter the pile structure.

Light fastness: Grade 2 to 4 typically. Silk is the most photosensitive of the natural upholstery fibres. The dyes used on silk are chemically susceptible to UV degradation. Silk velvet should not be used in rooms with significant natural light exposure and should not be used on curtains where direct sunlight will fall on the fabric face. See our light fastness guide for full context.

Pile appearance: The most lustrous of all velvet pile types. Silk produces an extraordinary depth of sheen that no other fibre can replicate. The visual effect is incomparable when correctly lit in a low-light residential interior.

Suitable applications: Decorative cushions, occasional chairs in low-use residential rooms, curtains in low-light environments, bed throws. Silk velvet is the choice where aesthetic impact is the sole requirement and durability, fire rating, and light fastness are secondary.

Not recommended for: Any contract application. South-facing rooms. Any room with significant footfall or regular seating use. Headboards where regular contact with hair products will degrade the pile.

Cost position: High to very high. Silk is the most expensive natural fibre and the pile density required for velvet construction multiplies the material cost significantly. Quality varies considerably between suppliers.

Linen Velvet

Fibre origin: Flax plant. Linen is a bast fibre extracted from the stalk of the flax plant. It is a strong, textural natural cellulose fibre with a characteristic irregularity of surface.

Martindale rub count: 15,000 to 25,000 typically for linen velvet, though construction varies. Kothea’s Linen Velvet achieves 20,000 Martindale rubs with a SI 1324 cigarette test pass. Linen velvet occupies the domestic to light contract range.

Fire rating: Not inherently Crib 5. Linen is a natural fibre with moderate fire resistance but does not pass BS 5852 Crib 5 without treatment or interliner. For contract use, FR treatment or a Schedule 3 interliner is required. Fabrics containing at least 75% natural fibres by weight may use a Schedule 3 interliner as an alternative to chemical treatment for some standards. Confirm the specific requirement with the relevant authority for the project environment.

Cleaning code: S or WS. Confirm on the data sheet. Linen is water-sensitive in pile form and wet cleaning can cause shrinkage and pile distortion.

Light fastness: Grade 4 to 5 with standard reactive dyes. Comparable to cotton velvet.

Pile appearance: Matte. Linen velvet has a distinctly textural, natural surface character very different from the smooth reflective pile of mohair or silk. The pile is less uniform than mohair or cotton and the fibre’s natural irregularity is visible in the surface of the cloth. This quality is valued in certain residential briefs where a craft or natural aesthetic is sought.

Suitable applications: Domestic upholstery, curtains, cushions, decorative headboards. A strong choice for residential briefs requiring a natural, relaxed aesthetic with moderate durability.

Not recommended for: Heavy contract use. High-humidity environments. Applications where uniformity of pile surface is required.

Cost position: Mid-range. Linen velvet is typically comparable in price to cotton velvet at equivalent construction weights.

Cashmere and Cashmere-Silk Velvet

Fibre origin: Undercoat of the Himalayan Cashmere goat. Cashmere is one of the finest natural fibres available, characterised by exceptional softness and warmth retention.

Martindale rub count: Low. Cashmere fibre is too fine and too short-staple to produce velvet with meaningful abrasion resistance for upholstery use. Cashmere velvet, and cashmere-silk velvet blends, are decorative fabrics. Kothea’s Cashmere Silk Velvet is specified for curtains only.

Fire rating: Topical treatment is technically possible but the handle and appearance of cashmere velvet are typically altered by the coating process. Cashmere velvet cannot be reliably specified for contract upholstery environments requiring Crib 5 certification.

Cleaning code: S. Dry-clean only.

Light fastness: Moderate. Cashmere is a protein fibre and susceptible to UV degradation. Not recommended for high-light environments.

Pile appearance: Extraordinarily soft handle with a subtle, fine lustre. The pile texture is unlike any other velvet and is immediately identifiable by touch. Cashmere-silk blends add luminosity to the characteristic cashmere warmth.

Suitable applications: Curtains, decorative cushions, bed throws, accent pieces in low-use residential rooms. Cashmere velvet is the choice where tactile experience is the primary specification criterion.

Not recommended for: Upholstery of any kind in regular use. Contract environments. Any application where durability or fire certification is required.

Cost position: Very high. Cashmere velvet is among the most expensive interior fabrics available.

Synthetic Velvet: Trevira CS and Polyester

Fibre origin: Petrochemical derivatives. Trevira CS is a branded inherently fire-retardant polyester fibre manufactured in Germany. Standard polyester velvet uses conventional polyester yarn.

Martindale rub count: High. Synthetic velvet typically achieves 50,000 to 150,000 Martindale rubs depending on construction. Synthetic fibres are inherently more resistant to mechanical abrasion than natural fibres of equivalent weight.

Fire rating: Trevira CS is inherently flame-retardant. The flame retardancy is a permanent property of the polyester polymer and survives cleaning. Standard polyester velvet requires topical treatment and may or may not achieve a full Crib 5 pass depending on construction. Always confirm the specific test result and certification for any synthetic velvet before specifying for contract use.

Cleaning code: W or WS typically. Synthetic fibres are more tolerant of water-based cleaning than natural fibres. Many synthetic velvets can be spot-cleaned with water-based upholstery cleaners.

Light fastness: Grade 6 to 7 typically. Synthetic fibres are inherently more UV-resistant than natural fibres. Solution-dyed synthetic velvet, where the colour is incorporated into the fibre during extrusion, achieves the highest light fastness ratings available in velvet form.

Pile appearance: Varies considerably by construction. High-quality synthetic velvet can closely approximate the appearance of natural velvet. Lower-quality synthetic velvet has a flatter, more uniform pile with less depth. The distinguishing quality of natural-fibre velvets, particularly mohair, is visible to an experienced eye in showroom conditions.

Suitable applications: Contract upholstery where fire certification and durability are the primary requirements. Healthcare environments. Transport seating. Applications where machine cleanability or high-frequency cleaning is required.

Not recommended for: Ultra-luxury residential briefs where natural fibre handle and appearance are client requirements. Marine environments without confirming IMO compliance separately.

Cost position: Lower to mid-range. Synthetic velvet is less expensive than mohair at equivalent construction weights, though high-specification Trevira CS velvet from major European mills approaches mohair pricing.

Alpaca Velvet

Fibre origin: Fleece of the South American alpaca. Alpaca is a protein fibre closely related to wool, with a finer and softer handle than most sheep’s wool and a moderate natural lustre.

Martindale rub count: 20,000 to 40,000 typically, depending on construction. Alpaca velvet performs similarly to a well-constructed wool velvet. It is suitable for domestic and light contract use but does not approach the rub counts achievable with mohair.

Fire rating: Alpaca is a natural protein fibre and, like wool and mohair, has moderate inherent fire resistance. However, alpaca velvet cannot be assumed to pass BS 5852 Crib 5 inherently without specific independent testing. Do not specify alpaca velvet for contract use on the basis of fibre type alone. Request the test certificate from the supplier.

Cleaning code: S typically. Confirm with the supplier.

Light fastness: Grade 4 to 5 with standard acid dyes. Comparable to mohair.

Pile appearance: Soft and slightly matte with a gentle natural lustre. Less directional sheen than mohair. The pile has a warmth of character distinct from both mohair and cotton.

Suitable applications: Luxury residential upholstery, cushions, and occasional seating. Alpaca velvet is a niche choice for residential briefs where natural fibre and unusual character are valued over contract performance.

Not recommended for: Heavy contract use. Applications where inherent Crib 5 certification is required.

Cost position: High. Alpaca fibre is less widely produced than mohair or cotton and carries a premium.

Specification Summary by Application

For heavy contract upholstery in hotels, restaurants, bars, and hospitality environments, mohair velvet with an independently certified Crib 5 pass achieved without topical treatment, and a rub count of 80,000 or above, is the most reliable natural-fibre specification. Synthetic Trevira CS velvet is the alternative where budget or client preference for machine-cleanable fabric applies.

For residential upholstery in moderate-use rooms, cotton velvet at 25,000 to 40,000 Martindale rubs is a sound mid-range specification. Linen velvet at 20,000 rubs suits briefs requiring a natural textural aesthetic.

For decorative applications, cushions, and occasional chairs in low-use rooms, silk velvet, cashmere velvet, or alpaca velvet are appropriate where budget allows and the client accepts the care requirements.

For south-facing rooms or high-light environments, confirm the specific ISO 105-B02 grade before specifying any velvet. Mohair in dark colourways, synthetic velvet, and solution-dyed fabrics offer the most reliable light fastness performance.

Frequently Asked Questions

What is the most durable velvet for contract upholstery?

Mohair velvet is the most durable natural-fibre velvet for contract upholstery, achieving Martindale rub counts of 80,000 to 100,000 depending on construction. It also carries an inherent BS 5852 Crib 5 fire rating without topical treatment, making it the only natural-fibre velvet that meets both the durability and fire certification requirements of most UK contract environments without additional cost or treatment. High-specification synthetic velvet using Trevira CS fibre can achieve comparable or higher rub counts and also carries inherent fire resistance, at a lower cost but with a different aesthetic.

What is the difference between mohair velvet and cotton velvet?

Mohair velvet is made from the hair of the Angora goat and achieves Martindale rub counts of 80,000 to 100,000 with an inherent Crib 5 fire rating. Cotton velvet is made from cotton fibre and typically achieves 20,000 to 60,000 Martindale rubs depending on construction, with no inherent Crib 5 rating. Cotton velvet requires topical FR treatment for contract use. Mohair velvet has a characteristic directional sheen and depth of colour that cotton velvet does not replicate. Cotton velvet is less expensive but requires additional investment in fire treatment for contract projects, narrowing the price advantage in practice.

Can silk velvet be used for upholstery?

Silk velvet is not suitable for upholstery in regular use. It typically achieves fewer than 15,000 Martindale rubs, which places it in the decorative category unsuitable for seating. Silk is also highly photosensitive, with a light fastness grade of 2 to 4, meaning it will fade in rooms with natural light exposure. Silk velvet cannot reliably achieve a BS 5852 Crib 5 certification for contract use. It is appropriate for decorative cushions, curtains in low-light environments, and occasional chairs in rooms with very limited use.

Does mohair velvet have an inherent Crib 5 fire rating?

Mohair fibre has natural flame-resistant properties and a correctly woven mohair velvet can achieve a BS 5852 Crib 5 pass without topical chemical treatment, depending on construction and backing. This is not guaranteed for all mohair velvets by fibre type alone and must be confirmed by an independent test certificate for the specific range. Kothea’s active mohair velvet ranges carry independently certified Crib 5 passes without topical treatment. Where this is confirmed, the certification does not depend on chemical coatings, is unaffected by cleaning, and does not alter the handle or appearance of the fabric. This distinguishes correctly certified mohair velvet from cotton, linen, and silk velvets, all of which require topical treatment to achieve Crib 5. Always request the independent test certificate from the supplier before specifying for contract use.

What velvet is best for south-facing rooms?

For south-facing rooms, specify velvet with an ISO 105-B02 light fastness grade of at least 6. Mohair velvet in dark colourways achieves grade 5 to 6. Synthetic velvet and solution-dyed fabrics typically achieve grade 6 to 7. Silk velvet and cashmere velvet should not be specified for south-facing rooms. Cotton and linen velvet achieve grade 4 to 5, which is borderline for sustained south-facing exposure. Always confirm the specific grade with the supplier for the colourway being ordered, as light fastness varies between colourways within the same range.

What is the difference between cut pile velvet and uncut pile velvet?

In cut pile velvet the pile loops are cut during production, producing upstanding individual fibres that create the characteristic dense, soft surface. In uncut pile or loop pile velvet the loops remain intact, producing a harder, more textural surface. Most upholstery velvet is cut pile. Some decorative velvets combine cut and uncut areas to create pattern, known as ciselé or voided velvet. For upholstery specification, cut pile velvet is the standard choice. Uncut or loop pile velvet may be specified where a more durable surface texture is required as the intact loops resist abrasion more effectively than cut pile.

How do I clean velvet upholstery without damaging the pile?

The cleaning method depends on the cleaning code assigned to the specific fabric. Most velvet upholstery is coded S, meaning solvent-based dry-cleaning agents only. Water applied to an S-coded velvet can cause watermarks and permanent pile distortion. Always work in the direction of the pile when applying any cleaning agent or brushing. For minor fresh stains on mohair velvet, a barely dampened lint-free cloth worked in the direction of the pile is acceptable as a first response. Serious staining should always be referred to a specialist dry cleaner experienced with velvet upholstery.

Is linen velvet suitable for contract upholstery?

Linen velvet is suitable for light contract use, subject to FR treatment and confirmation of the Martindale rub count for the specific range. A well-constructed linen velvet at 20,000 Martindale rubs meets the minimum threshold for general contract use. However, linen velvet does not pass BS 5852 Crib 5 inherently and requires topical treatment or an appropriate interliner for contract environments. For heavy contract use requiring 40,000 rubs or above and full Crib 5 certification, mohair velvet or synthetic velvet are more appropriate specifications.

For the tactile properties of each velvet type and how hand differs between fibres, see our fabric hand and tactile properties guide.

For velvet specification in hotel and hospitality projects, see our hotel fabric specification guide. For velvet on walls and headboards, see our wall panels and headboards guide.

Kothea offers mohair velvet, linen velvet, and cashmere silk velvet from its active range. To For when velvet is the wrong choice for a project, see our when not to use velvet guide. For pilling resistance by velvet type, see our pilling resistance guide. For mohair thermal properties in hospitality, see our mohair thermal properties guide.

For full specification data including Martindale rub counts, fire ratings, and light fastness grades by range, see the mohair velvet upholstery page and the silks page.

For guidance on using velvet as an acoustic treatment in home studios and music rooms, see our fabric for home studio acoustics guide.

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BS 5852 Crib 5: Complete Guide for Upholstery Specification

Brown faux leather chair from April Hamilton

BS 5852 Crib 5: A Complete Guide for Interior Designers and Specifiers

BS 5852 Crib 5 is the fire safety standard required for most contract upholstery in the United Kingdom. If you are specifying fabric for a hotel, restaurant, bar, office, healthcare environment, or any other commercial interior, Crib 5 compliance is the baseline expectation. This guide explains what the standard is, how the test works, the critical difference between inherent and topical certification, and how to specify correctly. For dye types and FR treatment compatibility — which dyes cause fading after treatment — see our dye types and FR treatment guide. For colour fastness and crocking specification, see our colour fastness and crocking guide. For hotel and hospitality projects see our hotel fabric specification guide. For wall panel and headboard applications, a different standard applies: see our guide to fabric for wall panels and headboards.For projects involving yachts or commercial vessels, a separate framework applies: see our guide to IMO marine fire standards for yacht interiors.

What Crib 5 Is

Crib 5 is shorthand for BS 5852 Ignition Source 5. BS 5852, titled Methods of Test for Assessment of the Ignitability of Upholstered Seating, is the British Standard that defines how upholstered furniture materials must behave when exposed to ignition sources of increasing intensity. The standard defines eight ignition source levels. The three that matter most in practice are Source 0 (a smouldering cigarette), Source 1 (a small flame equivalent to a lit match), and Source 5, which is the Crib 5 test.

The name comes from the wooden structure used as the ignition source. A crib is a small lattice of dry timber pieces, stacked five tiers high, weighing approximately 17 grams. The number 5 refers to the number of tiers. The crib is placed on the upholstery assembly and ignited. The test is designed to simulate an ignition event more intense than a match flame, comparable to a burning pile of paper, and is the realistic minimum for contract environments where furniture may be exposed to more severe ignition risks than a smouldering cigarette.

The Three-Stage Test

BS 5852 Crib 5 is not a single test in isolation. To achieve a Crib 5 certification, a fabric must first pass both the cigarette test (Source 0) and the match test (Source 1). Only materials that pass both of these lower-level tests are eligible to proceed to the Crib 5 stage. A material that fails the cigarette or match test cannot be certified to Crib 5 regardless of how it performs under the wooden crib.

For more detail on the cigarette and match stages of BS 5852, see our post on the cigarette and match tests.

In the cigarette test, a smouldering cigarette is placed in the crease between the seat and back of the upholstered test rig. The material must show no ignition and no progressive smouldering.

In the match test, a small burner flame is held against the upholstery for 20 seconds. The material must self-extinguish immediately and show no spread of flame.

In the Crib 5 test, the lit wooden crib is placed on the upholstered assembly. All flaming must cease within 10 minutes. The fire must not spread beyond defined limits or penetrate the filling material. There must be no self-sustaining smouldering after the crib has burned out.

The Composite Nature of the Test

This is the point most frequently misunderstood in specification. BS 5852 does not test the fabric in isolation. It tests the full composite assembly: the fabric cover, the foam or filling, and any interliner, all as they would be used together in the finished piece of furniture.

A fabric that achieves Crib 5 certification in one configuration with a specific foam may not achieve it when applied over a different foam. A certificate from a fabric supplier confirms the fabric was tested in a specific configuration. If the foam or filling used in your project differs from the foam used in the test, the certificate may not be valid for your application.

Always confirm with your fabric supplier the exact configuration under which the Crib 5 test was conducted, including the foam specification, before relying on that certificate for a contract project.

Inherent Versus Topical Certification

The single most important distinction in specifying a Crib 5 fabric is whether the certification is inherent or achieved through topical treatment. The practical consequences are significant.

Inherent Crib 5 means the fire resistance is a property of the fibre itself. The yarn from which the fabric is woven is non-combustible or self-extinguishing by its nature, independent of any chemical application. Mohair velvet is the primary example in the Kothea range. Mohair fibre is inherently resistant to ignition, and a correctly woven mohair velvet carries an inherent Crib 5 pass without any treatment being applied. The certification is permanent, unaffected by cleaning, does not alter the handle or surface appearance of the fabric, and carries no additional cost for FR treatment.

Topical or back-coated treatment is applied to a fabric that is not inherently fire resistant. The fabric passes through a bath of fire-retardant chemicals, which are bonded to the reverse of the fabric through a coating process. The resulting fabric can achieve a Crib 5 pass, but with three important caveats.

First, the BS 5852 standard requires a water-soak test as part of full certification. The fabric is soaked in water to simulate cleaning and then retested. Many fabrics that pass the dry Crib 5 test fail after the water-soak stage. An indicative test without the water-soak is not a complete Crib 5 certificate. Do not rely on an indicative certificate for contract projects without confirming with the client and fire officer that it is acceptable.

Second, the coating process can affect the appearance and handle of certain fabrics. Pile fabrics such as velvets are particularly susceptible. Immersion or back-coating can flatten the pile, stiffen the handle, or leave residue on the face of the fabric. This is one of the reasons mohair velvet with an inherent pass is preferable for contract use over cotton or linen velvet that requires treatment.

Third, a topically treated fabric may need re-treatment if cleaned by a method that degrades the coating. Professional cleaning must use methods compatible with the treatment. Confirm the appropriate cleaning regime with the treatment provider before specifying.

For a detailed guide to the treatment process and the difference between Crib 5 and BS 7176, see our post on FR treatment, BS 7176, and the Crib 5 test.

BS 7176 and Hazard Categories

BS 7176, Specification for Resistance to Ignition of Upholstered Furniture for Non-Domestic Seating, extends the BS 5852 framework by categorising different commercial environments into hazard levels and specifying the appropriate ignition source requirement for each.

Low hazard covers environments such as offices. Medium hazard covers hotels, theatres, and healthcare waiting areas. High and extreme hazard cover environments such as prisons, secure psychiatric units, and offshore installations.

For most hospitality and commercial interiors the relevant category is Medium Hazard, and the standard associated with it is effectively Crib 5. The practical difference between specifying to BS 5852 Crib 5 and specifying to BS 7176 Medium Hazard is that BS 7176 includes the water-soak stage explicitly and requires the certificate to document the specific end-use environment and foam specification. In complex or sensitive projects, specifying BS 7176 Medium Hazard rather than simply Crib 5 gives a more complete and defensible specification. The treatment applied to achieve both is the same.

When Crib 7 Is Required

Crib 7 follows the same principle as Crib 5 but uses a larger wooden crib, seven tiers high, producing a more intense ignition source. It is required in high and extreme hazard environments: primarily prisons, secure psychiatric units, and some offshore or industrial installations. The Regulatory Reform (Fire Safety) Order 2005 assigns responsibility for determining the appropriate hazard category to the responsible person managing the building, not to the designer or fabric supplier. If a project falls into a high hazard category, engage a specialist fire safety consultant before specifying.

Crib 5 fabric, when combined with an appropriate FR foam, can sometimes achieve a Crib 7 pass as a composite. This must be verified by testing and documented with the relevant certificate. Do not assume that a Crib 5 fabric will achieve Crib 7 without independent testing.

For a full explanation of Crib 7 and when it applies, see our post on what is Crib 7.

Curtain Fabrics and the Different Standard

BS 5852 applies to upholstery. Curtain fabrics are governed by a separate standard, BS 5867, which tests vertical hanging fabrics rather than upholstered composites. The two standards are not interchangeable. A curtain fabric certified to BS 5867 is not automatically suitable for upholstery use, and a Crib 5 certified upholstery fabric is not automatically certified for use as a curtain in a contract environment. Always confirm the correct standard for the specific application before specifying.

Kothea Fabrics and Crib 5

Mohair velvet from Kothea carries an inherent BS 5852 Crib 5 pass across all active mohair velvet ranges. The inherent certification means no treatment is required, no additional cost is incurred, the certification survives cleaning, and the handle and surface of the fabric are unaffected. The primary Mohair Velvet range achieves 100,000 Martindale rubs alongside its inherent Crib 5 certification, combining contract-grade durability with the highest fire safety standard for most commercial projects.

Faux Leather 3 from Kothea carries a BS 5852 Crib 5 certification alongside a Martindale rub count in excess of 200,000, making it among the most specification-complete fabrics available for severe contract environments including transport seating, healthcare, and hospitality.

Cotton velvet requires topical treatment to achieve a Crib 5 pass and is not supplied by Kothea with an inherent certification.

How to Specify Correctly

State the standard in full. Ask for BS 5852 Ignition Source 5 (Crib 5), not just Crib 5. The full reference removes ambiguity.

Confirm inherent or topical. Ask the supplier explicitly whether the certification is inherent to the fibre or achieved through topical treatment. If topical, ask whether the full water-soak test was completed and request the certificate confirming it.

Confirm the composite configuration. Ask which foam was used in the test. If your project uses a different foam, the certificate may not cover your specific application.

Use a UKAS-accredited treatment house. If your project requires a fabric to be treated, specify that treatment must be carried out by a UKAS-accredited company. This ensures the process is correctly executed and independently verifiable.

Request the full test certificate. An indicative result is not a certificate. For contract projects, require the independent test certificate before the fabric is upholstered.

Consider BS 7176 for complex environments. For hotel bedrooms, healthcare, or any environment where the hazard category is uncertain, specifying BS 7176 Medium Hazard rather than Crib 5 alone provides a more defensible specification at no additional treatment cost.

Crib 7: The Standard Above Crib 5

Crib 7 is the ignition source immediately above Crib 5 in the BS 5852 series. Where Crib 5 uses a wooden crib of approximately 17 grams with a specific timber species and construction, Crib 7 uses a larger and more severe crib of approximately 126 grams. The test assembly is the same — a seat and back pad covered in the fabric being tested — but the larger ignition source represents a significantly more demanding fire scenario.

Crib 7 is not widely required in mainstream UK contract specification. The environments where it is applicable include some prison and secure accommodation furniture, certain defence and government procurement specifications, and some highly specific public sector contracts where the risk assessment has determined that the standard Crib 5 level of protection is insufficient. It is also referenced in some transport seating specifications, though IMO standards apply in the marine context rather than BS 5852.

For most hotel, restaurant, office, and residential contract interiors, Crib 5 is the correct and sufficient standard. Specifiers who encounter a Crib 7 requirement should confirm with the project’s fire risk assessor whether it is genuinely required for the specific application, as it is a materially more demanding test and limits the fabric options available considerably. Very few standard upholstery fabrics carry a certified Crib 7 pass. Purpose-made fire-retardant fabrics with specialist construction and treatment are typically required.

If your project has a Crib 7 requirement, contact us directly to discuss suitable fabric options for the specific application.

For surface spread of flame requirements for wall and ceiling linings — a separate standard from Crib 5 — see our BS 476 Part 7 guide.

For fabric sustainability certifications including GOTS and Oeko-Tex, see our fabric sustainability certifications guide. For healthcare fire standards including BS 7176, see our healthcare fabric guide.

For how the Building Safety Act 2022 affects fabric fire certification documentation in higher-risk buildings, see our Building Safety Act and fabric specification guide.

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What is Crib 7?

For the full guide to BS 5852 Crib 5 and when Crib 7 applies, see: BS 5852 Crib 5: A Complete Guide for Interior Designers and Specifiers.

Crib 7 uses a larger wooden crib than Crib 5. That is the right answer, but here is the explanation.

In the UK there are various tests for the flammability of fabrics, varying in their applicability to domestic and contract environments such as hotels and hospitals. Fabric treated to a Crib 5 standard is suitable for most contract uses. Crib 7 is a more stringent test, and fabric that passes it is suitable for more hazardous environments such as prisons and offshore installations.

During testing, the fabric is spread over a frame and exposed to a burning wooden crib placed on or beneath it. The larger the crib, the more intense the ignition source. The Crib 7 crib is larger than the Crib 5 crib, so the fabric is exposed to a more severe flame.

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