Fire rating M1, B1, Cs1d0: what differences for a hotel?

7-min read — Updated November 2025

A curtain that does not comply with fire standards is a safety-commission file that gets stuck at opening. An architect who writes "fire-retardant fabric" in a CCTP without specifying the classification is a legal risk and an ambiguity that will be settled against the project owner. Yet fire ratings applied to furnishing textiles remain one of the most poorly mastered points in the drafting of hotel briefs.

This article sorts out the three classifications you will encounter on 95% of hotel projects: M1 (French standard), B1 (old German/European standard) and Cs1d0 (harmonised Euroclass). Goal: give you the right words to write in a CCTP, the right questions to ask a supplier, and the right requirements to check at acceptance.

1. Why hotels are subject to reinforced fire standards

A hotel is an ERP (Public-Access Establishment) of type O. Occupants sleep — so they are not immediately alerted in case of fire start. Evacuation paths go through narrow corridors. Common areas (lobby, restaurant, ballroom) sometimes concentrate several hundred people. In this context, French regulation (decree of 25 June 1980 as amended, and its ERP adaptations) imposes strict requirements on decoration and furnishing materials.

For vertically hung textiles — curtains, sheers, wall hangings, textile acoustic screens — the minimum regulatory requirement is a fire reaction rated M1 or European equivalent. For certain specific spaces (basement rooms, conference rooms without natural smoke extraction), the required level may rise to M0.

In practice, the safety commission checks at opening — and during subsequent periodic visits — that the operator can produce a fire-rating test report for each installed textile. No test report = non-compliance = potential activity block.

2. The French M classification: M0, M1, M2, M3, M4

The "M" classification is historically the French system for classifying fire reaction of construction and fit-out materials. It goes from M0 (non-combustible) to M4 (easily flammable), with M1 as the standard for hospitality.

M0 — Non-combustible

No combustion under flame exposure. Typically reserved for mineral materials (glass wool, certain silicate panels). Unattainable for a textile.

M1 — Non-flammable

The material, exposed to a flame, may degrade thermally but does not propagate fire. This is the standard classification for any furnishing textile in ERP type O hospitality. Curtains, sheers, and wall hangings must all be at least M1.

M2 — Hardly flammable

The material can ignite but combustion remains contained. Insufficient for a hotel room or common area. Acceptable for certain ad-hoc decorative furniture accessories.

M3 and M4

Moderately to easily flammable materials. Prohibited in ERP type O for hung textiles. Encountered in unregulated domestic furnishing.

3. The German B classification (DIN 4102): B1, B2, B3

Before European harmonisation, the German DIN 4102 standard was widely used, notably by German and Austrian fabric editors who supply a large part of the European hospitality market.

• B1 — Hardly flammable. It is the functional equivalent of the French M1, although test protocols are slightly different.
• B2 — Normally flammable. Unsuitable for ERP hospitality.
• B3 — Easily flammable. Domestic use only.

A fabric marked B1 in a German editor's catalogue can therefore be used in French hospitality, provided a French re-classification test report is available. Some editors (Création Baumann, Kvadrat) systematically provide a double M1+B1 test report — these are the ones to favour to avoid administrative back-and-forth at the commission.

4. The Euroclasses (EN 13501-1): the harmonised system

Since 2002, the European Union has introduced a harmonised system: the Euroclasses, defined by the EN 13501-1 standard. They break down fire reaction into three axes — main performance (A1 to F), smoke production (s1 to s3), and flaming droplets (d0 to d2).

Reading a Euroclass: the format XY-s?d?

A fabric classified Cs1d0 means: category C (limited combustion), s1 (low smoke production), d0 (no flaming droplets). This triad is what matters in hospitality, not just the main letter.

M → Euroclass equivalences for hung textiles

French classification	Equivalent Euroclass	Hospitality use
M0	A1 or A2-s1,d0	Non-combustible — not applicable to textiles
M1	B-s1,d0 / Cs1d0	ERP type O standard — mandatory in rooms and common areas
M2	C-s2,d0	Not accepted in ERP type O hung textile
M3	D-s2,d0	Prohibited in ERP type O

The key point: a Cs1d0 fabric is legally equivalent to M1 in France since the decree of 21 November 2002. An architect or CFO can accept this classification in a CCTP without requesting a national re-test — provided the test report is issued by a notified European laboratory.

5. "In-mass" fireproofing vs impregnation fireproofing

Beyond classification, the nature of treatment changes everything. Two routes coexist:

In-mass fireproofing (or "intrinsic fibre")

The fibre itself is non-flammable by chemical construction. Trevira CS®, FR polyester, certain heart-treated wools. The M1 / Cs1d0 classification is permanent, independent of the number of washes. It is the preferred technical solution for hospitality — more expensive at purchase (+15 to 25%), but with no maintenance cost or future non-compliance risk.

Impregnation fireproofing

A standard fabric (cotton, linen, viscose) is dipped in a chemical bath that deposits flame-retardant compounds. The treatment is effective when new — but it gradually fades with washing, typically after 4 to 8 cycles. Apparent cost is low at purchase, but it must be re-treated regularly (€150 to €400 excl. VAT per curtain depending on size) to maintain compliance.

How to know which has been used?

Require the fabric data sheet and look for the mention "FR in mass", "intrinsically flame retardant" or "Trevira CS". If the sheet says "FR treated" without further detail, it is probably impregnation. If in doubt, ask about classification durability after 25 washing cycles — a true in-mass FR retains the classification, an impregnation treatment loses it.

6. The rating test report: this essential document

For each curtain installed in a hotel, the operator must be able to produce a fire-rating test report issued by a notified laboratory (in France: LNE, CTICM, LEPMI; in Europe: MPA Stuttgart, BRE, TNO). This 2 to 4-page document mentions:

• Fabric commercial reference and fibre composition
• Test protocol (NF P 92-503 for M1, EN 13823 for Euroclasses)
• Raw results and assigned classification
• Test report validity period (generally 5 years)
• Laboratory signature and accreditation number

At worksite acceptance, require the centralised collection of all textile test reports, archived in a "Fire safety — textiles" file delivered to the operator. Without this file, the safety commission may refuse opening.

7. Practical case — Urban 4★ hotel, 120 rooms

Here is how to correctly write the "fire" section of a textile CCTP for a typical project:

« All curtain, sheer and wall-hanging fabrics shall be classified M1 (NF P 92-503) or European equivalent B-s1,d0 / Cs1d0 (EN 13501-1), obtained by in-mass fireproofing (intrinsically non-flammable fibre such as Trevira CS® or equivalent). The contractor shall provide the original test report for each reference, issued by a notified laboratory, valid at the installation date. Fabrics treated by chemical impregnation are expressly refused. »

This 5-line paragraph closes almost all potential disputes with the supplier and secures the operator vis-à-vis the safety commission.

FAQ — Fire standards and hospitality

Is a Cs1d0 fabric really equivalent to M1?

Yes, since the amended decree of 21 November 2002, equivalences are officially recognised. A European Cs1d0 test report issued by a notified laboratory equals M1 in France for an ERP type O.

Can a non-FR fabric be treated afterwards?

Technically yes, via impregnation — but it is a degraded solution. The classification obtained is non-permanent, costs €80-150 excl. VAT/curtain per re-treatment, and generates an administrative burden of re-issuing test reports. To avoid in high-end hospitality.

Is the test report valid for life?

No. A test report has a validity period (generally 5 years). After this date, the manufacturer must re-submit the sample to a laboratory for renewal. In renovation, check that the test reports provided are valid.

Are sheers subject to the same requirements?

Yes. In ERP type O, any vertically hung textile must be classified M1 minimum, regardless of its weight or transparency. An untreated cotton voile sheer is prohibited in a hotel room — even installed behind a compliant blackout curtain.

What does an operator risk by installing non-compliant curtains?

If the safety commission visits: unfavourable opinion, replacement request within 30-90 days, and in the worst case, administrative closure. In case of fire, civil and criminal liability of the manager. Saving on textile is never worth this risk.

In summary

Three classifications dominate French hospitality: M1 (national standard), B1 (equivalent German standard), and Cs1d0 (harmonised Euroclass). All three guarantee the same level of safety for a hotel curtain, provided they are obtained by in-mass fireproofing and documented by a valid notified-laboratory test report.

To secure a project: systematically write in the CCTP "M1 or equivalent Cs1d0, in-mass", refuse chemical impregnations, and organise centralised collection of test reports at acceptance. These three reflexes cover 98% of fire-regulation risks on a hospitality worksite.