Thin insulation in public buildings in France: A2 class or thermal screen

What article AM 8 says exactly

The French fire and panic safety regulation for buildings open to the public, the order of 25 June 1980, devotes its article AM 8 to insulation products. It applies as soon as the insulation layer exceeds 5 mm, or 10 mm on floors, whether in walls, façades, roofs, floors, their faces or plenums. A 13 mm thin reflective insulant is therefore fully within its scope.

These provisions also cover 5th-category establishments: article PE 13 makes the rules of chapter III of book II, title I^er, on the fire behaviour of materials, applicable, and article AM 8 belongs to them.

The text leaves two routes, and one of them is enough:

• the product is classified at least A2-s2, d0 on a vertical wall, a ceiling or a roof, and A2FL-s1 on a floor;
• or it is protected by a thermal screen placed on the faces liable to be exposed to a fire coming from inside the building. Under the standard temperature-time curve, that screen must play its part for at least a quarter of an hour for vertical walls and floors, half an hour for the other walls.

The A2 classification reflects a very limited contribution to fire, measured by testing; many mineral insulants reach it. R'BULL Pro 13 is classified B-s1, d0: it therefore falls under the second route, the thermal screen. This is not a tolerance, it is the solution the text provides for, and the user guide devotes most of its pages to it.

One exception is worth knowing, but it has an end date: until 31 May 2027, acoustic absorbent linings whose thermal resistance is below 0.5 m².K/W, or whose thermal conductivity exceeds 0.065 W/m.K, are not subject to article AM 8. It covers acoustic products, not thermal insulation, and the wording that applies to applications filed from 1 June 2027 does not carry it over.

Euroclasses: what B-s1, d0 means

The reaction to fire of a construction product is expressed in Euroclasses, from A1, non-combustible, to F, unclassified, with two indices: s for smoke production, from s1 to s3, and d for flaming droplets or debris, from d0 to d2.

R'BULL Pro 13 is classified B-s1, d0: a high level of reaction to fire for an organic insulant of this type, with the lowest smoke production and no flaming droplets. It remains below the A2-s2, d0 level required by the first route of article AM 8. The classification was obtained by AITEX, report No. 2025AN2499, on tests carried out on 6 October 2025, for an assembly bonded to a fibre-cement substrate; it does not transfer without reservation to every installation configuration.

This classification establishes the product's reaction to fire within the field of application covered by the report. It does not exempt anyone from complying with article AM 8 where that article requires an A2 classification or a thermal screen.

Thermal screens accepted without justification

The user guide for combustible insulants, annexed to the order of 6 October 2004, defines screens that require no further justification, provided their composition and the installation rules it sets are respected. Two equivalences first: a separating element classified as fire resistant for half an hour counts as a quarter-hour screen for vertical walls and floors, and a one-hour fire-resistant element counts as a half-hour screen for the other walls.

On a vertical wall, the following are accepted without justification:

• a 12.5 mm plasterboard lining, or a 14 mm calcium silicate board;
• a 50 mm inner lining wall in masonry, plaster blocks or honeycomb panels;
• a 15 mm sprayed plaster render on mechanically fixed metal reinforcement;
• a timber or wood-based panel lining, in the thicknesses of table 1 of the guide, for example 18 mm of solid timber below 600 kg/m³.

On a roof, the solution depends on the load-bearing element:

• roof with a concrete or masonry structure: the load-bearing element that forms the ceiling and is fire resistant for half an hour acts as the screen;
• roof with a profiled steel deck: between the deck and the insulant, an 18 mm plasterboard, a 20 mm calcium silicate board, 60 mm of rock wool at 110 kg/m³, 50 mm of expanded perlite or 60 mm of cellular glass;
• roof with a continuous timber deck: the thicknesses are given in table 2 of the guide.

These thicknesses are minimums, and they can be reached with several layers.

The installation rules that go with the screen

A screen only works if it stays in place and remains continuous. The guide therefore sets rules that the site must follow.

Continuity. Joints are set over a frame member, fitted with a profile, interlocked, or filled with a non-combustible or intumescent material. The screen is mechanically fixed, to the wall or to a frame that is itself mechanically fixed; the fixings may not be plastic. Ducts, light fittings and boxes may pass through, after provision is made and the opening is sealed.

Barriers. The insulant and any air gap in contact with it are interrupted where they cross floors and vertical walls subject to a fire resistance requirement. Where there is an air gap, the insulant must be classified at least E, which a B-s1, d0 product satisfies, and no air gap ventilated towards the inside is allowed. On a lightweight roof, the barriers form cells of at most 300 m², whose largest dimension does not exceed 30 m, with a barrier in a material classified A2-s2, d0 and at least 30 cm wide; where the covering has a ventilated air gap on its underside, that barrier is a piece of solid timber at least 7 cm wide.

There is nothing exotic about these rules for thin reflective insulation: they describe an ordinary assembly, a plasterboard ceiling or a lining on a frame, in which the product is protected and the air gaps are controlled.

In practice, with an R'BULL Pro 13

The reasoning comes down to four questions.

• Does article AM 8 apply? Yes: the insulation thickness exceeds 5 mm.
• Is the product A2? No, it is B-s1, d0. The thermal screen route applies.
• Which screen? Half an hour on ceilings and roofs, a quarter of an hour on vertical walls, taken from the list in the guide or justified by a test report.
• And the air gaps? They are interrupted at fire-resistant walls, not ventilated towards the inside of the volume, and the barrier is suited to the covering.

When we write that a product is suitable for buildings open to the public, this is what we mean: in establishments governed by the general provisions of article AM 8, R'BULL Pro 13 is installed behind a thermal screen that complies with the regulation and the user guide.

Specific provisions, tied to the type of establishment, to its activity or to certain parts of the building, may require more. Mountain refuges are the example: article REF 28 requires, as a tightening of article AM 8, category M 0 materials for internal thermal insulation. Compliance is therefore checked project by project, and the judgement belongs to the design team and to the competent safety commission, on the basis of the assembly actually described.

What changes on 1 June 2027

The order of 19 February 2026 does not touch up article AM 8: its article 43 replaces it entirely, from 1 June 2027, for applications for works authorisation filed from that date, as its article 48 provides.

The two main routes are kept: a classification of at least A2-s2, d0 on vertical walls, ceilings and roofs, A2FL-s1 on floors, or protection by a thermal screen for a quarter of an hour on vertical walls and floors, half an hour for the other walls.

The main change concerns products that follow neither route. Today, installing them requires a favourable opinion from the Commission centrale de sécurité, issued on the basis of an appraisal by the CECMI; from 1 June 2027, they will be the subject of an assessment by an approved laboratory or group of laboratories in reaction to fire and fire resistance.

The first paragraph is rewritten too, more briefly: it carries over neither the reference to the M0 classification for products not yet CE marked, nor the exception that today covers certain acoustic absorbent linings.