The short answer
"Fire-rated" cladding is cladding classified for its reaction to fire under the European Euroclass system used in UK Building Regulations. Materials are graded from A1 (the highest, effectively non-combustible) down through A2, B, C, D, E to F (no performance determined or worst-performing). Class A1 materials do not contribute to fire; Class A2 are of very limited combustibility. The classification also carries suffixes for smoke (s1–s3) and flaming droplets (d0–d2), so a board might be rated, for example, A2-s1,d0. For taller relevant residential buildings, Building Regulations require external wall materials to be of limited combustibility — broadly A2 or A1. The right class for any building is set by Approved Document B and should be confirmed with building control.
Fire ratings on cladding can look like code. This page explains what the Euroclass letters and suffixes mean, what counts as non-combustible, and where the highest classes are required.
Euroclass reaction-to-fire at a glance
- A1non-combustible, highest
- A2very limited combustibility
- B to Eincreasing combustibility
- Fnot classified / worst
- Suffixessmoke (s) and droplets (d)
The Euroclass system explained
UK Building Regulations classify the reaction to fire of construction products using the Euroclass system (from the European standard BS EN 13501-1). It ranks how a material behaves when exposed to fire — whether it ignites, contributes heat and spreads flame:
- A1 — non-combustible; makes effectively no contribution to fire.
- A2 — limited combustibility; contributes very little.
- B, C, D, E — progressively greater contribution to fire, from very limited up to materials that ignite and spread flame more readily.
- F — no performance determined, or worst-performing.
The higher the class (A1 being top), the better the fire performance. The classification is a property of the tested material, which is why the whole wall build-up still has to be considered as a system.
Smoke and droplet sub-classifications
The main letter is usually followed by two suffixes that describe additional behaviour, because heat is not the only hazard in a fire:
- Smoke (s1, s2, s3) — how much smoke the material produces, with s1 the least and s3 the most.
- Flaming droplets/particles (d0, d1, d2) — whether the material produces burning droplets that can spread fire, with d0 producing none and d2 the most.
So a high-performing board might be described as A2-s1,d0: limited combustibility, least smoke, no flaming droplets. When a specification or regulation calls for a class, it often includes these suffixes, so check the full classification rather than just the letter. Class A1 materials are generally not required to declare smoke and droplet suffixes because they do not burn.
| Class | Meaning | Typical examples |
|---|---|---|
| A1 | non-combustible | brick, stone, some metals |
| A2 | limited combustibility | some fibre cement, mineral boards |
| B–D | combustible, varying | many timber/composite products |
| E–F | readily combustible / unclassified | untreated low-grade materials |
Indicative examples only; the declared classification for a specific product must be checked, not assumed.
Where the highest classes are required
The class a building needs is set by Approved Document B and depends mainly on the building's height and use. For relevant residential buildings above a defined height, the Building Regulations require materials in the external wall to be of limited combustibility — broadly Euroclass A2 or A1 — through the ban on combustible materials. For lower buildings, including most individual houses, a wider range of classes can be acceptable, so combustible materials such as certain timber and composite products may be used where justified for that building type and location. Because the thresholds are technical and have changed in recent years, the required class for a specific project should be confirmed with building control.
Choosing fire-rated cladding sensibly
When fire performance matters, look for the cladding's declared Euroclass classification in its documentation, including the smoke and droplet suffixes, and match it to what the building requires rather than the highest available. Remember that the insulation, cavity and cavity barriers behind the cladding all affect overall fire behaviour, so a high cladding class does not by itself make a wall safe. Non-combustible options commonly used on houses include fibre cement, brick slips, masonry and metal; where combustible materials are used, their acceptability depends on the building. Keep the product classifications and system specification on record for compliance, insurance and resale, and rely on professionals for the fire-critical judgement.
Frequently asked questions
What does Euroclass A2 mean for cladding?
Euroclass A2 means the material has limited combustibility — it contributes very little to a fire. It is usually quoted with smoke and droplet suffixes, such as A2-s1,d0. For taller relevant residential buildings, external wall materials generally need to be A2 or A1 under the combustible-materials ban.
Is timber cladding fire-rated?
Timber is combustible, so untreated timber sits in the lower Euroclass bands, though fire-retardant treatments can improve its classification. Timber can still be acceptable on many lower-rise houses where Approved Document B allows it, but it is generally not permitted on the external walls of taller relevant residential buildings.
What do s1, s2 and d0 mean on a fire rating?
They are sub-classifications: the 's' value describes smoke production (s1 least, s3 most) and the 'd' value describes flaming droplets (d0 none, d2 most). A rating like A2-s1,d0 means limited combustibility with the least smoke and no flaming droplets, so check the full code, not just the letter.
Sources & further reading
Figures on this page are typical UK ranges drawn from published sources and depend on your specific property. They are guidance, not a quotation.