ProjectCalcWhat the standard is
BS EN 13501-1 is the standard that classifies the reaction to fire performance of construction products. It is the classification the approved documents use when they say a material must "be class B-s3, d2 or better" or that something may be "class D-s3, d2".
Approved Document B draws on it in several ways: materials achieving class A1fL or A2fL-s1 in accordance with BS EN 13501-1 are exempted in certain circumstances, and the Appendix that explains the roof covering designations notes that "class F is assigned when a product fails to attain class E" and that untested products cannot be classified.
How to read a designation
A designation like B-s3, d2 is three judgements joined together, not one grade:
| Part | What it is | What the values mean |
|---|---|---|
| Main class — the letter | The reaction to fire of the product as a whole | A1 and A2 are the least combustible, then B, C, D and E. F means the product failed to attain class E and cannot be used where a class is required. |
| s — smoke production | How much smoke the burning product produces, as a sub-class 1, 2 or 3 | s1 is the least smoke, s3 the most. |
| d — flaming droplets | Whether burning material falls away as droplets or particles, sub-class 0, 1 or 2 | d0 produces none, d2 the most. |
"Or better" therefore means better on the main class, with the sub-classes attached — which is why an "A2-s3, d2" product is not automatically better than a "B-s3, d2" one in the terms the approved document is using: A2 is a stricter main class, and the surface spread of flame question is what the main class answers.
Where the ratings bite in a dwelling
The most common place a householder meets these classes is the classification of wall and ceiling linings in Approved Document B Volume 1, Table 4.1:
- small rooms up to 4 m² and garages up to 40 m² within a dwellinghouse — D-s3, d2;
- other rooms, including garages — C-s3, d2;
- circulation spaces within a dwelling, and other circulation spaces — B-s3, d2.
The other place is outside the building. External surface materials of a wall facing the relevant boundary, where the wall is on or within 1,000 mm of that boundary, must be class B-s3, d2 or better. Roof coverings are classified under a separate scheme, the BROOF(t4) designations, which are not BS EN 13501-1 classes.
The wall covering allowance
There is a specific allowance in Table 4.1 that matters when you are decorating rather than building: wallcoverings which conform to BS EN 15102, achieving at least class C-s3, d2, and bonded to a class A2-s3, d2 substrate, are also acceptable. That is the route by which a wallcovering can go into a circulation space.
What this means when you are buying
- Ask for the classification, not a claim. A product either has a classification from test under BS EN 13501-1 or it does not; a phrase like "fire retardant" is not a class.
- Match the class to the location. The class needed in a hallway (B-s3, d2) is stricter than the class needed in a small storeroom or a garage within a house (D-s3, d2).
- Board, plaster, paint and covering all count. A lining is a build-up: the classification of the finished surface is what the table is asking about.
- Untested is not a class. Nothing can be assumed into a classification it has not been tested for.
Edition status — what the approved document cites, and what is current
An approved document names the edition of a standard that existed when it was written. That edition is not necessarily the current one. The table below sets out, for every standard this page relies on, the title as published, the edition the approved document cites, and the edition BSI catalogues today (22 September 2026). Where the cited edition is withdrawn, the page says so; where we could not confirm the replacement, no current edition is stated.
| Standard | Title as published | Edition cited by the approved document | Current edition (BSI) |
|---|---|---|---|
| BS EN 13501-1 | Fire classification of construction products and building elements — Classification using data from reaction to fire tests | BS EN 13501-1 — cited by Approved Document B with no edition given | BS EN 13501-1:2018 — Current (as BS EN 13501-1:2018 - TC, 31 January 2019). BS EN 13501-1:2007+A1:2009 is Withdrawn |
| BS EN 15102 | Decorative wallcoverings. Roll form | BS EN 15102 — cited by Approved Document B with no edition given | BS EN 15102:2019 — Current (30 June 2019). BS EN 15102:2007+A1:2011 is Withdrawn |
Source: BSI catalogue records read at knowledge.bsigroup.com on 22 September 2026. Each title, designation, status and date in the last two columns was read from the BSI catalogue page for that standard.
Last verified 22 September 2026. Every requirement quoted on this page was read from the primary source listed below on that date, not from a summary. If a figure could not be confirmed in the primary source it is not on this page.
Where these figures come from
- Approved Document B: Fire safety, Volume 1: Dwellings — 2019 edition incorporating 2020, 2022, 2025 and 2026 amendments (Table 4.1 and its note on BS EN 15102; paragraph 11.8; Appendix B on designation of roof coverings) — GOV.UK publications, "Fire safety: Approved Document B", checked 22 September 2026.
- BSI catalogue (“BSI Knowledge”) — product record for each standard listed above: title, current edition and status — knowledge.bsigroup.com, checked 22 September 2026.
Guidance only, not advice
This page is a plain-English summary of published regulations and standards, written to help you plan a job. It is not professional advice, it is not a substitute for the actual document, and it is not a building-control decision.
Building regulations are enforced by your local authority (or an approved inspector) and the facts of a particular job can change the answer. Confirm with your local building control before you start work, and where a job is structural, get it designed by a suitably qualified person. If this page and the source document disagree, the source document wins.