Fibre Reinforced Facade Encyclopedia: Testing and standards
BS 476 is a British Standard series of fire test methods whose parts fall into two entirely different families. Parts 4, 6, 7 and 11 are reaction-to-fire tests on materials and surfaces, and produce the surface spread of flame classifications Class 1 to Class 4 and the regulatory grade Class 0. Parts 20 to 24 are fire resistance tests on elements of construction, and produce ratings in minutes for loadbearing capacity, integrity and insulation. Quoting a BS 476 result without naming the part tells the reader nothing, because the two halves of the series answer opposite questions.
Class 0 is not a BS 476 class at all. It is a Building Regulations term, defined in the English Approved Documents as a material that achieves Class 1 surface spread of flame to BS 476 Part 7 and also meets fire propagation limits in BS 476 Part 6. A supplier quoting Class 0 is quoting a regulation, not a test.
At a glance
| Property | Typical value | Note |
|---|---|---|
| Part 4 | Non-combustibility test for materials | Reaction to fire; pass or fail |
| Part 6 | Fire propagation test for materials | Reaction to fire; gives index I and sub-index i1 |
| Part 7 | Surface spread of flame test | Reaction to fire; Class 1 (best) to Class 4 |
| Part 11 | Heat emission from building materials | Reaction to fire |
| Parts 20 to 24 | Fire resistance of elements of construction | Fire resistance; minutes, not classes |
| Part 21 | Loadbearing elements | Fire resistance |
| Part 22 | Non-loadbearing elements | Fire resistance; the part most often quoted for partitions |
| Class 1 | Surface spread of flame not exceeding the Part 7 limits | Reaction to fire only |
| Class 0 | Part 7 Class 1 plus Part 6 index I not more than 12 and sub-index i1 not more than 6 | A regulatory grade, not a test result |
| Status in England | Superseded by EN 13501-1 for most purposes |
The reaction-to-fire parts
BS 476 Part 7 mounts a vertical specimen beside a radiant panel and records how far flame travels across its surface in the first minute and a half and over ten minutes. Class 1 is the best result and Class 4 the worst. It measures surface flame spread only. It says nothing about how much heat the product releases, how much smoke it makes, or whether it burns through.
BS 476 Part 6 addresses part of that gap. A specimen is exposed in a small chamber and the temperature rise in the flue gives a fire propagation index I, made up of three sub-indices, of which i1 covers the first three minutes. A low index means the product contributes little to the early growth of a fire.
Part 4 is the British combustibility furnace test, the equivalent in function to AS 1530.1, EN ISO 1182 and ASTM E136. Like all of them, it is a test a polymer composite cannot pass. Fibre reinforced polymer has an organic matrix that burns, so it is classified by Parts 6 and 7, by EN 13501-1, or by a full-scale facade test, never by Part 4.
What Class 0 actually is
Class 0 has no existence in BS 476. It is a definition written into the English Building Regulations guidance, and it combines two test results: Class 1 under Part 7 and, under Part 6, an index I not exceeding 12 with sub-index i1 not exceeding 6. A material can be Class 1 without being Class 0, because Class 1 is about surface flame travel and Class 0 adds a limit on fire propagation.
The grade was widely used for internal linings and, before 2018, for external cladding in England. It is a surface classification: it does not mean non-combustible, it does not mean limited combustibility, and a Class 0 material can have a substantial calorific value. That distinction was central to the criticism of pre 2018 cladding practice, where Class 0 panels with combustible cores satisfied the wording of the guidance.
The fire resistance parts
BS 476 Parts 20 to 24 are a different subject entirely. They place a full-size element, a wall, floor, beam, column or door assembly, in front of a furnace following the standard time and temperature curve and record how long it maintains loadbearing capacity, integrity and insulation. Part 20 gives the general principles, Part 21 covers loadbearing elements, Part 22 non-loadbearing elements, Part 23 components and Part 24 ventilation ducts.
The result is a period in minutes against each criterion, the same idea as an Australian fire resistance level under AS 1530.4 and a European classification under EN 13501-2. It belongs to the tested assembly and not to any material in it. A cladding panel has no BS 476 Part 22 rating, for the same reason it has no FRL.
Where BS 476 is still used
In England the national classifications have been progressively displaced by the European system. Regulation 7(2) and the 2018 ban on combustible materials in the external walls of relevant buildings are written in EN 13501-1 terms, requiring Class A2-s1,d0 or better, and Approved Document B has moved to the European classes for the purposes it still covers.
The standard remains in active use elsewhere. Hong Kong’s Code of Practice for Fire Safety in Buildings and Singapore’s SCDF Fire Code continue to reference BS 476 parts alongside or instead of EN classifications, and several Middle Eastern and South East Asian authorities accept Class 0 for internal linings. A product sold into those markets is still asked for Part 6 and Part 7 reports.
BS 476 has never been referenced by the National Construction Code for the purposes this page describes. An Australian project needs AS 1530.1 for combustibility, AS 1530.3 indices or an AS 5637.1 group number for reaction to fire, AS 1530.4 for fire resistance, and AS 5113 for the external wall system (check the NCC edition adopted in your jurisdiction). A BS 476 report is supporting information for a fire engineer, not a compliance document.
Where the ShapeShell systems sit
ShapeShell-RC is a glass fibre reinforced concrete system and is Not Deemed Combustible under AS/NZS 1530.1, tested by Ignis Labs, which is the Australian equivalent of the BS 476 Part 4 question.
ShapeShell-RT is a fibre reinforced polymer system. It is combustible and cannot pass a combustibility furnace test under any standard, including BS 476 Part 4. It holds an AS 5637 Group 1 classification from AWTA Product Testing, is classified B-s2,d0 under EN 13501-1 by Intertek Testing Services, and passed the full-scale BS 8414 and AS 5113 test at BRE Global. For a project in a market that still asks for BS 476, the EN classification and the full-scale result are the documents to put forward.
Standards and references
- BS 476-4 Non-combustibility test for materials
- BS 476-6 Method of test for fire propagation for products; BS 476-7 Method of test to determine the classification of the surface spread of flame of products
- BS 476-20 to BS 476-24 Fire resistance of elements of construction
- Approved Document B (England), definitions of Class 0 and Regulation 7(2)
- EN 13501-1 and EN 13501-2, the European classifications that have replaced BS 476 for most English purposes
- AS 1530.1, AS 1530.3, AS 5637.1 and AS 1530.4, the Australian equivalents
Related terms
Questions specifiers ask
Is Class 0 the same as non-combustible?
No. Class 0 is a surface classification defined in the English Building Regulations guidance, combining BS 476 Part 7 Class 1 with fire propagation limits under Part 6. A Class 0 material can be fully combustible and can have a high calorific value.
What is the difference between Class 1 and Class 0?
Class 1 is the best surface spread of flame result under BS 476 Part 7. Class 0 requires Class 1 and, in addition, a BS 476 Part 6 fire propagation index I not exceeding 12 with sub-index i1 not exceeding 6.
Which BS 476 parts are fire resistance tests?
Parts 20 to 24. Part 20 gives the general principles, Part 21 covers loadbearing elements, Part 22 non-loadbearing elements, Part 23 components and Part 24 ventilation ducts. Those results are in minutes, not classes.
Can a BS 476 result be used for NCC compliance in Australia?
No. The NCC references AS 1530.1, AS 1530.3, AS 5637.1, AS 1530.4 and AS 5113. A BS 476 report can be supporting evidence for a fire engineer’s Performance Solution but does not satisfy a Deemed-to-Satisfy provision.
Is BS 476 still current?
It is still published and still referenced in Hong Kong, Singapore and several other jurisdictions. In England the European classifications under EN 13501-1 have taken over for external walls and most other purposes.
Specifying into a market that mixes British, European and Australian fire standards? The Global Facade Fire Standards Atlas sets the regimes side by side. Open the fire standards atlas
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies. Last updated September 2026.