- Much of the guidance in this document is given in terms of performance in relation to British or European Standards for products or methods of test or design or in terms of European Technical Approvals. In such cases the material, product or structure should:
- A. be in accordance with a specification or design which has been shown by test to be capable of meeting that performance; or
Note: For this purpose, laboratories accredited by the United Kingdom Accreditation Service (UKAS) for conducting the relevant tests would be expected to have the necessary expertise.
- B. have been assessed from test evidence against appropriate standards, or by using relevant design guides, as meeting that performance; or
Note: For this purpose, laboratories accredited by UKAS for conducting the relevant tests and suitably qualified fire safety engineers might be expected to have the necessary expertise.
For materials/products where European standards or approvals are not yet available and for a transition period after they become available, British standards may continue to be used. Any body notified to the UK Government by the Government of another Member State of the European Union as capable of assessing such materials/products against the relevant British Standards, may also be expected to have the necessary expertise. Where European materials/ products standards or approvals are available, any body notified to the European Commission as competent to assess such materials or products against the relevant European standards or technical approval can be considered to have the appropriate expertise.
- C. where tables of notional performance are included in this document, conform with an appropriate specification given in these tables; or
- D. in the case of fire-resisting elements:
- i: conform with an appropriate specification given in Part II of the Building Research Establishments’ Report Guidelines for the construction of fire-resisting structural elements (BR 128, BRE 1988); or
- ii: be designed in accordance with a relevant British Standard or Eurocode
Note: Different forms of construction can present different problems and opportunities for the provision of structural fire protection. Further information on some specific forms of construction can be found in:
- Timber – BRE 454 Multi-storey timber frame buildings – a design guide 2003 ISBN: 1 86081 605 3
- Steel – SCI P197 Designing for structural fire safety: A handbook for architects and engineers 1999 ISBN: 1 85942 074 5
Note: Any test evidence used to substantiate the fire resistance rating of a construction should be carefully checked to ensure that it demonstrates compliance that is adequate and applicable to the intended use. Small differences in detail (such as fixing method, joints, dimensions and the introduction of insulation materials etc.) may significantly affect the rating.
2. Building Regulations deal with fire safety in buildings as a whole. Thus they are aimed at limiting fire hazard.
The aim of standard fire tests is to measure or assess the response of a material, product, structure or system to one or more aspects of fire behaviour. Standard fire tests cannot normally measure fire hazard. They form only one of a number of factors that need to be taken into account. Other factors are set out in this publication.
3. Factors having a bearing on fire resistance, that are considered in this document, are:
A. fire severity;
B. building height; and
C. building occupancy.
4. The standards of fire resistance given are based on assumptions about the severity of fires and the consequences should an element fail. Fire severity is estimated in very broad terms from the use of the building (its purpose group), on the assumption that the building contents (which constitute the fire load) are similar for buildings in the same use.
A number of factors affect the standard of fire resistance specified. These are:
A. the amount of combustible material per unit of floor area in various types of building (the fire load density);
B. the height of the top floor above ground, which affects the ease of escape and of firefighting operations, and the consequences should large scale collapse occur;
C. occupancy type, which reflects the ease with which the building can be evacuated quickly;
D. whether there are basements, because the lack of an external wall through which to vent heat and smoke may increase heat build-up and thus affect the duration of a fire, as well as complicating firefighting; and
E. whether the building is of single storey construction (where escape is direct and structural failure is unlikely to precede evacuation).
Because the use of buildings may change, a precise estimate of fire severity based on the fire load due to a particular use may be misleading. Therefore, if a fire engineering approach of this kind is adopted, the likelihood that the fire load may change in the future needs to be considered.
5. Performance in terms of the fire resistance to be met by elements of structure, doors and other forms of construction is determined by reference to either:
A. (National tests) BS 476 Fire tests on building materials and structures, Parts 20-24:1987, i.e. Part 20 Method for determination of the fire resistance of elements of construction (general principles), Part 21 Methods for determination of the fire resistance of loadbearing elements of construction, Part 22 Methods for determination of the fire resistance of non-loadbearing elements of construction, Part 23 Methods for determination of the contribution of components to the fire resistance of a structure, and Part 24 Method for determination of the fire resistance of ventilation ducts (or to BS 476-8:1972 in respect of items tested or assessed prior to 1 January 1988); or
B. (European tests) Commission Decision 2000/367/EC of 3 May 2000 implementing Council Directive 89/106/EEC as regards the classification of the resistance to fire performance of construction products, construction works and parts thereof.
All products are classified in accordance with BBS EN 13501-2:2003 Fire classification of construction products and building elements. Classification using data from fire resistance tests, excluding ventilation services (excluding products for use in ventilation systems).
BS EN 13501-3:2005 Fire classification of construction products and building elements. Classification using data from fire resistance tests on products and elements used in building service installations: fire resisting ducts and fire dampers (other than smoke control systems).
BS EN 13501-4:2007, Fire classification of construction products and building elements, Part 4 – Classification using data from fire resistance tests on smoke control systems.
The relevant European test methods under BS EN 1364, 1365, 1366 and 1634 are listed in Appendix F.
Table A1 gives the specific requirements for each element in terms of one or more of the following performance criteria:
A. resistance to collapse (loadbearing capacity), which applies to loadbearing elements only, denoted R in the European classification of the resistance to fire performance;
B. resistance to fire penetration (integrity), denoted E in the European classification of the resistance to fire performance; and
C. resistance to the transfer of excessive heat (insulation), denoted I in the European classification of the resistance to fire performance.
Table A2 sets out the minimum periods of fire resistance for elements of structure.
Table A3 sets out criteria appropriate to the suspended ceilings that can be accepted as contributing to the fire resistance of a floor.
Table A4 sets out limitations on the use of uninsulated fire-resisting glazed elements. These limitations do not apply to the use of insulated fire-resisting glazed elements.
Information on tested elements is frequently given in literature available from manufacturers and trade associations.
Information on tests on fire-resisting elements is also given in such publications as:
Association for Specialist Fire Protection Yellow Book – Fire protection for structural steel in buildings, 4th edition. See Appendix F.
6. Performance in terms of the resistance of roofs to external fire exposure is determined by reference to either:
- A. (National tests) BS 476-3:2004 External fire exposure roof tests; or
- B. (European tests) Commission Decision 2005/823/EC amending Decision 2001/671/ EC Establishing a classification system for the external fire performance of roofs and roof coverings
Constructions are classified within the National system by two letters in the range A-D, with an AA designation being the best. The first letter indicates the time to penetration; the second letter a measure of the spread of flame.
Constructions are classified within the European system as BROOF(t4), CROOF(t4), DROOF(t4), EROOF(t4) or FROOF(t4) (with BROOF(t4) being the highest performance and FROOF(t4) being the lowest) in accordance with BS EN 13501-5:2005 Fire classification of construction products and building elements – Classification using data from external fire exposure to roof tests.
BS EN 13501-5 refers to four separate tests. The suffix (t4) used above indicates that Test 4 is to be used for the purposes of this Approved Document.
Some roof covering products (and/or materials) can be considered to fulfil all of the requirements for the performance characteristic “external fire performance” without the need for testing, subject to any national provisions on the design and execution of works being fulfilled. These roof covering products are listed in Commission Decision 2000/553/EC of 6th September 2000 implementing Council Directive 89/106/EEC as regards the external fire performance of roof coverings.
In some circumstances roofs, or parts of roofs, may need to be fire-resisting, for example if used as an escape route or if the roof performs the function of a floor. Such circumstances are covered in Sections 2, 4 and 6.
Table A5 gives notional designations of some generic roof coverings.
Reaction to fire
7. Performance in terms of reaction to fire to be met by construction products is determined by Commission Decision 200/147/EC of 8 February 2000 implementing Council Directive 89/106/EEC as regards the classification of the reaction to fire performance of construction products.
Note: The designation of xxxx is used for the year reference for standards that are not yet published. The latest version of any standard may be used provided that it continues to address the relevant requirements of the Regulations.
All products, excluding floorings, are classified as †A1, A2, B, C, D, E or F (with class A1 being the highest performance and F being the lowest) in accordance with BS EN 13501-1:2002 Fire classification of construction products and building elements, Part 1 – Classification using data from reaction to fire tests.
†The classes of reaction to fire performance of A2, B, C, D and E are accompanied by additional classifications related to the production of smoke (s1, s2, s3) and/or flaming droplets/particles (d0, d1, d2).
The relevant European test methods are specified as follows:
- BS EN ISO 1182:2002 Reaction to fire tests for building products – Non-combustibility test
- BS EN ISO 1716:2002 Reaction to fire tests for building products – Determination of the gross calorific value
- BS EN 13823:2002 Reaction to fire tests for building products – Building products excluding floorings exposed to the thermal attack by a single burning item
- BS EN ISO 11925-2:2002 Reaction to fire tests for building products, Part 2 – Ignitability when subjected to direct impingement of a flame.
- BS EN 13238:2001 Reaction to fire tests for building products – conditioning procedures and general rules for selection of substrates.
8. Non-combustible materials are defined in Table A6 either as listed products, or in terms of performance:
- A.(National classes) when tested to BS 476-4:1970 Fire tests on building materials and structures – Non-combustibility test for materials or BS 476-11:1982 Fire tests on building materials and structures – Method for assessing the heat emission from building materials.
- B. (European classes) when classified as class A1 in accordance with BS EN 13501-1:2002 Fire classification of construction products and building elements. Classification using data from reaction to fire tests when tested to BS EN ISO 1182:2002 Reaction to fire tests for building products – Non-combustibility test and BS EN ISO 1716:2002 Reaction to fire tests for building products – Determination of the gross calorific value.
Table A6 identifies non-combustible products and materials, and lists circumstances where their use is necessary.
Materials of limited combustibility
9. Materials of limited combustibility are defined in Table A7:
- A. (National classes) by reference to the method specified in BS 476-11:1982;
- B. (European classes) in terms of performance when classified as class A2-s3, d2 in accordance with BS EN 13501-1:2002 Fire classification of construction products and building elements. Classification using data from reaction to fire tests when tested to BS EN ISO 1182:2002 Reaction to fire tests for building products – Non-combustibility test or BS EN ISO 1716:2002 Reaction to fire tests for building products – Determination of the gross calorific value and BS EN 13823:2002 Reaction to fire tests for building products – Building products excluding floorings exposed to the thermal attack by a single burning item.
Table A7 also includes composite products (such as plasterboard) which are considered acceptable, and where these are exposed as linings they should also meet any appropriate flame spread rating.
10. Flame spread over wall or ceiling surfaces is controlled by providing for the lining materials or products to meet given performance levels in tests appropriate to the materials or products involved.
11. Under the National classifications, lining systems which can be effectively tested for ‘surface spread of flame’ are rated for performance by reference to the method specified in BS 476- 7:1997 (or 1987 or 1971) Fire tests on building materials and structures. Method of test to determine the classification of the surface spread of flame of products under which materials or products are classified 1, 2, 3 or 4 with Class 1 being the highest.
Under the European classifications, lining systems are classified in accordance with BS EN 13501-1:2002 Fire classification of construction products and building elements, Part 1 – Classification using data from reaction to fire tests. Materials or products are classified as A1, A2, B, C, D, E or F, with A1 being the highest. When a classification includes ‘s3, d2’, it means that there is no limit set for smoke production and/or flaming droplets/particles.
12. To restrict the use of materials which ignite easily, which have a high rate of heat release and/ or which reduce the time to flashover, maximum acceptable ‘fire propagation’ indices are specified, where the National test methods are being followed. These are determined by reference to the method specified in BS 476-6:1989 or 1981. Index of performance (I) relates to the overall test performance, whereas sub-index (i1) is derived from the first three minutes of test.
13. The highest National product performance classification for lining materials is Class 0. This is achieved if a material or the surface of a composite product is either:
- A. composed throughout of materials of limited combustibility; or
- B. a Class 1 material which has a fire propagation index (I) of not more than 12 and sub-index (i1) of not more than 6.
Note:Class 0 is not a classification identified in any British Standard test.
14. Composite products defined as materials of limited combustibility (see paragraph 9 and Table A7) should in addition comply with the test requirement appropriate to any surface rating specified in the guidance on requirements B2, B3 and B4.
15. The notional performance ratings of certain widely used generic materials or products are listed in Table A8 in terms of their performance in the traditional lining tests BS 476-6:1989 and BS 476-7:1997 or in accordance with BS EN 13501-1:2002.
16. Results of tests on proprietary materials are frequently given in literature available from manufacturers and trade associations.
Any reference used to substantiate the surface spread of flame rating of a material or product should be carefully checked to ensure that it is suitable, adequate and applicable to the construction to be used. Small differences in detail, such as thickness, substrate, colour, form, fixings, adhesive etc, may significantly affect the rating.
17. A thermoplastic material means any synthetic polymeric material which has a softening point below 200ºC if tested to BS EN ISO 306:2004 method A120 Plastics – Thermoplastic materials – Determination of Vicat softening temperature. Specimens for this test may be fabricated from the original polymer where the thickness of material of the end product is less than 2.5mm.
18. A thermoplastic material in isolation can not be assumed to protect a substrate when used as a lining to a wall or ceiling. The surface rating of both products must therefore meet the required classification. If, however, the thermoplastic material is fully bonded to a non- thermoplastic substrate, then only the surface rating of the composite will need to comply.
19. Concessions are made for thermoplastic materials used for window glazing, rooflights, and lighting diffusers within suspended ceilings, which may not comply with the criteria specified in paragraphs 11 to 16. They are described in the guidance on requirements B2 and B4.
20. For the purposes of the requirements B2 and B4 thermoplastic materials should either be used according to their classification 0-3, under the BS 476-6:1989 and BS 476-7:1997 tests as described in paragraphs 11 to 16, (if they have such a rating), or they may be classified TP(a) rigid, TP(a) flexible, or TP(b) according to the following methods:
i: Rigid solid pvc sheet;
ii: Solid (as distinct from double- or multiple-skin) polycarbonate sheet at least 3mm thick;
iii: Multi-skinned rigid sheet made from unplasticised pvc or polycarbonate which has a Class 1 rating when tested to BS 476-7:1997 or 1971 or 1987; and
iv: Any other rigid thermoplastic product, a specimen of which (at the thickness of the product as put on the market), when tested to BS 2782:1970 as amended in 1974: Method 508A Rate of burning (Laboratory method), performs so that the test flame extinguishes before the first mark and the duration of flaming or afterglow does not exceed five seconds following removal of the burner.
Flexible products not more than 1mm thick which comply with the Type C requirements of BS 5867-2:1980 Specification for fabrics for curtains and drapes – Flammability requirements when tested to BS 5438:1989 Methods of test for flammability of textile fabrics when subjected to a small igniting flame applied to the face or bottom edge of vertically oriented specimens, Test 2, with the flame applied to the surface of the specimens for 5, 15, 20 and 30 seconds respectively, but excluding the cleansing procedure; and
i: Rigid solid polycarbonate sheet products less than 3mm thick, or multiple-skin polycarbonate sheet products which do not qualify as TP(a) by test; or
ii: Other products which, when a specimen of the material between 1.5 and 3mm thick is tested in accordance with BS 2782:1970, as amended in 1974: Method 508A, has a rate of burning which does not exceed 50mm/minute.
Note: If it is not possible to cut or machine a 3mm-thick specimen from the product then a 3mm test specimen can be moulded from the same material as that used for the manufacture of the product.
Note:Currently, no new guidance is possible on the assessment or classification of thermoplastic materials under the European system since there is no generally accepted European test procedure and supporting comparative data.Notes:If it is not possible to cut or machine a 3mm-thick specimen from the product then a 3mm test specimen can be moulded from the same material as that used for the manufacture of the product.
Fire test methods
21. A guide to the various test methods in BS 476 and BS 2782 is given in PD 6520 Guide to fire test methods for building materials and elements of construction (available from the British Standards Institution). A guide to the development and presentation of fire tests and their use in hazard assessment is given in BS 6336:1998 Guide to development and presentation of fire tests and their use in hazard assessment.
Application of the fire resistance standards in table A2:
- Where one element of structure supports or carries or gives stability to another, the fire resistance of the supporting element should be no less than the minimum period of fire resistance for the other element (whether that other element is loadbearing or not).
There are circumstances where it may be reasonable to vary this principle, for example:
- where the supporting structure is in the open air, and is not likely to be affected by the fire in the building; or
- where the supporting structure is in a different compartment, with a fire-separating element (which has the higher standard of fire resistance) between the supporting and the separated structure; or
- where a plant room on the roof needs a higher fire resistance than the elements of structure supporting
2. Where an element of structure forms part of more than one building or compartment, that element should be constructed to the standard of the greater of the relevant
- Although most elements of structure in a single storey building may not need fire resistance (see the guidance on requirement B3, paragraph 4.4(a)), fire resistance will be needed if the element:
- is part of (or supports) an external wall and there is provision in the guidance on requirement B4 to limit the extent of openings and other unprotected areas in the wall; or
- is part of (or supports) a compartment wall, including a wall common to two or more buildings, or a wall between dwellinghouse and an attached or integral garage; or
- supports a gallery
For the purposes of this paragraph, the ground storey of a building which has one or more basement storeys and no upper storeys, may be considered as a single-storey building. The fire resistance of the basement storeys should be that appropriate to basements.
Table A3 – Limitations on fire – protecting suspended ceilings (see Table A1, Note 4)
Table A4 – Limitations on the use of uninsulated glazed elements on escape routes (These limitations do not apply to glazed elements which satisfy the relevant insulation criterion, see Table A1)
Table A5 – Notional designations of roof coverings
Table A6 – Use and definitions of non-combustible materials
Table A7 – Use and definitions of materials of limited combustibility
Table A8 – Typical performance ratings of some generic materials and products