B7 For the purpose of inhibiting the spread of fire within a dwelling house, the internal linings:
(a) shall have, either a rate of heat release or a rate of fire growth and a resistance to ignition which is reasonable in the circumstances; and
(b) shall offer adequate resistance to the spread of flame over their surfaces.
2.1 Internal Fire Spread (linings)
2.1.1 General
The purpose of the requirement of Regulation B7 is to ensure that the fire spread over the internal linings is inhibited.
2.2 Performance
The requirement of B7 may be met as follows:
(a) In relation to the European fire tests and classification system, the requirement of B7 will be met if the heat released from the internal linings is restricted by making provision for them to have a rate of fire growth and a resistance to ignition which is reasonable in the circumstances; or
(b) The requirement of B7 may be met if the spread of fire over the internal linings of the building is restricted by making provision for them to have low rates of surface spread of flame and in some cases to have a low rate of heat release or a rate of fire growth, so as to limit the contribution that the fabric of the building makes to fire growth.
The extent to which this is necessary is dependent on the location of the lining.
2.3 Introduction to Provisions
2.3.1 Fire Spread and Lining Materials
The choice of materials for the lining of walls and ceilings can significantly affect the spread of a fire, and its rate of growth, even though they are not likely to be the materials first ignited. This is particularly important in circulation spaces where linings would offer the main vehicle for fire spread, and where rapid spread would be most likely to prevent occupants from escaping.
Several properties of lining materials influence fire spread. These include the ease of ignition and the rate at which the lining material gives off heat when burning. The guidance relating to the European fire tests and classification provides for control of internal fire spread through control of these properties.
2.3.2 Floors and Stairways
It is impractical to attempt to control the materials used to cover floors and stairways through Building Regulations, and no provisions are made in this Document about them.
2.3.3 Furniture and Fittings
Furniture and fittings can have a major effect on fire spread but it is impractical to attempt to control them through Building Regulations and no provisions is made in this Document about them.
2.3.4 Other Controls on Linings Properties
There are provisions for the control of fire growth in Section 4, sub-section 4.4 concerning the external surface of walls and in sub-section 4.6 concerning the surface of rooflights in connection with the performance of roof coverings.
2.3.5 Classification of Performance
Appendix A describes the different classes of performance for materials used as a wall or ceiling lining and the appropriate methods of test, including performance ratings for thermoplastic materials, referred to as TP(a) rigid and TP(b).
The European classifications are described in I.S. EN 13501-1: 2007 +A1:2009, Fire classification of construction products and building elements, Part 1 - Classification using data from reaction to fire tests. They are based on a combination of four European test methods:
I.S. EN ISO 1182: 2010, Reaction to fire tests for building products - Non combustibility test;
I.S. EN ISO 1716: 2010, Reaction to fire tests for building products - Determination of the gross calorific value;
I.S. EN 13823: 2010, Reaction to fire tests for building products - Building products excluding floorings exposed to the thermal attack by a single burning item; and
I.S. EN ISO 11925-2: 2010, Reaction to fire tests for building products, Part 2 - Ignitability when subjected to direct impingement of flame.
For some building products, there is currently no generally accepted guidance on the appropriate procedure for testing and classification in accordance with the European fire tests. Until such time that the appropriate European test and classification methods for these building products are published, classification may only be possible using existing national test methods.
The National classifications used are based on tests in BS 476: Parts 6 and 7. Tests in BS 2782 are used for classification of thermoplastic materials.
Table A5 of Appendix A gives typical performance ratings which may be achieved by some generic materials and products.
2.3.6 Assessment of Performance
Combustible linings can contribute significantly to the spread of fire in a building and their use should be restricted. The fire performance of lining materials is especially important in circulation spaces and on escape routes. An assessment of the likely performance of lining materials should take account of the following:
the performance of the lining materials in accordance with the criteria indicated in paragraphs A7 to A19 of Appendix A,
the extent and thickness of the lining materials,
the likely interaction between wall and ceiling linings and between linings and any combustible fittings or fixtures,
the extent of voids behind the lining materials and the existence of electrical services in such voids.
Care should be taken to ensure that any products which are used to treat lining materials for the purpose of inhibiting spread of flame are applied, and maintained, strictly in accordance with the specification applicable to the relevant test certification supplied by the manufacturer of such products.
Surface treatment of linings is not, in general, a suitable method of achieving class B - s3, d2 (European class) or Class 0 (National class) performance (see A10 of Appendix A). However, in the case of existing lining materials, which satisfy the assessment criteria indicated above, surface treatment to achieve the required performance may be considered.
Note: Care should be taken to ensure that a build-up of combustible paints does not reduce the classification of any wall or ceiling lining.
2.4 General Provisions
Subject to the variations and specific provisions described in the paragraphs below, the surface linings of walls and ceilings should meet the following classifications as outlined in Appendix A Table A5.
(a) Class D - s3, d2 (European class) or Class 3 (National class) in bathrooms, toilets and shower rooms.
(b) Class C - s3, d2 (European class) or Class 1 (National class) in other rooms.
(c) Class C - s3, d2 (European class) or Class 1(National class) in circulation spaces.
2.5 Variations and Special Provisions
2.5.1 Walls
Part of the surface of a wall in a room may be of a class lower than specified in 2.4, (but not lower than Class D - s3, d2 (European) or Class 3 (National)) if the area of that part (or, if there are two or more such parts, the total area of those parts) does not exceed –
(a) half the floor area of the room, or
(b) 20 m2: and
any individual part should not exceed 5 m2 and should be separated from any other such part by a distance of not less than 2 m;
Note: A wall does not include a door or glazing in a door.
2.6 Thermoplastic Materials
Thermoplastic materials (see Appendix A, paragraphs A15, A16) which cannot meet the performance specified in paragraph 2.4 can be used in windows, rooflights and lighting diffusers in ceilings if they comply with the provisions of the following paragraphs:
2.6.1 Windows
External windows to rooms (though not to circulation spaces) may be glazed with thermoplastic materials, if the material can be classified as a TP(a) rigid product. Internal glazing should meet the provisions in par. 2.4 above.
2.6.2 Rooflights
Rooflights to rooms and circulation spaces (with the exception of protected stairways) may be constructed of a thermoplastic material if:
(a) the lower surface has a TP(a) (rigid) or TP(b) classification (see paragraph A16, Appendix A)
(b) the size and disposition of the rooflights accords with the limitations in Table 2.1, Diagram 8 and Table 4.4 to Section 4.
2.6.3 Lighting Diffusers
Lighting diffusers are translucent or open structured elements that allow light to pass through. They may be part of a luminaire or used below rooflights or other sources of light. The following provisions apply only to lighting diffusers which form part of a ceiling and are not concerned with diffusers of light fittings which are attached to the soffit of, or suspended beneath a ceiling (see Diagram 7).
Diagram HB7 - Lighting diffuser in relation to ceiling - Extract from TGD B Vol. 2
Thermoplastic lighting diffusers should not be used in fire protecting or fire resisting ceilings, unless they have been satisfactorily tested as part of the ceiling system that is to be used to provide the appropriate fire protection.
Ceilings to rooms and circulation spaces (but not protected stairways) may incorporate thermoplastic lighting diffusers if the following provisions are observed:
(a) Wall and ceiling surfaces exposed within the space above the suspended ceiling (other than the upper surfaces of the thermoplastic panels) should comply with the general provisions of par. 2.4, according to the type of space below the suspended ceiling.
(b) If the diffusers are of classification TP(a) (rigid), there are no restrictions on their extent.
(c) If the diffusers are of classification TP(b), they should be limited in extent as indicated in Table 2.1 and Diagram 8.
Table HB2 - Limitations applied to thermoplastic lighting diffusers in suspended ceilings and thermoplastic rooflights - Extract from TGD B Vol. 2
Diagram HB8 - Layout restrictions on TP(b) thermoplastic lighting diffusers and rooflights - Extract from TGD B Vol. 2
Thermoplastic materials which have a lesser performance than TP(b) should not be used for lighting diffusers which form part of a ceiling.
