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1. Certain standards in Part D are expressed in terms of performance. The methods of meeting the requirements for fire resistance, non-combustibility and external fire exposure designation of roofs are given below.
FIRE RESISTANCE OF ELEMENTS OF STRUCTURE
2. For the purpose of these standards the fire resistance for loadbearing capacity, integrity and insulation of an element of structure must be verified by a laboratory accredited for conducting the relevant test by the United Kingdom Accreditation Service or equivalent European body. Other than for loadbearing capacity, where it is impractical to test a complete component, a suitable sample may be tested and an assessment of the performance of the complete component made accordingly. The appropriate use of a product which has been tested by an independent testing laboratory or which has a European Technical Approval as defined in the Construction Products Directive (89/106/EEC), and which complies with these standards, will also meet the relevant standard.
3. Reference may be made to -
a. tests described in paragraph 4 below;
b. in the case of structural steelwork, BS5950: Part 8: 1990 Code of Practice for fire resistant design;
c. in the case of structural use of timber, BS5268: Part 4: Section 4.2: 1990;
d. in the case of structural use of concrete, BS8110: Part 2: 1985: Section 4.3 "Tabulated data (method 1)";
e. an appropriate specification given in the Building Research Establishment Report (BR128) "Guidelines for the Construction of Fire Resisting Structural Elements" (BRE, 1988).
4. The construction must be capable of meeting for the required time the criteria specified in either -
a. clause 10 of BS476: Part 20: 1987, when read in conjunction with —
i. for loadbearing elements - BS476: Part 21: 1987,
ii. for non-loadbearing elements - BS476: Part 22: 1987,
iii. for components - BS476: Part 23: 1987,
iv. for ventilation ducts - BS476: Part 24: 1987,
v. for fire door assemblies with non-metallic leaves - BS8214: 1990: Sections 1 and 2; or
b. where tests on the component or type of construction were carried out before 1 January 1989, BS476: Part 8: 1972.
5. When considering the fire resistance of existing doors it would be reasonable to consider the door and the frame separately, and if upgrading is necessary it may be sufficient to replace only the door rather than the complete door set.
NON-COMBUSTIBILITY
6. Where a material is required to be non-combustible it must be certified as such according to the test specified in BS476: Part 4: 1970. However, plasterboard complying with BS1230: Part 1: 1985 or any other material with a non-combustible core at least 8mm thick having combustible facings (on one or both sides) not more than 0.5mm thick fully bonded to the non-combustible sub-strata can be regarded as non-combustible, as can materials such as concrete, fired clay, ceramics, metals other than magnesium/aluminium alloys, which must be assessed in each individual case, plaster and masonry containing not more than 1 per cent by weight or volume of organic material, and concrete bricks or blocks complying with BS6073: Part 1: 1981. In addition, a non-combustible double-skinned panel containing thermal insulation, other than non-combustible thermal insulation, must be edge sealed so that the thermal insulation material is protected from fire by the non-combustible panel containing it.
EXTERNAL FIRE EXPOSURE DESIGNATION OF ROOFS
7. Where the designation of a roof covering or rooflight is specified by reference to a lettered system of designation this means a roof covering or rooflight which achieves that designation when tested along with any substrate in accordance with BS476: Part 3: 1958.
OTHER SOURCES OF INFORMATION
8. Results of tests on proprietary materials and elements of structure are given in the following publications -
Building Research Establishment Report: "Results of the Fire Resistance Tests on Elements of Building Construction" (BRE, 1975).
Building Research Establishment Report: "Results of Fire Resistance Tests on Elements of Building Construction; Volume 2" (BRE, 1976).
"Fire Protection for Structural Steel in Buildings," second edition, (Association of Specialist Fire Protection Contractors and Manufacturers, 1992), (available from the Specialist Fire Protection Association).
9. Information on tested materials and elements of structure is also frequently given in literature available from manufacturers and trade associations.
10. Any reference used to substantiate the fire resistance or other rating of a construction 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 fixing methods, joints, dimensions etc. may significantly affect the rating.
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