Committees responsible for this British Standard

The preparation of this British Standard was entrusted by Technical Committee FSH/22, Fire resistance tests, to Subcommittee FSH/22/8, Test procedures for external fire exposure to roofs, upon which the following bodies were represented:

Association of British Roofing Felt Manufacturers

BRE — Building Research Establishment

BRE/LPC Laboratories

British Rigid Urethane Foam Manufacturers’ Association

Concrete Tile Manufacturers Association

Eurisol (UK Mineral Wool Association)

Fibre Cement Manufacturers Association Ltd.

Flat Glass Manufacturers’ Association

Flat Roofing Alliance

Gypsum Products Development Association

Home Office

Mastic Asphalt Council Ltd.

National Association of Rooflight Manufacturers

National Federation of Roofing Contractors

National GRP Construction and Engineering Federation

OPDM — Building Division

UK Steel Association

Warrington Fire Research Centre

First published June 1958

Second edition November 1975

Third edition June 2004

The following BSI references relate to the work on this British Standard:

Committee reference FSH/22/8 Draft for comment 03/109613

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 14 June 2004

Foreword

This Part of BS 476‑3 has been prepared by Subcommittee FSH/22/8. It is based on BS 476‑3:1958 and it supersedes BS 476‑3:1975 which is withdrawn.

The start and finish of text introduced or altered by amendment is indicated in the text by tags . Tags indicating changes to text carry the number of the amendment. For example, text altered by Amendment No. 1 is indicated by .

The tests described in this part of BS 476 are designed to give information concerning the hazard that exists of fires spreading to the roof of a building from a nearby fire outside the building itself. The tests are not concerned with the behaviour of a roof when subjected to the effects of fire on its underside.

A preliminary test is made in which a specimen section of the roof is subjected to the effects of flame in the absence of radiation. Unless the specimen is so affected by this test that it is obvious it would not pass the principal tests, i.e. the penetration and the spread of flame tests, these are then carried out using the radiated heat apparatus.

When subjected to the penetration test, specimens are exposed to radiation of intensity 12 kW/m² measured on the surface of the specimen. This can be regarded as, for example, the intensity incident on a roof 7.6 m above ground level from a fire 13.7 m away in a building with a facade of 15.2 m × 15.2 m and 50 % window openings. Because wind will tend to carry any surface flames through any fissures in a roof, provision is made in the test to simulate the effect of a wind of 6.7 m/s (15 miles per hour) by applying suction to the lower side of the roof specimen during the test.

In the spread of flame test, however, the intensity of radiation varies over the exposed surface of the specimen. The distance to which the fire spreads downwards over the specimen thus gives a measure of the minimum intensity required to ignite the surface when a small ignition source such as a brand is present.

NOTE This intensity can be interpreted as being equivalent to the distances given in Table B.1, between an exposed roof 7.6 m above ground level and a burning building with a facade 15.2 m × 15.2 m and 50 % window openings.

This British Standard calls for the use of substances and/or procedures that may be injurious to health if adequate precautions are not taken. It refers only to technical suitability and does not absolve the user from legal obligations relating to health and safety at any stage.

This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

Summary of pages

This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 11 and a back cover.

The BSI copyright notice displayed in this document indicates when the document was last issued.

1 Scope

The tests given in this British Standard are designed to enable measurement of:

capacity of a representative section of a roof to resist penetration by fire when the external surface is exposed to radiation and flame; and
distance of the spread of flame on the outer surface of the roof covering under certain conditions.

Roofs are graded according to the angle at which they are tested, the time for which they resist penetration by fire, and the distance of superficial spread of flame on their external surface.

An additional test for rooflights is given in Annex C.

2 Normative references

3 Terms and definitions

4 Classification

4.1 Roof system

4.2 Fire resistance of roof system

5 Three stage test method incorporating burning brands, wind and supplementary radiant heat

5.1 Apparatus

5.2 Calibration

5.3 Test conditions

5.4 Test specimen

5.5 Conditioning

5.6 Test environment

5.7 Test procedure

5.8 Observations and measurements

5.9 Test report

BS 476-3:2004+A2:2007

Fire tests on building materials and structures - Classification and method of test for external fire exposure to roofs

Current

Published:

14 Jun 2004