Section 14 Roof coverings

Roof coverings

  1. Introduction
    1. Other controls on roofs
    2. Classification of performance
      1. Separation distances
        1. Plastic rooflights
          1. Unwired glass in rooflights
            1. Thatch and wood shingles

            Introduction

            14.1The provisions in this section limit the use, near a boundary, of roof coverings which will not give adequate protection against the spread of fire over them. The term roof covering is used to describe constructions which may consist of one or more layers of material, but does not refer to the roof structure as a whole. The provisions in this Section are principally concerned with the performance of roofs when exposed to fire from the outside.

            14.2The circumstances when a roof is subject to the provisions in Section 13 for space separation are explained in paragraph 13.1.

            Other controls on roofs

            14.3There are provisions concerning the fire properties of roofs in three other Sections of this document. In the guidance to B1 (paragraph 5.3) there are provisions for roofs that are part of a means of escape. In the guidance to B2 (paragraph 6.12) there are provisions for the internal surfaces of rooflights as part of the internal lining of a room or circulation space. In the guidance to B3 there are provisions in Section 7 for roofs which are used as a floor and in Section 8 for roofs that pass over the top of a compartment wall.

            Classification of performance

            14.4The performance of roof coverings is designated by reference to the test methods specified in BS 476-3: 2004 or determined in accordance with BS EN 13501-5:2005, as described in Appendix A. The notional performance of some common roof coverings is given in Table A5 of Appendix A.

            Rooflights are controlled on a similar basis and plastic rooflights described in paragraph 14.6 and 14.7 may also be used.

            Separation distances

            Diagram 47

            14.5The separation distance is the minimum distance from the roof (or part of the roof) to the relevant boundary, which may be a notional boundary.

            Table 16 sets out separation distances according to the type of roof covering and the size and use of the building. There are no restrictions on the use of roof coverings designated AA, AB or AC (National class) or BROOF(t4) (European class) classification. In addition, roof covering products (and/or materials) as defined 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 can be considered to fulfil all of the requirements for performance characteristic “external fire performance” without the need for testing provided that any national provisions on the design and execution of works are fulfilled. That is, the roof covering products (and/ or materials) defined in this Commission Decision can be used without restriction.

            Plastic rooflights

            14.6Table 17 sets out the limitations on the use of plastic rooflights which have at least a Class 3 (National class) or Class D-s3, d2 (European class) lower surface and Table 18 sets out the limitations on the use of thermoplastic materials with a TP(a) rigid or TP(b) classification (see also Diagram 47). The method of classifying thermoplastic materials is given in Appendix A.

            14.7When used in rooflights, a rigid thermoplastic sheet product made from polycarbonate or from unplasticised PVC, which achieves a Class 1 (National class) rating for surface spread of flame when tested to BS 476-7:1971 (or 1987 or 1997) Surface spread of flame tests for materials, or Class C-s3, d2 (European class) can be regarded as having an AA (National class) designation or BROOF(t4) (European class) classification, other than for the purposes of Diagram 30.

            Unwired glass in rooflights

            14.8When used in rooflights, unwired glass at least 4mm thick can be regarded as having an AA designation (National class) designation or BROOF(t4) (European class) classification.

            Thatch and wood shingles

            Table 16

            14.9Thatch and wood shingles should be regarded as having an AD/BD/CD designation or EROOF(t4) (European class) classification in Table 16 if performance under BS 476-3: 1958 2004 or EN 1187:XXX (test 4) respectively cannot be established.