Building standards technical handbook 2019: domestic

The building standards technical handbooks provide guidance on achieving the standards set in the Building (Scotland) Regulations 2004. This handbook applies to a building warrant submitted on or after 1 October 2019 and to building work which does not require a warrant commenced from that date.

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Annex 2.B Reaction to fire

2.B.0 Introduction

The performance criteria in terms of reaction to fire can be satisfied by the European Harmonised fire tests. BS EN 13501-1: 2018 provides the reaction to fire classification procedure for all construction products within the scope of the Construction Products Regulations.

2.B.1 Reaction to fire classification

For all construction products, the consideration is of a fire, initiated in a room, which can grow and eventually reach flashover. This scenario includes three fire situations corresponding to three stages in the development of a fire:

  • the first stage includes initiation of the fire by ignition of a product, with a small flame, on a limited area of a product,

  • the second stage addresses fire growth eventually reaching flashover. It is simulated by a single burning item in a corner of the room, creating a heat flux on adjacent surfaces. For floorings, fire is seen to grow in the room of origin, creating a heat flux on the floorings in an adjacent room or corridor, through a door opening, and

  • in the post-flashover phase all combustible products contribute to the fire load.

Currently, there is no recognised European Harmonised fire test for facades or construction products exposed to a fire in a cavity. It has therefore been necessary to use the reaction to fire classification system in BS EN 13501-1: 2018 for external wall cladding systems in certain circumstances.

2.B.2 Harmonised European Standards

Non-combustibility test (EN ISO 1182) identifies products that will not, or not significantly, contribute to a fire, regardless of their end use. The assumption is that products classified as A1 make no contribution to fire growth or to the fully developed fire. A product classified as A1 is assumed to present no smoke hazard.

The European Commission has drawn up a list of products which, under specified conditions, can be considered to be class A1 without testing. This information is given in the Commission Decision 96/603/EC (OJ L 267 19.10.1966 p23) as amended by 2000/605/EC (OJ L 258 12.10.2000 p36) and 2003/424/EC (OJ L 144 12.6.2003 p9).

Heat of combustion test (EN ISO 1716) determines the potential maximum total heat release of a product when completely burning, regardless of its end use.

Single burning item test (EN 13823) evaluates the potential contribution of a product to the development of a fire, under a fire situation simulating a single burning item in a room corner near to that product. When a classification includes “s3, d2” this means that there is no limit set for smoke production and/or flaming droplets/particles.

Ignitability test (EN ISO 11925-2) evaluates the ignitability of a product under exposure to a small flame.

Table 2.8. Reaction to Fire

European Classification [1] Fire Test Additional Classification

BS EN ISO: 1182: 2010 and BS EN ISO: 1716: 2018 or

Products made from only 1 or more of the materials considered as Class A1 without the need for testing, as defined in Commission Decision 96/603/EC of 4th October 1996 establishing the list of products belonging to Class A1 “No contribution to fire” provided for in the Decision 94/611/EC implementing Article 20 of the Council Directive 89/106/ EEC on the construction products. None of the materials contain more than 1.0% by weight or volume (whichever is the lower) of homogeneously distributed organic material.

A2 BS EN: 13823: 2010+A1: 2014 and BS EN ISO: 1182: 2010 or BS EN ISO: 1716: 2018 Smoke production and flaming droplets / particles
B, C and D BS EN: 13823: 2010+A1: 2014 and BS EN ISO: 11925-2: 2010. Smoke production and flaming droplets / particles
E BS EN ISO: 11925-2: 2010. Flaming droplets / particles

Additional information:

Reference to the reaction to fire performance of construction products throughout Section 2: Fire includes homogeneous and non-homogeneous products as defined in BS EN 13501-1: 2018. When reference is made to European Classification A2, B, C and D, all references include sub-indices “s3, d2” and are not repeated to simplify the text. s3-d2 means there is no limit set for smoke production and/or flaming droplets/particles.

In buildings where external wall cladding systems achieve a European Classification A1 or A2, the following products, where used as part of such a wall, need not achieve the same classification:

  • cavity trays

  • any part of a roof (other than a part of a roof pitched at an angle of 70º or more to the horizontal) if that part is connected to an external wall

  • door frames and doors

  • electrical installations

  • insulation and water proofing materials used below ground level

  • intumescent and fire stopping materials where the inclusion of the materials is necessary for compliance with the standards in Section 2 (Fire)

  • membranes

  • seals, gaskets, fixings, sealants and backer rods

  • thermal break materials where the inclusion of the materials is necessary for compliance with the standards in Section 6 (Energy), or

  • window frames and glass.

2.B.3 Classified without Further Testing

Additionally there is a procedure by which certain products can be assigned a particular fire classification without the need for testing. Such products have well established reaction to fire performance and have been agreed by the Standing Committee on Construction. Agreements relating to such products which may be ‘classified without further testing’ (CWFT) are published in the Official Journal of the EC and are listed on the Nando-CPD database on the EC website.

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