External fire spread - Performance requirements

It is the view of the Department that the requirements of regulation 36 in Part E will be met – (a) if the external walls are constructed so that (i) the risk of ignition from an external source, and the spread of fire over their surfaces, is restricted by making provision for them to have low rates of heat release; (ii) the materials used to construct external walls and attachments to them in a building of any height and how they are assembled do not contribute to the rate of fire spread up the outside of a building. (b) if the amount of unprotected area in the side of a building is restricted so as to limit the amount of thermal radiation that can pass through the wall, taking the distance between the wall and the boundary into account; and (c) if the roof is constructed so that the risk of spread of flame and/or fire penetration from an external fire source is restricted, in each case so as to limit the risk of a fire spreading from the building to another building beyond the boundary, or vice versa. The extent to which this is necessary is dependent on the use of the building, its distance from the boundary and, in some cases, its height.