Construction of escape stairs – materials of limited combustibility

Other than in a dwellinghouse every escape stair and its associated landings should be constructed of materials of limited combustibility where – (a) it is the only stair serving the building (or part of the building), unless the building is of two or three storeys and is of Purpose Group 1(a) or Purpose Group 3; (b) it is within a basement storey, unless it is within a flat with more than one storey; (c) the height to any storey which it serves is more than 18 m above ground or final exit level; (d) it is a firefighting stairway (see Section 6); or (e) it is external, except in the case of a stair that connects the final exit level with a floor or flat roof less than 6 m above or below final exit level. Combustible materials may be added to the upper surface of these stairs except in the case of firefighting stairways.