ABSTRACT
The spread of fire within a building can be restricted by subdividing it into separate compartments by walls and/or floors of fire resisting construction. Timber is a popular material for the construction of suspended floors of buildings where the spans are small enough for it to be the most economic material from the aspect of strength/weight ratio and where there are no requirements for sound insulation or fire resistance. The size of the structural timbers used as joists in a suspended timber floor is determined by the strength of the timber, the load to be carried, the span of the floor and the spacing of the timbers. Ceilings suspended below floors provide a ready route for the spread of smoke and flame through the cavity thus created. A suspended ceiling may be taken to contribute to the overall fire resistance of the floor construction. Lighting diffusers fitted as part of a ceiling obviously affect the fire-resisting qualities of that ceiling.
