Limitations on Class 3 plastic rooflights and thermoplastic rooflights and lighting diffusers in suspended ceilings

Table 3.2 Limitations on Class 3 plastic rooflights and thermoplastic rooflights and lighting diffusers in suspended ceilings | Minimum classification of lower surface | Use of space below rooflight or diffuser | Maximum area of each rooflight or diffuser panel (m²) | Maximum total area of rooflights or diffuser panels as a percentage of floor area of the space in which the ceiling is located (%) | Minimum separation distance between rooflights or diffuser panels (m) | |---|---|---|---|---| | TP(a) | Rooms or circulation spaces (except protected stairways) | No limit | No limit | No limit | | Class 3 or TP(b) | Rooms | 5 | 50 | 3 | | Class 3 or TP(b) | Circulation spaces (except protected stairways) | 5 | 15 | 3 | Notes: (1) Small rooflights or diffuser panels may be grouped together provided that the overall size of the group and the space between one group and any others comply with the limitations given in Diagram 3.1. (2) Lighting diffusers of a TP(a) flexible material are limited to panels of not more than 5 m². (3) There are no limitations on Class 3 materials in certain small rooms. (4) It may not be possible to use the maximum total percentage because the minimum 3 m separation distance must be maintained. (5) Class 3 rooflights to rooms in non-residential purpose groups may be spaced 1.8 m apart provided that the rooflights are evenly distributed and do not exceed 20% of the area of the room.