3.4.3.1 — Exit Width Based on Occupant Load

(1) Except as permitted by Sentence (3), the minimum aggregate required width of exits serving floor areas intended for assembly occupancies, residential occupancies, business and personal services occupancies, mercantile occupancies, and industrial occupancies shall be determined by multiplying the occupant load of the area served by, (a) 6.1 mm per person for ramps with a slope of not more than 1 in 8, doorways, corridors and passageways, (b) 8 mm per person for a stair consisting of steps whose rise is not more than 180 mm and whose run is not less than 280 mm, or (c) 9.2 mm per person for, (i) ramps with a slope of more than 1 in 8, or (ii) stairs, other than stairs conforming to Clause (b). (2) The minimum aggregate width of exits serving floor areas intended for a care, care and treatment or detention occupancy shall be determined by multiplying the occupant load of the area served by 18.4 mm per person. (3) The minimum aggregate width of means of egress serving a Group A, Division 4 occupancy shall be determined by multiplying the occupant load of the area served by, (a) 1.8 mm per person for, (i) aisles, (ii) stairs other than exit stairs, and (iii) ramps and passageways in vomitories and exits, and (b) 2.4 mm per person for exit stairs. (4) Except as required by Sentence (5), the required exit width need not be cumulative in an exit serving two or more floor areas located one above the other. (5) The required exit width for an exit stair in an assembly hall or theatre serving more than one balcony level shall conform to the appropriate requirements for stairs serving interconnected floor spaces in Article 3.2.8.4. (6) If more than one exit is required, every exit shall be considered as contributing not more than one-half of the required exit width. (7) The width of an exit shall be not less than, (a) 1 100 mm for corridors and passageways, (b) 1 100 mm for ramps not serving patients’ or residents’ sleeping rooms, (c) 1 100 mm for stairs, not serving patients’ or residents’ sleeping rooms, that serve more than two storeys above the lowest exit level or more than one storey below the lowest exit level, (d) 900 mm for stairs, not serving patients’ or residents’ sleeping rooms, that serve not more than two storeys above the lowest exit level or not more than one storey below the lowest exit level, (e) 1 650 mm for stairs and ramps serving patients’ or residents’ sleeping rooms, (f) 1 050 mm for doorways serving patients’ or residents’ sleeping rooms, and (g) 790 mm for doorways not serving patients’ or residents’ sleeping rooms.