(1) Seats shall be arranged in rows having unobstructed passage of not less than 400 mm measured horizontally between plumb lines from the back of the seats in one row and the edge of the furthest forward projection of the seats in the succeeding row.
(2) Aisles shall:
(a) comply with the requirements of sections 10, 11 and 12;
(b) be perpendicular, as far as possible, to rows of seats and located so that there be no more than 7 seats between any seat and an aisle; the foregoing provision shall not apply if the 3 following conditions are complied with:
i. a door leading directly to an exit shall be provided at the ends of every 3 rows of seats; and
ii. every third row of seats shall terminate at the side walls; and
iii. the number of seats in a row shall not exceed 100;
(c) be at least 900 mm wide at the point of origin and shall increase uniformly by 25 mm every 1 m in the direction of exit; the width of aisles may be uniform if both ends thereof are clear;
(d) be not less than 1,100 mm in width and shall not be closer than 3.6 m to a stage area using scenery of scenic elements when such aisles cross other aisles;
(e) have a gradient of not more than 1 in 8 without steps; should the gradient be greater, steps may be used, provided that:
i. they comply with paragraphs a and b of subsection 2 of section 21, except for the width of the tread;
ii. they be as wide as the aisle;
(f) be continuously illuminated while the building is occupied.