9.8.4.7.Spiral Stairs (See Note A-9.8.4.7.)

(1) Spiral stairs shall have (a) handrails on both sides, the outer handrail being not less than 1 070 mm high, (b) a clear width not less than 660 mm between handrails, (c) risers that are not more than 240 mm high, (d) treads that (i) are a minimum of 190 mm deep at a point 300 mm from the centre line of the handrails at the narrower edge, (ii) have a consistent angle and uniform dimension, and (iii) turn in the same direction, and (e) not less than 1 980 mm clear height. (2) Spiral stairs conforming to Sentence (1) are permitted to be used as the only means of egress where they serve not more than 3 persons. (3) Except as permitted by Sentence (2), spiral stairs shall not serve as an exit.