(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 inside handrail,

            (ii)   have a consistent angle and uniform dimension, and

           (iii)   turn in the same direction, and

    (e)   a clear height not less than 1 980 mm.

    (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.

Article Ontario Regulation 332/12 Building Code,   Information published by oncodes.ca for educational purposes only.