The Ontario Building Code | Bleachers
(1) Steps provided in aisles of bleachers of the telescopic type shall,
(a) have risers not more than 250 mm high, and
(b) have treads with a run not less than 280 mm.
(2) If the vertical distance between seating platforms in bleachers is more than 280 mm, an intermediate step shall be provided the full width of the aisle and proportioned to provide two equal risers between platforms.
(3) If the vertical distance between seating platforms in bleachers is more than 450 mm, two intermediate steps shall be provided the full width of the aisle so that there are three equal risers between platforms.
(4) If the passageway between rows of seats is not a closed deck, footboards shall be provided so that,
(a) the total width of the footboards shall be not less than three-quarters of the centre-to-centre spacing between rows of seats, and
(b) the spacing between footboard members shall be not more than 25 mm.
(5) openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings above footboards and below the seats in rows of bleachers shall be of a size that will prevent the passage of a sphere having a diameter more than 100 mm.