London : Règlement no CP-24, art. 4.5.9.2 — Stairs – Residential – Not within The stair tread rise and run for residential stairs not within dwelling unit shall not exceed these dimensions

Stairs – Residential – Not within The stair tread rise and run for residential stairs not within dwelling unit shall not exceed these dimensions:

• a) maximum rise 210 mm (8 1/4”)
• b) minimum tread 240 mm (9 1/4”)
• c) minimum run 212 mm (8 ½”)
• d) if run is less than 240 mm (9 ½”), a 25 mm (1") nosing is required
• e) existing winders of not more than 3 in 90 degree and not more than 2 sets between floors are permitted and where each tread is not less than 30 degrees and each tread are not greater than 45 degrees