23. Permanent ladders: Permanent ladders used to replace service stairs shall:
(1) be of safe construction and solidly anchored to withstand a mass of 90 kg at the centre of the rungs with a safety factor of 4;
(2) for ladders exceeding 9 m, have rest platforms equipped with guardrails, at least at 6 m intervals;
(3) have a free space behind the rungs of at least 150 mm;
(4) have a free space on each side of at least 375 mm and forward of at least 800 mm, measured from the centre of a rung;
(5) extend 900 mm beyond the top storey;
(6) be provided with guardrails surrounding the floor opening with a removable gate for access to the ladder;
(7) be provided with crinolines or cages or a fall arrestor in compliance with CAN/CSA Standard Z259.2.1-98 Fall Arresters, Vertical Lifelines and Rails, where there is danger of a fall greater than 6 m.
Subparagraphs 3 and 4 of the first paragraph apply only to permanent ladders built, installed or modified on or after 2 August 2001.