3.6.1. Any building under construction shall be provided with 2 means of egress by means of permanent or temporary stairs which shall:(a) be built for the entire height from the ground or underground to the working level as soon as the work has attained a height of 2 storeys or 6 m above ground;
(b) be extended as work progresses without adversely affecting construction work;
(c) never be extended at less than 2 storeys from the upper working level; and
(d) be built of steps with a depth more than 150 mm.