(1) Every exit shall have a wall or a well-secured guard on each side where,
(a) the difference in level is more than 600 mm between the walking surface and the adjacent surface, or
(b) the adjacent surface within 1 200 mm of the walking surface has a slope of more than 1 in 2 away from the walking surface.
(2) Except as required by Sentence (4), the height of guards for exit stairs and exit ramps, as well as their landings, shall be not less than 1 070 mm.
(3) The height of guards shall be measured vertically to the top of the guard from,
(a) a line drawn through the outside edges of the tread nosings, or
(b) the surface of the ramp or landing.
(4) The height of guards for exterior stairs and landings more than 10 m above adjacent ground level shall be not less than 1 500 mm measured vertically to the top of the guard from the surface of the landing or a line drawn through the outside edges of the tread nosings.
(5) Except as provided in Sentence (6), openings through any guard that is required by Sentence (1) shall be of a size that will prevent the passage of a sphere having a diameter more than 100 mm unless it can be shown that the location and size of openings that exceed this limit do not represent a hazard.
(6) Openings through any guard that is required by Sentence (1) and that is installed in a building of industrial occupancy shall be of a size that will prevent the passage of a sphere having a diameter more than 200 mm unless it can be shown that the location and size of openings that exceed this limit do not represent a hazard.
(7) In a stairway, a window for which the distance measured vertically between the bottom of the window and a line drawn through the outside edges of the tread nosings is less than 900 mm, or a window that extends to less than 1 070 mm above the landing, shall,
(a) be protected by a guard that is,
(i) located approximately 900 mm above a line drawn through the outside edges of the tread nosings, or
(ii) not less than 1 070 mm high measured to the top of the guard from the surface of the landing, or
(b) be fixed in position and designed to resist the lateral design loads specified for guards and walls in Articles 4.1.5.14. and 4.1.5.16.
(8) Unless it can be shown that the location and size of openings do not present a hazard, a guard shall be designed so that no member, attachment or opening located between 140 mm and 900 mm above the level being protected by the guard will facilitate climbing.