(4) Bridges, balconies and vestibules which constitute horizontal exits shall:(a) have no steps;
(b) comply with the requirements of subsection 3 of section 21 respecting gradients;
(c) be made of materials with a fire-resistance rating of at least 3/4 of an hour;
(d) have a clear width at least as great as that of the exit doorways opening into them but in no case shall such width be less than 1,100 mm;
(e) be provided with well secured guards of not less than 1,070 mm in height;
(f) be located so that openings adjacent to exits are more than 2.4 m from such exits or closed with materials with a fire-resistance rating of a least 3/4 of an hour.