(1) Subject to the requirements of sections 7, 8, 11, 12 and 23, every wall, floor, ceiling and stairway forming a component of an interior exit-way in any occupancy-unit falling within the categories set forth in Table XV shall have a fire-resistance rating of not less than one hour, unless otherwise approved by the local authority:

Provided that doors in access doorways to such exit-ways shall have a fire-resistance rating of not less than half an hour.

TABLE XV
OCCUPANCY-UNITS IN WHICH INTERIOR EXIT-WAYS MUST HAVE FIRE PROTECTION

(2) Every wall-lining, to the walls of an exit-way referred to in subsection (1), shall be of non-combustible material.

(3) Every doorway forming a component of exit-way referred to in subsection (1), and windows opening on to such exit-way, shall comply with the following requirements—

a) Every such doorway, other than a doorway forming an exit, shall be protected by an approved self-closing or automatic fire-door having a fire-resistance rating of at least one hour;

b) Every window-opening formed in an internal wall abutting a component of such exit-way shall be protected by a non-openable or self-closing fire-window having a fire-resistance rating of not less than one hour, situated with the sill at a height of at least 1,8 metres above floor-level;

c) In an internal wall abutting such an exit-way, other than an interior dead-end passageway which is not served by two separate exit-ways, there shall be not more than one openable window or fan-light shall not exceed 1 400 square centimetres;

d) In an internal wall abutting an interior dead-end passageway which is not served by two separate exit-ways, there shall be no ventilation-openings, other than door-openings, apart from air-bricks or louvres, situated within a height of 600 millimetres from the floor-level, and the ventilation area of such openings shall not exceed 200 square centimetres per 4,5-metre length of passageway, which-ever is the greater;

e) Every doorway formed in any external wall which abuts any component of such exit-way, and which is within a distance of 4,5 metres in any direction, from a stairway forming a component of such exit-way, shall be protected by an approved self-closing or automatic fire-door having a fire-resistance rating of at least half an hour;

f) Every window-opening, except an opening having a window not exceeding 0,5 square metre in area serving a water-closet or bath-room, formed in any external wall which abuts any component of an exterior exit-way, and which is within a distance of 4,5 metres, in any direction, from a stairway forming a component of such exit-way, shall be protected by –

i) An approved self-closing fire-window; or

ii) A window provided with an approved self-closing or automatic metal shutter;

In each case having a fire-resistance rating of not less than half an hour;

g) Every window-opening formed in any external wall abutting a dead-end exterior passageway which is not served by two separate exit-ways shall have its sill not less than 1,8 metres above the floor-level of such passageway.

(4) One stairwell or, where required by the local authority, more than one stairwell in each building shall be provided with—

a) An entrance-lobby on each floor, with entrance and exit doorways complying with paragraph (a) of subsection (3), such lobby measuring not less than 2 metres by 1,5 metres, with a ceiling at least 300 millimetres higher than the top of the doorway openings; and

b) A mechanical supply system, introducing outside air to the stairwell and lobbies at a rate which will maintain a pressure, with all doors closed, of 2,50 millimetres water gauge minimum above ambient.

(5) Supply systems mentioned in subsection (4) shall be—

a) Arranged to come into operation automatically when fire is detected, by means approved by the local authority;

b) Powered both from mains-supply and from an emergency alternator driven by compression-ignition engine to come into operation automatically in case of failure of mains-supply.

(6) Wherever the floor of any room in a building of a business, commercial or industrial occupancy is subdivided or obstructed by partitions, counters, benches, seats, tables, shelving, cupboards, goods and other obstructions which are of such a nature or weight as to be not readily removable in case of fire, such obstructions shall be so arranged as to leave aisles or openings between them, to enable the occupants of such room to reach a point of access to an exit-way.

(7) The aisle or openings referred to in subsection (6) shall be not less than 750 millimetres in width, but, where the public have access to them, such aisles shall be of such greater width, as would be required in terms of section 26.