(1) Except as provided in this section, every room used for the storage or keeping of flammable liquids and substances shall be constructed as a separate building, which shall be distinct from any other building.

(2) if, in the opinion of the load authority, it is impracticable to construct a room for the storage or keeping of flammable liquids and substances as a separate building, such room may be constructed as part of a building, subject to the following conditions—

a) such room shall be completely separated from the remainder of such building by walls having a fire-resistance rating of not less than four hours and by a ceiling constructed in the form of two parallel slabs of solid reinforced concrete of at least 100 millimetres in thickness, having a layer of asbestos of not less than 25 millimetres in thickness between such slabs;

b) there shall be no openings whatsoever in such walls and ceiling;

c) every such room shall have at least one external wall;

d) every such room shall be on the ground storey, and shall have a solid floor of incombustible material laid directly on the ground;

e) notwithstanding the provisions of paragraph (a) with regard to the construction of the ceiling, the roof of any such room not having another storey above it shall be of solid reinforced concrete of not less than 125 millimetres in thickness;

f) not more than 900 litres of flammable liquids or more than 1,5 cubic metres, in the case of other flammable substances not being flammable liquids, shall be stored in such room;

g) such room shall have no windows, but shall be ventilated by an approved mechanical ventilation system, if required by the local authority, or by air-brick openings, set in the exterior and interior faces of the external walls, in the ratio of 1 500 square centimetres for every 5 square metres or remaining part thereof of the floor area of such room;

h) fifty per centum of such air-bricks shall be located in such walls immediately above the level of the door-sill or sills, and the remainder located as near to the ceiling-level as is practicable;

i) the backs of all such air-bricks shall be covered with woven wire gauze of copper, brass or bronze, with an aperture size of not more than 0,71 millimetre, securely fixed to the air-bricks;

j) every door to any such room shall comply with the following requirements—

i) the door and the frame thereto shall be constructed of iron or steel of not less than 5 millimetres in thickness, so as to have a fire-resistance rating of not le than two hours;

ii) the door shall overlap the frame by 50 millimetres on all sides, shall be close-fitted into the frame and shall be hung to open outwards;