(1) Subject to the provision of subsection (9), every room in a building which—

(a) contains an air-conditioning plant or a boiler, furnace-incinerator or similar appliance in which heat is generated; and

b) serves the whole or greater part of an occupancy-unit;

shall be separated from the remainder of the building by walls, floor and ceiling of non-combustible construction having a fire resistance rating of not less than one and a half hours:

Provided that, if such room contains a steam-boiler which operates at a pressure of more than 70 kilopascals with a rating of more than 7,5 kilowatts, such fire-resistance rating shall be not less than two hours.

(2) There shall be no openings in any such separating-walls, floors or ceilings, except through a lobby separating such room from the remainder of the building.

(3) Such lobby shall have walls, floor and ceiling with a fire-resistance rating equal to that of the walls, floor and ceiling of the room it serves.

(4) The doorways to such lobby and such room shall be protected by self-closing fire-doors having a fire-resistance rating of not less than one hour, and the doorway between such lobby and the remainder of such building shall be further protected by a fire-shutter having a fire-resistance rating of not less than one hour.

(5) Where the fuel used in the appliances mentioned in subsection (1) is a liquid fuel, every doorway in such room shall be provided with a raised sill high enough to form a well, which will contain, without leakage, the maximum amount of fuel kept in such room, plus 25 per centum of such amount.

(6) A heat-sensitive device shall be fitted close to the appliance and arranged to shut a fire-valve, installed in the fuel line(s) near the point of entry to the room, when the temperature in the vicinity of the appliance is within the range 68 degrees Celsius to 74 degrees Celsius. Where ambient temperatures may exceed 49 degrees Celsius the device may be set to operate at a maximum temperature of 93 degrees Celsius. The five-valve(s) and associated parts shall comply with the requirements of B.S. 799.

(7) Every such room shall have not less than two alternative means of egress, as widely separated as possible, to an exit-way or street or public place.

(8) Every such room and lobby shall be provided with permanent means of ventilation, adequate to remove such products of combustion as may be emitted into such room, and so designed that the temperature of any combustible material adjacent to any appliance mentioned in subsection (1) will not exceed 80 degrees Celsius.

(9) The provisions of this section shall not apply to domestic cooking-stoves, fire-places, heaters or other such domestic appliances, or to electrode boilers.

(10) The installation of oil-fired equipment shall comply with B.S. C.P. 3002.

(11) The installation of domestic butane-gas or propane-gas burning-appliances shall comply with B.S. C.P. 339 or S,A.B.S. 087.