(1) In any occupancy-unit in which there are no windows in external walls, the provisions of this section shall be observed except by written permission of the local authority under special circumstances.

(2) A mechanical system of ventilation shall be provided, complying with the requirements of Chapter 10.

(3) Where any ventilation-duct passes through a wall forming an occupancy-separation structure, such duct shall be fitted, at the point where it passes through such wall, with a damper or other shut-off device actuated by an automatic device, which will close the duct in the event of a rise in temperature above that at which device is set.

(4) Every habitable room shall have at least one external wall, and in such wall there shall be provided at least one opening, closed by a panel which can be readily and rapidly opened from the inside.

(5) Such panels shall be in addition to the access openings required by subsection (6) of section 20, and shall have an equal minimum size and maximum height above floor-level to that required for such access openings, and every such panel shall be clearly marked, on its inner face, ÖPENABLE”, in block letters of not less than 150 millimetres in height.

(6) Where the external wall or walls of any habitable room have a length exceeding 12 metres, there shall be one such panel for each 12 metres, or remaining part thereof, of such length, and the distance between such panels shall not exceed 12 metres.

(7) All interior wall-linings shall be of non-combustible material or other material as may be approved by the local authority in certain circumstances.

(8) Every habitable room shall have at least one doorway giving access to an exit-way, and every such doorway shall be served by not less than two separate exit-ways.

(9) Every room shall be regarded as having a fire-load of not less than moderate fire-load for the purposes of subsections (13) and (14) of section 24.

(10) All connexions for fire-hoses, hose-reels and all similar equipment shall be sited in readily accessible positions.

(11) There shall be provided an automatic fire-extinguishing system.