(1) Every occupancy-unit shall—

a) Be classified into one of the classes and grades of construction specified in this section; and

b) Be erected in accordance with the section of these by-laws in which the structural requirements appropriate to the relevant grade are specified.

(2) Grade A construction. – Every occupancy-unit which falls into one or other of the following five classes shall be erected in accordance with the requirements specified in this Chapter for grade A construction—

Class 1. —Institutional occupancy-units in which persons are involuntarily detained or in which persons, who by reason of infirmity are unable to help themselves, are housed, of one or more storeys height;

Class 2. —Theatres, cinemas and opera-houses of one or more storeys in height, and occupancy-units containing a place of assembly above the ground storey;

Class 3.—Institutional and public and assembly occupancy-units, other than those in classes 1 and 2, of three or more storeys or over 10,5 metres in height, places of worship over 13,5 metres in height, and schools and colleges, whether residential or otherwise, exceeding two storeys in height;

Class 4.—Business, commercial or industrial occupancy and residential occupancy-units of five or more storeys or over 15 metres in height;

Class 5.—Storage occupancy-units of two or more storeys or over 10,5 metres in height, but excluding units for the storage of flammable liquids and substances, as provided for in section 44.

(3) Grade B construction. —Every occupancy-unit which falls into one or other of the following three classes shall be erected in accordance with the requirements specified in this Chapter for grade B construction—

Class 6. —Institutional and public and assembly occupancy-units, other than those in classes 1 and 2, not exceeding two storeys or 10,5 metres in height, and places of worship 13,5 metres

Class 7. —Business, commercial or industrial occupancy-units and residential occupancy-units not exceeding four storeys or 15 metres in height, but exceeding, in the case of dwelling-houses, two storeys in height, and, in the case of all other residential occupancy-units and all business, commercial or industrial occupancies, exceeding one storey in height;

Class 8. –Storage occupancy-units not exceeding one storey or 10,5 metres in height, but exceeding 6 metres in height, but excluding units for the storage of flammable liquids and substances, as provided for in section 44.

(4) Grade C construction. – Every occupancy-unit which falls into one or other of the following two classes shall be erected in accordance with the requirements specified in this Chapter for grade C construction–

Class 9. –Business, commercial or industrial occupancy-units not exceeding one storey in height;

Class 10. –Storage occupancy-units not exceeding one storey or 6 metres in height or 7 000 cubic metres in capacity, but excluding units for the storage of flammable liquids and substances, as provided for in section 44.

(5) Grade D construction. – Every occupancy-unit which falls into the following class shall be erected in accordance with the requirements specified in this chapter for grade D construction—

Class 11. – Dwelling-houses not exceeding two storeys in height.

(6) Nothing contained in this section shall be constructed as prohibiting the erection of a particular occupancy-unit which complies with the requirements of a higher grade of construction than that under which such occupancy-unit falls in terms of this section, and, if a unit is so constructed, the cubic capacity of such occupancy-unit may be increased to that applicable to such higher grade of construction, as set out in section 6.

(7) Where there is any doubt or dispute as to the grade of construction or the fire-load category into which an occupancy-unit falls, the decision of the local authority shall be final.