(1) Walls less than 215 millimetres in thickness shall not be corbelled, nor, in a cavity-wall, shall a leaf less than 215 millimetres in thickness corbelled :

Provided that nothing in this section shall be construed as preventing walls overhanging their supports in accordance with the provision of section 22.

(2) In a single-storey dwelling-house or dwelling-units, a 215 millimetres solid foundation-wall may be corbelled to support a cavity-wall of a maximum over-all thickness of 300 millimetres:

Provided that –

i) the total projection does not exceed 50 millimetres on either side;

ii) the foundation-wall is corbelled out to provide a solid bearing of the full total thickness of the cavity-wall in accordance with section 22;

(3) Except as may be permitted in the requirements for constructions specified in Chapter 22, and as set out in this section, no corbel shall be used to support wall.

(4) No corbel from a masonry less than 330 millimetres in thickness shall be used to support a floor or a roof, except that, in dwellings-houses or dwelling-units only, wall not less than 215 millimetres in thickness may be corbelled to support a timber floor.

(5) Walls built of hollow building-units shall not be corbelled.