(1)
Masonry exterior walls, other than cavity walls, in 1- storey buildings and the top storeys of 2- and 3- storey buildings shall be not less than 140 mm thick, provided the walls are not more than 2.8 m high at the eaves and 4.6 m high at the peaks of gable ends.
(2)
The exterior walls of the bottom storeys of 2- storey buildings, and exterior walls of the bottom 2 storeys of 3- storey buildings shall be not less than 190 mm thick.
(3)
In exterior walls composed of more than one wythe, each wythe shall be not less than 90 mm thick.