(1) Except where the local authority considers it to be unnecessary or inadvisable, all walls shall be plumb, and shall be adequately braced during construction.

(2) Except for concrete and soil-cement building-units, which shall be kept in a dry condition, all masonry building-units shall be thoroughly wetted with water immediately before being laid.

(3) Except in rubble stone walls, and where permitted by the local authority, all masonry building -units shall be laid in mortar joints shall be filled, and shall be not less than 5 millimetres and not more than 20 millimetres in thickness.

(4) No portion of a masonry wall shall be built up during building operations more than 1 metre above the top of any other portion of such wall.