(1) Horizontal damp-proof courses.-Every horizontal damp-proof course shall be constructed to the full width of the wall resting upon it, and shall also extend full width of any wall-plate which may rest upon the damp-proof course.

(2) For the purpose of this section, a cavity-wall shall be regarded as two separate walls.

(3) Where composed of sheeting, horizontal damp-proof courses shall be lapped not less than 100 millimetres at the joints.

(4)Vertical damp-proof courses.-If in any solid wall the horizontal damp-proof course is not situated at least 150 millimetres above the finished ground-level, a vertical damp-proof course (or water course if required) shall be taken up the outer face of the wall from the horizontal damp-proof course to at least 150 millimetres above the external-finished ground-level, and there finished off in such a manner as to prevent the entry of moisture; and shall be protected by brick-work of not less than 65 millimetres in thickness, or by such other method as may be approved by the local authority.