Buildings.
9 feet in height and parapets not exceeding 3 feet in height shall not be included in measuring the height of such wall.
(3) Any external wall of a building exceeding 35 feet in length, clear of cross walls, shall be secured at the level of each upper floor, and at the ceiling or roof, with wrought-iron tie-rods not less than one and a quarter inches in diameter, spaced not more than 12 feet apart and extending through such external wall and the nearest parallel wall of such building. The tie-rods shall have screwed ends with nuts bearing upon wrought-iron washer plates not less than 18 inches square by half an inch in thickness, or cast-iron washer plates to be approved by the Building Authority, and the brickwork of each wall for its full thickness and for an area of two feet square round the end of each tie-rod shall be built in cement-mortar : Provided that the Building Authority may modify or dispense with the requirements of this subsection whenever he may consider such requirements unnecessary.
[19]
9. The thickness of every cross wall shall be at least two thirds of the thickness prescribed by section 17 in that behalf for an external wall or party wall of the same height and length and belonging to the same class of building as that to which such cross wall belongs, unless, in any particular case, the Building Authority shall specially authorize a less thickness. But if such cross wall supports a superincumbent external wall the whole of such cross wall shall be of the thickness prescribed for an external wall or party wall of the same height and length and belonging to the same class of building as that to which such cross wall belongs.
[20]
[CAP. 123
Thickness of cross walls to be that of main walls, two-thirds of partition walls.
10. Partition walls not exceeding 12 feet in height and the external walls of latrines, bathrooms and stair hoods not exceeding 8 feet in height may be constructed of brick in cement-mortar of a thickness of 4 inches, or of reinforced concrete or of such other material and of such thickness as the Building Authority may permit.
[21]
11. (1) Every wall of every new building shall have a damp-proof course composed of materials impervious to moisture to be approved by the Building Authority extend-
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