Section 168(6) in West Bengal Municipal (Building) Rules, 2007
(6)The party-walls of a masonry or framed building or the end wall of a ferro-concrete building must be built of stone or brick bedded in lime or cement mortar for their full height and if the Board of Councillors so direct, must be carried up to a thickness of not less than 0.25 metre above the roof, flat or gutter to such a height as will give a distance of at least 0.5 metre measured at right angles to the slope of the roof above the highest part of the roof, flat or gutter.
