Section 117(1) in Kolkata Municipal Corporation Building Rules, 2009
(1)The roof of a building-shall be so constructed or framed as to permit effectual drainage of the rain-water there from by means of sufficient rain water pipes of adequate size, wherever required, so arranged, joined and fixed as to ensure that the rain water is carried away from the building without causing dampness in any part of the walls or foundations of the building or those of an adjacent building.
