Section 120 in West Bengal Municipal (Building) Rules, 2007
120. Drainage of roofs.
The roof of a building shall be so constructed or framed as to permit effectual drainage of the rain water therefrom by means of a sufficiency of rain-water pipes of adequate size so arranged, joined and fixed as to ensure that the rainwater is carried away from the building without causing dampness in any part of the walls or foundation of the building or those of an adjacent building.
