Section 30(19) in Punjab Urban Planning and Development Building Rules, 2018
(19)Roofs. - (i) The roof of a building shall be so designed and constructed as to effectively drain water by means of sufficient rain water pipes of size as specified in the National Building Code of India, 2016, as amended from time to time wherever required, so arranged, jointed and fixed as to ensure that the rain water is carried away from the building without causing dampness in any part of the walls, roof or foundations of the building or an adjacent building.(ii)The rain water pipes shall be connected to a drain or a sewer which connects the rain-water pipe to the road gutter or in any other approved manner.(iii)The rain-water pipes shall be affixed to the outside of the external walls of the building or in recesses or chases cut or formed in such external walls or in such other manner as may be approved by the Authority.(iv)It is desirable to conserve rain water using suitable rain water harvesting techniques including by roof water collection. For this purpose, the provisions made in Part 9- Plumbing Services (including Solid Waste Management), Section 2 Drainage and Sanitation of the National Building Code of India, 2016 shall be followed.
