Section 13(3A)(a) in The Bombay Rents, Hotel and Lodging House Rates Control Act, 1947
(a)that the new building to be erected by him shall subject to the provisions of any rules, by laws or regulations made by a local authority], contain not less than 3 two times the number of residential tenements, and not less than two times the floor area, contained in the premises sought to be demolished.