Section 81(9) in Kolkata Municipal Corporation Building Rules, 2009
(9)The plot having an existing heritage building or a water body, the internal road width between such buildings may be allowed to be 3.5 m. irrespective of the length of such internal road on the recommendation of the Municipal Building Committee without disturbing such heritage building or water body provided that the existing heritage building or water body or both taken together occupy at least 25% of the land area.
