Building laws are complex in India and it is important to know that any major home improvement or construction of a new building requires the permission/sanction of the relevant local authorities. The legal regime governing unauthorized constructions is governed by state and local laws rather than one pan India law.
Athena Legal's Principal associate, Rohan Ahuja, and Associate Rhea Dubey authored an article in moneycontrol.com where they discuss the Unauthorised constructions in Delhi and Mumbai and discussing the rules, penalties, and what not to do.