Building, renovating or doing up a home in Mumbai

• Renovating a flat you own: read "Renovating a flat in Mumbai" for what your society and the city need from you, then the costs below.
• Doing up a new flat: check the building's occupancy certificate (OC) before you take possession or start interiors.
• Building a house: your plans need approval before any work on site, filed by a registered architect.

Under section 342 of the MMC Act, "tenantable repairs" need no proposal to BMC: plastering, painting, pointing, changing floor tiles, WC, bath, tap, sanitary and electrical repairs, and replacing a roof with the same material. In October 2025 the Bombay High Court confirmed that such repairs need no BMC permission.

Anything that changes the structure does need a BMC proposal: altering beams, columns or load-bearing walls, changing room dimensions, lowering floors, or adding a mezzanine or loft. Under the model bye-laws your society will also ask for the local authority's permission for structural changes and supervision by a structural engineer.

• Get your society's written NOC before work starts. Working hours, deposits, lift use and debris rules are set by each society, so ask for them in writing.
• Don't enclose balconies, flower beds or terraces into rooms. BMC treats them as violations of the sanctioned plan; residents have been booked under the MRTP Act for it.
• Debris: BMC's Debris on Call service collects household debris free up to 500 kg (book through the MyBMC app or BMC's helpline). Illegal dumping is fined ₹20,000 under the 2025 bye-laws.
• In July 2026 the Bombay High Court asked the state to frame rules on which flat alterations need permission, due by January 2027. Check whether they have been issued before you plan wall changes.

Check that the building has its occupancy certificate (OC) before you take possession or start interiors; BMC issues OCs through its AutoDCR system, so the builder should be able to give you the OC number. In December 2025 MahaRERA held that "fit-out possession" without an OC is not valid possession, and buyers who refused it were not in default.

In BMC limits, building proposals are filed online on AutoDCR by a registered architect or licensed surveyor; owners can't file directly. Approval runs in stages: the IOD, then the commencement certificate (CC) for the plinth and the rest of the building, then the occupancy or building completion certificate. Some areas inside the city, such as Bandra-Kurla Complex and Wadala, are planned by MMRDA instead.

Most Mumbai "new homes" are society redevelopments. A government resolution of 30 September 2026 replaced the 2019 rules: appointing a developer now needs written approval from at least 51% of all members.

• Monsoon: most of the year's 2,200–2,500 mm of rain falls between June and September. Finish waterproofing and exterior work before June.
• Old buildings: buildings over 30 years old need a structural audit under section 353B of the MMC Act. BMC publishes a list of dangerous (C1) buildings before each monsoon; 174 were listed in April 2026.
• Seismic zone III, under the 2016 code (a 2025 revision was withdrawn in March 2026).
• Water: BMC cut supply by 10% from May 2026, so plan wet work (curing, tiling) with your society's water in mind.

We found no reliable published per-sq-ft figure for interiors in Mumbai. Use the renovation and interiors calculators at Mumbai rates, and get 2–3 quotes on the same drawings.