The BMC dangerous buildings list sorts old structures into C1, C2A, C2B and C3. What each category means, the 2026 figures, how to challenge an audit, and how to weigh repair against redevelopment.
Every year before the monsoon, the BMC dangerous buildings list is published and the same questions follow. What does C1 actually mean? If our building is C2B, do we have to move out? Can a structural audit be challenged? And should a society in an old building repair it or push for redevelopment? This guide answers those questions in plain language, with the 2026 figures that have been published, and with the practical view of a contractor who carries out repair and finishing work on Mumbai's older buildings.
It is written by Chamunda Constructions, a civil and finishing contractor in Kandivali West, founded in 2004 by Bhadresh Chavda. We are not structural engineers and we do not issue structural audits or categories. What follows is general information and not legal or engineering advice. If your building has received a notice, or you are concerned about its safety, speak to a structural engineer registered with the BMC and, where necessary, a lawyer, and follow the directions of the authorities.
What the BMC dangerous buildings list is
The Brihanmumbai Municipal Corporation surveys buildings across the city every year ahead of the monsoon and publishes a list of those it has declared dangerous and dilapidated. The best-known part of that list is the C1 category, the buildings judged unsafe for occupation. The list covers private buildings and, separately, municipal buildings, and it is published ward by ward on the BMC's website, mcgm.gov.in.
Separately, MHADA's Mumbai Building Repairs and Reconstruction Board carries out its own pre-monsoon survey of cessed buildings, the old, mostly pre-1969 tenanted buildings in the island city for which the state collects a repair cess. The two lists are different and are published by different authorities, which causes some confusion each year.
The four categories: C1, C2A, C2B and C3
Buildings that are structurally assessed are placed in one of four categories. The descriptions below are drawn from summaries of the BMC's dilapidated building policy by the planning consultancy Kutir Group and from press coverage in the Asian Age. Your building's structural audit and any BMC notice are the documents that actually govern what you must do.
- C1: dangerous, unsafe and unfit for habitation. The building needs to be vacated and demolished.
- C2A: partially dangerous. Major structural repairs are needed, with the dangerous part of the building vacated while the work is done. Some press coverage describes C2A as requiring the dangerous parts to be removed.
- C2B: major structural repairs are needed, but the building does not have to be vacated for them.
- C3: minor repairs are needed.
A useful way to remember it: C1 means leave, C2A means leave the dangerous part and repair, C2B means repair while you stay, and C3 means maintain. Only C1 requires the whole building to be vacated. A category is not permanent either: a C2B building left unrepaired can deteriorate into C2A or C1, and a C3 building that is maintained properly can stay in C3 for many years.
The 2026 figures on dangerous buildings
According to BMC data reported by the Free Press Journal on 27 May 2026, as of 30 April 2026 Mumbai had 141 existing private buildings in the C1 category, of which 79 were still occupied. The report said the largest concentration of dangerous private structures was in the western suburbs, naming wards including H-East, H-West, K-East, K-West, P-North, P-South, R-South and R-Central, which together cover areas from Bandra and Santacruz through Andheri, Goregaon and Malad to Kandivali and Borivali.
For MHADA's cessed buildings, the Free Press Journal reported on 30 May 2026 that the Mumbai Building Repairs and Reconstruction Board's pre-monsoon survey had identified 82 highly dangerous cessed buildings in the island city, housing 2,736 occupants: 2,256 residential and 480 non-residential. Forty-three of those buildings had also been on the previous year's list. MHADA published the survey on its own website in early June.
For context, the Free Press Journal reported in May 2025 that the BMC's pre-monsoon survey that year had identified 134 dilapidated buildings, down from 188 in 2024. The counts are not always measured on exactly the same basis from year to year, so the trend is a guide rather than a precise series.
Why so many dangerous buildings are still occupied
The fact that more than half of the city's C1 private buildings were still occupied in April 2026 surprises people who have not lived in one. The Free Press Journal's reporting noted that the BMC cannot forcibly evict occupants and listed the reasons residents give for staying: no alternative accommodation, uncertainty about when or whether redevelopment will happen, court stays on evacuation, and doubts about whether a developer will actually pay rent.
Those concerns are real, and in older tenanted buildings they are made sharper by the fear of losing tenancy rights. But the category exists because an engineer has concluded the building is unsafe. A family that stays in a C1 building through the monsoon is carrying a risk that no amount of repair on the inside of their own flat can reduce.
How a building gets its category: the structural audit
Under Section 353B of the Mumbai Municipal Corporation Act, 1888, every owner and occupier of a building that has been in use for more than 30 years must have it examined by a structural engineer registered with the corporation, and submit a structural stability certificate. The 30 years run from the earliest of the completion certificate, permission to occupy, or physical occupation of at least half the built-up area. The certificate is due within a year of the building crossing 30 years and every ten years after that, or sooner if the commissioner requires it.
In practice, a structural audit involves a visual survey of the building and non-destructive and sometimes destructive tests on concrete and reinforcement, such as rebound hammer and ultrasonic pulse velocity tests, carbonation tests and core samples. The engineer then recommends a category and the repairs needed. If repairs are recommended, the owners and occupiers are required to carry them out.
For a co-operative housing society, the obligation sits with the society's managing committee. A committee that has not commissioned an audit on a building over 30 years old is not only out of compliance; it is making decisions about repair and redevelopment without the one document that tells it how much time it has.
Challenging a structural audit or C1 classification
A structural audit can be wrong, and a C1 classification has serious consequences, so there is a route to challenge it. As described by the housing society lawyer Sharmila Ranade in the Free Press Journal in November 2023, occupants who disagree with an audit can obtain an independent report, for example from an institution such as IIT Bombay or VJTI, and place it before the BMC's Technical Advisory Committee within a stated period. The TAC hears the structural consultants and gives a decision that is binding on the parties.
- Read the audit report in full, not just the category.
- Take independent advice quickly; the time allowed for submitting a rival report is short.
- Commission a second opinion from a qualified and credible institution or engineer.
- Submit it to the TAC through the proper channel, and keep proof of submission.
- Keep residents informed in writing, and keep minutes of every society decision.
The Bombay High Court has in recent years examined how the BMC's guidelines for declaring buildings C1 operate, according to Free Press Journal coverage. Procedures can change as a result of such cases, which is one more reason to take current legal advice rather than relying on a general article.
What happens after a C1 notice
Once a private building is declared C1, the BMC issues notices under Section 354 of the Mumbai Municipal Corporation Act requiring occupants to vacate and the building to be pulled down. Press coverage of past years' lists has recorded the BMC disconnecting water and electricity to C1 buildings, demolishing vacated structures, and many cases being held up in court. The exact steps and timing vary, and residents who receive a notice should seek legal advice immediately.
For residents, the practical priorities are safety first, then documentation. Before leaving, record your tenancy or ownership documents, photographs of your flat, and all correspondence with the society, landlord or developer. Those records are what protect your right to return to a redeveloped building.
It also helps to stay organised as a group. Residents of a vacated building scatter across the city, and a society that stops meeting often loses months when decisions are needed later. Agree before leaving how the committee will communicate, where documents will be kept, and how members who move away will take part in meetings. The 2026 co-operative society rules allow members to attend and vote at general body meetings by video conference, provided the proceedings are recorded and participants can be identified, which makes that easier than it used to be.
What residents should do, category by category
C1. Follow the authorities' directions and move to safety. Then work with the society or landlord on redevelopment, taking legal advice on your rights. A C1 building is not a repair candidate; the question is how it is rebuilt and on what terms.
C2A. The dangerous part needs to be vacated and major structural repairs carried out under a structural engineer's design and supervision. The society should appoint the engineer quickly, get a repair scheme and estimate, and decide whether repair is sensible given the building's age, or whether redevelopment should be pursued in parallel.
C2B. Major structural repairs are needed but occupants can stay. This is the category where a society has the most genuine choice. A well-designed and properly executed repair can extend a building's life by years; a cosmetic repair that plasters over corroding reinforcement will not.
C3. Minor repairs. Treat this as maintenance: waterproofing, crack repair, plaster, drainage and similar work, done properly and on time so the building does not slide into a worse category. Our article on the post-monsoon repair window explains why the weeks after the rains are the best time to do it.
Repair vs redevelopment: how to decide
The choice between repair and redevelopment is rarely purely technical. A society weighing it is usually balancing five things.
- The structural audit: the category and the engineer's view of the building's remaining life after repair.
- The repair cost and how it compares to the value the repair buys in extra years.
- The redevelopment potential of the plot and whether a credible offer exists or is likely.
- The members: their ages, finances, attachment to the building and appetite for years of disruption.
- Time: a building in C2A or C2B cannot wait indefinitely for a redevelopment decision.
One common pattern works well: carry out the repairs the audit requires to keep the building safe, and pursue redevelopment calmly alongside. That avoids the worst outcome, a society that neither repairs nor redevelops while the building deteriorates, and it stops redevelopment negotiations being conducted under the pressure of a building that is getting worse every monsoon.
Redevelopment options have widened. Societies can choose builder-led redevelopment, self-redevelopment or, in some areas, participation in a cluster scheme. Our guides to self-redevelopment and to cluster redevelopment explain the trade-offs, and our article on the 2026 redevelopment numbers shows how fast the market has moved.
What good structural repair work looks like
For buildings in C2A, C2B and C3, the quality of the repair decides whether the building's category improves or worsens over the next ten years. The structural repair itself, such as treatment of corroded reinforcement, jacketing of columns or replacement of damaged slabs, must be designed by the structural engineer and executed under their supervision. The civil and finishing work around it matters just as much, because water is the usual cause of the corrosion in the first place.
- Find and stop the water first: terrace waterproofing, external cracks, leaking downtakes and bathroom seepage.
- Repair concrete only after corroded reinforcement has been exposed, cleaned and treated to the engineer's specification.
- Use repair mortars and systems specified by the engineer, not general-purpose plaster.
- Re-waterproof bathrooms and terraces properly, with a ponding test before covering.
- Replaster and repaint external walls with attention to drip details and sills, so water is thrown clear of the wall.
- Keep records and photographs of every stage, including what was found when areas were opened up.
Our articles on terrace waterproofing for Mumbai buildings and on monsoon seepage cover the waterproofing side of this in more detail.
Why the western suburbs figure so heavily
The western suburbs dominate the private C1 list for the same reason they dominate redevelopment. Large parts of Bandra, Andheri, Goregaon, Malad, Kandivali and Borivali were built up in the 1960s, 1970s and 1980s, and a large share of those buildings is now 40 to 60 years old. The JLL and NAREDCO Maharashtra report released on 3 September 2026 puts the Western Suburbs' share of the city's ageing stock at 22.4 per cent.
Chamunda Constructions is based in Kandivali West, in R-South ward, one of the wards named in the 2026 coverage. Many of the buildings we are asked to look at in Kandivali, Malad and Borivali are exactly this vintage, and the conversation almost always starts with water: seepage that has been patched for years, until the structural audit reveals what it has been doing to the concrete behind the plaster.
Warning signs residents should report
Residents often notice problems long before an audit does. None of the signs below on its own means a building is dangerous, but each one is worth reporting to the society's committee in writing, and several together are a reason to ask for an engineer's inspection rather than waiting for the next scheduled audit.
- Cracks in beams or columns, especially diagonal cracks or cracks that are widening over time.
- Rust stains bleeding through plaster, or concrete that has spalled to expose reinforcement.
- Sagging slabs, balconies or chajjas, or cracks along the junction between a balcony and the main structure.
- Doors and windows that have started to jam where they used to close freely.
- Persistent seepage through ceilings, particularly below terraces and bathrooms.
- Plaster falling from ceilings or external walls.
- Unauthorised alterations in other flats or shops, such as removed walls or cut columns.
In an emergency, such as visible movement, loud cracking sounds or falling concrete, leave the area and call the BMC's disaster control and the emergency services. A general article is no substitute for that.
What a committee should do this autumn
This article is being published at the end of September, as the monsoon withdraws. For a society in an older building, the next three months are the most useful of the year. The monsoon has just shown exactly where water gets in, the walls are drying, and there is time to plan and complete repairs before the next rains.
- Walk the building with the committee and mark every damp patch, crack and leak, with the date.
- Check whether the structural audit is due or overdue, and commission it if so.
- If an audit already exists, read its recommendations again and list what has not been done.
- Get a repair scheme priced, with the water-related work first.
- Decide, at a properly convened general body meeting, what will be done and how it will be paid for.
- Book the work early enough that it finishes well before the next monsoon.
The 2026 amendments to the Maharashtra co-operative society rules also set minimum annual contributions to a society's sinking fund and repair and maintenance fund, according to summaries by several law firms. A committee planning major repairs should check what those funds hold and how the new rules affect spending from them; our article on the 2026 housing society rules covers the changes.
Cessed buildings and tenanted buildings
Cessed buildings in the island city follow a different framework from co-operative housing societies in the suburbs. MHADA's Mumbai Building Repairs and Reconstruction Board is responsible for repairs to cessed buildings and runs its own survey and transit accommodation, and tenants in those buildings have protections under the tenancy and MHADA laws. The JLL and NAREDCO Maharashtra report puts the number of cessed buildings needing replacement at around 13,500.
If you live in a cessed or tenanted building, the rights and processes that apply to you are specific enough that you should take advice from someone who deals with MHADA and tenancy matters regularly. The categories in this article still describe how dangerous a building is, but who acts, who pays and where residents go can be quite different.
A maintenance routine that keeps buildings out of the list
Most buildings do not become dangerous suddenly. They get there through years of small leaks left unrepaired. A simple annual routine does more to keep a building out of the C categories than any single large repair.
- Inspect the terrace, downtakes and external walls every year after the monsoon, and repair what you find before the next one.
- Commission the structural audit on time, and act on its recommendations.
- Do not allow members' renovations to break waterproofing or cut into structural members; our article on society NOC for flat renovation covers how to control this.
- Keep a repair log with dates, contractors and photographs.
- Budget for repairs through the society's repair and maintenance fund rather than waiting for emergencies.
How Chamunda Constructions can help
Chamunda Constructions carries out civil repair, waterproofing and finishing work for housing societies, working to the structural engineer's design where structural repair is involved. That covers terraces, bathrooms, external plaster and painting, lobbies, staircases and common areas, as well as complete finishing when a society redevelops. We do not issue structural audits or categories; that is the engineer's role, and we work alongside them.
If your society has an audit report and is deciding what to do, Bhadresh Chavda can visit, walk the building with the committee, and explain what the civil and finishing side of the repair would involve and in what order. That visit costs nothing and commits the society to nothing.