FSI, FAR and Plan Deviations: The Overbuilding Risk a Bengaluru Buyer Inherits

A buyer looking at a smart four floor apartment block in a Bengaluru suburb in 2026 was told by the builder that the fourth floor was a recent addition, squeezed in because demand was strong. It sounded like good news, more homes, a busy project. It was in fact a warning. The sanctioned plan allowed three floors, and that extra floor was an unapproved deviation that could deny the whole building its occupancy certificate. This guide explains what FSI and FAR mean for a buyer, what a deviation looks like on the ground, and why the risk of one lands squarely on you.

The short answer. FSI, or floor space index, also called FAR, is the ratio that caps how much can be built on a plot, and the sanctioned plan fixes the floors, area, setbacks and height that a builder is allowed. When construction exceeds those limits it is a deviation, and a deviated building can be denied its occupancy certificate, face demolition or sealing, and struggle to get loans and clean utility connections. The buyer inherits that risk, so compare the sanctioned plan against what is actually built before you pay.

What are FSI and FAR, and why should a buyer care?

FSI and FAR both describe the same idea: the ratio of total built up floor area to the size of the plot, which the authorities use to control how much building a piece of land can carry. A higher permitted ratio means more buildable area, and the sanctioned plan for a project translates that ratio into concrete limits on the number of floors, the setbacks around the building, the height and the parking. For a buyer this matters because those limits are what make a building legal, and a builder who exceeds them to squeeze in more saleable flats is not doing you a favour, but creating a liability that attaches to the property. The FSI is not an abstract planning term; it is the rulebook that decides whether the flat you are buying is a legal home or an unauthorised one. It also helps to know that the permitted ratio varies by location, plot size and road width, which is why one project can legitimately rise higher than another nearby. A builder will sometimes point to a taller building down the road as proof that extra floors are fine, but that comparison means nothing unless the two plots carry the same permission. What protects you is not the neighbourhood norm but the specific sanction issued for the specific plot you are buying into.

What does a plan deviation actually look like?

A deviation is any gap between what the sanctioned plan permits and what has actually been built, and the common forms are easy to picture once you know to look. An extra floor above the approved count is the classic case, but deviations also show up as reduced setbacks with the building sitting closer to the boundary than allowed, as more built up area than the FSI permits, as a greater height, or as parking space quietly converted into additional sellable rooms. Some are obvious on a site visit and some only appear when you lay the sanctioned plan next to the finished structure. The problem is common enough in the city that surveys have found a large share of new buildings departing from their approved plans, which is exactly why a buyer cannot assume compliance and has to check.

What happens to a buyer who buys a deviated flat?

The buyer of a deviated property takes on the legal and financial risk, and a building that breaches its plan can be denied the occupancy certificate that makes it lawfully livable. Without that certificate a flat can attract higher property tax as a penalty, its utility connections can remain on a temporary and disconnectable footing, and banks are more reluctant to lend against it. In serious cases the civic body has the power to seal or demolish the offending portion, and where the deviation obstructs setbacks or public safety that power is real rather than theoretical. Crucially, the authority's action is against the building, not the builder's promise to you, so a buyer who paid for a flat in an unauthorised floor can find the recourse is limited and the loss personal. This is why the deviation risk is the buyer's problem to price, not the builder's to wave away. The resale angle sharpens the point further. Even if the authority never acts, the next buyer's lawyer will run the same comparison you should have run, and a known deviation can shrink your pool of future buyers or push down the price you can command. A flat that cannot produce a clean occupancy certificate is harder to sell and harder to mortgage, so the cost of a deviation is not only the risk of enforcement but the drag it puts on the property's value for as long as you hold it.

Can deviations be regularised?

Some minor deviations can be regularised, but the tolerance is limited and you cannot assume a serious breach will be forgiven. Bengaluru's civic body has a process to regularise residential building deviations up to a modest threshold, on the order of 15 percent from the sanctioned plan, on payment of charges. That can bring a small, genuine overshoot back within the law, but it does not cover large deviations such as an entire unapproved floor, and it should never be treated as a routine backstop that makes deviation harmless. Rules and thresholds in this area change, so confirm the current regularisation position with the civic body rather than relying on a builder's assurance that everything can be sorted out later. A deviation you are told will be regularised is not the same as one that has been. It is worth understanding why the threshold is deliberately low. Regularisation exists to accommodate small, good faith construction variances, not to give cover to builders who knowingly add saleable area beyond what the land can legally carry. Reading it as a routine escape hatch is exactly the mistake that leaves buyers exposed, because the large deviations that most inflate a builder's profit are precisely the ones the scheme is designed not to forgive.

How do you check for a deviation before buying?

Ask for the sanctioned plan and compare it, point by point, against what has actually been built or is being built. Request the approved plan and the approval documents from the builder or seller, and check the number of floors, the setbacks, the built up area and the parking against the physical structure and the specific unit you are buying. For an under construction purchase this comparison is your single most useful check, because it is done before the money is committed. Confirm too that the project has, or is on track to receive, its occupancy certificate, since that certificate is the authority's own confirmation that the building matches its plan. If the builder is reluctant to share the sanctioned plan, or the built structure plainly does not match it, treat that as a serious flag rather than a paperwork delay. A simple count on a site visit catches many cases: stand in front of the building and count the floors, then check that number against the sanction. If they do not match, no explanation about market demand or a pending revision should reassure you until the paperwork actually says so.

What should you do if you find a deviation?

Pause, quantify the deviation, and get a professional view before you decide anything. A small, regularisable overshoot is a different proposition from an extra floor or a gross setback breach, and only by measuring the gap against the sanctioned plan can you tell which you are facing. Have an architect or a lawyer who knows the local rules assess whether the deviation is within the regularisable range and what it would take to fix, and factor any regularisation cost or risk into your offer, or walk away. Do not accept a verbal promise that the deviation will be regularised after you buy, because once you own the flat that promise is worth little and the liability is yours. The safest deals are the ones where the sanctioned plan and the building already agree.

Your FSI and deviation checklist for Bengaluru

Work through these seven steps before you commit to a flat.

1. Ask the builder or seller for the sanctioned building plan and the approval documents.
2. Compare the approved number of floors against the floors actually built.
3. Check the setbacks, height and built up area against the sanctioned limits.
4. Confirm the parking provision has not been converted into sellable space.
5. Verify the project has or is on track to receive its occupancy certificate.
6. If you find a deviation, have an architect or lawyer measure it against the plan.
7. Factor any regularisation cost or risk into your offer, or walk away from a serious breach.

The takeaway for a Bengaluru buyer

An extra floor or a shaved setback can look like a bonus and be a burden, because the FSI limits a builder bends are the same limits that decide whether your flat is legal. The authority enforces against the building, so the day the deviation catches up with the project, it catches up with the owners, and by then the builder may be long gone. Protect yourself the simple way: get the sanctioned plan, lay it next to the structure, and buy only where the two agree or where any gap is small and genuinely regularisable. It is a comparison anyone can make with the right document in hand, and it is the difference between a legal home and a liability dressed up as a good deal.

Last updated 2026-09-10. PropNewz Team.