Buyer guide · Mumbai and Thane
FSI and TDR meaning: why a Mumbai or Thane builder can add floors, and how to check
FSI, premium FSI, TDR and fungible FSI in plain words, two checks on MahaRERA that show whether a building can still grow and whether the CC covers your floor, and your say if plans change.
By Ashwin · Updated · Not legal advice
FSI, premium FSI, TDR and fungible
| Part | What it is |
|---|---|
| Basic (zonal) FSI | What the plot gets as of right |
| Premium FSI | Extra FSI the builder buys from the municipal corporation |
| TDR | FSI bought from another plot’s owner, on a development right certificate |
| Fungible FSI | Extra area on payment, for balconies, ducts and the like; in Mumbai, up to 35% for homes |
How much of each a plot may use depends on the zone and the width of the road in front. In Mumbai’s suburbs, a plot on a 12–18 m road gets 1.0 basic, up to 0.5 premium and up to 0.7 TDR: 2.2 in all, before fungible FSI.
Mumbai: DCPR 2034, Table 12. Thane follows the state’s Unified DCPR (2020), with its own figures. Rules change often; the sanctioned plan is what counts for a building.
1Check if the building can grow
If a project’s plans use less than its permissible area, the builder can add floors or towers later by loading premium FSI or TDR. That changes density, lifts and parking per flat, and how long construction goes on.
- Time
- 5 min
- Cost
- Free
- Where
- MahaRERA
How to check
- Open the project’s page on MahaRERA (our search guide shows how).
- Under Land Area & Address Details, compare Permissible Built-up Area with Sanctioned Built-up Area of the Project applied for Registration.
- If the sanctioned figure is well below the permissible one, ask the builder what else they plan to build, and where.
- Read the draft agreement for clauses that let the builder use “future” or “balance” FSI or TDR on the plot.
58%
of active projects have room to build more
68 of 118 we read on MahaRERA
Watch out for
- A layout plan with “future development” marked over the garden or open space shown in the brochure.
- Agreement clauses where you consent in advance to any future plan change.
2Check the CC covers your floor
The commencement certificate (CC) is often issued in stages: to the plinth first, then more floors as FSI and TDR are paid for. A floor above the CC can’t legally be built yet.
- Time
- 5 min
- Cost
- Free
- Where
- MahaRERA
How to check
- On the MahaRERA page, find Building Details. Each row shows the sanctioned floors and CC Issued up-to (No. of Floors).
- If your flat is above the CC floor, ask when the next CC is expected and what it depends on.
- Open the CC itself in the page’s documents and check its date and the floors it names.
51%
of buildings have a CC for fewer floors than planned
47 of 92 active buildings we read; 6 had none yet
45
had a CC for every planned floor
a “full CC”
A part CC isn’t wrong in itself; it is common. What matters is whether the floors you’re buying are covered, and when the rest will be. More in our OC and CC guide.
3Your say if plans change
RERA limits what a builder can change after you sign. Your own flat can’t be altered without your consent, and the building’s plans and common areas need two-thirds of buyers.
- Law
- RERA Act, section 14
- Changes to your flat’s plan or specifications: your consent.
- Other changes to the sanctioned plans, layout, buildings or common areas: prior written consent of at least two-thirds of the buyers, not counting the builder.
- Minor changes recommended by the architect are allowed, with notice to buyers.
Watch out for
- A consent form handed round at possession or with the agreement, worded broadly.
- Plans on MahaRERA revised after you booked: compare the dates of the uploaded plans.
What it doesn’t tell you: Courts have read section 14 strictly, including against blanket consent clauses, but outcomes depend on the facts. For a dispute, see our MahaRERA complaint guide or a lawyer.
Quick answers
What is FSI in real estate?
Floor space index: the total built-up area a builder may construct divided by the plot area. An FSI of 2 on a 1,000 m² plot allows 2,000 m² of built-up area.
What is TDR?
Transferable development rights: FSI generated on one plot, for example when land is given up for a road or a slum scheme, issued on a certificate and sold for use on another plot. Builders use it to add floors.
What is fungible FSI?
Extra built-up area a builder can buy, meant for balconies, ducts and similar spaces. In Mumbai it is up to 35% for homes under DCPR 2034.
What does “CC issued up to (no. of floors)” mean on MahaRERA?
The number of floors the commencement certificate currently covers. It is often lower than the sanctioned floors because the CC is issued in stages; floors above it can’t legally be built until the next CC.
Can a builder add floors after I book?
Only within the approvals, and changes to the building’s sanctioned plans or common areas need the prior written consent of two-thirds of buyers under section 14 of the RERA Act. Minor changes recommended by the architect are allowed.
The checklist
| Check | Where | Time |
|---|---|---|
| Permissible vs sanctioned built-up area | MahaRERA page | 2 min |
| CC floors vs your floor | Building Details on MahaRERA | 2 min |
| Future FSI or TDR clauses | Draft agreement for sale | 15 min |
| Layout plan: what’s marked for later | MahaRERA documents | 10 min |
See it for a project
Our reports read the building permits, the CC floor by floor, and the plans on file, so you know what is approved before you pay. Each project’s preview is free.
More: carpet area vs built-up area, and conveyance and who owns the land.
Sources
- Development Control and Promotion Regulations for Greater Mumbai, 2034: Table 12 and regulation 31(3).
- Unified Development Control and Promotion Regulations for Maharashtra, 2020 (applies to Thane).
- The Real Estate (Regulation and Development) Act, 2016: section 14.
- MahaRERA public project pages: 166 registrations in Kanjurmarg, Bhandup, Mulund, Vikhroli, Ghatkopar and Thane, read 2026-09-28 – 2026-10-15.