Introduction
In Tamil Nadu’s construction and real estate sector, Floor Space Index (FSI) and Premium FSI play a vital role in determining how much you can legally build on a plot of land. For developers, landowners, and investors, understanding these rules is essential as they directly affect project feasibility, costs, and building approvals.
FSI
FSI stands for Floor Space Index (also known as Floor Area Ratio – FAR in some places).
It is a development control regulation used by urban planning and building authorities to regulate how much construction is allowed on a given piece of land.
In Tamil Nadu, the Floor Space Index (FSI) ranges from 1.5 to 3.25, with 2.0 being the generally permissible limit in most cases.
FSI = Total Built-up Area / Plot Area
Example:
- When you have a plot area of 1,000 sq.ft and if permissible FSI is 2.0,
you can build 2,000 sq.ft of building area and for FSI 3.0 you can built 3000sq.ft building area.
Note:
The basic permissible FSI depends on the location of the plot , Approach road width, Building height & building type (Commercial / Residential / Public building / Industrial Buildings)
Premium FSI in Tamil Nadu
Premium FSI refers to the extra buildable floor area allowed over and above the normally permissible FSI (Floor Space Index). By paying additional charges to the government, developers can legally utilize more construction space on a plot. This helps maximize land use, especially in urban areas with high demand for built-up space, and ensures projects remain profitable and compliant with building approval rules.
Road Width and Premium FSI eligibility
Premium FSI is allowed only if the property abuts certain minimum road widths:
Road Width | Premium FSI (% of normally allowable FSI) | Example – normally permissible FSI 2.0 |
| 18 m & above | +50% | 3.0 |
| 12 m – below 18 m | +40% | 2.8 |
| 9 m – below 12 m | +30% | 2.6 |
How Premium FSI Charges are Computed :
Premium FSI charges are linked to the Guideline Value of the site:
- For Non-High-Rise Buildings → 50% of Land Guideline Value for the excess FSI area (up to 18.3m height)
- High-Rise Buildings → 40% of Guideline Value for the excess FSI area (above 18.3m height)
If a site falls under multiple survey numbers, the highest Guideline Value among them will be considered.
Example:
Proposed land area: 10,000 sq.ft
Guideline value (GLV) of the plot: ₹500 per sq.ft
Abutting road width: 15.0 m
Normally permissible FSI: 2.0
Buildable area = 10,000 × 2.0 = 20,000 sq.ft
Premium FSI applicable: +40% (since road width is between 12 m and 18 m)
Additional FSI = 0.8 = 8,000 sq.ft
- Total built-up area achievable = 20,000 + 8,000 = 28,000 sq.ft
Cost Calculation for Premium FSI:
Premium FSI charges = 50% of GLV
50% of ₹500 = ₹250 per sq.ft
Charges for additional 8,000 sq.ft = 8,000 × 250 = ₹20,00,000
- In this case, the developer has to pay ₹20 lakh as Premium FSI charges to utilize the extra 8,000 sq.ft.
Conclusion
Understanding FSI and Premium FSI in Tamil Nadu is essential for developers, landowners, and investors. Base FSI depends on location, road width, and building type, while Premium FSI provides additional area for a fee. By following the rules and calculating costs carefully, you can maximize land use, stay compliant, and improve project outcomes.
Related: ( https://propdoc.in/understanding-panchayat-approvals-dtcp-approvals/ )
