CMDA/DTCPApartment Related IssuesBuilding Plan ApprovalReal Estate Updates


FSI or Floor Space Index

The Tamilnadu Government has Notified the new Development and Building Rules, in 2019. It is applicable for the whole of Tamilnadu. Its known as Tamilnadu Combined Development and Building Rules, 2019.

These Rules categorise buildings as High Rise and Non High Rise buildings. Buildings with height upto 18.30 Meters are Non High Rise Buildings. For these Non High Rise Buildings, the maximum Floor Space Index allowed is 2.

Floor space index, also known as FSI, helps us calculate the maximum floor area that one can construct in a Plot.

Calculation of Constructable Area

FSI allowed is 2. This means, the total plinth area one can construct is twice the area of the plot. For example, if the plot area is 2400 sqft, the total plinth area of all floors that can be constructed in that plot can be upto 4800 sqft. There are exemptions for some constructions while computing the Floor Area. Later in this Article we give the list of exemptions.

The calculation of FSI is not that simple. The road width, plot width and height of the buildings also decide the constructable area. This is so because of the need to provide Set Back Spaces around the building.

For details about Set Back Spaces, click HERE. As a result, achieving the allowed FSI may not be possible many times.

Definition of FSI

FSI is one of the tools under the Rules with which the Government regulates the construction activity.
In the Rules the FSI is defined as under:
FSI  is the quotient obtained by dividing the total covered area (plinth) on all floors except the areas exempted under these regulations  by the plot area which includes part of the site used as exclusive passage.
Total covered area on all floors

Plot area

Exemptions from FSI Norms

The exempted areas are also given in the Rules. According to the Rules, the following shall not be counted towards FSI and plot coverage computation: 
1. In the terrace above the top most storey, areas covered by stair-case rooms and lift rooms and passages thereto, architectural features, elevated tanks (provided its height below the tank from the floor does not exceed 1.5 metre) and WC (with floor area not exceeding 10 sq.m)
2. Staircase and lift rooms and passage thereto in the stilt parking floor or upper floors used for parking
3. Staircase and lift rooms and passage thereto in the basement floor or floors used for parking.
4. Area of the basement floor or floors used for parking
5. Area of the stilt parking floor provided it is open on sides, and used for parking. In cases where upper floor or floors over a stilt parking floor is proposed for parking.
6. Servants or drivers bath room and water closet for each block in cases of Non High Rise Buildings and High Rise Buildings at ground floor or stilt parking floor
7. Watchman booth
8. Caretaker booth or room in ground floor or stilt parking floor

Achievable FSI Affects Value of the Property

The market value of properties of the same size, in the same locality with different abutting Road Width, and different shapes, will differ. Higher the Abutting Road Width, higher the rate the property will fetch. Also properties with good width or frontage. This is so because higher FSI could be achieved in a property having wider Abutting Road, Frontage, and proper shape. This means more income by way of increased Floor Area that can be constructed and sold.
For example, consider a plot of 2400 sqft on a narrow road of say, 15′ width. Further the property has got a small frontage. In this case full FSI 2 may not be possible. This is because of the need to provide Set Back Spaces. Since the total constructable area may low, the profitability from the construction venture will also be low. So, the price the Land will fetch also will be low.

Benefits of Increased FSI

Apart from allowing new constructions to build more floor area,as a result of this higher FSI,(earlier the FSI was 1.5 only), redevelopment activities are on the increase. Buildings/apartments constructed years ago, with old FSI norms are being redevloped now. This is a win win situation both for the occupants/owners as well as for the promoters.


6 thoughts on “FLOOR SPACE INDEX Chennai

  1. Sir, I am having a breadth of 22 feet and 100ft in length. Could you suggest the best possible area to utilize the ground floor, first floor and second with setbacks. As my plot breadth is very small how can I arrive the setback area. Please explain.

  2. Sir…The new building rules doesn’t say anything about exclusion of balcony for FSI calculation

  3. G.Sankaran i am having 2500 SQ.Ft with breath of 35 feet and length in 70 feet road. what current fsi limit for residendial building construction

  4. my aunty having land of 3600 sqft at ramakrishna st, next to sai baba mandir, perambur, the road width is 33 feet, what is the fsi now at present if she goes for construction, upto how many floors, please reply


Leave a Reply