Last Updated on 3 months by ChennaiRealties
The Tamil Nadu Government has notified the new Development and Building Rules, in 2019. It is applicable for the whole of Tamil Nadu. Its known as Tamilnadu Combined Development and Building Rules, 2019.
These Rules categorises buildings as High Rise and Non High Rise buildings. Buildings with a height up to 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
The 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 square feet, the total plinth area of all floors that can be constructed in that plot can be up to 4800 square feet. There are exemptions for certain constructions when 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 often.
The 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 follows:
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.
FSI = Total covered area on all floors
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 computations:
1. In the terrace above the topmost 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 meters), and WC (with floor area not exceeding 10 sq. meters).
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 passages 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 floors 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. A caretaker booth or room in ground floor or stilt parking floor
Achievable FSI Affects the Value of the Property
The market value of properties of the same size, in the same locality with different abutting road widths and different shapes, will differ. The wider the abutting road, the higher the price the property will fetch. Also properties with good width or frontage. This is so because a higher FSI could be achieved in a property with a 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 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 be low, the profitability of the construction venture will also be low. So, the price the land will fetch also 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.