#10 What is FSI (Floor Space Index)? Why it is Followed?
FSI means the ratio between the area of a covered floor (Buildup area) to the area of that plot (land) on which a building stands.
This numeric value indicates the total amount of area (on all floors) you can build upon a plot.
How to calculate FSI for building?
FSI regulates by Directorate of Town and Country Planning (DTCP) department.
They will regulate the FSI value based on city zone, type of building and other amenities.Construction companies or builders can only build up to the FSI imposed by the government.
FSI × Plot Area = Built-up Area
What is FSI in construction?
FSI Example Calculation
To explain Floor Space Index (FSI),
Assume you have a land of 2000 sq.ft and you want to construct a building on that land.
First thing, you need to know is what type of building you are planning to construct?
- Ordinary Building – Up to 2 floors less than 4 flats/dwelling units,
- Special Building – more than 2 floors not exceeding 4 floors,
- Multi-storeyed Building – Exceeding 4 floors
There are other types of buildings also exist. (Industrial Building, Group housing etc).
For the sake of this example, we stick to these types.
Based on your building type, find out your zone FSI, which you can find on your state govt’s official website. Generally, different buildings have different FSI regardless of the location. For the same location, FSI can vary for ordinary building and special buildings.
Let say, your zone FSI is 1.5 for special buildings. Now you can build (2000*1.5 ) 3000 Sq.ft covered area on your land. It can be either 2 floors of 1500 sq.ft or 3 floors of 1000 sq.ft without affecting other municipal rules.
Note:-
You have to follow other municipal rules such as,
- Minimum plot extent area
- Front, back, side and rear setback
- OSR and parking space.
What is Premium FSI?
Regardless of zone, location and building type, there are some allowable deviations.
Premium FSI, If you need to extend the allowable Floor Space Index (FSI), you have to pay a premium fee to the govt. To avail this FSI, the abutting road of the land must be at least 30 feet.
- 30 – 40 Feet Road Width – 20 % Premium FSI
- 40 – 60 Feet Road Width – 30 % Premium FSI
- more than 60 Feet Road Width – 40 % Premium FSI
If the land location of the building has 30 – 40 feet abutting roadway, then you can make avail the premium FSI of 20% which means you can build 20% more than allowable FSI.
For Example, If you have 1000 Sq.ft Land located near 30 feet road (where normal FSI is 1.5), then you can make avail of the premium FSI 20% by paying the premium fee. So,
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Refer Above Government order for Chennai region.
Reference: https://www.civilology.com/
Why FSI is important to follow??
FSI (Floor Space Index ) is required to limit stress on city resources and is good concept. But in india & many other countries in the world, the government got it wrong by not considering holistic approach for it. Let the FSI be fixed to 2.0 but this should be applicable as overall value for city master planning. City should have 25% Park area & 25% Road area. Remaining 50% area should have FSI of 4.0. This way we will not burden city resources as well as keep area more greener with lesser traffic due to lesser commuting distance.
Let's consider below for better understanding:
Total City Area = 100 units.
Park Area = 25 units.
Road Area = 25 units.
Construction Ground Area = 50 units.
Constructable Area ( Ground + Higher Floors) = 200 units => FSI = 4.0.
If an apartment keeps 50% open area, effective FSI for construction (built up area) would be 8.0.
Currently much lesser greener park area and much lesser road area is made available causing more air pollution, more traffic, costlier real estate. As FSI is less, cities have grown horizontally requiring more travel for residents, as city areas are more distant apart. Commuting for office, shopping, recreation has increased a lot because of this. City master planning has flawed greatly.