Floor Space Index is the ratio between the total Built up Area to the area of plot on which a building is to be constructed. This numeric value indicates the total amount of area that you can split amongst different floors . FSI is dependant on the height restriction of that particular area, city zone , land use pattern , special building, plot coverage etc., You can find out FSI for a particular zone from the government’s website. The FSI varies from the value of 1 upto 3 depending on various zones of residential land use and these values of FSI can be used on the ground floor after referring plot coverage , front back and side setback , Open space reservation of that particular zone. In special cases where there is a need of ample amount of area to be constructed more than the available FSI; the Floor space index can be bought after looking into road width parameters and these type of FSI are called the premium FSI. As per CMDA
- Road width of 18m and above would be 40%,
- Road width of12m and below would be 30% and
- Road width of 9m and below would be 20% of the total allowed FSI
The Premium FSI is allowed only on specific area ; rates and charges may vary in different zones as prescribed by CMDA
For example you have a plot of 2400 Sft and a FSI of 1.5 on your zone
Step 1 - The first thing you will have to know that you are allowable to build upto 3600 sft in your plot. And this 3600 sft area has to be split up amongst different floors
Step 2 – Know your road width , plot width and height of the building that you are planning , all these information will give you a guideline of the set back that has to be planned. In case of special building you will have to consider the OSR also. The remaining area after all these consideration would be your left out area for construction.
Step 3 – Now you can divide the total buildable area into different number of floors (it is also important to consider height restrictions in that particular zone).
There it is , you find out your FSI and distribute it among different floors as per your detailed requirement.