Floor Space Index (FSI)
Floor Space Index
The ratio between built-up area and the plot area a building stands on — and why it matters before you buy.
What is an FSI?+
FSI stands for Floor Space Index, also known as Floor Area Ratio (FAR). FSI means the ratio between the area of a covered floor (built-up area) to the area of the plot (land) on which a building stands.
Who decides FSI?+
Development authorities such as DTCP (Tamil Nadu), CMDA (Chennai), BDA (Bengaluru), MMRDA (Mumbai) and DDA (New Delhi) establish FSI regulations — rather than the central government. This is why FSI varies across states and cities.
What is included in FSI?+
FSI typically covers the entire slabbed area, depending on each state's or city's development regulation (DR). Elements like stilt area, staircase area, OTS area, sunshades, conduits and cantilever extensions may be included or excluded from FSI based on local rules.
What is a special / influenced FSI?+
Certain zones designated as "influenced areas" have stricter or more relaxed FSI norms — for example CMRL influenced zones, MRTS influenced zones, or Airport Authority of India zones.
What is a premium FSI?+
Most projects opt for premium FSI based on site conditions and building type, allowing additional floor area over the base FSI.
What is a permissible deviation?+
Development authorities permit certain deviations to account for site conditions or human error, with the permitted percentage varying by authority.
What is the FSI of Tamil Nadu?+
As of October 30, 2018, the Floor Space Index of Tamil Nadu is 1:2.
Carpet Area
Carpet Area
The usable area inside your walls — and how RERA carpet area is defined.
What is carpet area?+
The usable area inside the walls, where one can literally spread a carpet, is known as the carpet area. Historically, definitions varied by location regarding cantilever projections and internal walls.
What is a RERA carpet area?+
Carpet area is the area that can be used to spread a carpet inside the house — the net usable area of the apartment. It includes the thickness of the internal walls but excludes the balcony or terrace.
Development Regulation (DR)
Development Regulation
Who sets the rules a building must follow, and what those rules cover.
Who is a development authority?+
A development authority is a government organization under the state government. Development authorities are responsible for dictating development regulation and enforcing it.
What is a development regulation?+
A development regulation is a set of guidelines established by development authorities, covering setbacks, definitions of terminology, jurisdiction-specific regulations, laws, policies and enforcement mechanisms.
Undivided Land Share (UDS)
Undivided Land Share
Your share of the land beneath the building — and why verifying it protects you as a homeowner.
What is a UDS?+
UDS is the portion of land allocated to a property owner in the development. A homeowner should ensure that the sum of all UDS sub-divisions equals the total land area of the development.
What is an acceptable UDS percentage?+
UDS percentages depend primarily on FSI utilisation. Deviations from permitted plans may compromise UDS, but generally don't affect an individual homeowner's share if it is proportional to sellable area — though enforcement penalties or demolition could impact owners.
What is acceptable UDS by building type?+
Reference benchmarks from existing developments:
• Ordinary building (6–12 m): 42–50%
• Special / Non-MSB (12–24 m): 46–54%
• High-rise / MSB (above 6 floors): 20–28%
Always match the UDS to the permitted plan.
Facing
Facing
How the direction a home faces affects light, ventilation and comfort.
Should I consider facing while buying a house?+
Absolutely yes! Facing has a real impact on light, ventilation and comfort.
Does facing have scientific benefit?+
Facing is calculated based on the direction of the property, and it certainly has scientific and practical benefits.
East facing+
Maximum daily sunshine keeps homes well-lit and occupants active and healthy. Street lights are predominantly on the opposite side of the property, which means more light during the night as well.
West facing+
Advantages: Less intense sunlight creates pleasant evenings; the evening sun helps combat skin diseases. Offers privacy and beautiful views with reduced daytime heat. Disadvantages: Street lights are predominantly placed on the western side, and transformers and powerful electric lines may pass on your side of the street.
North facing+
North facing is the most requested facing, as it is a neutral facing that offers no real disadvantages.
South facing+
South-facing houses enjoy the southern breeze and evening sunlight, combining the benefits of multiple exposures for optimal comfort.
Facing Ergonomics
Facing Ergonomics
Designing a home to make the most of its facing.
East facing ergonomics+
Position neem trees visibly from elevation windows; place the garden on the southern side for cooling. Locate staircases on the south side so upper floors receive breezes rather than humidity.
West facing ergonomics+
Provide at least a 1.5-metre front setback; use decks instead of balconies. Position the garden on the northern side and staircases on the southern side. North-facing entrances are recommended for upper floors.
North facing ergonomics+
Ground-floor entrance facing north; upper floors via eastern access. Position living rooms facing east with low-sill windows. Extend balconies as cantilevered structures facing north to maximise breezes.
South facing ergonomics+
Use generously sized, low-sill windows on the eastern side for natural light and garden views in living areas. Locate bedrooms on the western side for breeze circulation; southern-facing balconies provide evening sunlight enjoyment.