The circulation area may be divided into two parts
- Horizontal circulation area
- Vertical circulation area
Horizontal circulation area
The horizontal circulation area of a building in the area of verandahs, passages, corridors, balconies, porches, etc. that are required for the horizontal movement by the users of the building, This may be 10% to 15% of the plinth area of the building.
Vertical circulation area
The vertical circulation area of a building in the area or space occupied by staircase, lifts, and the entrance hall adjacent to them which are required for the vertical movement of the users of the building, this may be 4% to 5% of the plinth area of the building.
The carpet area of a building is the useful area or livable area or lettable area. This is the total floor area minus the circulation area (verandahs, corridors, passages, lifts, entrance hall, etc.) and many other non-usable areas as – bath, WC, air-conditioning room, etc. For office building, carpet area is the lettable area or usable area, and for residential building, carpet area is the livable area and should exclude the kitchen, pantry, stores, and entrance to other rooms which are not used for living purpose.
The carpet area of a building or any storey shall be the floor area excluding the following
- Sanitary accommodation (bath & WC)
- Corridors and passages
- Kitchen and pantry
- Stores in domestic buildings
- Entrance hall and porches
- Staircase and mumties
- Shafts for lifts
- Air-conditioning ducts and air-conditioning plant room
The carpet area of an office building maybe 60% to 75% of the plinth area of the building with a target of 75%. The carpet area of a residential building maybe 50% to 65% of the plinth area of a building with a target of 65%. For a framed structure, multistoried building, the area occupied by the walls maybe 5% to 10% of the plinth area (3% of the external wall and 2% of an internal wall) for ordinary buildings without the plinth area.
Note: The plinth area, floor area, circulation area, carpet area, etc, should be measured or taken separately for each storey or floor.
Floor Area Ratio = The total covered area of all floors/Plot Area