Measurement of plinth and carpet areas of buildings as per IS 3861


Royal Member
Plinth area shall mean the covered built up area at the floor level of any storey or at the floor level of the basement.
Carpet area shall mean the cover area of the usable rooms at any floor level.

Mezzanine floor - an intermediate floor in between two main floors having minimum height of 2.2 m (or minimum 1.8m where rules of the local bodies permit) from the floor and having proper access to it.

Stairs cover (mumty) is the roofed space over a stair case and its landing, built to enclose only the stair for the purpose of providing protection from weather and not used for human habitation.

Loft is an intermediate storage area in between two main floors.

Porch is a covered surface (with roof supported on pillars or otherwise), used for the purpose of pedestrian or vehicular approach to a building.

measure lengths to the nearest 0.01m. work out areas to the nearest 0.01sq.m.

The areas of each of the following categories shall be measured separately:-
(a) Basement
(b) floor without cladding (stilted floor)
(c) floors including top floor which may be partly covered
(d) mezzanine floor, and
(e) garage.

Measurement of plinth area
following areas shall be include where occurring in each category of plinth area
(a) Area of the wall at the floor level excluding plinth offsets it any. When the building consists of columns projecting beyond the cladding, the plinth area shall be measured up to external face of the cladding (in case of corrugated sheet cladding outer edge of corrugation shall be considered)
(b) internal shaft for sanitary installations and garbage chute, provided these do not exceed 2 sq.m in area, vertical duct for air conditioning, and lift well including landing
(c) stair cover (mumty)
(d) machine room, and
(e) porch.

The following shall not be included in the plinth area
(a) Additional floor for seating in assembly buildings/theatres and auditoriums
(b) cantilevered porch
(c) balcony
(d) area of loft
(e) internal sanitary shaft and garbage chute provided these are more than 2 sq.m in area
(f) area of architectural band, cornice.,etc.,
(g) area of vertical sun breaker or box louver projecting out and other architectural features for example slab projection for keeping flower pots
(h) open platform
(j) terrace at floor one
(k) spiral staircase including landing, and
(l) towers, turrets domes projecting above the terrace.

Wall area means the area on plan occupied by walls (including thickness of finishing/dado if the height of such finish is more than 1 m from floor finish) on any particular floor and qualifying for inclusions in the plinth area.

The following shall be excluded from the wall area
(a) Pilaster along wall not exceeding 300 sq.m in area, and
(b) Chullah platform projecting beyond the face of the wall.

Carpet area shall mean the plinth area less the area of following portions
(a) wall area
(b) verandah
(c) corridor and passage
(d) entrance hall and porch
(e) staircase and staircover i.e. mumty (in a hall or basement the area of portion up to 1m beyond the last step of staircase shall be treated as part of the staircase)
(f) lift shaft and machine room for lift
(g) bath room and lavatory
(h) kitchen and pantry
(j) store
(k) canteen
(m) air conditioning duct and plant room
(n) shaft for sanitary piping
(p) stilled floor and garage