In order to unify and standardise the method of measurement of plinth, carpet and rentable areas of buildings, the Method of Measurement of Works of Civil Engineering Sectional Committee, CED44 of Bureau of Indian Standards has brought out and Indian Standards, namely IS3861:1975 Method of Measurement of Plinth Carpet and Rentable Areas of Buildings (first revision).
The standards defines various important terms like plinth areas, carpet area, rentable area, balcony, staircover (mumty), loft and porch. It stipulates that the areas of basement, floor without cladding (stilled floor), floors including top floor, which may be partly covered, mezzanine floor, and garage shall be measured separately. For measurement of plinth area of the above categories, the various areas required to be included and those not to be included in the plinth area are clearly mentioned. From the plinth areas as worked out above, the carpet areas if obtained by deducting the are of wall in accordance with the method given in the standard, which details the wall areas to e include and excluded. The carpet area so obtained shall exclude the areas of portions like verandah, corridor and passage, entrance hall and porch staircase and stair-cover (mumty), shaft and machine room for lift, bathroom and lavatory, kitchen and pantry, store, canteen, air-conditioning duct and plant room and shaft for sanitary piping in accordance with the provisions of the standard.
Apart from plinth and carpet areas, the standard also gives the method of measurement of rentable areas for residential and non-residential buildings by adding certain areas to the carpet area. It clearly mentions the areas to be included and excluded while working out the rentable areas.
It is recommended that the architects, engineers, government detects, engineers government departments, contractors, builders, developers and promoters and all other concerned should adopt/implement this Indian Standard for uniform implementation of the standard method of measurement of areas of buildings, especially in the interest of common consumer.
Now RERA is also having definition on carpet area. Any area wall to wall, below internal walls, column and all usable FSI is counted in carpet area.