In 2010, BOMA International published “Multi-Unit Residential Buildings: Standard Methods of Measurement (2010) or ANSI/BOMA Z65.4-2010.
The primary purpose of the multi-unit residential standard is to provide an objective benchmark in comparing values associated with rental apartments, residential condominiums and other types of community type buildings used for living in. The standard does not pertain to single-unit homes, duplex or triplex buildings, townhomes, row houses, etc.
The standard outlines two distinct methods of calculating multi-unit residential buildings. Method A or the “Gross Method” produces a larger area since it measures each unit including the full thickness of the exterior wall and the full thickness of walls separating living units from common areas. Method B or the “Net Method” measures living units to the inside finished surface of the exterior wall and to the inside surface of walls separating living units from common areas.
Both methods include the areas of private balconies, but balconies are considered “Limited Common Area” and not included in the area of a living unit. The area of balconies are however, included in the Construction Gross Area.