Fannie Mae requires appraisers to use the American National Standards Institute (ANSI) Z765 standard to measure the following types of properties when valuing them for loans that Fannie Mae will purchase:
Single-family homes: Detached or attached, including manufactured housing
Townhouse-style condominium units: Also known as attached single-family houses, these units have their own roof and foundation, dividing walls, and don't share utilities with other houses
Detached condominium units: Also known as "site condos"
The ANSI standard does not apply to apartment-style units in condo or co-op projects, or to two- to four-unit properties. For apartment-style units, appraisers should use interior perimeter measurements to calculate the gross living area (GLA).
And,
@Fernando - it is ANSI Not ANZI...you are confusing it with NAZI...an easy mistake to make when dealing with FNMA.