Square footage, according to Corelogic’s James Siebers, is one of the most important pieces of data to collect on a home. Appraisers and Realtors use square footage to determine the price of a home, assessors use it to determine taxes, and insurance agents use it to determine premiums.
Anyone who is measuring the square footage of a home should base the square footage on the TLA, or Total Living Area available, says Siebers. All measurements of a home’s square footage should be the same if they are made according to this standard – and they should not change, unless additions or subtractions are made.
The American National Standards Institute states that a properly measured TLA should include the stairs and landing areas, but not any open foyer. Areas below the soil grade should be listed separately, and any room counted in the square footage should have a ceiling at least seven feet in height.