How do appraisers calculate the square footage of a house?

One process involved in purchasing a home is having the house appraised by a Mississippi licensed appraiser to determine value. When a lender is involved, the lender will order an appraisal that includes calculating the square footage of the heated and cooled, finished areas to determine the size. If a lender is not involved, some purchasers choose to engage an appraiser to determine the size of the house.

There is a common misconception, among some, that square footage is calculated from the inside of the house; this is not the case. When measuring a house, appraisers are required to use a standard of measurement, such as those provided by the American National Standards Institute, Inc. (commonly referred to as ANSI Standards). Listed below are some facts, from ANSI, about square footage calculations that may be of interest:

  • For detached single-family houses, the finished square footage is measured from the outside walls, not inside.
  • Only square footage of finished areas is used in the calculations. A finished area is suitable for year-round use, embodying walls, floors, and ceilings that are similar to the rest of the home.
  • To be included in finished square footage calculations, finished areas must have a ceiling height of at least 7 feet.
  • For a room with sloping ceilings, such as a “bonus” room over a garage, to be included in the square footage calculation, the floor located under the sloping ceilings must have a clearance of at least 5 feet. Also, pertaining to a room with a sloping ceiling, at least one-half of the finished square footage in that room must have a ceiling height of at least 7 feet; no portion of finished area that has a ceiling height of less than 5 feet can be included in finished square footage.
  • Garages and unfinished areas cannot be included in the calculation of finished square footage.
  • Finished areas above garages are included in the finished square footage ONLY when they are connected to the home by continuous finished areas such as hallways or staircases.
  • A finished staircase descending from a finished area is counted as finished square footage on the level from which it descends.
  • A staircase descending into a basement is counted in the finished square footage of the first floor, whether the basement or the stairs is finished or not.
  • There are two categories of finished square footage: above grade and below grade. If any portion of a level is below grade, the entire level is considered below grade and must be calculated separately.

Before marketing your home, is it always wise to consult with a REALTOR®. A REALTOR® can put you in touch with a licensed appraiser who has the expertise to accurately determine the size of your home.