The ANSI Standard

In 1996, the American National Standards Institute (ANSI) adopted a standard for measuring single-family residential buildings, called the American National Standard Z765-1996. This standard was last revised in 2003. The standards were developed by consulting with several industry groups, including Realtors, builders, architects, and appraisers. The ANSI standards are NOT LAW, only a voluntary guide. The ANSI Standard is the accepted method by National Association of Realtors and by the North Carolina Real Estate Commission. The ANSI standard bases floor area calculations on the exterior dimensions of the building at each floor level, and include all interior walls and voids. "Finished area" is defined as “an enclosed area in a house suitable for year-round use, embodying walls, floors, and ceilings that are similar to the rest of the house.”

A 16-page booklet describing the ANSI standards with examples and illustrations can be purchased for $20.00 (plus $4.00 shipping and handling) from the National Association of Home Builders (NAHB) Research Center in Maryland at 301-249-4000.

The North Carolina Real Estate Commission gives this guideline for “Heated Living Area”:

“Living area (sometimes referred to as "heated living area" or "heated square footage") is space that is intended for human occupancy and is:

1.                  Heated by a conventional heating system or systems (forced air, radiant, solar, etc.) that are permanently installed in the dwelling - not a portable heater - which generates heat sufficient to make the space suitable for year-round occupancy;

2.                  Finished, with walls, floors and ceilings of materials generally accepted for interior construction (e.g., painted drywall/sheet rock or paneled walls, carpeted or hardwood flooring, etc.) and with a ceiling height of at least seven feet, except under beams, ducts, etc. where the height must be at least six feet four inches [Note: In rooms with sloped ceilings (e.g., finished attics, bonus rooms, etc.) you may also include as living area the portion of the room with a ceiling height of at least five feet if at least one-half of the finished area of the room has a ceiling height of at least seven feet.]; and

3.                  Directly accessible from other living area (through a door or by a heated hallway or stairway).”

How to Measure a House to ANSI Standard and in Compliance with NCREC Guidelines

Tools needed:

• a 100-foot measuring tape (fiberglass measuring tapes graduated in tenths of a foot (instead of inches, also known as “engineer’s scale”) are the best; (Available at Lowe’s or Home Depot in the tool department)
• a sturdy 25-foot retractable steel measuring tape (like the ones carpenters use)
• a letter-size tablet of graph paper (10 squares per inch works best for most houses)
• a pencil and eraser
• a calculator

If you measure a lot of houses, you should upgrade your tool kit with the following items:

• a laser measurement device such as a Disto Laser Distance Meter (info available from https://ptd.leica-geosystems.com/en/Laser-Distancemeter_5061.htm) or  for a less expensive option from Stanley FatMax™ Tru-Laser™ Distance Measurer (info available from https://www.stanleytools.com/)
• an adjustable gauge for measuring unusual corner angles (such as the "Mite-R-Gage" by Nowlin, Inc(available at https://www.mitergage.com/ )
• a computer program such as "Apex" (available at https://www.apexwin.com/ ) or "Winsketch" (available at https://www.winsketch.com/ )
• a medium-size standard screwdriver

(from How to Measure a House by Ed Odham © 2005-2012)

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