The NAHB Research Center, an ANSI Accredited Standards Development Organization, is officially beginning the process of revising or reaffirming the American National Standard for Single-Family Residential Buildings, Square Footage – Method of Calculating, ANSI Z765-2003. 

The standard was developed by a consensus committee with oversight by the NAHB Research Center to address the need for uniformity in calculating and reporting the measurements of square footage — or living area — of dwellings in the U.S.

The standard was approved by ANSI in 1996, and it is the first voluntary standard in the nation for measuring square footage in a single-family home.

It is extremely important for builders to have a uniform way of calculating square footage, because it is a key factor in establishing the value of a newly built home.

As it is, there are a variety of local practices for arriving at a final measurement of square footage, and there can be a surprising amount of variation in the results depending upon what parameters are used.

For example, it is open to interpretation as to whether below-grade areas, added features such as an air conditioned sun porch, finished attic space and other rooms are included in the final measurement of a home’s square footage.

Last updated in 2003, the standard's rules take into consideration such parameters as the ceiling height of rooms to be included — at 7’, or 6’4” from hanging beams, ruling out crawl spaces — and the non-inclusion of unfinished basements, attic space or any space that is below ground level.

Also, garage space or space within a separate guest or pool house is not included in the total area.

Importantly, local jurisdictions, appraisal boards and commerce departments have adopted the ANSI Z765 standard as a requirement for real estate transactions, valuation and basis for property tax assessments.

In line with the ANSI-prescribed consensus process, all interested parties may contribute to revising or reaffirming the standard by submitting proposed changes or by applying to join the consensus committee.

All committee business will be conducted by conference call and email.

Notices and tentative agendas will be posted online 30 days in advance of all meetings.

For forms for proposed changes and consensus committee membership, click here. All submissions must be made by email by June 14.

For updates on the standard development process, visit www.nahbrc.com/sqft2012.

For more information, email Tom Kenney at the NAHB Research Center.