Floor Plan Measurement Standards

How do you calculate the total sqft? 

Why is the total area different from the strata plan/existing floor plan?

SeeVirtual's Floor Plan measuring practice for residential properties is based on the following:

  • ANSI Z765-2003: Square Footage - Method for Calculating
  • American Measurement Standard
  • Section 68 of the Strata Property Act
  • Builder Bulletin 22: Floor Area Calculations from ONHWP where the ANSI standard does not cover.

ANSI Z765-2003, published by NAHB (National Association for Home Builders) and ANSI (American National Standards Institute), published in 2003, addresses Attached and Detached Single-Family Residential Buildings.

American Measurement Standard, Second Edition, published in 2010 by Institute of Housing Technologies, addresses Attached and Detached Single-Family Residential Buildings.

Section 68, Strata Property Act, from Statutes and Regulations of British Columbia, addresses the strata lot boundaries in BC.

The ANSI Standard is a voluntary guide and is intended to be applied as a whole.  The standard calculates the total finished square footage from the exterior with inspection of the interior (for areas that do not qualify as finished area), whereas we calculate the floor area from the interior with measurements of the exterior wall thicknesses.  (ANSI is also used as the main method of area calculation by Real Estate Licensing Courses.)  This is the main published standard we follow for attached and detached single-family residential buildings.

The American Measurement Standard is also a voluntary guide and is intended to be applied as a whole.  It is more comprehensive than ANSI Z765-2003 and also widely accepted by organizations.  It generally complies with ANSI Z765-2003, except for a few discrepancies.  This is the secondary standard we follow when specifically requested or required this method of calculation.

The Strata Property Act sets the statute and regulation governing strata properties in BC.  This is the standard we follow for strata properties.

The ONHWP Bulletin is a mandatory adherence in Ontario if the floor area is mentioned in the sales material or in the Agreement of Purchase and Sales.  It also provides a standard for calculating square footage for detached and attached single-family houses, townhouses and high-rise units.  This bulletin provides a tolerance percentage when doing sqare footage comparison.

SeeVirtual's Floor Plan measuring practice for commercial properties follows ANSI/BOMA Z65.1-1996 - Standard Method for Measuring Floor Area in Office Buildings.  


All our Measurement Standard, Procedures and Disclaimers are written for residential properties, unless specified otherwise.


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