Guides · Floor Plan Measurement
ANSI Z765 is the American National Standard for measuring residential square footage. Since April 2022 Fannie Mae and Freddie Mac require all conventional loan appraisers to follow ANSI Z765-2021. Understanding the standard is essential for appraisers, agents, and anyone interpreting a residential floor plan measurement.
ANSI Z765 (full title: "Square Footage — Method for Calculating: ANSI Z765-2021") is published by the National Association of Home Builders and approved by the American National Standards Institute. It defines exactly how to measure and report residential square footage so any two appraisers applying it to the same property get the same result. Before mandatory adoption, practices varied widely — one appraiser might include the finished basement, another wouldn't.
Exterior measurement: GLA must be measured from the exterior walls. Interior wall-to-wall measurements are not compliant. Above-grade only: Space is above-grade only if the floor level is at or above finished exterior grade on all sides. Walk-out and daylight basements are below-grade regardless of exposure. Finished space only: Permanent walls, floor covering, and ceiling required. Rough framing or unfinished mechanical rooms excluded. 7-foot ceiling minimum: The majority of a space's floor area must have ≥7-ft ceilings. Areas below 5 feet don't count at all. 5–7 ft areas count only as part of a larger finished space. Cape Cod knee-wall rooms measured only where ceiling exceeds 5 feet. Heated and cooled: Connected to HVAC system. Three-season porches and unheated rooms excluded.
Basement and below-grade space (reported separately). Attached or detached garages. Unheated porches and three-season rooms. Carports. Attic space below 5-foot ceiling height. Utility rooms with inadequate ceiling height.
1. Trace the exterior perimeter of each above-grade finished floor — click the outside face of exterior walls. 2. Exclude the garage; draw it as a separate polygon if needed. 3. Exclude unheated areas. 4. For steeply sloped ceilings (finished attics, Cape Cod rooms), only include floor area where ceiling exceeds 5 feet.
Starting April 2022 ANSI Z765 compliance became mandatory for all Fannie Mae/Freddie Mac appraisals. Appraisers who don't follow the standard risk having appraisals rejected by lenders. This mandate has made consistent, reproducible floor plan measurement tools increasingly valuable for appraisers and the agents they work with.
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