GLA and Measurement Standards · 5 min read

Gross Building Area (GBA) vs GLA: What Is the Difference?

GBA and GLA both measure square footage, but they count different things and are used in different contexts. Mixing them up in an appraisal report is a common mistake that can affect value conclusions and lender compliance. Here is how to keep them straight.

What is Gross Living Area (GLA)?

GLA is the standard measurement for residential appraisals. It counts only above-grade, finished living area that meets minimum ceiling height requirements under ANSI Z765 (at least 7 feet over at least 50% of the floor area).

What is excluded from GLA: basements (even finished ones), below-grade walkout levels, garages, unfinished attics, covered porches, and any space that does not meet the ceiling height threshold. GLA is the number that goes on the URAR form and drives comparable adjustments.

What is Gross Building Area (GBA)?

GBA is a broader measurement. It includes all enclosed space within the exterior walls of a structure -- finished and unfinished, above grade and below grade, livable and non-livable. Think of it as the total footprint of everything under the roof.

A house with 1,800 sq ft of above-grade GLA, a 900 sq ft finished basement, and a 400 sq ft attached garage would have:

• GLA: 1,800 sq ft (above-grade finished only)
• GBA: 3,100 sq ft (GLA + basement + garage)

When is each used?

GLA is used for residential property appraisals -- single-family homes, condos, townhouses. Fannie Mae, Freddie Mac, and FHA-backed loans require ANSI Z765-compliant GLA. It is what your comparable sales adjustments are based on.

GBA is more common in commercial and multi-family appraisals, where total building size matters more than habitable living area. It also appears in construction and insurance contexts where you need to account for the entire structure, not just the livable portion.

For a typical residential appraisal, you will report GLA on the URAR form. Finished basement area is reported separately (below-grade finished area). Garage square footage is noted but not included in either GLA or the below-grade figure -- it gets its own line.

Other related measurements

A few more terms you may encounter, and how they differ:

• Total Finished Area (TFA): All finished space, including basements and finished lower levels. Higher than GLA, lower than GBA.
• Gross Floor Area (GFA): Often used interchangeably with GBA in commercial contexts. Includes all floors of the building.
• Net Rentable Area (NRA): Commercial leasing measurement -- the space a tenant actually occupies, excluding common areas and mechanical spaces.
• Assessor square footage: Calculated by the county using its own methodology, which may or may not align with ANSI Z765. Common source of discrepancies between appraised GLA and public records.

The practical takeaway

For residential appraisals: use GLA. It is the ANSI-compliant, lender-required, comparable-adjusted figure. Everything else (basements, garages, porches) gets reported separately.

If a homeowner or agent quotes you a larger number and calls it "square footage," they are almost certainly including below-grade area, garage, or both -- which would inflate the figure compared to the ANSI-compliant GLA you are required to report.

PlanSnapper is designed for GLA calculation specifically. When you trace a floor plan and label above-grade vs below-grade areas, it calculates each separately so you have the right numbers for each section of the URAR.