FAQ · 5 min read

How Do I Measure a Garage for an Appraisal?

Garages are never included in GLA — that is the baseline rule. Under ANSI Z765, Gross Living Area is above-grade, finished, habitable space. A garage, regardless of how finished or well-lit it is, does not qualify.

But garages still need to be measured accurately because they contribute to the overall property value and are reported separately on the appraisal form.

How to measure a garage

Measure the exterior dimensions of the garage structure. Walk the outside and measure the length and width of the garage walls, then multiply. For a 20 ft x 22 ft attached garage, you would report 440 sq ft.

Do not use interior dimensions — the convention for garages follows the same exterior measurement approach as the main dwelling. This ensures consistency when comparing to other properties on the sales grid.

Attached vs detached garages

For an attached garage, the garage shares at least one wall with the house. Measure the garage as a separate structure: from the outside of the garage walls, not the outside of the house. Do not double-count the shared wall — measure the garage perimeter independently.

For a detached garage, the measurement is straightforward — walk the exterior and record the dimensions. Note it separately as a detached structure on your form.

How to report it

On the standard 1004 or 1073 form, garages are reported in the improvements section. Typical format: "2-car attached garage, 440 sq ft" or "1-car detached garage, 200 sq ft." The area contributes to value but is reported as a separate feature, not added to GLA.

Converted garages: proceed carefully

Garage conversions are one of the most common GLA disputes in residential appraisal. If a garage has been converted to a bedroom, office, or living room, it may qualify as GLA — but only if all of the following apply:

• Permits were pulled and the conversion is legal
• The space meets the minimum ceiling height requirement (7 ft under ANSI Z765)
• The space is finished, conditioned (heated/cooled), and accessible from the living area
• The space is above grade
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If any of those conditions are not met, the converted garage stays out of GLA. An unpermitted conversion should be called out explicitly in the appraisal and typically reported as non-GLA finished area.

Carports, tandem spaces, and oversized bays

Carports (open on at least one side, no garage door) are measured and reported separately from garages — they typically contribute less value than an enclosed garage. Measure the covered area and note the configuration.

Tandem garages (two cars parked front-to-back in a single bay) are measured the same way — exterior dimensions of the full bay. Report the total square footage and note the tandem configuration.

Related: What counts as GLA? · Exterior vs interior measurement · Ceiling height requirements for GLA