How an appraiser counts a garage
| What you build | How it is reported (Fannie Mae B4-1.3-05) | What that means for value |
|---|---|---|
| Detached garage, unfinished | Separate line in the sales comparison grid | Valued by what comparable sales with and without a garage show |
| Detached garage with a finished room above | "Any detached structure(s) with finished area(s) must be reported on a different line", not in the home's finished area or room count | The finished room does not count as a bedroom or square footage of the house |
| Finished area attached to the house with no interior access | Reported separately as "noncontinuous finished area" | Also a separate adjustment |
| Basement or other below-grade finished rooms | Reported separately; "may add substantially to the value" | Shows that separate lines can still carry real value |
National cost-recovery surveys do not answer this one: the National Association of REALTORS 2025 Remodeling Impact Report scores a garage door replacement, not a new garage (NAR, April 2025). We found no official national figure for what a detached garage adds, so we do not give one.
What a garage costs against home values
Usual filed value is the median job value contractors declared on garage permits. The single-family value figure is the one each city's compare pages use for the home-value control.
| City | Garage permits | Usual filed value | Single-family value figure | Usual days, issue to final |
|---|---|---|---|---|
| Cleveland, OH | 303 | $22,275 | $99,000 | 139 |
| Greensboro, NC | 119 | $38,700 | $177,000 | 156 |
| St. Louis, MO | 355 | $13,000 | $200,000 | 335 |
| Cincinnati, OH | 111 | $20,000 | $201,000 | 332 |
| Chicago, IL | 1,821 | $26,312 | $250,000 | 106 |
| Saint Paul, MN | 431 | $17,472 | $276,000 | 263 |
| Minneapolis, MN | 706 | $24,775 | $349,000 | 143 |
| Nashville, TN | 769 | $37,309 | $421,000 | not recorded |
| Colorado Springs, CO | 136 | $36,160 | $462,000 | 133 |
| Denver, CO | 989 | $29,882 | $631,000 | not recorded |
| Scottsdale, AZ | 212 | $60,604 | $1,197,000 | not recorded |
The pattern: garage costs move far less than home values. Cleveland's usual garage permit ($22,275) is not far below Minneapolis's ($24,775), while the home value figure is a fraction of it. Where the garage is a large share of what the whole house sells for, the buyer pool that will pay for it is the thing to check. Where it is a small share, as in Denver ($29,882 against $631,000) or Scottsdale, the question is mostly whether local buyers expect one.
Decide in five minutes
- Look up three recent sales on your street or nearest blocks: with a garage and without. That gap is close to what an appraiser will use.
- Compare it with the usual garage value for your city in the table, or the builder spread in our detached garage cost guide.
- If you want a room above the garage to count as living space, read what is an ADU first; a detached room is not counted in the house.
- Check the setback and size limits before you price it: do I need a permit for a garage.
Compare every Minneapolis garage builder by permit record →
What this does not tell you
We do not have sale prices, so we cannot measure what a garage added to any house. The single-family value figure is a city-level figure, not your house's value. Filed values are what builders declared to the city, which can be below the final invoice. Nashville, Denver and Scottsdale do not record a final date we can use for garages.
How we know this
Garage permits are each city's detached garage (or accessory garage) permits in its window, three years ending September 2026. Usual filed value is the median declared value; days are the median from issue to final inspection. The single-family value figure is the one each city's compare pages use for the home-value control. Appraisal rules are quoted from Fannie Mae Selling Guide section B4-1.3-05, and the NAR report was checked for garage projects, both read 23 October 2026.
Numbers come from City of Chicago building permits (Chicago Data Portal); City and County of Denver residential construction and demolition permits; City of Minneapolis construction permits (CCS); City of Cleveland building permits; City of Scottsdale building permits (the City's open-data permit file up to January 2026, and the City's SPUR permit system since), with the contractor named on each permit; Metro Nashville (Davidson County) building and trade permits, data through October 19, 2026. Nobody paid to be on this page and nobody can.
Compare every Chicago garage builder →
Questions
- Does a detached garage increase property value?
Usually, but not as living space. Fannie Mae's appraisal rules say a detached structure, even one with finished area, is reported on its own line in the comparison grid and not counted in the house's finished area. So it adds what local buyers pay for a garage, which the appraiser reads from nearby sales.
- Are detached garages worth the investment?
Compare the usual cost with what houses sell for. A Cleveland garage permit is filed at $22,275 against a single-family value figure of $99,000; a Scottsdale one at $60,604 against $1,197,000. Where the garage is a large share of the house's value, it is harder to get back at sale.
- How much does a detached garage cost?
The usual filed value of a garage permit runs from $13,000 in St. Louis to $60,604 in Scottsdale in our cities; $24,775 in Minneapolis and $26,312 in Chicago. Our detached garage cost guide has 16 cities.
- Does finishing the garage add living space for the appraisal?
Not if it is detached. Fannie Mae says any detached structure with finished area must be reported on a different line and 'not included as part of the subject's reported finished area' or room count. A finished, legal ADU is treated differently; see our ADU guides.
- How long does it take to build a detached garage?
The permit usually took 143 days from issue to final in Minneapolis, 106 in Chicago and 139 in Cleveland. That is the whole build plus inspections, not the construction days.
Build your own list
Every firm with that kind of permit on record. Pick what you value. The list moves.
Related guides
- Detached garage cost: what garage permits show in 16 cities
- Do I need a permit to build a garage? The rule in 14 departments, and how many get filed
- Do I need a permit to build a garage in Chicago? Yes: the express detached-garage permit and its limits
- Home improvement costs in Chicago, IL (2026): what 9 kinds of jobs were filed at
For one city
- B4-1.3-05, Improvements Section of the Appraisal Report — Fannie Mae Selling Guide (accessed 2026-10-23)
- 2025 Remodeling Impact Report — National Association of REALTORS Research Group (2025-04-09; accessed 2026-10-23)