What this is
The Garage Apartment is a concept. It is an original idea we drew for lots where the best place for a second home is above the cars. It is not a finished build and it is not an approved plan. A real version starts with your lot, your town’s rules and drawings from a licensed designer.
The plan on this page shows the upper floor only. The garage below is not counted in the interior area.
Who it suits
It suits an adult child or a long-term tenant who is fine with stairs. It is a poor fit for anyone who may need a walker or a wheelchair later. For that, look at the Stay Cottage instead.
It also suits a tight lot. Many zoning codes limit lot coverage, meaning how much of your lot buildings may cover. Stacking the home on top of the garage uses the same patch of ground for both, and building over a garage you already have adds no new footprint at all. The catch is that an existing garage often needs structural work to carry a second floor (Angi, 2026), and sometimes it is simpler to rebuild it.
How it lives
An enclosed stair climbs from its own door at ground level, so nobody walks through the garage or out into the snow to get home. At the top, the living room and kitchen share the front of the floor. A short hall leads back to the bathroom, a laundry closet and the bedroom.
Headroom drives this design. A habitable room needs a ceiling at least 7 feet high (2025 Residential Code of New York State, sec. R313.1), and floor under a sloped ceiling lower than 5 feet does not count toward a room’s minimum size (2025 Residential Code of New York State, sec. R312.3). Raised side walls and dormers keep most of the floor usable instead of losing the edges under the roof slope.
What changes the cost
- New or added on. Adding a floor to an existing garage reuses its foundation, though the footings and framing may need strengthening. Building new means paying for a new foundation, but you start from known conditions.
- The floor between. The garage is cold, so the apartment floor needs full insulation. Expect your designer and code office to spell out the fire-resistant construction between the cars and the living space.
- Stair and roof. An enclosed stair and a roof framed for headroom both add cost compared with a one-level cottage.
- Utilities. Water, sewer or septic, and power still have to reach the garage, in trenches kept from freezing.
What to check with your town
- Height limits. Some towns cap how tall a detached ADU can be. The City of Rochester’s draft zoning code, which is not law yet, would cap a detached ADU at 15 feet or the height of the house, whichever is lower (City of Rochester, draft zoning code, April 2026). A two-story garage apartment cannot fit under a cap like that.
- Where it sits. The Village of Pittsford requires an ADU in a detached garage to be in the rear yard, with at least 500 square feet of living space, by special use permit (a permit a board grants case by case, usually after a public hearing) (Village of Pittsford, sec. 210-24.3).
- Attached or detached. If the garage is attached to the house, the apartment counts as an attached unit, which needs walls and floors with a 1-hour fire rating between the two homes (2025 Residential Code of New York State, sec. R302.3).
- Owner occupancy. Many towns require the owner to live on the property. Pittsford asks for a notarized affidavit (Village of Pittsford, sec. 210-24.3).
Look up your area on the New York rules page, or start with the property checker.
What moves the price
- Building new, or adding a floor to an existing garage
- Fire separation and insulation between the garage and the apartment
- Stair, headroom and roof framing
- Distance to water, sewer or septic, and power
What to check in each municipality
A first comparison with the codes we’ve read. A listed restriction identifies a conflict with this concept. Other results require local confirmation; missing research does not mean a ban or approval. Your zoning district, your lot and the municipality’s review still decide.
| Municipality | Screen | Size rule | Checked |
|---|---|---|---|
| Town of Clarkson | Below the 600 sq ft one-bedroom minimum | No more than 30% of the main home's living space (unit minimums 450 sq ft efficiency, 600 sq ft one-bedroom) | October 4, 2026 |
| Village of Fairport | Detached restriction: Detached ADUs are prohibited | 650 sq ft | October 4, 2026 |
| Town of Penfield | Detached units are excluded from the researched in-law route | No more than 30% of the total area of the residence | October 4, 2026 |
| Village of Pittsford | Only within this code’s size limits; check them | No square-foot cap; house-size and structure-size tests apply | October 4, 2026 |
| Town of Canandaigua | Requires local confirmation of the district, size rule and approvals | No separate cap; the district's bulk and area rules for a single-family home apply | October 3, 2026 |
| Town of East Bloomfield | Family members only, so it can’t be rented, and a detached unit must be removed when family stops using it. Only within this code’s size limits; check them | Detached: 500 to 850 sq ft gross floor area. In-law apartment: no size cap found | October 3, 2026 |
| Town of Perinton | Detached restriction: Living in accessory buildings is barred in the covered residential districts | Not applicable | September 16, 2026 |
| City of Rochester | Rule change under study; confirm the current route with the municipality | Conversion: building at least 1,500 sq ft and lot at least 6,000 sq ft, plus unit minimums | October 4, 2026 |