ADU rules in Rochester

Rochester's zoning code contains no accessory dwelling unit use of any kind: a full-text scan of Chapter 120 turns up zero occurrences of 'accessory dwelling', 'accessory apartment' or any synonym. The closest thing the code allows in a back yard is a 'guesthouse or servants quarters', which under §120-163A(1)(g) may not contain kitchen facilities and may not be used as a rental unit or for permanent occupancy as a dwelling. Every other detached residential accessory structure on the §120-163A(1) list (garage, shed, playhouse, pool house) is non-habitable, and detached accessory structures are capped at 15 feet in the residential districts. A separate dwelling in the back yard would need a use variance from the Zoning Board of Appeals, a very high bar under New York law.

There is no ADU category, but a second unit created inside or attached to an existing house is a 'dwelling unit conversion' and is allowed where two-family dwellings are a permitted use: the R-2 Medium-Density (§120-17C) and R-3 High-Density (§120-26C) Residential Districts. It is flatly barred in R-1 Low-Density, where §120-8 permits only single-family dwellings and §120-10 prohibits any conversion that increases the number of residential units. Even in R-2 and R-3 the conversion must clear all of §120-166: a lot of at least 6,000 sq ft, a building with at least 1,500 sq ft of habitable floor area, a minimum size for the new unit, and full off-street parking compliance. The definition of 'dwelling unit conversion' covers additions and enlargements, not just interior remodeling, so a bump-out addition holding the second unit is judged by the same standards.

Because Rochester regulates the added unit as a full second dwelling unit rather than as a subordinate accessory unit, §120-166A(1) sets floors rather than a ceiling: 500 sq ft of habitable floor area for a zero-bedroom unit, 650 for one bedroom, 800 for two, 950 for three, 1,100 for four, 1,250 for five. §120-166A(2) bars any conversion in a structure with less than 1,500 sq ft of habitable floor area, which rules out small bungalows entirely. The outer envelope comes from the district instead: in R-2, principal buildings are limited to 2 1/2 stories and 35 feet with 50% maximum lot coverage, and detached accessory structures to 15 feet.

Nothing in Chapter 120 conditions a two-family dwelling or a dwelling unit conversion on the owner living on the property; the only owner-occupancy rule in the zoning code applies to bed-and-breakfast establishments, defined in §120-208 as 'an owner-occupied and -operated dwelling'. New York has no statewide ADU statute, so nothing preempts the city either way. Owner occupancy does change inspection duties rather than zoning rights: under Property Code §90-16C an owner-occupied one-family dwelling, or an owner-occupied two-family outside the Lead Paint High-Risk Area, can apply to be exempted from the rental certificate of occupancy requirement, and the exemption lapses when the owner-occupant moves out. The pending draft zoning code would add a true owner-occupancy mandate for ADUs, but it is not law.

The §120-173C(1) table requires one off-street space per dwelling unit for single-family detached, semidetached, two-family and attached dwellings, and §120-166A(4) makes full compliance with §120-173 a precondition of any conversion that adds a unit, so a house that today has one legal space must add a second. There is no automatic transit-proximity waiver, but §120-173E allows an alternative parking plan: on-street spaces on an arterial or collector street within 1,000 feet can satisfy up to 20% of the requirement, a transit credit is available within 1,000 feet of a bus stop, and shared parking within 1,000 feet is eligible. Plans supplying five or fewer spaces are decided administratively by the Director of Zoning and Permitting; six or more need a special permit from the Planning Commission.

There is no ADU permit, so the path depends on the district and on whether the conversion standards are met. In R-2 or R-3, a conversion that satisfies every §120-166 standard is administrative: the Director of Zoning and Permitting issues a certificate of zoning compliance under §120-189 (required for any change in use or occupancy and for work needing a building permit), then the work needs a building permit and a fresh certificate of occupancy. A conversion that misses any §120-166 standard goes to the Zoning Board of Appeals on an unnecessary-hardship or area-variance showing under §120-195, which is a noticed discretionary hearing. In R-1, or for any detached unit anywhere, the only route is a use variance. Properties in a Preservation District or designated as Buildings of Historic Value also need a certificate of appropriateness from the Preservation Board.

Zoning puts no cap on renting a lawfully created second unit and imposes no owner-occupancy or minimum-lease rule. The constraint sits in Property Code Chapter 90: §90-16A requires a valid certificate of occupancy before any one-family or two-family dwelling may be occupied, and §90-16A(2)(e) forces one within 90 days whenever a one- or two-family stops being occupied by the owner or the owner's spouse, child, parent or sibling. The certificate follows a city inspection, lasts six years for a one- or two-family outside the Lead Paint High-Risk Area and three years inside it, and doubles as the Lead Safety Certificate for the New York State Lead Rental Registry under Public Health Law §1377. Owners must also register the building under §90-20. Rochester has no short-term rental licensing law anywhere in its Municipal Code as of legislation through 06-16-2026; the only overnight-lodging use inside a house is a bed-and-breakfast, an owner-occupied special permit use under §120-132.