ADU rules in Yonkers

Yonkers allows no detached backyard ADU anywhere in the city. The Zoning Ordinance's only accessory apartment definition (§ 43-8) is 'an apartment unit that has been added onto, or created within, and is accessory to a single-family detached dwelling,' which excludes a freestanding cottage, and § 43-22B(4) states flatly that an accessory apartment 'shall be located only within the principal dwelling building.' Table 43-1's Residential Accessory Uses schedule lists no accessory apartment, accessory dwelling or second dwelling in any of the 17 districts it covers, and § 43-27 provides that any use not specifically listed as permitted is prohibited. Detached accessory structures are separately capped at one story or 15 feet (§ 43-40D(3)) and the enumerated list of permitted accessory residential structures in § 43-41 runs from decks to pigeon coops without any habitable unit. The only route to a detached second unit is a use variance from the Zoning Board of Appeals under § 43-85, which requires proof of unnecessary hardship.

New attached, basement or internal accessory apartments are prohibited too. Section 43-22 is titled 'Preexisting accessory apartments' and only protects units that already existed when the Zoning Ordinance was adopted on 9-19-2000: subsection A continues units that already held a certificate of occupancy, subsection B provides a one-time legalization path for undocumented preexisting units whose owners applied within 60 days of adoption, and subsection C prohibits every accessory apartment that does not meet A or B. Because Table 43-1 never lists an accessory apartment as a permitted or special-permit accessory use, § 43-27's catch-all makes a newly created internal unit an illegal use regardless of how it is built. A homeowner who converts a basement or attic without approval is exposed to enforcement under § 43-153, and no certificate of occupancy can issue for it (§ 43-152A(1)).

Because the ordinance authorizes no new accessory apartments, it sets no square-footage or percent-of-house cap. The only size controls apply to units continued under the § 43-22 grandfather clause: § 43-22B(8) limits an accessory apartment to no more than two bedrooms, § 43-22B(7) allows no more than one accessory apartment per lot, and § 43-22B(6) requires the lot and all structures on it to conform to the bulk requirements of the district (Table 43-3). If a homeowner instead wins a use variance to become a legal two-family, the unit is sized by the district's dimensional standards rather than by any ADU rule. For reference, detached accessory structures generally may not exceed one story or 15 feet and, together, may not cover more than 60% of the rear yard or 75% of the rear and side yards combined (§ 43-40D(2) and (3)).

Owner occupancy is a continuing condition, not a one-time filing. Both § 43-22A and § 43-22B(5) require that the owner of the lot 'occupy and maintain the principal dwelling building on that lot as his or her primary residence,' and § 43-22A conditions the relatives-only occupancy right on that continuing residence. The Department of Housing and Buildings' Standard Accessory Apartment Affidavit makes the owner swear to living in the house, to naming the relative occupants, and to the fact that on a sale the property will be 'offered and sold only as a ONE FAMILY DWELLING,' with occupancy by anyone other than the new owners unlawful unless a new application for 'Accessory Apartment Status' is approved before occupancy. New York has no statewide ADU statute and no preemption of local owner-occupancy rules, so nothing overrides this.

Section 43-22B(9) requires that the lot holding an accessory apartment 'provide at least two off-street parking spaces,' the same figure Table 43-4 assigns to a single-family detached dwelling, so a lawful grandfathered unit adds no space beyond the normal two. Table 43-4 sets 2 spaces per dwelling unit for two-family and three-family dwellings, so converting to a legal two-family requires four; Zoning Board of Appeals Case #5840 (59 Virginia Place, resolution dated February 22, 2024) had to grant a one-space parking variance for exactly that reason. There is no transit-proximity or small-unit reduction that reaches single-family neighborhoods: the reduced-parking provisions in §§ 43-137 through 43-139 apply to apartment houses, live-work buildings and downtown or D-MX tracts. Section 43-127 bars any certificate of occupancy until required parking is actually established.

None of permitted, conditional-use or varies describes Yonkers, because there is no approval pathway for a new ADU at all. Table 43-1 lists accessory apartments neither as a permitted accessory use (P or Ps) nor as a special use (S) in any district, and § 43-27 prohibits unlisted uses, so a special use permit under Article VII is not available. The only administrative permit that touches accessory apartments is the § 43-22B(1)(a) certificate of occupancy application to the Commissioner of the Department of Housing and Buildings for a preexisting unit, made on department forms with the Standard Accessory Apartment Affidavit and an interior inspection; that is a legacy legalization and transfer process, not a way to create a unit. Anything new needs a discretionary use variance from the Zoning Board of Appeals under § 43-85, which demands proof that no permitted use yields a reasonable return, that the hardship is unique and not self-created, and that neighborhood character is preserved.

Section 43-22A and § 43-22B(10) limit occupancy of a lawful accessory apartment to the lot owner's or spouse's parents, children, grandchildren, siblings, and nephews and nieces, while the owner lives in the principal dwelling. The Department of Housing and Buildings affidavit spells out the consequence: 'No rent will be charged' to the named relatives, and 'The Accessory Apartment will not be rented out'; if the relatives move out the unit reverts to the owners' own use. The unit cannot be sold separately, since the house may be sold only as a one-family dwelling. Yonkers has no short-term rental ordinance: a phrase search of the entire City Code for 'short-term rental' returns zero results, and Chapter 39 (adopted 6-23-2021 by L.L. No. 9-2021) licenses hotels and motels offering 'transient lodging accommodations to the general public,' not homes. Because transient lodging is not a listed residential use, § 43-27 makes short-term renting of an accessory apartment prohibited in residence districts as well.