Yonkers, NY Accessory Structures: ADU Rules (2026)

Section 43-22 governs accessory apartments that already existed before this chapter's adoption; it does not create a general path to build a brand-new accessory apartment citywide. Subsection A covers apartments that already hold a valid certificate of occupancy or certificate of completion: those may continue, subject to occupancy conditions. Subsection B covers apartments that existed before adoption but were never issued a certificate of occupancy; those can be legalized only by filing a complete application with the Commissioner of the Department of Housing and Buildings within 60 days of the chapter's adoption, allowing inspection of both the apartment and the principal dwelling, and meeting nine additional standards: the apartment must sit in a district where single-family detached dwellings are permitted, on a lot where a single-family home is the principal use, entirely inside that principal building, with the owner occupying the house as a primary residence, full compliance with the district's bulk rules, no more than one accessory apartment per lot, no more than two bedrooms, at least two off-street parking spaces, and occupancy limited to a defined list of relatives.

Any accessory apartment that fails to meet either subsection A or B, and that has no certificate of occupancy, is flatly prohibited under Section 43-22C.