North Hempstead, NY Accessory Structures: ADU Rules (2026)

Town Code § 70-231 defines a mother-daughter residence as a one-family home altered to include an apartment approved by conditional use permit under § 70-225B(6). Nine conditions must all be met: the apartment cannot exceed 700 gross square feet; cooking facilities inside it cannot exceed 60 square feet; the fee owner must reside on the premises; the apartment occupant must be the fee owner's parent or child; the home cannot have a separate exterior entrance serving only the apartment; there can be no exterior stairway to the second floor; the building can have only one interior staircase running between any two floors; the property can carry only one meter per utility; and no exterior deck may be attached above ground level.

Because these are conjunctive conditions, adding a private entrance, a second interior stairway, or a second gas meter disqualifies the unit even if the square footage limits are respected. Applicants file with the Board of Zoning and Appeals; under § 70-225B(6)(a), the standard 300-foot property-owner mailed-notice requirement of § 70-225B(3) does not apply to mother-daughter applications, but the applicant must instead obtain written consents from, or give written notice to, all adjoining property owners. A mother-daughter residence legally operating with a valid permit as of April 1, 1997, is treated as a legal nonconforming use, but any structural work done after that date must bring the unit into conformance with the current § 70-231 conditions.

Because North Hempstead's zoning code has no separate accessory-apartment or garage-apartment permit track outside this mother-daughter framework, a garage or basement conversion rented to an unrelated tenant is not authorized under this provision.