Tonawanda, NY Accessory Structures: ADU Owner Occupancy (2026)

Beyond the size and placement standards for accessory dwelling units in § 215-24.3B, the Town Board added a separate owner-occupancy condition at § 215-24.3C to keep ADUs tied to owner-occupied single-family homes rather than becoming investor-owned duplex rentals. At least one of the dwellings on the lot, whether the primary house, the accessory dwelling unit, or the in-law suite, must be occupied by the property owner and maintained as that owner's primary residence. To prove it, the owner must sign an affidavit before a notary public affirming the property is their primary residence, and file that affidavit with the Code Enforcement Officer.

The obligation does not end at the first sale: whenever the property changes hands, the new owner has 30 days from the closing date to sign and submit a fresh notarized affidavit, so the occupancy condition is verified again with every transfer of title. The Town Board also closed off a common workaround by prohibiting the individual sale of an accessory dwelling unit or in-law suite apart from the single-family dwelling; the ADU cannot be carved off and sold or subdivided as its own parcel or condominium unit.

Together, the affidavit and no-separate-sale rules mean a Tonawanda ADU can only function as a secondary living space attached to an occupied single-family property, never as a stand-alone rental unit controlled by an absentee owner. The Code Enforcement Officer, who also administers Chapter 54's building permit process, keeps the filed affidavits on record and can request a new one whenever an ownership change is discovered.