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Accessory Dwelling Units

Accessory Dwelling Units (ADUs) are independent living facilities within or attached to a single-family dwelling. ADUs can also be incorporated into an accessory structure, such as a barn or garage, on lot with a single family dwelling. ADUs are often referred to as accessory apartments or in-law apartments. Accessory dwelling units are often considered an affordable living option for many, particularly young workers, students, and older adults. Many communities allow ADUs, often with a Conditional User Permit, where single family dwellings are permitted.

On March 16, 2016, Governor Hassan signed Senate Bill 146, New Hampshire’s Accessory Dwelling Unit (ADU) law, which takes effect on June 1, 2017. Communities should review any existing ADU ordinances to ensure compliance with the new law. Under the new law, an "accessory dwelling unit" is defined as a residential living unit that is within or attached to a single-family dwelling, and that provides independent living facilities for one or more persons, including provisions for sleeping, eating, cooking, and sanitation on the same parcel of land as the principal dwelling unit it accompanies. The resources listed below, including RPC's model ordinance, are intended to help communities comply with the new ADU law.