Accessory Dwelling Units

New ordinance language for accessory dwelling units (ADUs) became effective April 20, 2023. Property records of all in-law apartments will be converted to accessory dwelling units, and new ADUs may be constructed with a building permit. Accessory dwelling units are self-contained residential units located within, attached to or detached from a single-family dwelling unit or mobile home located on the same parcel of land. These are designed to provide more flexibility for property owners compared to in-law apartments, and can function similarly to a two-family dwelling unit, with notable space and occupancy restrictions. ADUs are permitted only on lots with a principal dwelling, are limited to 900 sf maximum size, and either the principal dwelling or ADU must be owner occupied. For more information, see the below attachments, or contact the Department of Planning and Code Enforcement at 207-513-3125 /  

Example: detached ADU

Example: ADU above attached garage

Additional Resources

ADU Fact Sheet

ADU Ordinance- Article XII, Section 11, Accessory Dwelling Unit