New ADU regulations address affordable housing shortage

A yellow accessory dwelling unit resembling a small house with a red door at night. The ADU's windows glow from warm lighting inside, giving it a cozy feeling. — PHOTO COURTESY OF BACKYARD ADUS.

more flexible accessory dwelling unit regulations go into effect 2024

Update 06/30/2023: The deadline for municipalities to comply with the new ADU legislation has been extended from July 1, 2023 to January 1, 2024 for municipalities with Town Council form of governments, and to July 1, 2024 for municipalities with Town Meeting governance.

ACCORDING to a February 2023 report by the Maine Affordable Housing Coalition, Maine is short approximately 25,000 affordable housing units, with only a small percentage of that number being added each year. Last year, the state adopted new affordable housing legislation (LD 2003) that aims to address this shortfall by loosening zoning restrictions on accessory dwelling units (ADUs). Accessory dwelling units are smaller, independent residential dwelling units located on the same lot as a standalone single-family home. The regulations go into effect January 1, 2024 for municipalities with Town Council form of governments and July 1, 2024 for municipalities with Town Meeting governance.

There are many elements of the new ADU legislation; here are some of the most notable:

The new law allows up to two dwelling units on plots zoned for single-family use and up to four for undeveloped parcels. Cities and towns are permitted to set ADU requirements that are less restrictive than the law provides, which means, for example, that they could allow more than one ADU per lot or permit one on a property that already has a two-family or multifamily home.

Where can ADUs be placed on a property? The new law is flexible: they can be within existing homes (such as a basement or second floor), attached to a home, in new structures or created from an accessory structure on the property, like a barn. Though municipalities can set a maximum size for ADUs, they must be at least 190 square feet in size. Homeowners will not need to provide additional parking for an ADU on their property.

The setback and size of an ADU will be determined by the local requirements for single-family homes and accessory structures—unless the town decides to make them more permissive.