ADU Requirements in Marlborough, MA

Marlborough is located in Middlesex County, Massachusetts. Under the 2024 Affordable Homes Act, homeowners in Marlborough can now build accessory dwelling units (ADUs) up to 900 square feet by-right, meaning no special permit is required for compliant projects.

An ADU in Marlborough can be a detached backyard cottage, an attached addition, or a conversion of existing space like a basement or garage. These units are perfect for housing aging parents, adult children, or generating rental income.