Let Us Construct Your Accessory Dwelling Unit

An ADU is a secondary housing unit on the same property as a main residence. ADUs are designed to be fully functional living spaces, which means they include their own kitchen, sleeping, and bathroom facilities.

Yes, as of February 2, 2025, you are generally allowed to build an Accessory Dwelling Unit-also known as an in-law suite, granny flat, or tiny home-on your property in Massachusetts, provided its in a single family zoning and meets state guide lines.

 Must be on the same lot as a principal single-family home in a zoning district that allows single-family dwellings by right or special permit. This applies to non-conforming lots too- no minimum lot size required.

• Size: Up to 900 square feet or 50% of the primary home's livable floor area (whcichever is less). Larger units may require a special permit.
• Types:  Can be attached (e.g., addition to the main house), detached (e.g. backyard cottage), or internal e.g., converted basement, attic, or garage).

No owner-occupancy requirement for the ADU or primary home, and you can rent it out long-term. Short-term rentals are allowed only if your town permits them for single-family homes (e.g., Airbnb).

Must comply with state health/safety laws like the building code, Fire Code, Title 5 septic standards, and lead laws. Shared septic/electric/water is fine unless state rules mandate upgrades (e.g., for capacity). No stricter local rules allowed beyond state minimums.

At most one additional space required; none if within 0.5 miles of public transit (commuter rail, subway, bus, or ferry).

Only one ADU per lot by right; additional ones need a special permit. It can't be used to subdivide the lot or convert to a condo without following separate laws.