MA · State directory
Massachusetts ADU rules
Official accessory dwelling unit regulations for 15 jurisdictions in Massachusetts, plus statewide law.
Not sure which city yet?
We have read the ordinances for 15 Massachusetts cities and lined them up side by side: detached vs internal, size limits, owner occupancy, and approval process.
Statewide ADU law
Massachusetts has state-level ADU legislation that applies across local jurisdictions. Local rules below may add requirements on top of state law.
- malegislature.govOfficial sourceVerified August 2026https://malegislature.gov/Laws/GeneralLaws/PartI/TitleVII/Chapter40A/Section3
- mass.govOfficial sourceVerified August 2026https://www.mass.gov/info-details/mass-general-laws-c40a-ss-1a
- mass.govOfficial sourceVerified August 2026https://www.mass.gov/info-details/accessory-dwelling-units
Cities
Amherst5 sources · verified August 2026Barnstable5 sources · verified August 2026Boston4 sources · verified July 2026Brockton3 sources · verified August 2026Cambridge6 sources · verified August 2026Easthampton5 sources · verified August 2026Lowell3 sources · verified August 2026New Bedford3 sources · verified August 2026Newton5 sources · verified August 2026Northampton4 sources · verified August 2026Pittsfield4 sources · verified August 2026Quincy5 sources · verified August 2026Somerville6 sources · verified August 2026Springfield4 sources · verified August 2026Worcester3 sources · verified August 2026
Don't see your Massachusetts city?
Tell us which city you need and we'll prioritize adding its official rules to the directory.
Request a cityReady to build?
Planning an ADU in Massachusetts?
Tell us about your project and we'll match you with vetted local designers and builders as we bring them online. No cost, no obligation.