Boston ADU Bylaw Analysis
NOT UPDATEDProvision-by-provision analysis of Boston's ADU bylaw against Massachusetts Chapter 150 and 760 CMR 71.00. 2 inconsistent provisions identified.
Boston Bylaw Consistency
Boston Zoning Code (BPDA Citywide ADU Program, ongoing zoning updates) · Last updated Ongoing (BPDA zoning updates)
Last reviewed: February 15, 2026
Note: Boston is the only municipality in Massachusetts exempt from G.L. c. 40A. The statewide ADU by-right law does not apply here. Boston has its own ADU programs including a $7,500 design grant and 0% loans up to $50K.
What This Means
Boston is exempt from the state ADU law entirely — it’s the only municipality in Massachusetts that doesn’t operate under G.L. c. 40A. Owner-occupancy is required and workshop attendance is mandatory, but internal, attached, and detached ADUs are all allowed. The zero-interest loan program (up to $50K for income-eligible homeowners) is a genuine advantage.
Permit Activity
44 of 69 approved (64%)Share of 2025 applications approved in 2025
Data Provenance
Reviewed: February 15, 2026
AG action: None
Bylaw source: Zoning Code · retrieved February 19, 2026
Version date not published; analysis based on publicly available text retrieved February 19, 2026
10 provisions analyzed against Chapter 150
Full Compliance Analysis Available
We've mapped 10 provisions in Boston's ADU bylaw against Massachusetts Chapter 150. Enter your details to get the full provision-by-provision analysis.