Attleboro, MA Accessory Structures: ADU Rules (2026)
ADU rules in Attleboro, MA, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- State Law
- Ch. 358 Acts of 2024: by right
- Max Size
- 900 sq ft or 50% of principal dwelling
- Types
- Attached, internal, or detached
- Owner Occupancy
- Cannot be required by municipality
Summary
Under Massachusetts law (Ch. 358 of Acts of 2024, effective Feb 2025), ADUs under 900 sq ft are allowed by right on single-family lots statewide, including Attleboro. ADUs must have a separate entrance and cannot exceed 900 sq ft or half the principal dwelling area. Both attached and detached ADUs are permitted.
No zoning ordinance or by-law shall prohibit, unreasonably restrict or require a special permit or other discretionary zoning approval for the use of land or structures for a single accessory dwelling unit, or the rental thereof, in a single-family residential zoning district; provided, that the use of land or structures for such accessory dwelling unit under this paragraph may be subject to reasonable regulations, including, but not limited to, 310 CMR 15.000 et seq., if applicable, site plan review, regulations concerning dimensional setbacks and the bulk and height of structures and may be subject to restrictions and prohibitions on short-term rental, as defined in section 1 of chapter 64G.
Full Breakdown
Massachusetts enacted ADU provisions as part of the 2024 Affordable Homes Act, building on MGL c.40A §3 and the MBTA Communities Act. Single-family homeowners may create one ADU by right. Municipalities cannot prohibit ADUs on single-family lots. This is a recent mandate and implementation is still developing across municipalities. Attleboro may adopt reasonable regulations including size limits, setbacks, and design standards but cannot effectively ban ADUs.
Violations & Fines
Municipalities cannot deny conforming ADU applications. Unpermitted ADU: standard building code enforcement under 780 CMR.
Frequently Asked Questions
Can I build an ADU on my property in Attleboro?
What are the size limits for an accessory dwelling unit in Attleboro?
Sources & Official References
Other rules in Attleboro
How Attleboro compares: Easiest Cities to Build an ADU·Compare Attleboro to another location·View the Massachusetts accessory structures overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.
ADU Rules in Nearby Cities
How other cities in Bristol County handle adu rules.