ADU Rules: Fall River vs Somerset
How do adu rules rules compare between Fall River, MA and Somerset, MA?
Fall River and Somerset have similar restriction levels.
Fall River, MA
Bristol County
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. Fall River Mayor Coogan raised concerns about the law but it applies regardless. ADUs must have a separate entrance and cannot exceed half the principal dwelling's floor area or 900 sq ft.
View full Fall River rules →Somerset, MA
Bristol County
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 in all Bristol County municipalities. Towns cannot prohibit ADUs or impose owner-occupancy requirements. Both attached and detached ADUs are permitted under the state framework.
View full Somerset rules →Key Facts Comparison
| Fact | Fall River | Somerset |
|---|---|---|
| State Law | Ch. 358 Acts of 2024 — by right | Ch. 358 Acts of 2024 — by right |
| Max Size | 900 sq ft or 50% of principal dwelling | 900 sq ft or 50% of principal dwelling |
| Effective Date | February 2, 2025 | - |
| Owner Occupancy | Cannot be required by municipality | Cannot be required |
| Applies Countywide | - | All municipalities must allow |
Highlighted rows indicate differences between cities.
Fall River FAQ
Can I build an ADU on my property in Fall River?
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. Fall River Mayor Coogan raised concerns about the law but it applies regardless. ADUs must have a separate entrance and cannot exceed half the...
What are the size limits for an accessory dwelling unit in Fall River?
State Law: Ch. 358 Acts of 2024 — by right. Max Size: 900 sq ft or 50% of principal dwelling. Effective Date: February 2, 2025. Owner Occupancy: Cannot be required by municipality.
Somerset FAQ
Can I build an ADU on my property in Bristol County?
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 in all Bristol County municipalities. Towns cannot prohibit ADUs or impose owner-occupancy requirements. Both attached and detached ADUs are permitted under the...
What are the size limits for an accessory dwelling unit in Bristol County?
State Law: Ch. 358 Acts of 2024 — by right. Max Size: 900 sq ft or 50% of principal dwelling. Applies Countywide: All municipalities must allow. Owner Occupancy: Cannot be required.
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