ADU Rules: Holbrook vs Wellesley
How do adu rules rules compare between Holbrook, MA and Wellesley, MA?
Holbrook and Wellesley have similar restriction levels.
Holbrook, MA
Norfolk County
Massachusetts 2024 Affordable Homes Act (MGL c. 40A §3) grants property owners the right to build ADUs on owner-occupied lots by right. Cities and towns cannot ban ADUs but may regulate size (up to 900 sq ft for internal ADUs). Norfolk County has no additional ADU rules.
View full Holbrook rules →Wellesley, MA
Norfolk County
Wellesley regulates ADUs under Section 5.13 of the Wellesley Zoning Bylaw. At the April 2025 Annual Town Meeting, Wellesley adopted Article 40.1 to amend its ADU bylaw, and the Massachusetts Attorney General approved the changes effective April 15, 2025. As of April 15, 2025, detached ADUs are permitted by-right in Single Residence Districts; a Special Permit is no longer required, consistent with the state Affordable Homes Act.
View full Wellesley rules →Key Facts Comparison
| Fact | Holbrook | Wellesley |
|---|---|---|
| State Law | MGL c. 40A §3 — Affordable Homes Act 2024 | - |
| ADUs by Right | Yes — on owner-occupied single-family lots | - |
| Max Size (Internal) | Up to 900 sq ft (municipalities may limit) | - |
| Bans Allowed? | No — cities cannot ban ADUs under new state law | - |
| County ADU Rule? | None — regulated by state law and each town | - |
| Local Code | - | Wellesley Zoning Bylaw §5.13 |
| Amendment | - | Art. 40.1 (April 2025 ATM) |
| AG Approval | - | April 15, 2025 |
| Detached ADUs | - | By-right (no Special Permit) |
| Annual Certificate | - | Required from Planning Dept. |
Highlighted rows indicate differences between cities.
Holbrook FAQ
Can I build an ADU on my property in Norfolk County?
Massachusetts 2024 Affordable Homes Act (MGL c. 40A §3) grants property owners the right to build ADUs on owner-occupied lots by right. Cities and towns cannot ban ADUs but may regulate size (up to 900 sq ft for internal ADUs). Norfolk County has no additional ADU rules.
What are the size limits for an accessory dwelling unit in Norfolk County?
State Law: MGL c. 40A §3 — Affordable Homes Act 2024. ADUs by Right: Yes — on owner-occupied single-family lots. Max Size (Internal): Up to 900 sq ft (municipalities may limit). Bans Allowed?: No — cities cannot ban ADUs under new state law.
Wellesley FAQ
Are detached ADUs allowed by-right in Wellesley?
Yes, as of April 15, 2025. The Massachusetts Attorney General approved Wellesley's Article 40.1 bylaw amendment, removing the Special Permit requirement for detached ADUs in Single Residence Districts. A building permit and annual Certificate of Compliance are still required.
How big can a Wellesley ADU be?
Under §5.13 and the MA Affordable Homes Act (G.L. c. 40A as amended), an ADU is capped at 900 sq ft or 50% of the primary dwelling's gross floor area, whichever is smaller.
Does Wellesley require an annual filing for ADUs?
Yes. Wellesley §5.13 requires an annual Certificate of Compliance (Notice of Accessory Unit) from the Planning Department in addition to the initial building permit from the Inspector of Buildings.
Compare other topics
See how Holbrook and Wellesley compare on other ordinance categories.
Want to add a third city?
Use our full comparison tool to compare up to three cities.
Open Comparison Tool