ADU Rules: Pepperell vs Waltham
How do adu rules rules compare between Pepperell, MA and Waltham, MA?
Pepperell and Waltham have similar restriction levels.
Pepperell, MA
Middlesex County
Under the 2024 MA Affordable Homes Act (MGL c.40A s.3A), ADUs up to 900 sq ft are allowed by-right on every single-family lot in Middlesex County. No owner-occupancy or special permit required.
View full Pepperell rules →Waltham, MA
Middlesex County
Waltham must permit Accessory Dwelling Units by-right under the 2024 Massachusetts Affordable Homes Act (MGL c.40A s.3A). ADUs up to 900 sq ft are allowed on single-family lots without special permits.
View full Waltham rules →Key Facts Comparison
| Fact | Pepperell | Waltham |
|---|---|---|
| State Law | MGL c.40A s.3A (Feb 2025) | - |
| Max Size | 900 sq ft or 50 percent | - |
| Owner-Occupancy | Not required | - |
| Parking Max | 2 spaces max | - |
| Review Type | By-right, no special permit | - |
| Governing law | - | MA Affordable Homes Act 2024 / MGL c.40A |
| Effective date | - | February 2, 2025 statewide |
| Max size | - | 900 sq ft or 50 percent of primary |
| Approval | - | By-right, standard building permit |
| Owner occupancy | - | Cannot be required |
Highlighted rows indicate differences between cities.
Pepperell FAQ
Can I build an ADU on my lot in Middlesex County?
Yes. As of February 2025, the Affordable Homes Act requires all MA municipalities to allow ADUs by right on single-family lots up to 900 sq ft.
Do I have to live on the property?
No. The statewide ADU law prohibits owner-occupancy requirements, so you can rent both units.
Waltham FAQ
Can I build an ADU in Waltham without a special permit?
Yes. Since February 2025, ADUs up to 900 sq ft are allowed by-right on single-family lots under state law.
Can I Airbnb my Waltham ADU?
The state law allows cities to prohibit short-term rentals (under 30 days) of ADUs. Check Waltham's current short-term rental rules.
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