ADU Rules in Arlington, MA
Arlington follows the Massachusetts state baseline with local regulations.
MEDIUM Confidence Data
MA
State Baseline: Affordable Homes Act
Up to 900 sq ft or 50% of principal dwelling (whichever is smaller). By-right approval statewide.
Zoning Districts
R0 — Residential R0
Low-density single-family residential
Default Zone
| Type | Approval | Max Size | Height | Parking | Owner Occ. |
|---|---|---|---|---|---|
| Detached ADU | By Right | 900 sq ft | 15 ft | 1 space | No |
| Attached ADU | By Right | 900 sq ft | 25 ft | 1 space | No |
| Interior Conversion | By Right | 900 sq ft | — | None | No |
R1 — Residential R1
Single-family residential
| Type | Approval | Max Size | Height | Parking | Owner Occ. |
|---|---|---|---|---|---|
| Detached ADU | By Right | 900 sq ft | 15 ft | 1 space | No |
| Interior Conversion | By Right | 900 sq ft | — | None | No |
R2 — Residential R2
Two-family residential
| Type | Approval | Max Size | Height | Parking | Owner Occ. |
|---|---|---|---|---|---|
| Interior Conversion | By Right | 900 sq ft | — | None | No |
Transit Stations
Properties near transit stations may qualify for parking exemptions.
Alewife (nearby)
SUBWAY
Arlington Center (bus)
BUS RAPID