What did Brookline adopt in 2026?
Town Meeting approved Article 14 by a vote of 234 to 1 with 3 abstentions, certified by the Town Clerk on May 29, 2026. It aligns Brookline's zoning by-law with the Affordable Homes Act and adds a "Protected Use ADU" category.
How big can a Brookline ADU be?
- Up to half the habitable gross floor area of the main home or 900 sq ft, whichever is less, by right.
- Up to 950 sq ft by special permit.
- A new detached ADU's footprint is capped at 600 sq ft in the S-0.75P, S-4, S-7, SC-7, T, F and M districts, and 700 sq ft in S-10 and SC-10.
How tall, and how close to the lot line?
A new or expanded detached ADU can be up to 22 feet tall. It must meet the house's side setback and half its rear setback and cannot sit in the front yard. A special permit can reduce the side setback to 10 feet, or 7.5 feet in certain districts, with screening along the lot lines where setbacks are not met by right.
What else should I know?
- Parking: no off-street parking is required for a protected-use ADU.
- Short-term rentals: not allowed in either the house or the ADU. See our rental guide.
- Ownership: the ADU cannot be sold separately or turned into a condominium.
- Building age: a building must be at least five years old before a permit to create an ADU in it is issued.
Is a by-right ADU enough for my plans?
It depends on the house. On a large home, the 900 sq ft cap is the limit; on a smaller one, the half-the-house rule binds first. If you need the extra 50 sq ft or a reduced setback, that means a special permit. The Green Line B, C and D branches run through Brookline, which helps with transit-related questions. We lay out the by-right and special-permit versions for you.
Related
As of October 2026. Source: Town of Brookline, Article 14 vote certified May 29, 2026; Mass.gov ADU guidance.
Check your Brookline lot
Send your address. We apply the Article 14 limits for your district before design.