Build an ADU in Brookline.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Brookline — by-right. A detached ADU can be up to 950 sf, and ADU setbacks match your lot's single-family setbacks.
3 districts
Each district's single-family setbacks — which your ADU follows. The primary residential district is highlighted.
Verified against the official Brookline zoning ordinance · source · 2026-07-07
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 88,000 sf (~2.02 ac)
Principal (and nearly town-wide) single-family district: all land not in the Industrial-Commercial or Downtown Village districts (601.00); single- and two-unit dwellings permitted (602.00.a). Front setback 30 ft from the FRONT LOT LINE (ROW line, not centerline — 'Setback' is…
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 88,000 sf (~2.02 ac)
Enumerated-lot village district around Main St/Meetinghouse Hill Rd/Milford St (610.04). SOLELY RESIDENTIAL uses must comply with the Sec 603.00 RA lot requirements (610.07), so the values recorded here for a residential/ADU project are the RA numbers: front 30 ft, side/rear…
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- 75% impervious
- Min lot
- 43,560 sf (~1.00 ac)
Commercial/industrial corridor along NH Route 13 plus enumerated lots (501.00). Front setback 30 ft from the front lot line; side/rear 15 ft; corner-lot side bordering the frontage increases to 25 ft (note: 25 ft here vs 30 ft in RA).
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Brookline ADU FAQ
Yes. Under NH RSA 674:71-73 (HB 577), one accessory dwelling unit is allowed by-right on single-family lots statewide, including Brookline (Hillsborough County). A detached ADU can be up to 950 sf.
In Brookline's RA zone, ADUs follow the single-family setbacks: 30 ft front, 15 ft side, and 15 ft rear. Brookline has 3 zoning districts in total — see the full table below. Confirm your exact zone with the town.