Build an ADU in New Boston.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in New Boston — by-right. A detached ADU can be up to 950 sf, and ADU setbacks match your lot's single-family setbacks.
6 districts
Each district's single-family setbacks — which your ADU follows. The primary residential district is highlighted.
Verified against the official New Boston zoning ordinance · source · 2026-07-07
- Front
- 50 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- 30% building
- Min lot
- 87,120 sf (~2.00 ac)
The town's dominant low-density rural residential district; one/two-family dwellings and ADUs are permitted uses. Frontlot minimum 2 acres (87,120 sf); BACKLOTS are allowed at 5 acres with a 50-ft frontage strip (driveway-capable) and have NO front-yard requirement (table…
- Front
- 50 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- 30% building
- Min lot
- 65,340 sf (~1.50 ac)
Mixed-type residential district near the village with better soils/roads; one-family, two-family and multi-family dwellings plus ADUs are permitted uses. One-family: 1.5 acres (65,340 sf) min lot, 150 ft frontage, 50/20/20.
- Front
- 50 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- 30% building
- Min lot
- 15,000 sf (~0.34 ac)
A manufactured housing PARK must be at least 15 acres; each manufactured housing SPACE within a park must be at least 15,000 sf (>=150 ft wide x >=100 ft deep) fronting an access road. Unit setbacks: no unit closer than 50 ft to a public street right-of-way; units incl…
- Front
- 50 ft
- Side
- 20 ft
- Rear
- 40 ft
- Max coverage
- 70% building
- Min lot
- 130,680 sf (~3.00 ac)
Commercial district (renamed Small Scale Planned Commercial; section amended 3/10/2026). Min lot 3 acres (130,680 sf); each lot must accommodate a 200-ft minimum square at the front 50-ft setback line.
- Front
- 50 ft
- Side
- 40 ft
- Rear
- 40 ft
- Max coverage
- 70% building
- Min lot
- 130,680 sf (~3.00 ac)
Light-industrial district. Min lot 3 acres (130,680 sf); each lot must accommodate a 200-ft minimum square at the front 50-ft setback line.
- Front
- 50 ft
- Side
- 75 ft
- Rear
- 75 ft
- Max coverage
- 30% building
- Min lot
- 1,089,000 sf (~25.00 ac)
Large-tract conservation/forestry district; ONE-FAMILY DWELLINGS ARE A PERMITTED USE (unlike many towns' conservation zones). Min lot 25 acres (1,089,000 sf); each lot must accommodate a 200-ft minimum square at the front 50-ft setback line.
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
New Boston 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 New Boston (Hillsborough County). A detached ADU can be up to 950 sf.
In New Boston's R-A zone, ADUs follow the single-family setbacks: 50 ft front, 20 ft side, and 20 ft rear. New Boston has 6 zoning districts in total — see the full table below. Confirm your exact zone with the town.