Build an ADU in Mason.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Mason — 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 Mason zoning ordinance · source · 2026-07-07
- Front
- 35 ft
- Side
- 35 ft
- Rear
- 35 ft
- Max coverage
- —
- Min lot
- 174,240 sf (~4.00 ac)
The townwide default district ('mainly a District of farms, dwellings and woodlands'); its boundaries are the entire town except the VR and HP village areas (Art XV.C), so most single-family homes are here.
- Front
- 35 ft
- Side
- 35 ft
- Rear
- 35 ft
- Max coverage
- —
- Min lot
- 88,000 sf (~2.02 ac)
Village district around Mason village ('mainly a District of dwellings'); permitted use is one-family year-round, seasonal or farm dwelling plus home occupations and accessory buildings (Art V.A.1-5). One setback standard covers all three yards: 'No building shall be located…
- Front
- 35 ft
- Side
- 35 ft
- Rear
- 35 ft
- Max coverage
- —
- Min lot
- 88,000 sf (~2.02 ac)
Small district protecting the historic village core (boundaries in Art XV.B). Art V.C.1 grants 'any use permitted in the VR District subject to the same provisions of use and area', so all VR dimensional standards apply by reference: 88,000 sq ft min lot, 200 ft frontage, and…
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Mason 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 Mason (Hillsborough County). A detached ADU can be up to 950 sf.
In Mason's GRAF zone, ADUs follow the single-family setbacks: 35 ft front, 35 ft side, and 35 ft rear. Mason has 3 zoning districts in total — see the full table below. Confirm your exact zone with the town.