Build an ADU in Cornish.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Cornish — 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 Cornish zoning ordinance · source · 2026-07-07
- Front
- 30 ft
- Side
- 30 ft
- Rear
- 30 ft
- Max coverage
- 12% lot
- Min lot
- 87,120 sf (~2.00 ac)
Principal single-family residential district ('mainly districts of residences and woodlands which are more densely settled and have better access than the Rural District', Art III.A.1.b). Minimum lot size 2 acres = 87,120 sf (Table 5.1).
- Front
- 30 ft
- Side
- 30 ft
- Rear
- 30 ft
- Max coverage
- 4% lot
- Min lot
- 217,800 sf (~5.00 ac)
Largest-lot rural district ('mainly a district of farms, residences and woodlands', Art III.A.1.a). Minimum lot size 5 acres = 217,800 sf (Table 5.1). Two-family dwellings require 6 acres. Front setback 30 ft is measured from the road RIGHT-OF-WAY (r.o.w.), not the centerline…
- Front
- 30 ft
- Side
- 10 ft
- Rear
- 10 ft
- Max coverage
- 20% lot
- Min lot
- 43,560 sf (~1.00 ac)
Densest district: residences, commercial establishments, community buildings and neighborhood businesses (Art III.A.1.c). Minimum lot size 1 acre = 43,560 sf (Table 5.1). Two-family dwellings require 2 acres.
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Cornish 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 Cornish (Sullivan County). A detached ADU can be up to 950 sf.
In Cornish's Residential zone, ADUs follow the single-family setbacks: 30 ft front, 30 ft side, and 30 ft rear. Cornish has 3 zoning districts in total — see the full table below. Confirm your exact zone with the town.