Build an ADU in Sandown.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Sandown — 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 Sandown zoning ordinance · source · 2026-07-07
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 10 ft
- Max coverage
- —
- Min lot
- 40,000 sf (~0.92 ac)
The town's principal (and only) residential district - 'Zone A is everything not located in Zone BE' (Art II Part B Sec 2). Front setback 30 ft measured from the EDGE of the public right-of-way providing frontage (not centerline) (Art III Part A Sec 1.A).
- Front
- 35 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- 75% impervious
- Min lot
- 40,000 sf (~0.92 ac)
Corridor district along Main Street (extends 1000 ft from the road centerline; Art I Part D Sec 1). Setbacks per Art II Part E Sec 4: frontage setback at least 35 ft, side and rear at least 20 ft; side/rear setbacks abutting residentially zoned lots must be at least 75 ft…
- Front
- —
- Side
- —
- Rear
- —
- Max coverage
- —
- Min lot
- —
OVERLAY district (adopted 1984), not a base zone - covers poorly/very poorly drained soils, ponds, marshes and perennial streams per the Town Wetland Conservation District Map. No structures are permitted on wetland soils, so no building setback/lot standards are stated.
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Sandown 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 Sandown (Rockingham County). A detached ADU can be up to 950 sf.
In Sandown's A zone, ADUs follow the single-family setbacks: 30 ft front, 15 ft side, and 10 ft rear. Sandown has 3 zoning districts in total — see the full table below. Confirm your exact zone with the town.