Build an ADU in Monroe.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Monroe — 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 Monroe zoning ordinance · source · 2026-07-07
- Front
- 50 ft
- Side
- 30 ft
- Rear
- 30 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
Principal single-family residential (village) district; intent is to maintain residential development as single-family, two-family and complementary non-residential uses for a balanced village area (Sec 202.1).
- Front
- 50 ft
- Side
- 30 ft
- Rear
- 30 ft
- Max coverage
- —
- Min lot
- 87,120 sf (~2.00 ac)
Residential district generally in transition from open to residential, intended to keep rural character while providing residential and complementary non-residential uses (Sec 202.2). Minimum lot size 2 acres = 87,120 sf (Sec 202.2).
- Front
- 50 ft
- Side
- 30 ft
- Rear
- 30 ft
- Max coverage
- —
- Min lot
- 130,680 sf (~3.00 ac)
Rural district (all Monroe land not in Zone A or B); intent is to maintain rural characteristics of openness, residential uses, limited compatible commercial, agri-business, forestry, agriculture and livestock (Sec 202.3).
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Monroe 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 Monroe (Grafton County). A detached ADU can be up to 950 sf.
In Monroe's A zone, ADUs follow the single-family setbacks: 50 ft front, 30 ft side, and 30 ft rear. Monroe has 3 zoning districts in total — see the full table below. Confirm your exact zone with the town.