Build an ADU in Manchester.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Manchester — by-right. A detached ADU can be up to 950 sf, and ADU setbacks match your lot's single-family setbacks.
9 districts
Each district's single-family setbacks — which your ADU follows. The primary residential district is highlighted.
Verified against the official Manchester zoning ordinance · source · 2026-07-05
- Front
- 25 ft
- Side
- 10 ft
- Rear
- 30 ft
- Max coverage
- 40% building
- Min lot
- 10,000 sf (~0.23 ac)
Side one/both 10/40. Building coverage.
- Front
- 50 ft
- Side
- 20 ft
- Rear
- 50 ft
- Max coverage
- 15% building
- Min lot
- 40,000 sf (~0.92 ac)
Side one/both 20/60. Building coverage.
- Front
- 20 ft
- Side
- 5 ft
- Rear
- 20 ft
- Max coverage
- 60% building
- Min lot
- 6,000 sf (~0.14 ac)
Side one/both 5/20. Building coverage.
- Front
- 15 ft
- Side
- 5 ft
- Rear
- 20 ft
- Max coverage
- 60% building
- Min lot
- 5,000 sf (~0.11 ac)
Duplex type: 6,000 front-loaded / 5,000 alley.
- Front
- 20 ft
- Side
- —
- Rear
- —
- Max coverage
- 75% building
- Min lot
- —
Uses Duplex/Townhouse/Apt types; side/rear not a single triple. Building coverage.
- Front
- 20 ft
- Side
- —
- Rear
- —
- Max coverage
- 70% building
- Min lot
- —
Front 10 min / 20 MAX. Form-based. Building coverage.
- Front
- 20 ft
- Side
- —
- Rear
- —
- Max coverage
- 75% lot
- Min lot
- —
Front 6 min / 20 max. Form-based.
- Front
- 20 ft
- Side
- —
- Rear
- —
- Max coverage
- 80% lot
- Min lot
- —
Front 10 min / 20 max. Form-based.
- Front
- 6 ft
- Side
- 0 ft
- Rear
- 0 ft
- Max coverage
- 100% building
- Min lot
- 10,000 sf (~0.23 ac)
HIGH-RISE type. Front 0 min / 6 MAX. Building coverage.
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Manchester 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 Manchester (Hillsborough County). A detached ADU can be up to 950 sf.
In Manchester's R-1A zone, ADUs follow the single-family setbacks: 25 ft front, 10 ft side, and 30 ft rear. Manchester has 9 zoning districts in total — see the full table below. Confirm your exact zone with the town.