Build an ADU in Durham.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Durham — by-right. A detached ADU can be up to 950 sf, and ADU setbacks match your lot's single-family setbacks.
15 districts
Each district's single-family setbacks — which your ADU follows. The primary residential district is highlighted.
Verified against the official Durham zoning ordinance · source · 2026-07-05
- Front
- 30 ft
- Side
- 10 ft
- Rear
- 20 ft
- Max coverage
- 33% impervious
- Min lot
- 20,000 sf (~0.46 ac)
Impervious 33%. Front tiered Minor/Collector 30 / Arterial 40.
- Front
- 40 ft
- Side
- 50 ft
- Rear
- 50 ft
- Max coverage
- 20% impervious
- Min lot
- 150,000 sf (~3.44 ac)
Front Minor/Collector 30, Arterial 40. Pre-2003 SF lots 120,000 sf.
- Front
- 40 ft
- Side
- 20 ft
- Rear
- 30 ft
- Max coverage
- 30% impervious
- Min lot
- 40,000 sf (~0.92 ac)
Front 30/40 tiered.
- Front
- 40 ft
- Side
- 50 ft
- Rear
- 50 ft
- Max coverage
- 20% impervious
- Min lot
- 150,000 sf (~3.44 ac)
Pre-2003 lots 120,000 sf.
- Front
- —
- Side
- —
- Rear
- —
- Max coverage
- 100% impervious
- Min lot
- 5,000 sf (~0.11 ac)
Setbacks none except per Note 5.
- Front
- —
- Side
- —
- Rear
- —
- Max coverage
- 100% impervious
- Min lot
- 5,000 sf (~0.11 ac)
Setbacks per Note 5.
- Front
- 50 ft
- Side
- 15 ft
- Rear
- 20 ft
- Max coverage
- 50% impervious
- Min lot
- 10,000 sf (~0.23 ac)
Front 30/50 tiered.
- Front
- 15 ft
- Side
- 5 ft
- Rear
- 15 ft
- Max coverage
- 80% impervious
- Min lot
- 5,000 sf (~0.11 ac)
- Front
- 15 ft
- Side
- 10 ft
- Rear
- 15 ft
- Max coverage
- 80% impervious
- Min lot
- 5,000 sf (~0.11 ac)
Max front setback 25 ft.
- Front
- 50 ft
- Side
- 15 ft
- Rear
- 20 ft
- Max coverage
- 30% impervious
- Min lot
- 30,000 sf (~0.69 ac)
Front 30/50 tiered.
- Front
- 100 ft
- Side
- 25 ft
- Rear
- 25 ft
- Max coverage
- 50% impervious
- Min lot
- 40,000 sf (~0.92 ac)
Front 50/100 tiered. Lot 40,000 SF / 80,000 other.
- Front
- 100 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- 50% impervious
- Min lot
- 40,000 sf (~0.92 ac)
Front 30/100 tiered.
- Front
- 50 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- 50% impervious
- Min lot
- 40,000 sf (~0.92 ac)
Front 30/50 tiered.
- Front
- 150 ft
- Side
- 150 ft
- Rear
- 150 ft
- Max coverage
- 50% impervious
- Min lot
- 150,000 sf (~3.44 ac)
- Front
- 50 ft
- Side
- 25 ft
- Rear
- 25 ft
- Max coverage
- 50% impervious
- Min lot
- 5,000 sf (~0.11 ac)
Overlay w/ own dims. 4,200 sf per DU.
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Durham 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 Durham (Strafford County). A detached ADU can be up to 950 sf.
In Durham's RA zone, ADUs follow the single-family setbacks: 30 ft front, 10 ft side, and 20 ft rear. Durham has 15 zoning districts in total — see the full table below. Confirm your exact zone with the town.