Build an ADU in Derry.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Derry — by-right. A detached ADU can be up to 950 sf, and ADU setbacks match your lot's single-family setbacks.
21 districts
Each district's single-family setbacks — which your ADU follows. The primary residential district is highlighted.
Verified against the official Derry zoning ordinance · source · 2026-07-05
- Front
- 35 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
1 acre or larger per soils.
- Front
- 35 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
SF/two-family tiered; conservative recorded. Multi-family 5,000 sf/unit, 30 ft yards.
- Front
- 35 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
Multi-family side/rear 30.
- Front
- 35 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
Single-family detached only.
- Front
- 35 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 87,120 sf (~2.00 ac)
2 acres or larger per soils.
- Front
- 35 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 130,680 sf (~3.00 ac)
3 acres or larger per soils.
- Front
- 35 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- —
- Min lot
- 30,000 sf (~0.69 ac)
30,000 sf w/sewer.
- Front
- 35 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- —
- Min lot
- 30,000 sf (~0.69 ac)
Frontage 200 ft.
- Front
- 35 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- —
- Min lot
- 30,000 sf (~0.69 ac)
Frontage 200 ft.
- Front
- 35 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- —
- Min lot
- 30,000 sf (~0.69 ac)
Frontage 125 ft.
- Front
- 8 ft
- Side
- 5 ft
- Rear
- 10 ft
- Max coverage
- —
- Min lot
- 30,000 sf (~0.69 ac)
Build-to: front is a MAXIMUM 8 ft.
- Front
- 20 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- 85% lot
- Min lot
- 10,000 sf (~0.23 ac)
Coverage 85% aggregate (bldg+accessory+parking).
- Front
- 35 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- —
- Min lot
- 30,000 sf (~0.69 ac)
Frontage 125 ft.
- Front
- 30 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- —
- Min lot
- 130,680 sf (~3.00 ac)
3 acres. Frontage 200 ft.
- Front
- 35 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- 25% lot
- Min lot
- 7,500 sf (~0.17 ac)
Front 35 Folsom Rd / 20 elsewhere (conservative 35).
- Front
- 50 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- —
- Min lot
- 653,400 sf (~15.00 ac)
Tract min 15 acres. Space min 7,200 sf.
- Front
- 30 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
1 acre. Frontage 125 ft.
- Front
- 30 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
1 acre w/sewer.
- Front
- 30 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
1 acre. Frontage 125 ft.
- Front
- 30 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
1 acre. Frontage 125 ft.
- Front
- 30 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
1 acre w/sewer.
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Derry 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 Derry (Rockingham County). A detached ADU can be up to 950 sf.
In Derry's MDR zone, ADUs follow the single-family setbacks: 35 ft front, 15 ft side, and 15 ft rear. Derry has 21 zoning districts in total — see the full table below. Confirm your exact zone with the town.