Build an ADU in Salem.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Salem — by-right. A detached ADU can be up to 950 sf, and ADU setbacks match your lot's single-family setbacks.
12 districts
Each district's single-family setbacks — which your ADU follows. The primary residential district is highlighted.
Verified against the official Salem zoning ordinance · source · 2026-07-05
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 30 ft
- Max coverage
- 30% building
- Min lot
- 25,000 sf (~0.57 ac)
25,000 w/sewer (else soil-based larger).
- Front
- 30 ft
- Side
- 30 ft
- Rear
- 30 ft
- Max coverage
- 30% building
- Min lot
- 87,120 sf (~2.00 ac)
2 ac single w/sewer; 4 ac duplex.
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 25,000 sf (~0.57 ac)
No coverage standard. Width 100 ft.
- Front
- 40 ft
- Side
- 30 ft
- Rear
- 30 ft
- Max coverage
- 25% building
- Min lot
- 87,120 sf (~2.00 ac)
2 acres.
- Front
- 30 ft
- Side
- 30 ft
- Rear
- 30 ft
- Max coverage
- 30% building
- Min lot
- 25,000 sf (~0.57 ac)
15,000 w/public water else 25,000 (conservative).
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 30 ft
- Max coverage
- 50% lot
- Min lot
- 25,000 sf (~0.57 ac)
50% LOT coverage. 37,500 duplex/mixed.
- Front
- 50 ft
- Side
- 25 ft
- Rear
- 25 ft
- Max coverage
- 30% building
- Min lot
- 65,340 sf (~1.50 ac)
1.5 acres.
- Front
- 100 ft
- Side
- 75 ft
- Rear
- 75 ft
- Max coverage
- 30% building
- Min lot
- 130,680 sf (~3.00 ac)
3 acres.
- Front
- —
- Side
- —
- Rear
- —
- Max coverage
- 90% lot
- Min lot
- —
90% LOT cov. Setbacks blank in table; see §490-501C(4)(a).
- Front
- 30 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- 70% lot
- Min lot
- —
70% LOT cov. Min-lot blank.
- Front
- 50 ft
- Side
- 40 ft
- Rear
- 40 ft
- Max coverage
- 30% building
- Min lot
- —
Frontage 300 ft. Min-lot not in table.
- Front
- 50 ft
- Side
- 50 ft
- Rear
- 50 ft
- Max coverage
- —
- Min lot
- 435,600 sf (~10.00 ac)
Own dimensional row. 10 acres, frontage 200 ft.
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Salem 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 Salem (Rockingham County). A detached ADU can be up to 950 sf.
In Salem's R zone, ADUs follow the single-family setbacks: 30 ft front, 15 ft side, and 30 ft rear. Salem has 12 zoning districts in total — see the full table below. Confirm your exact zone with the town.