Build an ADU in Belmont.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Belmont — by-right. A detached ADU can be up to 950 sf, and ADU setbacks match your lot's single-family setbacks.
6 districts
Each district's single-family setbacks — which your ADU follows. The primary residential district is highlighted.
Verified against the official Belmont zoning ordinance · source · 2026-07-06
- Front
- 50 ft
- Side
- 25 ft
- Rear
- 25 ft
- Max coverage
- 60% lot
- Min lot
- 43,560 sf (~1.00 ac)
Primary single-family residential district. Min lot size 1 acre (43,560 sf) - does NOT reduce with municipal sewer or sewer+water (stays 1 acre in all utility tiers, Table 2). Max 1 dwelling unit per acre.
- Front
- 50 ft
- Side
- 25 ft
- Rear
- 25 ft
- Max coverage
- 60% lot
- Min lot
- 43,560 sf (~1.00 ac)
Multi-family residential district. Min lot size 1 acre (43,560 sf), constant across utility tiers. Max 2 dwelling units per acre (reduced from 4 by the March 8, 1994 amendment; density for multi-family restricted to elderly occupancy per federal regulation may be 8 du/acre).
- Front
- 50 ft
- Side
- 50 ft
- Rear
- 50 ft
- Max coverage
- 30% lot
- Min lot
- 130,680 sf (~3.00 ac)
Most-restrictive rural district. Min lot size 3 acres (130,680 sf), constant across utility tiers. Max density .33 dwelling units per acre (i.e. 1 unit per 3 acres). Min frontage 180 ft (all tiers). Coverage: max 30% of lot as non-green area (the lowest coverage cap).
- Front
- 25 ft
- Side
- 25 ft
- Rear
- 25 ft
- Max coverage
- 60% lot
- Min lot
- 21,780 sf (~0.50 ac)
Compact village district (smallest lot minimums). Min lot size 0.5 acre (21,780 sf) base; stays 0.5 acre with municipal sewer and with sewer+water. Max 2 dwelling units per acre (reduced from 4 by the March 8, 1994 amendment).
- Front
- 50 ft
- Side
- 15 ft
- Rear
- 20 ft
- Max coverage
- 75% lot
- Min lot
- 87,120 sf (~2.00 ac)
Commercial district. Min lot size 2 acres (87,120 sf) base, reducing to 1 acre (43,560 sf) with municipal sewer and to 0.5 acre (21,780 sf) with municipal sewer+water. Min frontage 200 ft base, 150 ft with sewer, 100 ft with sewer+water.
- Front
- 50 ft
- Side
- 15 ft
- Rear
- 20 ft
- Max coverage
- 75% lot
- Min lot
- 87,120 sf (~2.00 ac)
Industrial district. Min lot size 2 acres (87,120 sf) base, reducing to 1 acre with municipal sewer and 0.5 acre with municipal sewer+water. Min frontage 200 ft base, 150 ft with sewer, 100 ft with sewer+water.
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Belmont 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 Belmont (Belknap County). A detached ADU can be up to 950 sf.
In Belmont's RS zone, ADUs follow the single-family setbacks: 50 ft front, 25 ft side, and 25 ft rear. Belmont has 6 zoning districts in total — see the full table below. Confirm your exact zone with the town.