Build an ADU in Lancaster.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Lancaster — by-right. A detached ADU can be up to 950 sf, and ADU setbacks match your lot's single-family setbacks.
7 districts
Each district's single-family setbacks — which your ADU follows. The primary residential district is highlighted.
Verified against the official Lancaster zoning ordinance · source · 2026-07-07
- Front
- 15 ft
- Side
- 10 ft
- Rear
- 10 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
Principal single-family residential district; characterized mainly by single-family dwellings (Sec 5.02). Setbacks per Sec 5.02 'Setbacks & Frontage': front yard >=15 ft, side yard >=10 ft, rear yard >=10 ft; front is measured from the nearest edge of the public/accepted…
- Front
- 15 ft
- Side
- 10 ft
- Rear
- 10 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
Town business district (retail, wholesale, service, offices, mixed-use). Setbacks per Sec 5.03: >=15 ft from any right-of-way and >=10 ft from side or rear property lines, EXCEPT that named downtown street frontages (portions of Main, Middle, Canal, Bunker Hill and Park…
- Front
- 15 ft
- Side
- 10 ft
- Rear
- 10 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
Wide range of commercial, multi-unit housing, mixed-use and industrial uses (Sec 5.04). Setbacks: >=15 ft from any right-of-way (except along Park, Canal and Mechanic Streets) and >=10 ft from side and rear property lines; garages and gasoline filling-station structures must…
- Front
- 50 ft
- Side
- 40 ft
- Rear
- 40 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
Lowest-intensity district: agriculture, forestry, outdoor recreation and single-family dwellings (Sec 5.05). Setbacks per Sec 5.05: front yard >=50 ft from the edge of the right-of-way; side and rear yards >=40 ft from the property line; no building/structure may be <50 ft…
- Front
- 0 ft
- Side
- 0 ft
- Rear
- 0 ft
- Max coverage
- —
- Min lot
- —
Form-based overlay subdistrict (Sec 5.01), the historic commercial core from Town Hall north to Bunker Hill Street. Per its Dimensional Building Table: principal-building front setback = 'Build-to at property line' (recorded as 0), side and rear setbacks = None (recorded as…
- Front
- 15 ft
- Side
- 10 ft
- Rear
- 10 ft
- Max coverage
- 60% lot
- Min lot
- 10,000 sf (~0.23 ac)
Form-based CBD subdistrict along Main Street from Bunker Hill Street to Depot Street (institutional/lower-density core). Dimensional Building Table: principal-building front setback 15-30 ft max (front recorded as the 15 ft minimum; the 30 is a maximum build-to cap), side 10…
- Front
- 30 ft
- Side
- 10 ft
- Rear
- 10 ft
- Max coverage
- 75% lot
- Min lot
- 10,000 sf (~0.23 ac)
Form-based CBD subdistrict from Depot Street to the Routes 2/3 intersection (auto-oriented transitional area). Dimensional Building Table: principal-building front setback 30-70 ft max (front recorded as the 30 ft minimum; 70 is a maximum build-to cap), side 10 ft, rear 10 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.
Lancaster 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 Lancaster (Coös County). A detached ADU can be up to 950 sf.
In Lancaster's Residential zone, ADUs follow the single-family setbacks: 15 ft front, 10 ft side, and 10 ft rear. Lancaster has 7 zoning districts in total — see the full table below. Confirm your exact zone with the town.