Build an ADU in Boscawen.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Boscawen — 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 Boscawen zoning ordinance · source · 2026-07-06
- Front
- 40 ft
- Side
- 20 ft
- Rear
- 40 ft
- Max coverage
- 25% building
- Min lot
- 80,000 sf (~1.84 ac)
PRIMARY single-family district (Art II 2.02(b)): 'maintain primarily single-family housing on large lots.' Min lot area for One Unit = 80,000 sf without municipal water or sewer; 40,000 sf with EITHER water or sewer; 40,000 sf with BOTH water and sewer (TABLE 2).
- Front
- 50 ft
- Side
- 25 ft
- Rear
- 50 ft
- Max coverage
- 20% building
- Min lot
- 120,000 sf (~2.75 ac)
Rural/agricultural zone (Art II 2.02(a)). Min lot area for One Unit = 120,000 sf without water or sewer; 80,000 sf with either water or sewer; 40,000 sf with both. Frontage 160 ft (either utility) / 120 ft (both utilities).
- Front
- 30 ft
- Side
- 10 ft
- Rear
- 10 ft
- Max coverage
- 30% building
- Min lot
- 40,000 sf (~0.92 ac)
Single- and multi-family medium-density zone, generally served by municipal water and sewer (Art II 2.02(c)). Min lot area for One Unit = 40,000 sf without water or sewer; 20,000 sf with either; 10,000 sf with both.
- Front
- 50 ft
- Side
- 10 ft
- Rear
- 20 ft
- Max coverage
- 40% building
- Min lot
- 40,000 sf (~0.92 ac)
Business/commercial zone (Art II 2.02(d)). Min lot area for One Unit = 40,000 sf without water or sewer; 30,000 sf with either; 20,000 sf with both. Frontage 100 ft (all utility tiers).
- Front
- 50 ft
- Side
- 10 ft
- Rear
- 20 ft
- Max coverage
- 40% building
- Min lot
- 80,000 sf (~1.84 ac)
Industrial/light-industrial zone; residential uses generally prohibited (Art II 2.02(e)). TABLE 2 lists no residential per-unit lot area for I (all '-'); the applicable min lot area is the Commercial/Industrial Uses row = 80,000 sf.
- Front
- 15 ft
- Side
- 10 ft
- Rear
- —
- Max coverage
- 50% impervious
- Min lot
- 40,000 sf (~0.92 ac)
Historic village mixed-use district; TABLE 2 shows 'See VD' for all VD dimensions, deferring to Art IV 4.02 'Village District Lot Requirements.' Min lot 40,000 sf. Frontage 100 ft Height limit 50 ft (measured finished grade to peak).
- Front
- —
- Side
- —
- Rear
- —
- Max coverage
- —
- Min lot
- —
Form-based redevelopment district for former industrial/mill properties (Art II 2.02(f)). TABLE 2 shows '*' for EVERY MRD dimension (lot area, setbacks, height, frontage, coverage): the Planning Board may approve a conditional use permit allowing variable dimensional…
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Boscawen 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 Boscawen (Merrimack County). A detached ADU can be up to 950 sf.
In Boscawen's R-1 zone, ADUs follow the single-family setbacks: 40 ft front, 20 ft side, and 40 ft rear. Boscawen has 7 zoning districts in total — see the full table below. Confirm your exact zone with the town.