Build an ADU in Franconia.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Franconia — by-right. A detached ADU can be up to 950 sf, and ADU setbacks match your lot's single-family setbacks.
4 districts
Each district's single-family setbacks — which your ADU follows. The primary residential district is highlighted.
Verified against the official Franconia zoning ordinance · source · 2026-07-07
- Front
- 50 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- 10% building
- Min lot
- 217,800 sf (~5.00 ac)
Principal single-family district: One-Family Residential Structure permitted by right; two-family, multi-family and most non-residential uses only by Special Exception (4.02). Min lot 5 acres (217,800 sf); frontage 200 ft; max 'building coverage' 10% (4.03.B — the table says…
- Front
- 50 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- 10% building
- Min lot
- 130,680 sf (~3.00 ac)
Denser residential/mixed district: one-family, two-family, multi-family, senior/workforce housing, B&B, restaurant, hotel (and more) permitted by right; manufactured housing and retail by Special Exception (4.02).
- Front
- 50 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- 10% building
- Min lot
- 43,560 sf (~1.00 ac)
Lot size is USE-TIERED, not utility-tiered: DWELLING lots min 1 acre (43,560 sf, recorded here — the tier that applies to homes/ADUs) at 10% max building coverage; NON-DWELLING lots min 1/2 acre (21,780 sf) at 30% max building coverage (4.03.B).
- Front
- 50 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- 10% building
- Min lot
- 87,120 sf (~2.00 ac)
Single tier for dwelling and non-dwelling uses: min lot 2 acres (87,120 sf); frontage 150 ft; max building coverage 10% (4.03.B). Front setback 50 ft from ROW CENTERLINE; side and rear 20 ft (4.03.C). Same coverage-definition and overlay caveats as other districts.
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Franconia 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 Franconia (Grafton County). A detached ADU can be up to 950 sf.
In Franconia's Residential A zone, ADUs follow the single-family setbacks: 50 ft front, 20 ft side, and 20 ft rear. Franconia has 4 zoning districts in total — see the full table below. Confirm your exact zone with the town.