Build an ADU in Gilsum.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Gilsum — 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 Gilsum zoning ordinance · source · 2026-07-07
- Front
- 50 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- —
- Min lot
- 87,120 sf (~2.00 ac)
Principal single-family residential district and town-wide catch-all: 'The Rural Residential District shall include all areas of Gilsum that are not designated to be in another zone' (Art III.B.5). Physical parameters (III.B.4): minimum lot size 2 acres = 87,120 sf; front…
- Front
- 30 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
Historic compact-village district along Route 10 / Main St., bounded to land within 300 ft of the centerline of the listed roads (Art III.A.6). Lot and yard requirements (III.A.4): minimum size 1 acre = 43,560 sf; front setback 30 ft; side and rear setbacks 20 ft each;…
- Front
- 50 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- —
- Min lot
- 87,120 sf (~2.00 ac)
Two mapped parcels only (the Blackstock-Houghton tract at the north end of Gilsum Village and a tract on the Mine Road / Alstead Hill), described metes-and-bounds in Art III.C.2. Physical parameters (III.C.1): minimum size 2 acres = 87,120 sf; front setback 50 ft; side and…
- Front
- 50 ft
- Side
- 20 ft
- Rear
- 20 ft
- Max coverage
- 50% lot
- Min lot
- 87,120 sf (~2.00 ac)
Commercial corridor district: all land on both sides of Route 10 with frontage and access from Route 10, measured inward from the highway right-of-way to 1,000 ft, excluding the Village (Residential) District (Art III.D.5).
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Gilsum 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 Gilsum (Cheshire County). A detached ADU can be up to 950 sf.
In Gilsum's RR zone, ADUs follow the single-family setbacks: 50 ft front, 20 ft side, and 20 ft rear. Gilsum has 4 zoning districts in total — see the full table below. Confirm your exact zone with the town.