Build an ADU in Chester.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Chester — by-right. A detached ADU can be up to 950 sf, and ADU setbacks match your lot's single-family setbacks.
5 districts
Each district's single-family setbacks — which your ADU follows. The primary residential district is highlighted.
Verified against the official Chester zoning ordinance · source · 2026-07-06
- Front
- 40 ft
- Side
- 25 ft
- Rear
- 25 ft
- Max coverage
- 15% impervious
- Min lot
- 87,120 sf (~2.00 ac)
Primary single-family residential district. Values shown are for the R1 Single Family row of Table 1: 2 acres (87,120 sf) min lot, 290 ft frontage, 15% max impervious surface, 40/25/25 setbacks, 2.5 stories/33 ft max height.
- Front
- 75 ft
- Side
- 50 ft
- Rear
- 50 ft
- Max coverage
- 40% impervious
- Min lot
- 87,120 sf (~2.00 ac)
Table 1 lists C1 and C2 on a single shared row: 2 acres (87,120 sf) min lot, 290 ft frontage, 40% max impervious surface, 75/50/50 setbacks, 2.5 stories/30 ft max height. The 'Maximum Building Width' column shows '30' for this row (a building-width limit, transcribed by…
- Front
- 75 ft
- Side
- 50 ft
- Rear
- 50 ft
- Max coverage
- 40% impervious
- Min lot
- 87,120 sf (~2.00 ac)
Shares the C1/C2 row in Table 1: 2 acres (87,120 sf) min lot, 290 ft frontage, 40% max impervious surface, 75/50/50 setbacks, 2.5 stories/30 ft max height. '30 ft' Maximum Building Width applies (separate from the impervious cap).
- Front
- —
- Side
- —
- Rear
- —
- Max coverage
- —
- Min lot
- —
Overlay/conservation district with no row in Table 1 — it imposes flood-plain development controls on top of the underlying base zone (R1/C1/C2), which supplies the dimensional/setback numbers. Front/side/rear/lot/coverage are null because this district borrows them from the…
- Front
- —
- Side
- —
- Rear
- —
- Max coverage
- —
- Min lot
- —
Overlay/conservation district with no row in Table 1 — it overlays the underlying base zone (which supplies dimensional/setback numbers) and adds wetland buffers and soil-based lot rules. Bounded by the 'Wetlands and Agricultural Soils Map 1984' (3.2.3).
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Chester 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 Chester (Rockingham County). A detached ADU can be up to 950 sf.
In Chester's R1 zone, ADUs follow the single-family setbacks: 40 ft front, 25 ft side, and 25 ft rear. Chester has 5 zoning districts in total — see the full table below. Confirm your exact zone with the town.