Build an ADU in Charlestown.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Charlestown — by-right. A detached ADU can be up to 950 sf, and ADU setbacks match your lot's single-family setbacks.
10 districts
Each district's single-family setbacks — which your ADU follows. The primary residential district is highlighted.
Verified against the official Charlestown zoning ordinance · source · 2026-07-07
- Front
- 25 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 15,000 sf (~0.34 ac)
Principal single-family residential district (covers most residential land in town). Every new building set back a minimum of 25 ft from the front property line and 15 ft from all other property lines (Sec 8.5.1.e, applied to A-1 via 8.5.2); front measured from the front…
- Front
- 25 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 15,000 sf (~0.34 ac)
Compact town-center residential/professional district. Minimum lot 15,000 sf, frontage 100 ft (Sec 8.5.1.f).
- Front
- 25 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 15,000 sf (~0.34 ac)
Historic North Main Street residential district. Minimum lot 15,000 sf, frontage 100 ft (Sec 8.5.3.f).
- Front
- 10 ft
- Side
- 10 ft
- Rear
- 10 ft
- Max coverage
- —
- Min lot
- —
Main Street business district. No minimum lot size and no minimum frontage are set in the Zoning Ordinance ('None' / '(S)' in the Table); frontage defaults to the Subdivision Regulations (100 ft w/ town water and sewer, 200 ft w/o).
- Front
- —
- Side
- —
- Rear
- —
- Max coverage
- —
- Min lot
- —
Special-purpose historic district: all property owned/occupied by Old Fort No Four Associates, Inc. The Table of Dimensional Requirements lists Zone C as 'None' for minimum lot size, frontage, front setback, side/rear setback and height - the ordinance sets no dimensional…
- Front
- 25 ft
- Side
- 25 ft
- Rear
- 25 ft
- Max coverage
- —
- Min lot
- 217,800 sf (~5.00 ac)
Watershed / drinking-water protection area. Only a one- or two-family dwelling is permitted, on a lot of no less than 5 acres (217,800 sf) (Sec 8.5.6.a). ADUs per Sec 8.4.12 are permitted only with a single-family principal dwelling on the same 5-acre lot.
- Front
- 20 ft
- Side
- 10 ft
- Rear
- 10 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
Catch-all district: all land/water in town not otherwise zoned (Sec 8.3). Minimum lot tiers by utilities: 1 acre (43,560 sf) if NOT served by municipal water or sewer (Sec 8.5.7.a) vs 0.5 acre if served by municipal water and/or sewer (Sec 8.5.7.b) - the CONSERVATIVE…
- Front
- 40 ft
- Side
- 40 ft
- Rear
- 40 ft
- Max coverage
- 40% building
- Min lot
- 80,000 sf (~1.84 ac)
Two industrial/business zones sharing one dimensional standard.
- Front
- 10 ft
- Side
- 10 ft
- Rear
- 10 ft
- Max coverage
- —
- Min lot
- —
Small-lot mixed residential/commercial protection district. No minimum lot size and no minimum frontage in the Zoning Ordinance ('None' / '(S)' in the Table); frontage defaults to Subdivision Regulations.
- Front
- 10 ft
- Side
- 10 ft
- Rear
- 10 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
Multi-use protection district for existing residential settlements. Each new lot a minimum of 1 acre (43,560 sf) (Sec 8.5.10.2.F / Table).
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Charlestown 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 Charlestown (Sullivan County). A detached ADU can be up to 950 sf.
In Charlestown's A-1 zone, ADUs follow the single-family setbacks: 25 ft front, 15 ft side, and 15 ft rear. Charlestown has 10 zoning districts in total — see the full table below. Confirm your exact zone with the town.