Build an ADU in Milton.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Milton — 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 Milton zoning ordinance · source · 2026-07-06
- Front
- 40 ft
- Side
- 25 ft
- Rear
- 30 ft
- Max coverage
- —
- Min lot
- 87,120 sf (~2.00 ac)
PRIMARY residential district — comprises roughly 90% of the town's land area (Sec 3.2 b.4), established for residential, agricultural, recreational and rural land uses at low density. Min lot size stated as 2.0 acres (87,120 sf); no municipal water/sewer tiering (unlike…
- Front
- 10 ft
- Side
- 15 ft
- Rear
- 10 ft
- Max coverage
- —
- Min lot
- 21,780 sf (~0.50 ac)
Established for single-family housing, apartments and two-unit dwellings at 0.5 acre (21,780 sf) minimum, and MUST be served by municipal water and sewer to receive HDR benefits (Sec 3.2 b.1).
- Front
- 25 ft
- Side
- 25 ft
- Rear
- 25 ft
- Max coverage
- —
- Min lot
- 43,560 sf (~1.00 ac)
Mixed-use district for residential, professional and retail uses at 1.0 acre (43,560 sf) minimum, served by municipal water and sewer where available; all lots/developments must connect when service is available (Sec 3.2 b.3).
- Front
- 25 ft
- Side
- 30 ft
- Rear
- 30 ft
- Max coverage
- —
- Min lot
- 87,120 sf (~2.00 ac)
Commercial/retail/manufacturing district at 2.0 acres (87,120 sf) minimum; must connect to municipal water/sewer when within 100 ft of the system (Sec 3.2 b.2). Max height 35 ft Min frontage 200 ft (or 150 ft on a cul-de-sac on an interior road).
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Milton 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 Milton (Strafford County). A detached ADU can be up to 950 sf.
In Milton's LDR zone, ADUs follow the single-family setbacks: 40 ft front, 25 ft side, and 30 ft rear. Milton has 4 zoning districts in total — see the full table below. Confirm your exact zone with the town.