Build an ADU in Milford.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Milford — by-right. A detached ADU can be up to 950 sf, and ADU setbacks match your lot's single-family setbacks.
8 districts
Each district's single-family setbacks — which your ADU follows. The primary residential district is highlighted.
Verified against the official Milford zoning ordinance · source · 2026-07-06
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 15,000 sf (~0.34 ac)
Primary single-family residential district (low-density, primarily single-family on individual lots). Min lot 15,000 SF WITH both municipal sewer AND water; 40,000 SF (or larger per soil/slope) if NOT served by both.
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 15,000 sf (~0.34 ac)
Higher-density residential (single, two-, multi-family). Single-family min lot = same as Res A: 15,000 SF (both municipal sewer AND water) / 40,000 SF (unserviced). All OTHER uses: 20,000 SF & 150 ft frontage (serviced) / 60,000 SF & 225 ft frontage (unserviced).
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 40,000 sf (~0.92 ac)
Rural low-density residential/agricultural. Single-family min lot 40,000 SF (or greater per soil/slope) with 150 ft frontage on a Class V or better road — CONFIRMED from the adopted redline (the struck-through prior text was 2 acres/87,120 SF and 200 ft; the older 2008…
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 20,000 sf (~0.46 ac)
Min lot 20,000 SF & 150 ft frontage (both municipal sewer AND water) / 60,000 SF & 225 ft frontage (unserviced). 30% min open space for uses other than single-/two-family.
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- —
NO minimum lot size or frontage where served by both municipal sewer AND water (only usable-open-space requirements apply); where NOT so served, min 40,000 SF (per soil/slope) and no minimum frontage. Corner lot: street-side setback 30 ft 30% min open space for all uses.
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 20,000 sf (~0.46 ac)
Business uses compatible with surrounding residential neighborhoods. Min lot 20,000 SF & 150 ft frontage (both municipal sewer AND water) / 60,000 SF & 225 ft frontage (unserviced). Corner lot: street-side setback 30 ft 30% min open space for uses other than single-/two-family.
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 20,000 sf (~0.46 ac)
Mixed commercial/industrial, vehicle-oriented business. Min lot 20,000 SF (both municipal sewer AND water) / 40,000 SF (unserviced, per soil/slope); 150 ft frontage on a Class V or better road in BOTH cases.
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 15 ft
- Max coverage
- —
- Min lot
- 20,000 sf (~0.46 ac)
Mixed commercial/industrial in park-like settings. Min lot 20,000 SF (both municipal sewer AND water) / 40,000 SF (unserviced, per soil/slope); 150 ft frontage in BOTH cases. Corner lot: street-side setback 30 ft 30% min open space for all uses.
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Milford 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 Milford (Hillsborough County). A detached ADU can be up to 950 sf.
In Milford's RA zone, ADUs follow the single-family setbacks: 30 ft front, 15 ft side, and 15 ft rear. Milford has 8 zoning districts in total — see the full table below. Confirm your exact zone with the town.