Build an ADU in Hopkinton.
New Hampshire's HB 577 lets you add one accessory dwelling unit on your single-family lot in Hopkinton — by-right. A detached ADU can be up to 950 sf, and ADU setbacks match your lot's single-family setbacks.
12 districts
Each district's single-family setbacks — which your ADU follows. The primary residential district is highlighted.
Verified against the official Hopkinton zoning ordinance · source · 2026-07-06
- Front
- 60 ft
- Side
- 30 ft
- Rear
- 60 ft
- Max coverage
- 20% building
- Min lot
- 120,000 sf (~2.75 ac)
PRIMARY / base rural single-family residential district (Sec 3.5.1): open-space conservation, agricultural use, and predominantly very-low-density single-family residential on individual lots or in conservation subdivisions; would not customarily have Precinct water/sewer.
- Front
- 60 ft
- Side
- 30 ft
- Rear
- 60 ft
- Max coverage
- 20% building
- Min lot
- 120,000 sf (~2.75 ac)
Sec 3.5.2: open-space conservation, some agricultural use, predominantly very-low-density residential; would not customarily have Precinct water/sewer. Min lot 120,000 sf; frontage 300 ft; depth 200 ft; max building coverage 20%; min open space 70%; height 35 ft…
- Front
- 40 ft
- Side
- 20 ft
- Rear
- 40 ft
- Max coverage
- 30% building
- Min lot
- 80,000 sf (~1.84 ac)
Sec 3.5.3: medium-density residential; may or may not have Precinct water/sewer. Frontage 250 ft; depth 140 ft; max building coverage 30%; min open space 30%; height 35 ft Conservation-subdivision dimensions differ (Section VIII).
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 40 ft
- Max coverage
- 30% building
- Min lot
- 60,000 sf (~1.38 ac)
Sec 3.5.4: highest-density non-village residential district; may have or be planned for Precinct water/sewer. Frontage 160 ft; depth 120 ft; max building coverage 30%; min open space 30%; height 35 ft Conservation-subdivision dimensions differ (Section VIII).
- Front
- 25 ft
- Side
- 15 ft
- Rear
- 40 ft
- Max coverage
- 30% building
- Min lot
- 15,000 sf (~0.34 ac)
Separate table row in the R-1 district applying to non-residential uses only. Min lot 15,000 sf; frontage 100 ft; depth 100 ft; max building coverage 30%; min open space 50%; height 35 ft Residential development in R-1 uses the main R-1 row above.
- Front
- 20 ft
- Side
- 10 ft
- Rear
- 30 ft
- Max coverage
- 40% building
- Min lot
- 15,000 sf (~0.34 ac)
New district added by 3-12-2025 amendment. Sec 3.5.6: predominantly high-density residential; may have or be planned for precinct water service; created to reflect the lot characteristics of the Amesbury Road and Pinewood Drive neighborhoods.
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 40 ft
- Max coverage
- 40% building
- Min lot
- 15,000 sf (~0.34 ac)
Sec 3.5.7: limited commercial, institutional, professional and personal service uses along with residential uses. Frontage 80 ft; depth 80 ft; max building coverage 40%; min open space 30%; height 35 ft Max gross floor area of commercial retail stores/restaurants 40,000 sf…
- Front
- 50 ft
- Side
- 40 ft
- Rear
- 50 ft
- Max coverage
- 40% building
- Min lot
- 110,000 sf (~2.53 ac)
Sec 3.5.8: research/development, manufacturing, processing, assembly, wholesaling, transportation-oriented uses. Min lot 110,000 sf; frontage 250 ft; depth 300 ft; max building coverage 40%; min open space 30%; MAX HEIGHT 45 ft (higher than other districts).
- Front
- 30 ft
- Side
- 15 ft
- Rear
- 40 ft
- Max coverage
- 40% building
- Min lot
- 15,000 sf (~0.34 ac)
Sec 3.5.5: high-density residential within the village center; may have or be planned for Precinct water/sewer. Frontage 80 ft; depth 80 ft; max building coverage 40%; min open space 30%; height 35 ft.
- Front
- 0 ft
- Side
- 10 ft
- Rear
- 10 ft
- Max coverage
- 60% building
- Min lot
- 7,500 sf (~0.17 ac)
Sec 3.5.10: limited commercial/institutional/professional/personal-service uses plus residential within the village center. Frontage 50 ft; depth 100 ft; FRONT SETBACK 0 ft (village storefront form); side 10 ft; rear 10 ft; max building coverage 60%; min open space 20%;…
- Front
- 25 ft
- Side
- 25 ft
- Rear
- 25 ft
- Max coverage
- 50% building
- Min lot
- 55,000 sf (~1.26 ac)
Sec 3.5.11: research/development, manufacturing, processing, assembly, wholesaling, transportation-oriented uses within the village center. Min lot 55,000 sf; frontage 150 ft; depth 200 ft; max building coverage 50%; min open space 30%; height 35 ft Max gross floor area of…
- Front
- —
- Side
- —
- Rear
- —
- Max coverage
- —
- Min lot
- —
Overlay district (Sec 3.5.9), not a base district — has NO row in the Section 4.2 dimensional table; provides protection for and appropriate use of wetland lands per Section XI. All dimensional fields null: they are governed by the underlying base district plus Section XI…
Form-based and downtown districts may use build-to lines instead of fixed setbacks (shown as “—”); verify your parcel's district before you build.
Hopkinton 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 Hopkinton (Merrimack County). A detached ADU can be up to 950 sf.
In Hopkinton's R-4 zone, ADUs follow the single-family setbacks: 60 ft front, 30 ft side, and 60 ft rear. Hopkinton has 12 zoning districts in total — see the full table below. Confirm your exact zone with the town.