Strafford County · New Hampshire
ADU rules in New Durham, NH
New Durham is a Strafford County town on Merrymeeting Lake.
New Durham is in our service area. This page covers what the town ordinance says about ADUs.
Town ADU rules
What’s allowed on your lot in New Durham.
New Durham allows an ADU by right, up to 1,000 sq ft, except in the Shorefront Conservation Overlay, where the town still asks for a conditional use permit.
- Size limit
- Max 1,000 sq ft gross living area (750 sq ft if the main house is under 1,000 sq ft); max 2 bedrooms
- Where it can go
- Attached, detached (attached to a barn or garage) or stand-alone; attached only in the Shorefront overlay
- Owner on site
- No town rule
- Parking
- At least 1 off-street space for the ADU; shared single driveway
- Approval
- By right; Conditional Use Permit in the Shorefront Conservation Overlay
- Rentals
- Stays under 7 days banned town-wide; 7-30 day rentals need a Special Exception
- Water setback
- Buildings 75 ft and leach fields 125 ft from water; 300 ft shorefront overlay
Allowed
- ApprovalADUs are allowed by right in every district that allows single-family homes, except the Shorefront Conservation Overlay District (SCOD), where the Planning Board must grant a Conditional Use Permit.Art. VI.L.2
- Attached or detachedThree kinds are defined. Attached: within or attached to the house. Detached: not attached to the house but attached to another structure such as a barn or garage. Stand Alone: attached to nothing. Only attached ADUs are allowed in the SCOD.Art. III Definitions; Art. VI.L.2.b
- How manyOne ADU per lot of record.Art. VI.L.3.a
- SizeGross living area up to 1,000 sq ft; if the main house has under 1,000 sq ft of living area, the ADU is capped at 750 sq ft. Max two bedrooms.Art. VI.L.3.c-d
- DesignAttached ADUs need an interior door and a common wall with the house. ADUs over attached garages may have more than one door in between.Art. VI.L.3.e
- DesignBuilding design and placement must show the ADU is clearly subordinate to the house.Art. VI.L.3.i
- LotADUs must meet building rules including setbacks and driveway requirements, and may not increase any nonconforming aspect of an existing structure or lot.Art. VI.L.3.b, f
- ParkingOne shared driveway for the house and ADU, and at least one off-street space for the ADU. In the SCOD, the ADU space is in addition to the four spaces every shorefront lot needs.Art. VI.L.3.g-h; VI.L.2.c
- SepticAdequate water and sewage per RSA 485-A:38; systems may be combined or separate. In the SCOD, nonconforming lots are capped at four bedrooms total (house plus ADU).Art. VI.L.3.k; VI.L.2.d
- LotOn conforming lots, every bedroom over four in a single-family home (including any ADU) raises the minimum lot area by one-fourth of the original minimum.Art. V.B.2.c.vii
- OtherSCOD ADU applicants must also give a stormwater management plan and, if applicable, Steep Slope and Water Quality overlay CUP information.Art. VI.L.2.a
- OtherBusiness use of an ADU is limited to a home occupation under the Home Occupation Ordinance.Art. VI.L.3.j
- RentalsSeparate Short-Term Rental Ordinance (adopted March 10, 2026): rentals under 7 days are banned in all districts. Rentals of 7 to 30 days need a Special Exception wherever housing is allowed. This covers any dwelling unit, not just ADUs.Short-Term Rental Ordinance, Definitions
- OtherIn Conservation Focus Areas (major subdivisions or larger site plans), overall density is capped at one single-family home with one ADU per five acres.Art. X.C.1
- ShorelandShorefront Conservation Overlay District: 300 ft inland from the normal high-water level of lakes and ponds over 10 acres and of the Cocheco, Merrymeeting and Ela Rivers. Buildings (except water-related structures) set back at least 75 ft from the reference line; leach fields 125 ft. Min shore frontage 150 ft. Max height 35 ft; accessory structures inside the 75 ft setback max one story / 12 ft. Buildings max 15% and total impervious max 20% of the lot. 50 ft natural waterfront buffer per RSA 483-B:8 and 483-B:9.V(a). New development needs 4 parking spaces. Town-wide, no new building within 75 ft of any water body or river (Art. V.E).Art. XIV.B-C; Art. V.E; Table 3
- State lawIn the Shorefront Conservation Overlay the town still asks for a conditional use permit and allows attached units only. State law makes one attached or detached ADU allowed by right.RSA 674:72, I; RSA 674:73
Not allowed
- Not allowedNo detached or stand-alone ADU in the Shorefront Conservation Overlay District.Art. VI.L.2.b
- Not allowedNo more than one ADU per lot; no more than two bedrooms.Art. VI.L.3.a, d
- Not allowedAn ADU may not increase any nonconforming aspect of a structure or lot.Art. VI.L.3.f
- Not allowedNo second driveway for the ADU.Art. VI.L.3.g
- Not allowedNo rentals under 7 days in any district.Short-Term Rental Ordinance (2026)
Read 2026-11-15 from Town of New Durham Zoning and Land Use Ordinance (Cover: "ADOPTED MARCH 8, 1971 / LATEST AMENDMENT MARCH 10, 2026"; certification: effective March 10, 2026, filed March 18, 2026). Anything not listed here, we check with the New Durham land-use office for your lot.
Setbacks
Front, side and rear in New Durham.
NH RSA 674:71-73 (HB 577) - one attached or detached ADU by right on a single-family lot
New Durham's dimensional table, as printed in the ordinance.
| District | Front | Side | Rear | Lot / cover / height |
|---|---|---|---|---|
| RRAprimaryResidential/Recreational/Agricultural District (all land outside the Town Center district)Art. V.B-G, Table 2, Table 3; Art. VIII.B.1. RRA frontage Table 2: 150 feet for 80,000 sq ft or less; 200 ft to 5 acres; 250 ft to 10 acres; 300 ft to 15 acres; 350 ft to 20 acres; 400 ft over 20 acres. RRA accessory buildings: Not stated separately (setbacks apply to any 'new building'). | Twenty (20) Feet | Fifteen (15) Feet | 15 feet ("fifteen (15) feet from the property line of an abutter") | Soil-based (Appendix A, Tables 1-2); "The minimum lot size shall be sixty thousand (60,000) square feet." · No base-district limit; SCOD buildings 15% / impervious 20%; Aquifer overlay impervious 20% · Height Thirty-five (35) Feet |
| TC/MUTown Center Mixed Use Zoning DistrictArt. IX.C, Table 5; Table 6 (Residential Dwelling, Single Unit: permitted by right). TC/MU frontage Article V Table 2 applies. TC/MU accessory buildings: Same as any building or structure. | 25 feet from the road right of way | 15 feet for any building or structure | 15 feet for any building or structure | Article V soil-based lot sizing applies (no separate minimum in Table 5); no lot may exceed a 4:1 width-to-length ratio · No coverage limit; max footprint of an individual building 6,000 feet · Height 35 feet (Article V.G applies) |
Verified 2026-11-15 against Town of New Durham Zoning and Land Use Ordinance. Towns amend ordinances, so confirm with the land-use office before you build. Official source
FAQ
ADUs in New Durham.
- How big can an ADU be in New Durham?
- Max 1,000 sq ft gross living area (750 sq ft if the main house is under 1,000 sq ft); max 2 bedrooms, per Art. VI.L.3.c-d as read 2026-11-15.
- Does the owner have to live on the lot in New Durham?
- No town rule (Town of New Durham Zoning and Land Use Ordinance).
- Can an ADU in New Durham be detached?
- Attached, detached (attached to a barn or garage) or stand-alone; attached only in the Shorefront overlay, under Art. III Definitions; Art. VI.L.2.b.
Planning an ADU in New Durham?
Call (978) 987-0089 and we will read the ordinance against your lot. See the ADU models