Strafford County · New Hampshire
ADU rules in Barrington, NH
Barrington is a Strafford County town on the Isinglass River.
This is a reference guide. Barrington is not on our service-area list, so call to ask whether we can take on a build there.
Town ADU rules
What’s allowed on your lot in Barrington.
Barrington permits an ADU by right in every district, up to 1,000 sq ft in or attached to the house and 750 sq ft in a detached building.
- Size limit
- Up to 1,000 sq ft inside or attached to the house; up to 750 sq ft finished floor in a detached accessory structure; max 2 bedrooms
- Where it can go
- Inside the house, attached, or in a detached accessory structure
- Owner on site
- Owner must live in one of the two units
- Parking
- 1 dedicated off-street space for the ADU
- Approval
- Permitted by right (P) in every district in Table 1; Zoning Administrator Certificate of Use required
- Water setback
- Shoreland district 75 ft from 4th-order streams and lakes or ponds over 10 acres; 100 ft from the Isinglass River
Allowed
- How manyOne ADU per property, max 2 bedrooms. No ADU on a property that already has more than one dwelling.§3.5.1(1)
- Attached or detachedAttached unit = within or physically connected to the house, or completely inside a preexisting detached structure. Detached unit = neither. ADUs in a detached accessory structure are allowed.§3.5.1(a)-(b)
- SizeInside or attached to the house: max 1,000 sq ft. In a detached accessory structure: max 750 sq ft of finished floor. No minimum size stated.§3.5.1(5)
- DesignExterior alterations, enlargements or extensions of the house or detached accessory structure are allowed to fit the ADU.§3.5.1(2)
- ParkingAt least one dedicated off-street parking space for the ADU.§3.5.1(3)
- LotA newly built detached accessory structure with an ADU must meet the Article 4 dimensional standards for a single-family dwelling.§3.5.1(4)
- OtherNo condo or separate ownership. Owner must record a restrictive covenant in favor of the Town at the Strafford County Registry of Deeds before the Certificate of Occupancy.§3.5.1(6), (6)(a)
- Owner on siteThe property owner must live in one of the two units.§3.5.1(7)
- SepticWithout municipal sewer, the septic system must meet NHDES requirements for the combined demand of the whole premises.§3.5.1(8)
- OtherNo impact fee is charged for ADUs.§3.5.1(9)
- ApprovalADU is 'P' (permitted by right) in GR, NR, V, TC, RC and the HCO overlay. A Zoning Administrator Certificate of Use is required. It lasts until the property is sold, and new owners must get a new one. Fees follow the Town fee schedule.§3.5.1(10)-(11); Table 1 Table of Uses
- OtherADUs are allowed in any type of mixed use development.§3.3.4(1)(b)
- ShorelandShoreland Protection District Overlay (SDO): any area within 75 ft of the shoreline of any fourth-order stream (as referenced in RSA 483-B) or any lake or pond over 10 acres, and within 100 ft of the mean high-water mark of the Isinglass River. Adding 100 sf or more of living space where any part of the septic is in the district triggers a septic evaluation (and replacement if failed). Lots of record before July 28, 1988 are exempt where conformance is impossible. State RSA 483-B also applies separately.Article 11, §11.2(1)-(2), §11.3(1), §11.4
Read 2026-11-15 from Town of Barrington, New Hampshire Zoning Ordinance (Cover: 'As amended March 10, 2026'; page footers 'Amended 3/10/2026 per Ballot Vote'). Anything not listed here, we check with the Barrington land-use office for your lot.
Setbacks
Front, side and rear in Barrington.
NH RSA 674:71-73 (HB 577) - one attached or detached ADU by right on a single-family lot
Barrington's dimensional table, as printed in the ordinance.
| District | Front | Side | Rear | Lot / cover / height |
|---|---|---|---|---|
| GRprimaryGeneral ResidentialTable 2; §4.2.1(1); §4.1.4; Table 1. GR frontage 250 ft. GR accessory buildings: Structures under 200 sq ft used for storage: no building permit and no setback requirements (wetland or property line); limit 2 per property up to 80,000 SF. | 40 ft | 30 ft | 30 ft | 130,000 sq. ft. (must include 60,000 sq. ft. free of poorly/very poorly drained soils, water, ledge, of which 35,000 sq. ft. contiguous uplands) · 40% (impervious surface, footnote f) · Height 35 ft / 2.5 stories |
| NRNeighborhood ResidentialTable 2; §4.2.1; Table 1. NR frontage 250 ft. NR accessory buildings: Same §4.1.4 rule for structures under 200 sq ft. | 40 ft | 30 ft | 30 ft | 130,000 sq. ft. (same upland rules as GR, §4.2.1) · 40% (impervious surface) · Height 35 ft / 2.5 stories |
| VVillage District (Residential)Table 2 and footnote (g); §4.2.2(4). V frontage 200 ft. | 40 ft | 30 ft | 30 ft | 80,000 (c) per Table 2. CONFLICT: Table 2 footnote (g) and §4.2.2(4) say single-family lots in the Village must meet §4.2.1, i.e. the GR/NR 130,000 sq. ft. standard. Both reported. · 40% (impervious surface) · Height 35 ft / 2.5 stories |
| TCTown CenterTable 2; §4.2.4(3); Table 1 note (13). TC frontage 40 ft. | 20 ft (k: 50 ft from right-of-way along Route 125 and Route 9) | 15 ft | 15 ft | 20,000 (h) in Table 2; residential structures only allowed as part of a PUD, with lot sizes set in Article 16 (§4.2.4(3)) · 80% (impervious surface) · Height 40 ft / 3 stories (j: no occupied residential space above 35 ft without sprinklers) |
| RCRegional CommercialTable 2; §4.2.3(2); Table 1 note (8). RC frontage 200 ft. | 75 ft (e)(l); 40 ft for lots not fronting Routes 4 and 125 | 30 ft | 30 ft | Residential: per §4.2.1, same as GR/NR (130,000 sq. ft.) (§4.2.3(2)); Table 2 shows 40,000 (d) for the district · 50% (impervious surface) · Height 40 ft / 3 stories (j) |
| HCOHighway Commercial District Overlay§8.4; Table 1. HCO frontage Same as base district. | Same as base district | Same as base district | Same as base district | Same as underlying GR or NR district · Same as base district · Height Same as base district |
Verified 2026-11-15 against Town of Barrington, New Hampshire Zoning Ordinance. Towns amend ordinances, so confirm with the land-use office before you build. Official source
FAQ
ADUs in Barrington.
- How big can an ADU be in Barrington?
- Up to 1,000 sq ft inside or attached to the house; up to 750 sq ft finished floor in a detached accessory structure; max 2 bedrooms, per §3.5.1(5) as read 2026-11-15.
- Does the owner have to live on the lot in Barrington?
- Owner must live in one of the two units (§3.5.1(7)).
- Can an ADU in Barrington be detached?
- Inside the house, attached, or in a detached accessory structure, under §3.5.1(a)-(b).
Planning an ADU in Barrington?
Call (978) 987-0089 and we will say whether we can build there. See the ADU models