Rockingham County · New Hampshire
ADU rules in North Hampton, NH
North Hampton is a Rockingham County town on the New Hampshire coast.
This is a reference guide. North Hampton 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 North Hampton.
North Hampton rewrote its ADU section on March 10, 2026. Inside, attached and detached units are all permitted, with a combined footprint limit of 800 sq ft.
- Size limit
- Footprint of all ADU floors combined max 800 sq ft; minimum 720 sq ft ground-floor or lower living area; max two bedrooms
- Where it can go
- Inside, attached, or detached
- Owner on site
- Owner must live in the house or the ADU
- Parking
- No ADU-specific parking rule
- Approval
- Permitted use; building permit and certificate of occupancy from the Building Inspector
- Water setback
- No structure or impervious surface within 100 ft of tidal lands or wetlands
Allowed
- OtherADUs are allowed in all districts that permit single-family homes, but not on rented or leased land. ADUs may be built at the same time as the house.§401.1-401.2
- ApprovalWritten permit from the Building Inspector before construction or conversion; a certificate of occupancy before use. ADU is a listed Permitted Use in R-1, R-2 and I-B/R.§401.3; §202.2 #9, §202.3 #8, §202.4 #23
- How manyOne ADU per single-family dwelling. Only lots with exactly one single-family dwelling qualify.§401.4-401.5
- Attached or detachedAn ADU may be inside, attached to, or detached from the house. An attached ADU may have its own entrance or share a common space.§401.6; §401.9
- SizeThe ADU footprint may not exceed 800 sq ft. For a multi-floor ADU, all floors count toward the 800 sq ft. Minimum 720 sq ft of ground-floor or lower living area (the same minimum applies to every dwelling unit in town, §203.14). Max two bedrooms.§401.7, 401.8, 401.10; §203.14
- LotAll zoning rules for a single-family home (lot dimensions, setbacks, coverage, aesthetics, building area, design review) apply to the ADU or to the house plus ADU.§401.11
- OtherAn ADU may be converted from a legal structure that existed on or before July 1, 2025, even if it violates current setback or lot-coverage rules.§401.12
- Owner on siteThe owner must live in either the house or the ADU.§401.13
- SepticThe owner shows the Building Inspector that water supply and septic design capacity are adequate for both units under NHDES standards (licensed septic designer certification if asked).§401.15
- ShorelandNo separate local shoreland overlay found; state RSA 483-B applies on its own terms. Wetlands Conservation District buffer is 100 ft from Tidal Lands, Wetlands and Isolated Non-Bordering Wetlands, including a 25 ft vegetative buffer. No structure or impermeable surface within 100 ft on undeveloped or developed lots, with fallback to 50 ft (wetlands) / 75 ft (tidal) for pre-March 11, 2003 lots where 100 ft leaves under 16,000 sf buildable. Additions to pre-2003 structures in the buffer: limited to the greater of 1,200 sf or 25% of the heated footprint inside the buffer.§501.6; §501.6.B-C (amended 3/11/2025)
Read 2026-11-15 from North Hampton Zoning Ordinance (Header on every page: 'March 10, 2026'; Section 401 '*3/14/2017, 3/13/2018, 3/8/2022, 3/14/2023, 3/10/2026'). Anything not listed here, we check with the North Hampton land-use office for your lot.
Setbacks
Front, side and rear in North Hampton.
NH RSA 674:71-73 (HB 577) - one attached or detached ADU by right on a single-family lot
North Hampton's dimensional table, as printed in the ordinance.
| District | Front | Side | Rear | Lot / cover / height |
|---|---|---|---|---|
| R-1primaryR-1 High Density District§203.1 Yard and Lot Requirements; §203.13; §301; §104.34. R-1 frontage 175 ft. R-1 accessory buildings: Front 30 ft and no closer to the road than the house unless 150+ ft from the road. Lots < 2 acres: accessory footprint max 1,008 sf. Side/rear: 15 ft (≤1,008 sf), 25 ft (1,008-1,440 sf), 35 ft (1,440-2,500 sf), 50 ft (2,500-4,000 sf). Otherwise CUP. | 30 ft | 25 ft | 25 ft | 87,120 sf (2.00 ac) · 35% (lots < 2 acres) / 25% (lots ≥ 2 acres); 'Lot Coverage' includes buildings, parking, drives, pavement and all impervious surfaces · Height 35 ft |
| R-2R-2 Medium Density District§203.1; §203.13; §301. R-2 frontage 175 ft. R-2 accessory buildings: Front 35 ft, same road-placement rule. Side/rear: 15 ft (≤1,008 sf), 30 ft (1,008-1,440 sf), 35 ft (1,440-2,500 sf), 50 ft (2,500-4,000 sf). Footprint caps 1,008 / 1,440 / 4,000 sf by lot size. | 35 ft | 30 ft | 30 ft | 87,120 sf (2.00 ac) · 35% (lots < 2 acres) / 25% (lots ≥ 2 acres), impervious · Height 35 ft |
| I-B/RIndustrial-Business/Residential§203.1; §203.8; §203.11; §301. I-B/R frontage 250 ft. I-B/R accessory buildings: Front 50 ft; accessory structures allowed regardless of footprint (§301.2). | 50 ft | 35 ft | 35 ft | 87,120 sf (2.00 ac) · 75%, impervious · Height 35 ft |
Verified 2026-11-15 against North Hampton Zoning Ordinance. Towns amend ordinances, so confirm with the land-use office before you build. Official source
FAQ
ADUs in North Hampton.
- How big can an ADU be in North Hampton?
- Footprint of all ADU floors combined max 800 sq ft; minimum 720 sq ft ground-floor or lower living area; max two bedrooms, per §401.7, 401.8, 401.10; §203.14 as read 2026-11-15.
- Does the owner have to live on the lot in North Hampton?
- Owner must live in the house or the ADU (§401.13).
- Can an ADU in North Hampton be detached?
- Inside, attached, or detached, under §401.6; §401.9.
Planning an ADU in North Hampton?
Call (978) 987-0089 and we will say whether we can build there. See the ADU models