| Max size | 1,000 sq ftconfirmed with the town |
|---|---|
| Min size | 800 sq ftconfirmed with the town |
| Bedrooms | Up to 2confirmed with the town |
| Type | Attached or detachedby right, building permit only |
| Parking | 1confirmed with the town |
| Owner-occupancy | yes but not formally enforcedconfirmed with the town |
| Short-term rental | Not stated |
| Utility connection | Tie into the existing electrical connection or choose a separate metersame statewide |
The July 2025 state law (RSA 674:71–73) overrides local ordinance language that conflicts with it — even language a town still has posted. Here's what that means in Atkinson:
Under state law, you get to choose between putting the required parking space on your own lot or at a legally dedicated off-site spot. Atkinson's ordinance says a space may be required but doesn't mention that choice — state law gives it to you regardless of what the town's text says.
State law protects your right to convert an existing garage or barn into an ADU even if it sits closer to the property line than current setback rules allow. Atkinson's ordinance doesn't explicitly restate that protection — it only mentions the ingress/egress condition — so a conservative reading by a local official is possible. State law almost certainly controls here, but it's worth confirming with the Building Inspector before assuming approval.
CONFIRMED WITH THE TOWN (July 22, 2026) — ADUs allowed: 1; maximum size 1,000 sq ft; minimum size 800 sq ft; up to 2 bedrooms; impact fees: None yet, likely will be imposed soon; parking: 1; detached-unit distance rule: none specified - fire department will review as part of initial application.; setbacks: Largest residential zone in Atkinson is R2 - 2 acre minimum - setbacks there are 30' side (or 100' total), front is up to 70', rear is up to75'. Town contact: Sue in Planning dept.
If the family wanted something smaller, you could do an addition rather than an ADU. Sue at the town was unclear on how this would work. Separate detached structures MUST be between 800-1000sqft.
Atkinson's Accessory Dwelling Unit ordinance (Zoning Ordinance §460) is unusual among NH towns in that it explicitly cites 'RSA 674:71-73' in its own text and carries '(2026)' amendment tags on several clauses — a strong signal the town proactively aligned its code with the 2025 state law (HB 577) rather than leaving stale pre-2025 language on the books. The core picture: one ADU is allowed by right (building permit only, no special exception or board hearing) on any lot with a single-family home, in every zoning district where single-family homes are permitted (RR-3, RR-2, TR-2, TC — not the commercial districts). Attached and detached units are both explicitly defined and allowed, including conversion of an existing detached structure (e.g., a garage) built before June 30, 2025. Size is capped at 1,000 sq ft with up to 2 bedrooms — notably MORE generous than the state's default 950 sq ft ceiling, since state law lets towns authorize a higher cap and Atkinson did. Owner-occupancy is required in either the main house or the ADU (town doesn't dictate which), and one extra off-street parking space is required only in districts that already require parking for single-family homes — language that closely mirrors the state law's own conditional structure. Two things aren't fully spelled out in the town's text, and state law resolves both in the homeowner's favor regardless: (1) Atkinson doesn't say you can put the required parking space off-site instead of on your own lot — state law gives you that choice; (2) the clause allowing conversion of a pre-existing structure doesn't explicitly say the conversion is protected even if the structure or lot is nonconforming as to setback/lot-coverage — state law requires that protection, so the town's silence doesn't take it away, but a cautious official could push back until it's pointed out. One former clause ('f') in §460:3 was deleted in the 2026 revision; the current ordinance does not show its prior text, so it's unclear what it said or whether it was itself a pre-2025 restriction being cleaned up. Impact fees (Article XVI of the town's regulations) and smoke-alarm requirements are addressed elsewhere in the town's code, if at all, and could not be confirmed here — check with the town before budgeting.
Get a free personalized report for your address in Atkinson — including where the 2025 law works in your favor.
Get My Free Atkinson ADU Report →House Bill 577 (2025) amended RSA 674:72, effective July 1, 2025. Wherever Atkinson's ordinance is stricter than this floor, the state law controls. Read the full NH ADU law explainer →
Yes — Atkinson allows one accessory dwelling unit (attached or detached) by right on any lot with a single-family home, in every district where single-family homes are permitted. Under RSA 674:72 (as amended effective July 1, 2025), one accessory dwelling unit — attached or detached — is allowed by right on single-family lots statewide.
1,000 sq ft — confirmed with the town. State law doesn't let any town cap ADU size below 750 sq ft.
Attached or detached (by right, building permit only). Since July 1, 2025, state law allows detached ADUs by right statewide — town provisions that prohibited them are superseded.
1 — confirmed with the town. State law caps what any town can require at one additional space, located on- or off-site at the owner's choice.
yes but not formally enforced — confirmed with the town. Where owner-occupancy is required, state law lets the owner choose which unit to live in.