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ADU Rules in Newbury, New Hampshire

Merrimack County · Reconciled with the 2025 state law · Last reviewed 2026-09-10
Allowed by rightOrdinance predates the 2025 law (2023)◷ Draft — awaiting human verification
The short answer
Yes — one ADU is allowed by right under the July 2025 state law. Newbury (which calls it an 'accessory apartment') permits it attached or as a conversion of an existing detached building in its Business, Residential, and Blodgett Landing Cottage Districts — and where the town still requires a hearing, state law overrides it.

The July 2025 state law guarantees one ADU by right — but Newbury's ordinance, last revised March 28, 2023, hasn't caught up: Blodgett Landing still requires a full Zoning Board hearing for every ADU (a requirement state law now overrides), the town still dictates where your ADU's door can be, and its 3-space parking rule may exceed what state law allows.

Newbury ADU rules at a glance

Max size1,000 sq ftmust be smaller than main house
Min size300 sq ftinterior floor area
BedroomsUp to 2
TypeAttached + detachedDetached: existing buildings only
Parking3 spaces totalfor both units combined
Owner-occupancyRequiredin either the ADU or the primary home
Short-term rental30-day minimum leaserules out short-term rentals
Utility connectionTie into the existing electrical connection or choose a separate metersame statewide
About minimum size: Newbury does set its own minimum ADU size — see the Min size row above. That's a town choice, not a state requirement: state law only limits how small a town may set its maximum (never below 750 sq ft).

Where Newbury's posted rules are superseded by state law

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 Newbury:

The law sides with youBlanket Special Exception (ZBA hearing) required for every ADU in the Blodgett Landing Cottage District

In Blodgett Landing, Newbury still makes you go before the Zoning Board of Adjustment and win a Special Exception just to add an ADU — even though a regular house is allowed there with no hearing at all. Since July 2025, state law entitles you to build one ADU there by right, with only a building permit, same as everywhere else in town.

The law sides with youDictated entrance location (side/rear or 'formal entrance' only) plus mandatory interior connecting door

Newbury's code tells you where your ADU's door has to be (side, rear, or through the main house's front door) and forces an interior connecting door between the units. State law says that choice — separate entrance or shared — belongs to you, not the town.

The law sides with youParking — 3 total spaces required with no established baseline principal-dwelling parking requirement (Residential & Business Districts)

If Newbury doesn't otherwise make a regular house provide off-street parking in the Residential or Business districts, then requiring 3 spaces the moment you add an ADU looks like it goes beyond the one-extra-space cap state law allows — and even where it applies, you're supposed to get to choose on-site vs. off-site, which the town's text doesn't offer.

Gray area — ask an attorneySpecial Exception triggered by Shoreland Overlay District location (Business & Residential Districts)

A large share of Newbury (a lake town) likely falls in the Shoreland Overlay. There, even in a district where ADUs are otherwise by-right, the town still requires a ZBA Special Exception. Whether an environmental overlay district can still impose this hearing after HB 577 is a genuine gray area worth an attorney's read.

The law sides with youNo stated exemption for setback/lot-coverage-nonconforming existing structures being converted to an ADU

If your garage or barn already sits too close to the property line under today's rules, Newbury's ordinance doesn't say you're still allowed to convert it into an ADU — but state law says you are, regardless of that nonconformity.

Gray area — ask an attorneyADU tied to an 'existing' single-family dwelling — no stated right to build the ADU alongside a brand-new house

Newbury's text reads as if you need a house first, then add the apartment — it never says you can build both at once. State law gives you that right either way; this is a gap in the town's wording, not a clear ban, but worth confirming with the Code Enforcement Officer before you plan a simultaneous build.

Gray area — ask an attorneySize cap tied to the principal dwelling's floor area could push the ADU below the state's 750 sq ft floor on small houses

On a small existing house (say, 700 sq ft), this 'must be smaller than the main house' rule could force your ADU under the 750 sq ft floor the state guarantees. It won't come up on an average-size home, but on Newbury's smaller camps and cottages it's a real edge case.

The full plain-English rundown

Since July 1, 2025, state law (RSA 674:71-73, as amended by HB 577) has guaranteed one ADU by right in every district that allows single-family homes — that is the operative rule today, and it overrides the stricter pieces of Newbury's 2023 ordinance described below. Newbury calls its ADU an 'accessory apartment' and allows one per lot in all three districts that permit single-family homes: Business (§4.10), Residential (§5.7), and Blodgett Landing Cottage (§6.12). The Mt. Sunapee Recreation District bans all residential use outright, so no ADU provision applies there — that's consistent with state law, which only requires ADU allowance where single-family homes are already permitted. Where Newbury lines up with the new state law: size limits (300–1,000 sq ft, both more generous than the state's 750–950 sq ft range), a max-two-bedroom cap (state only bars capping at ONE bedroom), and owner-occupancy of either unit (state-compliant, since it doesn't dictate which unit). Where Newbury's 2023 ordinance is now out of step with the July 2025 law: (1) in the Blodgett Landing Cottage District, EVERY accessory apartment still requires a full Zoning Board of Adjustment Special Exception hearing — even though regular houses are allowed there by right — which is exactly the kind of gatekeeping HB 577 eliminated; (2) the town dictates that your ADU's entrance must be on the side or rear of the building (or through the house's main entrance) and mandates an interior connecting door between the units, when state law and NH Housing's own guidance say that choice belongs to the homeowner; (3) in the Residential and Business Districts, the ordinance requires 3 total parking spaces on any lot with an ADU, with no general off-street parking requirement found anywhere else in the ordinance for an ordinary single-family home — which looks like it exceeds the state's 'up to one extra space, and only if the town already requires parking for the house' rule; (4) if your property sits in the Shoreland Overlay District (common on a lake town like Newbury), a Special Exception is required there too, even in districts where ADUs are otherwise by-right — a genuine gray area for an attorney to weigh in on; (5) the ordinance never explicitly protects your right to convert a setback-nonconforming existing garage or barn into an ADU, something state law guarantees; and (6) the text reads as though the principal dwelling must already exist before you add an apartment, without addressing the state-law right to build both at the same time. Newbury has not amended this ordinance since HB 577 passed — where the town text and the statute collide, the statute controls. See conflicts[] for full citations.

What does this mean for YOUR property?

Get a free personalized report for your address in Newbury — including where the 2025 law works in your favor.

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What New Hampshire law guarantees in every town

House Bill 577 (2025) amended RSA 674:72, effective July 1, 2025. Wherever Newbury's ordinance is stricter than this floor, the state law controls. Read the full NH ADU law explainer →

One ADU by rightEvery single-family lot in New Hampshire may add one accessory dwelling unit — attached or detached — as a matter of right. No special exception, variance, or conditional-use permit can be required for the ADU itself.
At least 750 sq ftA town may cap ADU size, but the cap can't be lower than 750 sq ft. (That's a ceiling on how strict a town can be — not a minimum you have to build.)
At most 1 extra parking spaceA town can require no more than one additional parking space for an ADU, and the owner chooses whether it's on-site or off-site.
No family-only ruleTowns can no longer require the ADU occupant to be related to you.
More than one bedroomA town can't limit an ADU to a single bedroom.
Separate utilities allowedA town can't force the ADU to share the main home's electrical service — a separate connection or meter is your choice.
Garage conversions protectedConverting an existing garage to an ADU is allowed even if the garage doesn't meet today's setbacks.
Owner-occupancy, either unitA town may require the owner to live on the property, but the owner picks which unit — the main home or the ADU.

Newbury ADU questions, answered

Can I build an ADU in Newbury, NH?

Yes — one ADU is allowed by right under the July 2025 state law. Newbury (which calls it an 'accessory apartment') permits it attached or as a conversion of an existing detached building in its Business, Residential, and Blodgett Landing Cottage Districts — and where the town still requires a hearing, state law overrides it. 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.

How big can an ADU be in Newbury?

1,000 sq ft — must be smaller than main house. State law doesn't let any town cap ADU size below 750 sq ft.

Can I build a detached ADU in Newbury?

Attached + detached (Detached: existing buildings only). Since July 1, 2025, state law allows detached ADUs by right statewide — town provisions that prohibited them are superseded.

Does Newbury require extra parking for an ADU?

3 spaces total — for both units combined. State law caps what any town can require at one additional space, located on- or off-site at the owner's choice.

Do I have to live on the property to have an ADU in Newbury?

Required — in either the ADU or the primary home. Where owner-occupancy is required, state law lets the owner choose which unit to live in.

ADU rules in nearby Merrimack County towns

AndoverBoscawenBowConcordEpsomFranklinHooksettHopkinton
These are Newbury's town-wide ADU standards under the 2025 state law — confirm your parcel's specific zoning district with the town, since a few districts can differ. This guide is an independent informational resource, not legal advice; verify with Newbury's planning department before you build.