HomeHillsborough County › Antrim, NH

ADU Rules in Antrim, New Hampshire

Hillsborough County · Reconciled with the 2025 state law · Last reviewed 2026-09-10
Allowed by rightReconciled with the 2025 state law✓ Verified by a real human here in NH · July 20, 2026
The short answer
Yes — Antrim allows 2 by-right ADUs (verified with the town), up to 1,500 sq ft.

Antrim ADU rules at a glance

Max size1,500 sq ftconfirmed with the town
Min sizenot specified
Bedroomsnot specified
TypeNot statednot addressed in the ordinance
Parking1 spot for each ADUconfirmed with the town
Owner-occupancynot specified
Short-term rentalNot statednot addressed in the ordinance
Utility connectionTie into the existing electrical connection or choose a separate metersame statewide
Want to build smaller? Neither Antrim nor state law sets a minimum ADU size — the 750 sq ft figure you may have heard is the smallest maximum a town is allowed to impose, not a size you have to hit.

The full plain-English rundown

CONFIRMED WITH THE TOWN (July 20, 2026) — ADUs allowed: 2 by-right; maximum size 1,500 sq ft; impact fees: None specified in zoning; parking: 1 spot for each ADU; detached-unit distance rule: no; setbacks: 30' front, 20' side and rear. Town contact: antrimnh.org - voicemails can take two days to return - Darby Wilson, planning assistant planning@antrimnh.gov 603-547-0494 Inspector is Dario (also for Concord, NH)- nhbuildinginspector@gmail.com.

Although 1500sqft is max size, ADU can't be more than 50% of the gross living area of primary dwelling. If ADU is attached, it needs to have a separate exterior entrance. Allowed in every zone except institutional. In residential zones, lot coverage max for dwellings is 35%

Max size is now 1,500sqft - and TWO ADUs are allowed by right - one attached one detached! Even if you build two, they can both be 1500sqft OR no more than 50% of primary dwelling unit. No distance regulations for detached. No new curb cuts - one parking spot per ADU - If attached, needs to have separate entrances. In new construction, alarms must be interconnected so all sound when one is triggered. No minimum square footage specified in zoning. Permitted in every zoning district except for institutional. Setbacks are 30' front, 20' side and rear. Residential is typically no more than 35% lot coverage. Maximum bedroom count is not specified. "Planning board is very progressive". No Impact fees. General building permit, no specific ADU permit. Short Term rental not specified but would fall under the town's short term zoning regs - no owner occupancy requirement stated in zoning reg.

What does this mean for YOUR property?

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

Get My Free Antrim ADU Report →

What New Hampshire law guarantees in every town

House Bill 577 (2025) amended RSA 674:72, effective July 1, 2025. Wherever Antrim'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.

Antrim ADU questions, answered

Can I build an ADU in Antrim, NH?

Yes — Antrim allows 2 by-right ADUs (verified with the town), up to 1,500 sq ft. 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 Antrim?

1,500 sq ft — confirmed with the town. State law doesn't let any town cap ADU size below 750 sq ft.

Can I build a detached ADU in Antrim?

Since July 1, 2025, state law allows detached ADUs by right statewide — town provisions that prohibited them are superseded.

Does Antrim require extra parking for an ADU?

1 spot for each ADU — 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.

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

not specified. Where owner-occupancy is required, state law lets the owner choose which unit to live in.

ADU rules in nearby Hillsborough County towns

AmherstBrooklineHollisHudsonLitchfieldManchesterMerrimackMont VernonNashuaPelhamWeareWindsor
These are Antrim'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 Antrim's planning department before you build.