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ADU Rules in Kensington, New Hampshire

Rockingham County · Reconciled with the 2025 state law · Last reviewed 2026-09-10
Allowed by rightUpdated 2026 — gaps remain✓ Verified by a real human here in NH · July 29, 2026
The short answer
Yes — Kensington allows one accessory dwelling unit (attached or detached) by right, by building permit only, in its Residential/Agricultural (RA) District.

Kensington rewrote its ADU ordinance effective March 6, 2026 to match the state's by-right law: a straight building permit (no more Conditional-Use-Permit hearing before the Planning Board), one parking space (not two), sizes between 650-900 sq ft, and an explicit right to convert a detached garage into an ADU even if it doesn't meet current setbacks. A couple of details — a 'must look subordinate' design clause and no stated choice on off-site parking — still deserve a second look, and some figures quoted verbally by town staff don't match the written ordinance.

Kensington ADU rules at a glance

Max size900 sq ftconfirmed with the town
Min size650 sq ftconfirmed with the town
BedroomsUp to 2confirmed with the town
TypeAttached or detachedgarage conversions expressly allowed
Parking1 spot onsiteconfirmed with the town
Owner-occupancyRequiredin either the ADU or the primary home
Short-term rentalNot statedordinance read was truncated
Utility connectionTie into the existing electrical connection or choose a separate metersame statewide
About minimum size: Kensington 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Where Kensington's posted rules are superseded by state law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 Kensington:

Gray area — ask an attorneyDesign-subordinate aesthetic requirement

State law says Kensington can only hold your ADU to the same look-and-feel standards it holds an ordinary house to, not stricter ones. Whether a blanket 'must look subordinate' rule crosses that line is an attorney call — the same open question that comes up in other NH towns with similar design-continuity clauses.

The law sides with youParking location choice

State law fills the silence here: the choice of on-site vs. a legally dedicated off-site spot is yours, not the town's to dictate. Kensington's ordinance requires one space but doesn't say where it must go.

The full plain-English rundown

CONFIRMED WITH THE TOWN (July 29,2026) — ADUs allowed: 1; maximum size 900 sq ft; minimum size 650 sq ft; up to 2 bedrooms; impact fees: No; parking: 1 spot onsite; detached-unit distance rule: No regs for a min or max distance from existing structure; setbacks: 25' Feet all around, no largest district whole town is all residential with a 2 acre minimum and 200ft of frontage. Town contact: Gino Rignoli - Building inspector.

Very minimal wording from the town on certain ordinances surounding ADUs, As per the BI the town is activally working on and changing these ordinances so make sure you call and check with any questions and concers as a rule or ordinance may have changed recently

Will let you build in the front yard depending on acerage, Smoke alarms do not need to be tied to the main house, Town had people try to use ADUs for STR and although there is no current ordinace on it is frowned upon and look forward to this being changed to a hard no in the future.

Kensington's ADU ordinance (Zoning §3.2.3) was substantially rewritten and adopted at Town Meeting on March 6, 2026 — well after the July 1, 2025 state law (RSA 674:71-73 as amended by HB 577) took effect — and the rewrite closes the town's single biggest gap: ADUs no longer require a Conditional Use Permit or a Planning Board hearing. They're now permitted by right with nothing more than a building permit application, and the 21-day advance-of-planning-board-meeting filing window that used to apply is gone. The ordinance also now directly quotes the state statute's language guaranteeing that an existing detached structure (like a garage) can be converted into an ADU even if it doesn't meet current setback or lot-coverage rules. Size must be between 650 and 900 sq ft of living area per the adopted ordinance text (town staff have verbally cited a 950 sq ft ceiling — a discrepancy that needs confirmation, though either number is within what state law allows), two bedrooms max, owner-occupancy required in either unit (a rule towns may lawfully impose), and only one extra off-street parking space (down from two under the old rules). Two things still merit scrutiny against the state floor: (1) a clause requiring the ADU to 'appear subordinate to the principal dwelling unit in design and placement' could be read as an aesthetic standard stricter than what's applied to an ordinary house — an attorney call; and (2) the ordinance doesn't say whether the required parking space can be located off-site, which state law guarantees is the owner's choice. Separately — a data-quality flag, not a legal one — some figures quoted verbally by town staff in mid-2026 don't match the written ordinance: a 100 ft front setback (which matches the town's separate Commercial/Industrial district requirement, not the RA district's written 25 ft standard), a 'no parking restrictions' statement (vs. the ordinance's clear 1-space requirement), and a 950 sq ft max size (vs. the ordinance's literal 900 sq ft). Re-confirm these with the town before relying on them. See conflicts[] for the two live state-law questions and resolved_by_town[] for what Kensington already fixed.

What does this mean for YOUR property?

Get a free personalized report for your address in Kensington — 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 Kensington'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.

Kensington ADU questions, answered

Can I build an ADU in Kensington, NH?

Yes — Kensington allows one accessory dwelling unit (attached or detached) by right, by building permit only, in its Residential/Agricultural (RA) District. 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 Kensington?

900 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 Kensington?

Attached or detached (garage conversions expressly allowed). Since July 1, 2025, state law allows detached ADUs by right statewide — town provisions that prohibited them are superseded.

Does Kensington require extra parking for an ADU?

1 spot onsite — 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 Kensington?

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 Rockingham County towns

AtkinsonAuburnBrentwoodCandiaChesterDeerfieldDerryExeterHampsteadHamptonLondonderryNorth HamptonNorthwoodPlaistowPortsmouthRaymondSalemSandownStrathamWindham
These are Kensington'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 Kensington's planning department before you build.