ADU Rules in Epsom, New Hampshire
Merrimack 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 · August 27, 2026
The short answer
Yes — Epsom allows one ADU (verified with the town), up to 850 sq ft.
Epsom ADU rules at a glance
| Max size | 850 sq ftconfirmed with the town |
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| Min size | not specified |
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| Bedrooms | Up to 2confirmed with the town |
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| Type | Not statednot addressed in the ordinance |
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| Parking | 1 Spot for ADUconfirmed with the town |
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| Owner-occupancy | Requiredin either the ADU or the primary home |
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| Short-term rental | Not statednot addressed in the ordinance |
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| Utility connection | Tie into the existing electrical connection or choose a separate metersame statewide |
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Want to build smaller? Neither Epsom 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 (August 27,2026) — ADUs allowed: 1; maximum size 850 sq ft; up to 2 bedrooms; impact fees: $300 application fee; parking: 1 Spot for ADU; setbacks: 50’ Front, 15’ sides, 20’ rear. Town contact: Jessica - Planning Department.
Epsoms town Zoning ordiance is outdated and has incorrect requirments regarding ADU's. There ordiance states only attatched ADU's are allowed. Pat informed Jessica in the planning department about HB 577 and to utilize that bill when updated the zoning ordiance
Pat verified on August 26, 2026
What does this mean for YOUR property?
Get a free personalized report for your address in Epsom — including where the 2025 law works in your favor.
Get My Free Epsom ADU Report →What New Hampshire law guarantees in every town
House Bill 577 (2025) amended RSA 674:72, effective July 1, 2025. Wherever Epsom'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.
Epsom ADU questions, answered
Can I build an ADU in Epsom, NH?
Yes — Epsom allows one ADU (verified with the town), up to 850 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 Epsom?
850 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 Epsom?
Since July 1, 2025, state law allows detached ADUs by right statewide — town provisions that prohibited them are superseded.
Does Epsom require extra parking for an ADU?
1 Spot for 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 Epsom?
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.
These are Epsom'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 Epsom's planning department
before you build.