| Max size | 950 sq ftconfirmed with the town |
|---|---|
| Min size | No town minimumbuild as small as code allows |
| Bedrooms | Up to 2confirmed with the town |
| Type | Attached or detachednew detached build allowed |
| Parking | 1 spot for ADUconfirmed with the town |
| Owner-occupancy | Requiredin either the ADU or the primary home |
| 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 Sandown:
We could not find any general off-street parking requirement for an ordinary single-family home in Sandown's Zone A (the town's 'two spaces per unit' rule applies only to the separate Elderly Housing District). If Sandown really has no such baseline requirement for regular houses, it has no authority under state law to impose ANY parking mandate on an ADU — and even if it does, you're entitled to choose whether that space sits on your own lot or at another legally dedicated off-site spot, not wherever the ordinance implies.
Sandown already charges a town-wide capital-facilities impact fee on any new dwelling unit, so applying it to ADUs isn't unique overreach on its face — but whether a small 950-sq-ft ADU should be assessed the same way as a full new single-family home, given its much smaller footprint and lower demand on schools/roads, is a real question a land-use attorney should look at before you pay it.
CONFIRMED WITH THE TOWN (August 19, 2026) — ADUs allowed: 1; maximum size 950 sq ft; up to 2 bedrooms; impact fees: Yes, $1,550; parking: 1 spot for ADU; detached-unit distance rule: No; setbacks: 15’ Side, 10’ Rear, 30’ Front. Town contact: Jason Chui - Building Inspector Code Enforcement Officer Septic/Well Inspector (603) 867-6085.
Pat confirmed requirments on August 19, 2026
Sandown's ADU rules changed dramatically in 2026. Until March 10, 2026, building an ADU in Sandown required a discretionary Special Exception from the Zoning Board of Adjustment — a hearing process, a size cap tied to your house's footprint (never less than 750 sq ft), a mandatory 4-vehicle off-street parking pad, a required interior connecting door, and a notice recorded against your deed. Sandown voters replaced that entire system on March 10, 2026 (Zoning Amendment Z-1, passing 637–511), deleting the old special-exception ordinance and enacting a new by-right process closely modeled on the state's 2025 ADU law (RSA 674:71-73 / HB 577). Under the new rules: you can get an ADU approved with just a building permit from the Building Inspector — no hearing, no ZBA, no Planning Board review. You can build it attached or detached, and you can build it at the same time as a brand-new house. It can be up to 950 sq ft with up to two bedrooms. If it's attached, you choose whether it has its own entrance or shares one with the house. You (or your successor) must live in one of the two units, but the town can't dictate which one. No separate septic system is required beyond what NH DES already requires for the added capacity. The town does still require the ADU to sit on land you own (not rented/leased) and bars selling it off as a separate condo unit — both of which state law explicitly allows towns to do. Two things are still worth pushing back on: (1) the ordinance requires one off-street parking space for the ADU with no stated on-site-or-off-site choice, and we could not find any general parking requirement for an ordinary Sandown house that would justify that mandate under state law's 'only if you already require it for the house' rule; and (2) the ordinance applies the town's standard capital-facilities impact fee to ADU construction, which may be worth challenging as disproportionate for a small unit. IMPORTANT: as of this review the Town had not yet posted an updated, consolidated zoning ordinance PDF — this analysis is built directly from the certified ballot language voters approved and the official election results confirming it passed, not from a republished code book, so a human should re-verify against the town's next official ordinance reprint.
Primary source: Town zoning ordinance (PDF) — New Article II – Part G 'Accessory Dwelling Units' adopted…
Get a free personalized report for your address in Sandown — including where the 2025 law works in your favor.
Get My Free Sandown ADU Report →House Bill 577 (2025) amended RSA 674:72, effective July 1, 2025. Wherever Sandown's ordinance is stricter than this floor, the state law controls. Read the full NH ADU law explainer →
Yes — Sandown now allows one accessory dwelling unit (attached or detached) by right, after voters rewrote the zoning ordinance in March 2026. 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.
950 sq ft — confirmed with the town. State law doesn't let any town cap ADU size below 750 sq ft.
Attached or detached (new detached build allowed). Since July 1, 2025, state law allows detached ADUs by right statewide — town provisions that prohibited them are superseded.
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.
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.