| Max size | 1,000 sq ftliving area, excl. entryways |
|---|---|
| Min size | No town minimumbuild as small as code allows |
| Bedrooms | Up to 2 |
| Type | Attached or detachedboth need a conditional use permit |
| Parking | "Adequate" off-streetno space count given |
| 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 Pelham:
Pelham's ordinance still requires you to go through a Conditional Use Permit process (Zoning Administrator for attached, Planning Board for detached) before you can build an ADU. Since July 1, 2025, state law entitles you to build one ADU by right — no board hearing or discretionary approval required — as long as you meet the same dimensional/building-code standards as any other home.
Pelham effectively reserves detached ADUs for large, high-quality-soil lots and requires the Planning Board to approve the location on your property. Post-HB 577, a detached ADU is a homeowner right in any district that allows single-family homes — the town can still apply its normal dimensional rules, but it can't gatekeep detached ADUs behind a 1.5-acre/45,000-sq-ft-soils threshold and a discretionary board sign-off.
Pelham bars a front-door entrance for an attached ADU. State law says the town can't restrict where your ADU's entrance goes — that choice belongs to you, the homeowner.
Pelham's ordinance reads as though the primary house must already exist before you add an ADU. Since July 2025, you're entitled to build the ADU at the same time as a brand-new home, not just as a later add-on.
Pelham's 'adequate parking' language is vague enough that it could be applied to demand more than the one extra space state law allows, and it doesn't spell out your right to put that space off-site. Worth confirming directly with the Planning Department before you finalize a site plan.
If your lot is already nonconforming (common on older Pelham lots), §307-74.N as written appears to block an ADU outright. State law protects your right to convert an existing structure into an ADU even on a nonconforming lot — this is a strong candidate for legal challenge, but it's a call for a NH land-use attorney, not a DIY reading.
What Pelham's ordinance (§307-74) actually says: You can add one ADU — attached to, within, or detached from your single-family home — capped at 1,000 sq ft of living area and 2 bedrooms. Either you or your tenant... no, either the main house or the ADU must be owner-occupied (your choice), and you file a one-page attestation with the Planning Department every April 1st confirming that. You can't subdivide or condo off the ADU separately from the house, and no more than 3 unrelated people can live in it. A detached ADU additionally needs a 1.5-acre lot with 45,000 sq ft of good (non-hydric) soil, an NHDES septic design sized for both units, and Planning Board sign-off on where it sits on your property.
What the town's ordinance won't tell you (state law overrides, effective July 1, 2025): (1) You should NOT need a Conditional Use Permit / board hearing at all — one ADU is a by-right use in any district that allows single-family homes, and that includes detached ADUs, not just attached ones. (2) The 1.5-acre/45,000-sq-ft-soils detached-ADU threshold is very likely unenforceable post-HB 577 — the state law's whole point was to guarantee a detached ADU as a right, not a discretionary approval reserved for big lots. (3) Pelham bars a front door on an attached ADU; state law says the entrance/exit choice is yours. (4) The ordinance's 'existing dwelling' language suggests you must build the house first and the ADU later — state law lets you build both at once. (5) If your lot is already nonconforming, the ordinance's 'conforming lots only' rule looks directly at odds with the state's guarantee that you can convert an existing structure (like a garage) into an ADU even on a nonconforming lot.
Bottom line: Pelham's size cap (1,000 sq ft) and bedroom cap (2) and owner-occupancy rule are all consistent with — or more generous than — state law. But the permitting process itself (CUP for every ADU, extra hurdles for detached units, the front-door ban, and the conforming-lots-only rule) reads like a pre-HB 577 ordinance that the town has not yet updated to match your current rights. Confirm directly with Pelham's Planning Department (which administers ADU CUPs) before assuming any of the above still applies as written, and consult a NH land-use attorney on the nonconforming-lot and detached-ADU-threshold questions specifically.
Get a free personalized report for your address in Pelham — including where the 2025 law works in your favor.
Get My Free Pelham ADU Report →House Bill 577 (2025) amended RSA 674:72, effective July 1, 2025. Wherever Pelham's ordinance is stricter than this floor, the state law controls. Read the full NH ADU law explainer →
Yes — Pelham allows one ADU (attached or detached) per single-family lot, but its ordinance still runs every ADU through a Conditional Use Permit that state law says towns can no longer require. 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.
1,000 sq ft — living area, excl. entryways. State law doesn't let any town cap ADU size below 750 sq ft.
Attached or detached (both need a conditional use permit). Since July 1, 2025, state law allows detached ADUs by right statewide — town provisions that prohibited them are superseded.
"Adequate" off-street — no space count given. 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.