| Max size | 800 sq fthabitable floor area |
|---|---|
| Min size | No town minimumbuild as small as code allows |
| Bedrooms | Not statedno bedroom cap found |
| Type | Attached by rightdetached: CUP per town's text |
| Parking | Not capturedpending verification |
| 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 Bow:
As of July 1, 2025, state law entitles you to build one detached ADU by right, with just a building permit — the same as an attached one. Bow's ordinance and its own homeowner-facing infographic still say a detached ADU needs Planning Board approval through a Conditional Use Permit, but that requirement is now overridden. This is the single biggest way Bow's posted materials are out of date.
If your house sits on an older, smaller (nonconforming) lot that isn't hooked up to municipal sewer, Bow's ordinance as written could be read to block your ADU — but the 2025 state law's by-right guarantee doesn't obviously carve out an exception for lot size. This is a genuine gray area that would benefit from a call to the town or a land-use attorney before assuming you're blocked.
Bow's ordinance doesn't say anything about converting an existing detached garage or other structure into your ADU when it doesn't quite meet current setback rules. Since July 2025, state law gives you that right regardless of what the local ordinance is silent on.
YOUR RIGHTS UNDER STATE LAW (RSA 674:71-73, as amended effective July 1, 2025 — these override any conflicting town rule):
- You are entitled to one ADU — attached OR detached — by right on a lot with a single-family home, wherever single-family homes are permitted. No Conditional Use Permit, special exception, or Planning Board hearing may be required for that one by-right unit. Bow's ordinance has not been updated to reflect this — treat its 'CUP required for detached' language as superseded. - If the town requires ADU parking at all, it's capped at one additional space, and you choose whether that space is on-site or at a legally dedicated off-site location. - Converting an existing garage or other structure into your ADU is protected even if it creates a setback or lot-coverage nonconformity — Bow's ordinance doesn't address this, so the state protection controls.
WHAT BOW'S ORDINANCE STILL SAYS (last amended March 2024, before the state law):
- One ADU is allowed per lot, attached to your house or in a detached structure. - Attached ADU: allowed by right — no hearing, just a building permit — in every one of Bow's base zoning districts (§7.04; §5.11.A.6.a). - Detached ADU: the ordinance still requires a Conditional Use Permit (CUP) from the Planning Board (§7.04; §5.11.A.6.b), and the town's own ADU infographic repeats this — but see above: state law now makes the detached unit by-right too. - Size cap: 800 square feet of habitable floor area (§7.04.C). That cap is lawful — state law lets towns cap ADU size, provided the cap is no lower than 750 sq ft, and 800 clears that floor. - Owner-occupancy: one of the two units (main house or ADU) must be owner-occupied — the ordinance doesn't say which one (§7.04.D). Owner-occupancy requirements are allowed under state law. - Lot requirement: the property must meet the base district's minimum lot area (2 acres) or minimum frontage (200 ft), OR be a nonconforming lot served by municipal sewer (§7.04.A). Bow's RU/R/R-1 districts all carry the same 2-acre / 200-ft standard (Table of Dimensional Regulations §6.07). Whether this condition survives the state law's by-right guarantee on a nonconforming lot is a genuine gray area — see conflicts. - Setbacks (general district standard, not ADU-specific): 35 ft front, 20 ft side, 20 ft rear. - Septic: if not on municipal sewer, you need an approved septic design sized for both units — the ADU counts as 1.5 bathrooms for capacity math. - No deed restriction or covenant needs to be recorded. - A Public Safety Impact Fee of $723 applies (per the town's ADU infographic). - No parking requirement specific to ADUs was found in the ADU section or the town's ADU materials — confirm against the town's Article 9 parking regulations before you rely on 'no parking required.'
BOTTOM LINE: Treat Bow's public-facing ADU material (ordinance §7.04 and the town infographic) as accurate for size, owner-occupancy, and setbacks, but OUT OF DATE on the detached-ADU permit process. As of July 2025 you should not need a CUP for a detached ADU — confirm this directly with the Community Development Department (603-223-3973) before assuming you need Planning Board approval.
Primary source: Town website — §7.04 last amended March 12, 2024 (amendment specifically…
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Get My Free Bow ADU Report →House Bill 577 (2025) amended RSA 674:72, effective July 1, 2025. Wherever Bow's ordinance is stricter than this floor, the state law controls. Read the full NH ADU law explainer →
Yes — and under the 2025 state law you're entitled to one ADU, attached OR detached, by right. Bow's ordinance still says a detached ADU needs Planning Board approval (a Conditional Use Permit), but state law now overrides that. 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.
800 sq ft — habitable floor area. State law doesn't let any town cap ADU size below 750 sq ft.
Attached by right (detached: CUP per town's text). Since July 1, 2025, state law allows detached ADUs by right statewide — town provisions that prohibited them are superseded.
Not captured — pending verification. 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.