| Max size | 950 sq ft |
|---|---|
| Min size | 750 sq ftminimum size of the unit |
| Bedrooms | Not statedno bedroom cap |
| Type | Attached yes; detached not statedno restriction on detached found |
| Parking | Not stated in ADU sectioncross-refers to town table; unverified |
| 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 Franklin:
If Franklin's B-2 business district allows single-family homes as a use, state law says ADUs must be allowed there too by right — regardless of the fact that Franklin's amendment doesn't add ADUs to B-2. The full Use Table needed to confirm whether B-2 permits single-family dwellings could not be reviewed, so this is a real gap worth a direct town/attorney check, not a confirmed violation.
State law caps required ADU parking at one extra space and gives the homeowner the on-site/off-site choice. Franklin's ADU section defers to its general § 305-19 parking table, which could not be reviewed for this record — if that table requires more than one extra space for the ADU, or doesn't give the homeowner the off-site option, state law overrides it, but the table itself is pending verification.
Franklin's ADU rules were substantially rewritten in a 2026 zoning amendment that replaces the old discretionary 'Family Apartment by Special Exception' system with a straightforward, by-right 'Accessory Dwelling Unit' permitted use in the RR, RS, R-1, R-2, R-3, C, and LP districts. An ADU application goes to the Planning and Zoning Director; if it meets the criteria, the Director issues a letter of authorization — no public hearing required, consistent with the state law's requirement that the one by-right ADU not be conditioned on a special exception or conditional-use permit. The size range is 750 sq ft minimum to 950 sq ft maximum. (One nuance: the 750 sq ft figure in state law is a floor on how low a town may set its size CAP, not a required minimum unit size — Franklin has chosen to also impose 750 sq ft as a minimum.) Owner-occupancy is required in either the principal unit or the ADU (documented by a notarized statement), one ADU per parcel, no condo conversion, and the ADU may be built at the same time as the principal dwelling — all consistent with RSA 674:71-73 as amended by HB 577. Two things could not be confirmed for this record: (1) Franklin's general off-street parking table (§ 305-19), which the ADU section cross-references instead of stating a number — so it's unknown whether the town stays within the state-allowed one extra space and gives homeowners the state-guaranteed choice of an on-site or off-site location; if it doesn't, state law overrides it; and (2) whether Franklin's B-2 business district — which lost its old 'Family Apartment' special-exception eligibility in this same amendment and was NOT added to the new ADU-permitted list — allows single-family homes (if it does, state law still requires an ADU there by right, amendment or not). Both are flagged as open items rather than guessed at. See conflicts[] for citations and resolved_by_town[] for what Franklin already fixed.
Primary source: eCode360 (General Code) — The city's recent amendment rewriting §§ 305-3, 305-13, and…
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Get My Free Franklin ADU Report →House Bill 577 (2025) amended RSA 674:72, effective July 1, 2025. Wherever Franklin's ordinance is stricter than this floor, the state law controls. Read the full NH ADU law explainer →
Yes — Franklin allows one accessory dwelling unit by right in its RR, RS, R-1, R-2, R-3, C, and LP districts. 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. State law doesn't let any town cap ADU size below 750 sq ft.
Attached yes; detached not stated (no restriction on detached found). Since July 1, 2025, state law allows detached ADUs by right statewide — town provisions that prohibited them are superseded.
Not stated in ADU section — cross-refers to town table; unverified. 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.