| Max size | 950 sq ft |
|---|---|
| Min size | 750 sq ftminimum size of the unit |
| Bedrooms | Not statedno bedroom cap |
| Type | Attached or detachedeither one, by right under state law |
| 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 or detached (either one, by right under state law). 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.