ADU rules in Salem

A detached backyard ADU is allowed by right on any lot that contains a single one-family dwelling. This is recent: until the Town Council's 2025 rewrite, 490-801(C)(10) read 'Detached accessory apartments are not allowed,' and that sentence was struck by Zoning Amendment Set #2 (Planning Board public hearing August 26, 2025; Council adoption September 22, 2025; codified with the note 'amended by Town Council August 29, 2025'). The Permitted Uses Table (Attachment 1) carries a single ADU row reading 'Permitted on lots containing one (1) single-family dwelling' spanning every zoning district, and 490-801(C)(11) lets an existing structure, 'including but not limited to detached garages,' be converted even if it violates current setback or lot coverage rules. Since August 31, 2026 a unit built inside a preexisting detached garage or barn is itself a detached unit under state law (RSA 674:71, III as amended by 2026 ch. 210), which changes nothing about what Salem requires, because 490-801 applies one set of conditions to both forms and Salem sets no separate dimensional standard for detached ADUs. The 2025 rewrite brought Salem into line with RSA 674:73, which since July 1, 2025 (2025 ch. 197, HB 577) says a municipality 'shall permit one detached accessory dwelling unit.'

An attached or internal ADU (an addition, or a basement or interior conversion) is allowed by right on the same terms as a detached one; 490-801 sets one common set of conditions and does not distinguish between the two forms. The 2025 amendment added definitions of 'attached accessory dwelling unit' and 'detached accessory dwelling unit' at 490-107 that tracked RSA 674:71 as it then read, so Salem's text still counts a unit 'completely contained within a preexisting detached structure' as attached even though state law has called that same unit detached since August 31, 2026. Nothing turns on the label in Salem: the only form-specific rule is 490-801(C)(10), which requires an attached unit to have 'either an independent means of ingress and egress or ingress and egress through a common space shared with the principal dwelling,' and the old requirement of an interior door between the two units was repealed. Only one ADU is allowed per single-family dwelling, and the lot may contain a maximum of one single-family dwelling.

490-801(C)(4) caps the unit at 950 square feet of floor space and limits it to two bedrooms. The 950 figure matches the state default in RSA 674:72, VII (an ADU 'shall not exceed 950 square feet unless otherwise authorized by the municipality,' and a municipality 'may not restrict the total living space to less than 750 square feet'), which HB 577 raised from the old 750 sq ft figure in 2025. The two-bedroom cap is permitted by state law, which only forbids limiting an ADU to one bedroom. Ordinary district dimensions still apply to the structure: in the Residential District, front and rear setbacks of 30 feet, side 15 feet, 30% building coverage, and a 35 foot or 2 1/2 story height limit; the Rural District requires 30 feet on all sides and the Recreational District 30 feet front, 15 feet side and rear.

490-801(C)(2) requires that 'the property owner must occupy one of the two units.' The owner may choose either unit, so a homeowner can live in the ADU and rent the main house or the reverse. Where the property is held by a trust, an LLC, or another 'unnatural person,' one of the two units must be the principal place of residence of the trust beneficiary or LLC member. The requirement survived the 2025 rewrite and remains lawful: RSA 674:72, VI still lets a municipality require owner occupancy of one of the units, so long as it does not specify which one. Salem enforces it by recording the ADU use as a deed addendum in the Rockingham County Registry of Deeds, drawn up by the Building Department and signed and notarized when the building permit issues.

490-801(C)(6) requires 'one additional off-street parking space' for the ADU and encourages garage and tandem parking. The same September 2025 amendment set rewrote the parking table at 490-701(E) to a single line, 'Housing: all residential land uses, 1 per dwelling unit,' replacing the former 2-spaces-per-unit standard for single-family dwellings and apartments, in order to comply with RSA 674:16, VII (a municipality 'shall not require more than one residential parking space per unit'). One space for the ADU is also the maximum RSA 674:72, IV allows. Note that the Town's ADU permit handout has not caught up: the version dated 7/21/25 still tells applicants that 'off street parking shall be provided for at least four (4) vehicles,' which the ordinance no longer requires.

Administrative review only. The Permitted Uses Table lists the accessory dwelling unit as permitted on any lot containing one single-family dwelling, in every district, and 490-801 says one ADU 'shall be permitted' if the listed conditions are met; there is no special exception from the Zoning Board of Adjustment and no Planning Board conditional use permit. In practice the owner files an accessory apartment/ADU permit application with Inspectional Services (Building Safety) at Town Hall, obtains Planning and Engineering sign-off, and pulls building, electrical and plumbing permits; the Building Department prepares the deed addendum for notarization and recording. Discretionary relief from the ADU standards is effectively closed off, because 490-801(C)(9) declares that 'variances from this section shall be contrary to the spirit and intent of this chapter.' Money due at certificate of occupancy: a $5,884 impact fee, plus water ($1,800) and sewer ($2,700) demand and benefit assessments where applicable.

Nothing in 490-801 limits who may occupy the ADU or requires a family relationship, and RSA 674:72, VIII forbids requiring one, so the unit can be rented on a normal lease. Because the owner must occupy one of the two units, only one of them can be rented out. Short-term renting is off the table: Salem's 2025 definitions amendment added 'SHORT-TERM RENTAL: the rental of any residential dwelling unit, or portion thereof, for residential occupancy of less than 30 consecutive days' and wrote into the accessory dwelling unit definition (and the single-family, multi-family and manufactured home definitions) that 'this use shall not be deemed to include such transient occupancies as hotels, motels, short-term rentals, rooming or boarding houses.' Salem has no separate short-term rental licensing chapter in its municipal code. Sale of the ADU as a separate property is barred: 490-801(C)(7) prohibits converting the structure and lot to a condominium or any other distinct form of ownership and requires the ADU use to be recorded by deed addendum, consistent with RSA 674:72, I.