ADU rules in Carson City

A detached ADU is allowed only on a lot of 12,000 square feet or larger, and only in the districts where the use table permits it. Carson City's use table lists the accessory dwelling unit as an administrative permit use in SF5A, SF2A, SF1A, SF21 and MH1A, a special use permit (conditional use) in SF12, SF6, MH12 and MH6, permitted as a primary use in the Agriculture (A) and Conservation Reserve (CR) districts, and prohibited in the mobile home park (MHP), multifamily duplex (MFD) and multifamily apartment (MFA) districts. The 12,000 square foot floor bites hardest in SF6, where the minimum parcel is 6,000 square feet (6,500 on a corner), so a large share of SF6 lots cannot host a detached unit at all. The rules date to the November 7, 2024 zoning rewrite (Ord. No. 2024-6 and Ord. No. 2024-7) and are unchanged in the code as codified through February 2026.

An attached ADU is allowed on a lot of 6,000 square feet or larger, half the lot Carson City demands for a detached unit, but it faces the same district-by-district permit matrix: administrative permit in SF5A, SF2A, SF1A, SF21 and MH1A, special use permit in SF12, SF6, MH12 and MH6, and prohibited in MHP, MFD and MFA. The code draws the attached line mechanically: a unit counts as attached if it shares a common wall with the primary residential structure for a contiguous distance of at least 10 feet, so a basement or interior conversion or a full addition qualifies while a breezeway-linked cottage does not. An existing accessory unit may add a kitchen only on full compliance with Division 1, and a building permit is required if the structure itself is altered.

The cap is the lesser of two numbers. First, the ADU's living space gross floor area must not exceed 50 percent of the assessed floor area of the primary residential structure, excluding garages, basements and other accessory structures. Second, a flat district cap applies: 700 square feet in the SF6, MH6, SF12 and MH12 districts and on any other residentially zoned lot under 21,000 square feet, or 1,000 square feet in the other single-family districts when the lot is 21,000 square feet or larger. Height is not separately capped for ADUs; the unit must simply meet the district maximum, which is 26 feet in SF6, SF12, SF21, MH6 and MH12, 32 feet in SF1A, SF2A and MH1A, and 40 feet in SF5A. Exceeding the size, height or site-design standards is possible only through a special use permit, and Carson City does grant them: an April 2026 notice advertised a hearing on a detached ADU on an MH12 lot proposed at more than 50 percent of the primary living area and more than 700 square feet.

Carson City imposes no owner-occupancy condition. Section 1.4 enumerates its standards exhaustively (site plan contents, minimum lot size, existing units, maximum size, setbacks, height, parking, site design, modifications, and water and sewer connections) and none of them touches who lives in either dwelling, and the CCMC 18.01.040 definition of accessory dwelling unit is likewise silent. Nothing elsewhere in Title 18 or in the licensing title conditions an ADU on owner residence. The zoning code in fact assumes an ADU may be a rental: CCMC 18.04.095(1)(f) carves a unit approved as an accessory dwelling unit out of the rule that two or more rental mobile home units on one parcel become a mobile home park. State law does not add a requirement either, because NRS 278.257 does not reach Carson City.

Carson City requires a minimum of one off-street space for a studio or one-bedroom ADU and one space per bedroom for a unit with multiple bedrooms, in addition to the parking already required for the primary residence, and the spaces must sit outside the required front-yard setback. In the SF6, MH6, SF12 and MH12 districts the guest parking must be on a paved surface. This is one of the stiffer ADU parking rules in the state: a three-bedroom ADU triggers three added spaces. Relief is available only through a variance, not through the special use permit that covers size and design relief. Note the state-law contrast: NRS 278.257(2)(b) forbids requiring more than one additional space, but that limit binds only counties of 100,000 or more and cities of 60,000 or more, and Carson City is under both thresholds, so the per-bedroom rule stands.

The path depends entirely on the zoning district. In SF5A, SF2A, SF1A, SF21 and MH1A an ADU needs an administrative permit: a noticed hearing before a hearing examiner within 65 days, who must make six findings (master plan consistency, neighborhood compatibility, traffic, impact on adjacent property, public services, and health and safety), may impose additional conditions, and may refer the matter to the Planning Commission instead. In SF12, SF6, MH12 and MH6 an ADU needs a special use permit: a public hearing before the Planning Commission on the same findings. In the Agriculture and Conservation Reserve districts an ADU is permitted as a primary use. In MHP, MFD and MFA it is prohibited. Even the lighter administrative track is discretionary rather than ministerial, so Carson City has no by-right ADU permit in any residential district.

Nothing in Section 1.4 or Title 18 limits renting an approved ADU, and the code contemplates rented units: CCMC 18.04.095(1)(f) exempts a unit approved as an accessory dwelling unit from the rule that turns two or more rental mobile home units on a parcel into a mobile home park. Renting a single ADU does not require a Carson City business license, because CCMC 4.04.005 excludes the rental of three or fewer residential units from the definition of business. Short-term rental is the murkier half. Carson City has no vacation-home-rental or short-term-rental licensing chapter, and the residential use table lists no short-term rental or vacation rental use at all; the only transient lodging use allowed in residential districts is a bed and breakfast inn by special use permit, and in SF21, SF12 and SF6 only inside the Historic District. Under CCMC 18.04.025 the Director decides unlisted uses case by case, so a homeowner planning nightly rental should get that determination in writing first. The room tax reaches only accommodations with four or more rooms for rental (CCMC 4.08.070), so a lone ADU falls outside it. No separate-sale provision exists; by definition the ADU sits on the same lot as the primary dwelling.