ADU rules in Jackson

Jackson's term is accessory residential unit (ARU), defined in LDR Sec. 6.1.11.B as a dwelling unit secondary to a principal use, expressly including a guesthouse; the stated intent is workforce housing. A detached ARU is allowed with an administrative Basic Use Permit in the NL-1 through NL-5 and NM-1 neighborhood zones, the legacy Rural Residential-Town (R) zone, and the mixed-use OR, CR-1 to CR-3, DC-1, DC-2, TS-1 and TS-2 zones (each zone's Subsection C use table). Density is 1 ARU per lot in NL-1 to NL-3 and R, 2 per lot in NL-4 and NL-5, and in NM-1 up to two ARUs on lots of 7,500 sf or more. In NL-3, NL-4, NM-1 and R, detached ARUs are only permitted on lots that meet minimum lot size, and in NL-3 and NL-4 ARUs are prohibited north of West Broadway in the Budge Drive area. ARUs are not an allowed use in the apartment zones NM-2 and NH-1 (the NH-1 intent text says apartments take the place of ARUs) or in the Mobile Home Park zone.

The ARU definition includes attached and internal forms (employee apartment, mother-in-law suite), and LDR Sec. 6.1.4.B.1.a.i provides that a detached dwelling attached to an accessory residential unit is still classified as a Detached Dwelling, so an attached or internal ARU rides on the same zone permissions and Basic Use Permit as a detached one. The minimum-lot-size gate in NL-3, NL-4, NM-1 and R applies only to detached ARUs, so an attached ARU remains available on substandard lots there. Note that among residential primary uses an ARU is accessory only to a Detached Dwelling (LDR Sec. 6.1.11.B.2); it is not available with apartments or attached dwellings except where a zone standard says otherwise (NM-1 Sec. 2.2.7.E.1.a allows ARUs with a duplex on lots with two street frontages or street plus alley). ARUs are also allowed as accessory to lodging, commercial, institutional and industrial primary uses.

In NL-1, NL-2 and the legacy R zone, a detached ARU on a lot smaller than 18,000 sf is capped at 500 sf of habitable floor area; in NL-3, NL-4 and NM-1 the small-lot threshold is 11,250 sf. All other ARUs (attached ARUs, and detached ARUs on lots at or above the threshold) are capped at 800 sf habitable. Habitable floor area is defined in Division 9.5 and excludes garages and unfinished attic space, so a 500 sf ARU over a garage is a common configuration. NL-5 sets no ARU-specific size cap (instead capping total units at 3 per lot, or 4 if all units are deed-restricted), and the OR, CR, DC and TS zone tables list no individual ARU size cap; zone FAR and accessory-structure standards control there. ARUs remain subject to each zone's accessory-structure setback and height standards.

No LDR provision requires the property owner to live in either unit, at application or ongoing. What Jackson requires instead is occupant qualification: ARU occupancy is restricted to people employed within Teton County under the Jackson/Teton County Housing Rules and Regulations, members of the same household unit occupying the principal dwelling (such as parents or adult children), or intermittent nonpaying guests of that household (LDR Sec. 6.1.11.B.3.b). NL-5 repeats the same restriction as a zone standard for apartments and ARUs. So an off-site owner may rent out both the main house and the ARU, but the ARU's occupants must qualify (in practice, work locally). Wyoming has no state ADU statute bearing on this.

Parking minimums are set in each zone's use table. In NL-1 through NL-5 and NM-1 an ARU needs 1 space if it has fewer than 2 bedrooms and is under 500 sf, otherwise 1.5 spaces; the legacy R zone requires 1 space per bedroom; OR, CR-1 to CR-3, DC-1, DC-2 and TS-2 require 1 space per dwelling unit and TS-1 requires 1.25. New ARUs must also provide EVSE-capable wiring for 1 space per dwelling unit (Sec. 6.2.2.F). Since Ordinance 1453 (3-2-2026) the Planning Director may grant administrative parking reductions under Sec. 6.2.2.A.1 where reliable information shows a lesser standard works. ARUs are exempt from the affordable workforce housing mitigation column in every zone table.

Every zone that allows ARUs requires a Basic Use Permit, marked B in the use tables: an administrative permit that the Planning Director shall approve upon finding compliance with the LDR standards, decided within 45 days of a sufficiency determination with no public hearing (LDR Secs. 6.1.1.B, 8.4.2). The town's Basic Use page confirms ARUs are on the BUP list. The only discretionary pocket is the legacy Business Park zone, where the Sec. 6.1.1 schedule shows ARUs as a Conditional Use Permit. Construction also needs a building permit under the IRC 2024, which Jackson adopted effective 1-1-2025 (Municipal Code Sec. 15.17.010); for residential building permit applications filed on or after 7-1-2026 the new Wyoming Fast Track Permits Act (W.S. 16-13-101 and 16-13-102, 2026 Wyo. Sess. Laws ch. 42) adds a completeness notice within 10 business days, a 30-day decision shot clock and a deemed-approved remedy at the building-permit stage; it does not change zoning entitlements.

An ARU may be rented long-term, but only to occupants who qualify under Sec. 6.1.11.B.3.b: employed within Teton County per the Jackson/Teton County Housing Rules and Regulations, household members of the principal dwelling, or intermittent nonpaying guests. Short-term rental (under 30 consecutive days) of any residential unit is a separate lodging use requiring a business license and its own Basic Use Permit; outside the Lodging Overlay and Planned Resort zones, STR use in the residential zones is capped at 3 separate rentals and 60 total rental days per calendar year, with annual BUP renewal, neighbor noticing, and a 5-year permit bar for violators (Sec. 6.1.5.C.2, program in force since 1-1-2024). Because paying guests are not among the qualified ARU occupants, an ARU itself cannot lawfully host paid short-term stays even at that limited scale; the nonpaying-guest path is the only intermittent-occupancy option. An ARU used to satisfy workforce housing mitigation under Division 6.3 carries a recorded deed restriction, and no accessory use may be subdivided or sold separately from its primary use (Sec. 6.1.11.A.2.d).