ADU rules in Sheridan

The zoning ordinance (Appendix A of the City Code) names 'accessory dwelling units' in exactly two places, both added by Ord. No. 2288 of 11-18-2024: the Section 9E Downtown Business Overlay District and the Section 9F Downtown Development Overlay District, where they are Special Exemption Uses requiring review and approval by the Board of Adjustment. No residence district (R-O, R-1, R-2, R-3, R-4) lists an accessory dwelling unit as a permitted use or a special exemption. In residence districts the only habitable backyard building the code contemplates is limited by Section 10.6: a rear accessory building may be used for residence purposes only by a member of the family residing in the main building or by persons employed on the premises, which makes it family or caretaker quarters rather than an independent unit. In the R-O Rural Residence District even that is closed, because an allowed accessory use must not include residential occupancy.

There is no attached or internal ADU category, so the question collapses into whether a district permits a second dwelling unit at all. R-1 permits only a 'one-family dwelling', defined in Section 2 as a detached building occupied by one family (which may include up to four boarders or lodgers), so carving an independent second housekeeping unit out of the house turns it into a two-family dwelling and is not allowed there; R-O is the same. R-2 permits a two-family dwelling outright, and a multiple-family dwelling for up to four families in a single detached building, with no minimum lot area per family, and R-3 permits multiple-family dwellings, so an internal or attached second unit is lawful by right in those districts, regulated as half of a duplex rather than as an ADU. In the two downtown overlays one-family and two-family dwellings are permitted except in the story abutting street grade, and accessory dwelling units are a Special Exemption Use.

Appendix A Section 10.8 is the only size control on a backyard unit in a residence district: an accessory building 'shall not exceed twenty (20) feet in height or the height of the main building, whichever is less' and 'may occupy not more than thirty (30) percent of a required rear yard.' Required rear yards are 40 ft in R-O, 20 ft in R-1 and R-2, and 15 ft in R-3, so the footprint allowance scales with lot width: on a 50 ft wide R-1 lot the required rear yard is about 1,000 sq ft and 30 percent of that is roughly 300 sq ft of footprint. Section 10.6 adds placement limits: a detached garage or other accessory building may not be erected on the front one-half of the lot, must be at least 5 ft from the main building and 3 ft from a side lot line, and must sit back at least 5 ft from an alley it opens onto. The overlays are looser, with no minimum lot size, no rear or side setback in 9E, and building height equal to the base zone maximum.

Nothing in Appendix A requires the property owner to live on the lot, at application or afterward, and the words owner-occupied and owner occupancy appear nowhere in the zoning ordinance. Sheridan instead restricts who may occupy the secondary unit: Section 10.6 allows a rear accessory building to be used for residence purposes only 'by a member of the family residing in the main building, or by persons employed on the premises.' That is a household-relationship test rather than an ownership test, so an absentee landlord is not barred, but the backyard unit's occupant must be family of whoever lives in the main house or work on the premises. The Board of Adjustment may attach conditions when it grants a Section 9E or 9F accessory dwelling unit special exemption, but the ordinance itself imposes no occupancy condition there. Wyoming has no statute on ADU owner occupancy, so the question is entirely local.

Appendix A Section 10.16's schedule assigns 2 spaces per dwelling unit to 'Single-family (attached or detached)' and 1.5 per dwelling unit to multi-family, and Section 4.1.E sends new R-1 construction to that schedule. R-2 (Section 5.E) and R-3 (Section 6.D) override it for newly erected structures with 1 space per single-family dwelling unit and 0.75 per multifamily dwelling unit, plus an on-street parking credit of one space for each abutting on-street space where overnight parking is allowed (20 ft of uninterrupted curb parallel, 14 ft at 45 degrees, 10 ft perpendicular), excluding designated snow routes. Because no ADU use exists, no separate ADU space is written anywhere; an added unit is counted at whatever per-dwelling-unit rate the building inspector applies. In the Section 9E and 9F downtown overlays there is no fixed residential minimum: the applicant submits a parking analysis when required by the Public Works Director, with credit for publicly owned off-street spaces within 750 ft and on-street spaces within 350 ft.

The only use the ordinance calls an accessory dwelling unit is a Special Exemption Use in the two downtown overlay districts, and special exemptions 'shall require additional review and approval by the Board of Adjustment, as outlined in Municipal Code Appendix A, Section 14.' The board holds a noticed public hearing and must find that the exemption is listed for the district, that the use is consistent with the goals, policies and recommended future land use of the adopted master plan, and that granting it is in harmony with the ordinance and not injurious to the neighborhood. Everywhere else there is no ADU application to file: a rear accessory building used as family or caretaker quarters under Section 10.6 needs only the building inspector's permit under Section 12, and a genuinely independent unit in a residence district would require a variance or a rezoning. Since 1 July 2026 the state Fast Track Permits Act shortens the building-permit clock (not the zoning entitlement), because Sheridan zones under W.S. 15-1-601 and adopted the 2024 International Residential Code by Ord. No. 2290 of 1-20-2025.

In R-O, R-1, R-2 and R-3 the Section 10.6 occupancy rule is the whole rental story for a detached secondary unit, since an arm's-length tenant is not an allowed occupant; renting the main house is fine, as is housing up to four boarders or lodgers inside a one-family dwelling under the Section 2 definition. A lawful two-family dwelling in R-2 or R-3, and an accessory dwelling unit approved by special exemption in the 9E or 9F overlays, carry no rental-term restriction in the ordinance, and no provision allows or forbids separate sale of a second unit. A search of the entire City Code returns zero hits for short-term rental, vacation rental, transient rental or Airbnb; the nearest regime is Chapter 14, carried forward from the 1937 Revised Ordinances, which defines a rooming house as any building used for receiving and lodging transient persons, persons for temporary stay, and persons for permanent stay, and requires the keeper to maintain a guest register open to police inspection. Bed and breakfast is a separate zoning use, a special exemption in R-1 and R-2, and boarding or lodging houses are permitted in R-3. Wyoming imposes no statewide short-term rental land-use preemption.