Casper, WY Accessory Structures: ADU Rules (2026)

The zoning code defines an accessory dwelling unit at § 17.08.010 as a habitable unit providing living, sleeping, eating, cooking and sanitation facilities that is added to, created within, or detached from a single-family home. The definition itself carries the substantive limits: either the principal dwelling or the ADU must be occupied by the property owner or an immediate family member, and the ADU can never be subdivided or sold off separately from the main house. Zoning district by zoning district, the code lists an ADU as a conditional use only in the R-2 One Unit Residential district under § 17.32.030(J), grouped alongside twin homes and personal service shops as uses the Planning and Zoning Commission must individually approve.

Getting that approval means filing a conditional use application with the fee set by council resolution, mailing notice to every owner within a three-hundred-foot radius, and a public hearing where the commission must find under § 17.12.240(G) that the ADU is consistent with the district's intent and will not impair neighboring property. Once granted, the permit runs with the land and binds later owners under § 17.12.240(A); the commission can attach conditions on parking, screening or building bulk under § 17.12.240(I).