ADU rules in Wyoming
Representative cities: Cheyenne, Casper.
ADU permit rule
ConditionalGenerally allowedcity authority
Fee basis
Valuation-based where a building department enforces (e.g., Cheyenne).
Typical timeline
Plan review through the local building department.
Setback
—
Area threshold
Local zoning sets size, setback, and parking limits.
Exempt if
No statewide ADU statute; an ADU requires zoning approval and a building permit only where the city/county enforces a code.
Go / no-go
allowed
Wyoming has NO mandatory statewide residential building code — Cheyenne, Casper, and other cities adopt the IRC locally (Cheyenne is on the 2024 I-Codes). Much unincorporated county land has no building permit at all. Verify with your local building department.
ADU official sources: City of Cheyenne — Building Permitting & Licensing · ICC — Wyoming Building Code Adoptions
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Frequently asked questions
Do I need a permit to build an ADU in Wyoming?
Per Wyoming rules, an ADU is "conditional" for a permit and the authority is "city". Wyoming has NO mandatory statewide residential building code — Cheyenne, Casper, and other cities adopt the IRC locally (Cheyenne is on the 2024 I-Codes). Much unincorporated county land has no building permit at all. Verify with your local building department. Always confirm with the issuing building department.
How big can an ADU be in Wyoming?
Area threshold: Local zoning sets size, setback, and parking limits.
What are the ADU setbacks in Wyoming?
Setback rules vary by city in Wyoming; confirm with the local planning or building department.
How much does an ADU permit cost in Wyoming?
Fee basis: Valuation-based where a building department enforces (e.g., Cheyenne).
State-wide sources: City of Cheyenne — Building Permitting & Licensing · ICC — Wyoming Building Code Adoptions