Tiny home on wheelsNo statewide tiny-home-on-wheels law. This sharpens an earlier draft: unlike Montana and North Dakota, which have adopted statewide codes with opt-in local enforcement, Wyoming has no mandatory statewide building or energy code at all. Cheyenne, Casper, Sheridan, and Teton County have adopted the 2024 I-Codes on their own; on land outside any code-adopting jurisdiction, there is effectively no building permit requirement or timeline. The one statewide exception is electrical work, administered under the 2023 National Electrical Code by the Wyoming Department of Fire Prevention & Electrical Safety — and Wyoming uniquely allows a homeowner to wire their own home without a licensed electrician (W.S. 35-9-123), as long as it's not being immediately resold.
ADU / accessory unitADU rules apply mainly within code-adopting cities; unincorporated land in non-adopting counties is the most flexible option in the country for this reason. Natrona County requires a 220 sq ft minimum for efficiency dwelling units; Teton County (Jackson Hole area) is far stricter at 750 sq ft, reflecting resort-area land-use pressure. Rural Carbon, Fremont, and Sheridan counties commonly have no building code at all.
Minimum square footageNone in code-non-adopting counties; ranges from roughly 220 sq ft (Natrona) to 750 sq ft (Teton) where a minimum applies
Foundation requirementHarsh winters (snow and frost load) drive real construction requirements even where no code is formally adopted — design criteria still matter regardless of enforcement