Accessory Dwelling Unit (ADU) Permit in Casper, Wyoming

Casper requires an accessory dwelling unit (adu) permit for: Property must be zoned R-2 (One Unit Residential) — Casper Municipal Code § 17.32.030(J) lists 'Accessory dwelling unit' as a conditional use in R-2 only; ADUs are not an allowed use in R-1, R-3, R-4, or R-5; A conditional use permit must be obtained from the Planning and Zoning Commission before applying for a building permit, per the conditional-use petition/hearing procedure in § 17.12.240 of Title 17; Per the ADU definition in § 17.08.010: either the principal dwelling unit or the ADU must be occupied by an owner of the property or an immediate family member of the owner; The ADU may not be subdivided or otherwise segregated in ownership from the principal dwelling unit (§ 17.08.010); Once zoning/conditional-use approval is obtained, the ADU is built and permitted under the standard residential building permit process (2024 IRC), subject to R-2's general minimum standards in § 17.32.040 (lot area, lot width, setbacks); Fee based on the value of construction per the combined valuation-based fee schedule (same schedule as new residential construction — no ADU-specific fee line exists). If your project isn't listed, confirm with City of Casper Community Development Department — Building Inspection Division at (307) 235-8254 before starting work.

In Casper, the published Initial Building Permit Fee is: $35. Additional published fees: Combined Building Permit Fee — valuation-based — Graduated table from $70 (valuation $1–$1,000) up to $841 (valuation $99,001–$100,000); over $100,000 = $806 + $5.60 per additional $1,000 or fraction thereof. These are the jurisdiction's own published figures — see the fee schedule table and source citations on this page.

Plan review for an accessory dwelling unit (adu) permit in Casper typically runs 10–30 business days. This is an estimate, not a published figure — confirm current review times with City of Casper Community Development Department — Building Inspection Division at (307) 235-8254.

You'll need: Conditional Use Permit Application; Building Permit Application; Plot Plan; Construction Drawings. See the required-documents checklist on this page for details on each.

Casper requires 4 inspection(s) for an accessory dwelling unit (adu) permit, in order: Footer/Foundation, Framing, Insulation, Final. Schedule each through City of Casper Community Development Department — Building Inspection Division ((307) 235-8254).

Apply through City of Casper Community Development Department — Building Inspection Division at 200 N David St, Casper, WY 82601. Phone: (307) 235-8254, email: building@casperwy.gov. Office hours: Mon–Fri 8:00 AM–5:00 PM (in-person/phone code consultation available 8:00–9:00 AM and 4:00–5:00 PM). Official information: https://www.casperwy.gov/services/building_and_inspections/index.php.

Only on property zoned R-2 (One Unit Residential). Casper Municipal Code § 17.32.030(J) lists 'Accessory dwelling unit' as a conditional use in the R-2 district — it is not an allowed use in R-1, R-3, R-4, or R-5. A conditional use permit from the Planning and Zoning Commission is required, and either the principal home or the ADU must be owner-occupied. There is no separate ADU ordinance or dedicated permit fee; once the conditional use is approved, the ADU is built under the standard residential building permit process.

Per the definition in Casper Municipal Code § 17.08.010, an accessory dwelling unit may not be subdivided or otherwise segregated in ownership from the principal dwelling unit, and either the principal dwelling or the ADU must be occupied by an owner of the property or an immediate family member of the owner.