Accessory Dwelling Unit (ADU) Permit in Unincorporated Campbell County, Wyoming
VerifiedCampbell County has a DEDICATED Accessory Dwelling Unit ordinance — Chapter 7 (Zoning Regulations) Section 45.70 — applicable in the R-L, R-R, R-S, R-1, and A-L Zoning Districts. Requires administrative Review Process 1 approval plus compliance with the 2024 IRC for construction.
Verified 2026-07-01 · Source
When you need this permit
- Applies only in R-L, R-R, R-S, R-1, and A-L Zoning Districts (Chapter 7 § 45.70(2))
- One ADU permitted per lot in R-L/R-R/R-S/R-1; one ADU per Primary Dwelling Unit in A-L (multiple allowed in A-L only if each Primary Dwelling meets the 10-acre minimum land area under § 15.10(1))
- Written verification required that the Homeowners' Association, Improvement & Service District, or recorded Covenants Agreement approves the specific ADU; if none of these entities exist for the subdivision, a Conditional Use Permit (§10.55, $200 fee) is required instead
- Maximum Building Footprint Living Area: the SMALLER of 60% of the Primary Dwelling Unit's footprint, or 1,100 sq. ft.
- Maximum height: cannot exceed the height of the Primary Dwelling Unit
- Detached ADUs may not be located in the front or side yard areas of the Principal Dwelling (except existing buildings under §45.70(6)(e))
- HUD Manufactured Homes, RVs, and boats are PROHIBITED as ADUs, except Park Model Homes are allowed in A-L/R-L/R-R districts where the Primary Dwelling is itself a manufactured home
- Attached ADUs must comply with the Two-Family Dwelling provisions of the currently adopted IRC, including Appendix AK sound transmission requirements
- Detached ADUs (new construction) must comply with the currently adopted IRC; attached garages to the ADU may not exceed the ADU's own allowable footprint
- Existing detached accessory structures converted to an ADU are not limited by a shop/garage-to-ADU area ratio, but the ADU living area itself cannot exceed the § 45.70(6)(a) size cap
- Septic/sewer: ADU's small wastewater system may interconnect with the Primary Dwelling's system (not prohibited) but must comply with Chapter 4 Building Regulations
Required documents
- Req
Zoning Certificate Application (for the ADU land use)
Land Use Permit application under Chapter 7 Zoning Regulations, Review Process 1
- Req
HOA / Improvement & Service District / Covenants Approval Letter
Written approval of the specific ADU from the applicable entity, or a copy of the recorded Covenants Agreement
- Req
Building Permit & Zoning Certificate Application
Required for the construction itself (attached or new-construction detached ADU) under the 2024 IRC
Fee schedule
| Fee type | Amount | Notes |
|---|---|---|
| ADU Zoning review (Review Process 1) | No fee | Not separately listed in the Chapter 7 § 10.25(7) fee table (which lists Zoning Certificate: No Fee); ADU review follows the same administrative Zoning Certificate process. |
| Conditional Use Permit (only if no HOA/I&S District/Covenants exists for the subdivision) | $200.00 | Chapter 7 Zoning Regulations, Section 10.25(7)(a)(vii) — Conditional Use Permit fee, required per § 45.70(4)(c) when no governing entity exists to approve the ADU directly |
| Building Permit for ADU construction | No fee | Chapter 4 Section 1.8.E 'All Other Permits: No fees.' |
Review timeline
~3–21 business days
Typical estimate — confirm current times with the Unincorporated Campbell County building department
Inspection process
- 1
Foundation
For new-construction detached or attached ADUs
- 2
Framing
Structural framing, fire/sound separation if attached
- 3
MEP Rough-In
Mechanical, electrical, plumbing rough-in
- 4
Final
All work complete, ready for occupancy
Tips
- Campbell County's ADU size cap is notably tight: the SMALLER of 60% of the primary home's footprint or 1,100 sq. ft. — confirm your primary dwelling's footprint before designing an ADU near the cap.
- Get the HOA/Improvement & Service District/Covenants approval FIRST — without it (and without a qualifying governing entity), you must go through a $200 Conditional Use Permit process instead of a simple administrative Zoning Certificate.
- An existing detached shop/garage converted into an ADU is NOT capped by a shop-to-ADU area ratio — only the resulting ADU living area itself is capped at the standard § 45.70(6)(a) size limit, which is more flexible than new construction.
- A2-L district ADUs can multiply (more than one per property) if each Primary Dwelling independently meets the 10-acre minimum lot size — a detail unique to Campbell County's agricultural-limited zoning.
Frequently asked questions
- Does unincorporated Campbell County allow Accessory Dwelling Units (ADUs)?
- Yes. Chapter 7 Zoning Regulations Section 45.70 creates a dedicated ADU category for the R-L, R-R, R-S, R-1, and A-L Zoning Districts, approved administratively (Review Process 1) subject to HOA/Improvement & Service District/Covenants approval.
- How big can an ADU be in unincorporated Campbell County?
- The maximum Building Footprint Living Area is the smaller of 60% of the Primary Dwelling Unit's footprint or 1,100 square feet, and the ADU's height cannot exceed the Primary Dwelling's height (Chapter 7 § 45.70(6)).
- What if my subdivision has no HOA to approve an ADU?
- If there is no Homeowners' Association, Improvement & Service District, or recorded Covenants Agreement for the subdivision, the ADU application is processed instead as a Conditional Use Permit under Chapter 7 Section 10.55, which carries a $200 fee.
Sources & verification
Verified against official sources. Last reviewed 2026-07-01.
- Campbell County Department of Public Works — Building, Planning & Zoning Division — official building department
- Campbell County Chapter 7 Zoning Regulations, Section 45.70 (Accessory Dwelling Units)
- Campbell County Chapter 4 Rules Regulating Construction (2024 IRC adoption, fees)
Fees, timelines, and adopted codes are researched from each jurisdiction's published records — see how we verify. Requirements change and vary by project, so always confirm the current details with the Unincorporated Campbell County building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.
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