Can I build an ADU on my property in unincorporated Natrona County?

Yes, if your property is in a zoning district where ADUs are a Permitted use (UA, MR-1, MR-2, SR, RR, and UR per Zoning Resolution Table 4.02) and you occupy the primary dwelling as your permanent residence. Density limits apply in agricultural/mountain districts (e.g., 1 ADU per 10 acres in UA/MR-1). Confirm eligibility with Natrona County Planning, then apply for a standard Building Permit.

How big can an ADU be in Natrona County?

An ADU may not exceed 50% of the primary dwelling's square footage or 1,000 gross square feet of habitable floor area, whichever is smaller, and its height cannot exceed the primary dwelling's height (Zoning Resolution § 4.11.05(A)(5)-(6)).

Do I have to live on the property to have an ADU in Natrona County?

Yes. Per § 4.11.05(A)(7), the property owner must occupy the principal dwelling as their permanent residence for an ADU to be permitted on the lot.

Accessory Dwelling Unit (ADU) Permit in Unincorporated Natrona County, Wyoming

Verified

Required for construction of an ADU on a residential property in unincorporated Natrona County. ADUs are expressly defined and regulated as a Permitted (P) accessory use in the Urban Agricultural (UA), Mountain Residential 1 & 2 (MR-1/MR-2), Suburban Residential (SR), Rural Residential (RR), and Urban Residential (UR) zoning districts under the Natrona Next Zoning Resolution § 4.11.05(A). Built under the standard county Building Permit process once zoning standards are confirmed with Planning.

Verified 2026-07-01 · Source

$70 (valuation $0–$2,500) up to $905 plus $9.24 per additional $1,000 over $98,000Building Permit Fee — valuation-based (same table as new construction)

When you need this permit

Zoning eligibility: ADU must be an accessory use to a legally permitted single-unit residential use in a district where ADUs are listed as Permitted (Table 4.02, districts include UA, MR-1, MR-2, SR, RR, UR) — confirm with Natrona County Planning Department before applying for the building permit
Number: One (1) ADU permitted per lot as accessory to a legally permitted single-unit residential use; in the UR district, the lot must be a minimum of 2 acres
Density in agricultural/mountain districts is expressed per-acre: e.g. UA and MR-1 allow 1 ADU per 10 acres (1 exempt ADU for agricultural-tax-status properties per 10 acres); MR-2 allows 1 ADU per 5 acres; SR and RR allow 1 ADU per lot
Setbacks: a detached ADU must comply with the zoning district's required (principal or accessory, as applicable) setbacks; an attached ADU must comply with principal building setbacks for its district
Height: an ADU must NOT exceed the height of the primary dwelling
Size: an ADU must not exceed 50% of the primary dwelling's square footage OR 1,000 gross square feet of habitable floor area, whichever is SMALLER
Occupancy: the property owner (title holder or contract purchaser) must occupy the principal dwelling as their permanent residence — owner-occupancy of the primary unit is mandatory
Use restriction: ADUs may not be sold separately from the primary residence, and must maintain architectural consistency with the primary dwelling
Once zoning compliance is confirmed, the ADU is built under the standard Natrona County Building Permit Application (select New Construction or Addition, per whether attached or detached) — plus separate Electrical, Plumbing, and Mechanical permits as applicable

Required documents

Req
Natrona County Building Permit Application (2025)
Standard application; ADUs are built under this same form once zoning is confirmed — select 'New Construction' for a detached ADU or 'Addition' for an attached one
Req
Site Plan Application (2025)
Required to confirm setback compliance and ADU placement on the lot relative to the primary dwelling
Opt
Natrona Next Zoning Resolution — § 4.11.05(A)
Governing ADU standard (definition, number, setbacks, height, size, occupancy, use restrictions); consult Natrona County Planning Department to confirm district-specific eligibility before applying

Fee schedule

Fee type	Amount	Notes
Building Permit Fee — valuation-based (same table as new construction)	$70 (valuation $0–$2,500) up to $905 plus $9.24 per additional $1,000 over $98,000	Natrona County Permit Fees, Resolution No. 45-20 — an ADU is charged under the same combined valuation-based building-permit fee schedule as any other new residential construction; no separate ADU fee line exists.

Review timeline

~5–15 business days

Typical estimate — confirm current times with the Unincorporated Natrona County building department

Inspection process

1
Footing / Foundation
Before concrete pour — required for detached ADUs with new foundations
2
Framing
Structural framing complete, before insulation or wall cover
3
MEP Rough-In
Mechanical, electrical, and plumbing rough-in before walls closed; separate trade permits required
4
Final
All work complete per approved plans, ready for occupancy

Tips

ADU eligibility is zoning-district-specific and acreage-dependent in the county's agricultural/mountain districts (UA, MR-1: 1 per 10 acres; MR-2: 1 per 5 acres) versus flat 1-per-lot in SR/RR, and 2-acre minimum lot size in UR — confirm your district and lot size with Natrona County Planning (via the Planning & Zoning page) BEFORE designing your ADU.
Owner-occupancy of the PRIMARY dwelling is mandatory under § 4.11.05(A)(7) — you cannot rent out the main house and live in the ADU, or own the property as a pure rental with neither unit owner-occupied.
Size cap is the SMALLER of 50% of the primary dwelling's square footage or 1,000 gross sq ft habitable — calculate both figures for your specific primary home.
ADUs cannot be sold separately from the primary residence — they remain a single conveyable property.

Frequently asked questions

Can I build an ADU on my property in unincorporated Natrona County?: Yes, if your property is in a zoning district where ADUs are a Permitted use (UA, MR-1, MR-2, SR, RR, and UR per Zoning Resolution Table 4.02) and you occupy the primary dwelling as your permanent residence. Density limits apply in agricultural/mountain districts (e.g., 1 ADU per 10 acres in UA/MR-1). Confirm eligibility with Natrona County Planning, then apply for a standard Building Permit.
How big can an ADU be in Natrona County?: An ADU may not exceed 50% of the primary dwelling's square footage or 1,000 gross square feet of habitable floor area, whichever is smaller, and its height cannot exceed the primary dwelling's height (Zoning Resolution § 4.11.05(A)(5)-(6)).
Do I have to live on the property to have an ADU in Natrona County?: Yes. Per § 4.11.05(A)(7), the property owner must occupy the principal dwelling as their permanent residence for an ADU to be permitted on the lot.

Sources & verification

Verified against official sources. Last reviewed 2026-07-01.

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 Natrona County building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.

Other permits in Unincorporated Natrona County

Residential Building Permit (New Construction)Residential Addition / Remodel Permit Electrical Permit Plumbing Permit Mechanical / HVAC Permit Roofing Permit (Reroof)Solar PV Permit Demolition Permit Commercial Tenant Improvement Permit Deck Permit

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