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

Required for construction of an ADU in unincorporated Laramie County. Zoning eligibility and dimensional/utility standards are set by Laramie County Land Use Regulations Section 3-1-107 Part E; construction standards follow 2024 IRC Appendix BC (Accessory Dwelling Units), which the county distributes as its official ADU building-code handout. A separate Non-Traditional Housing Approval Permit from Planning and Zoning is required in addition to the building permit.

Verified 2026-07-01 · Source

When you need this permit

  • Zoning: ADU is allowed in all urbanized residential zoning districts (URLD, URMD, URHD, MU, PUD) with central water and sewer, and in rural residential districts (RRH/LU) with a minimum lot size of 10.5 acres
  • Size: no larger than 50% of the floor area of the principal dwelling in URLD/URMD/URHD/MU/PUD districts; may be up to the same size as the principal dwelling in LU and RRH districts; per the Guidance for Residential Projects handout, allowable square footage is 50% of the primary dwelling up to a maximum of 1,200 square feet
  • A principal dwelling must be built on the lot BEFORE an application for an ADU is submitted
  • ADU must be situated on the same lot as the principal dwelling and must meet setback, parking, and maximum lot-coverage requirements
  • In URLD/URMD/URHD/MU districts, ADU must connect to South Cheyenne Water & Sewer District for water/sewer service
  • In RRH/LU districts, ADU requires a septic permit from Laramie County Environmental Health and any necessary well approvals from the Wyoming State Engineer's Office; prior approval from South Cheyenne Water & Sewer District or Environmental Health is required BEFORE a building permit is issued
  • Under 2024 IRC Appendix BC (the county's cited ADU construction standard): ADU permitted only within an existing single-family detached dwelling or existing townhouse unit within IRC scope; only one ADU per primary dwelling unit; owner must reside in either the primary dwelling or the ADU as of permit approval; ADU must have a separate house number; ADU must be not less than 190 sq ft and not more than 50% of the primary dwelling's area, capped at 1,200 sq ft; ADU must have a separate entrance from the primary dwelling; maximum of two bedrooms; separate heating system, ducting, and climate controls required (BC105.1); ready access to service disconnects and overcurrent devices required (BC105.2); ready access to gas shutoff valves required (BC105.3); water service may be shared with separate accessible shutoffs (BC105.4)
  • A Non-Traditional Housing Approval Permit (Planning and Zoning application) is required in addition to the building permit application
  • IRC Letter required for modular-home ADUs stating the code the unit was built to

Required documents

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Fee schedule

Building Permit Fee — same valuation-based table as new constructionLaramie County Building Permit Fee Schedule (PDF); the Guidance for Residential Projects treats an ADU as a standard valuation-based residential permit
Varies by project valuation — see Laramie County 2022 Building and Plan Review Fee Schedule
Plan Review Fee
65% of the Building Permit Fee

Review timeline

Plan reviewUnincorporated Laramie County’s published plan-review target
7–10 business days

How long did your Accessory Dwelling Unit (ADU) Permit permit actually take in Unincorporated Laramie County?

Anonymous — one question, no email. Answers are combined and only shown once at least 5 people have reported.

Inspection process

  1. 1

    Foundation

    Before concrete pour

  2. 2

    Rough Framing / Rough MEP

    Framing, mechanical, electrical, plumbing rough-in before covering

  3. 3

    Final

    Required before occupancy

See the full Unincorporated Laramie County inspection guide — scheduling & re-inspection fees →

Tips

  • Contact Laramie County Planning (307-633-4303 / planning@laramiecountywy.gov) FIRST, before applying for a building permit — the Non-Traditional Housing zoning approval must be secured, and in RRH/LU districts, Environmental Health or the South Cheyenne Water & Sewer District must approve septic/sewer capacity BEFORE a building permit is issued.
  • In rural (RRH/LU) zoning districts, an ADU requires a minimum 10.5-acre lot — this is a much larger minimum lot size than in the urbanized residential districts, where public water/sewer service is instead the qualifying condition.
  • The county's max-size figure (50% of primary dwelling, capped at 1,200 sq ft) as stated in the Guidance for Residential Projects handout is consistent with, but numerically distinct from, the IRC Appendix BC construction-code cap (50% of primary dwelling, capped at 1,200 sq ft, with a 190 sq ft floor) — both apply; the more restrictive number in a given case controls.

Frequently asked questions

The property must already have a principal dwelling built on it before an ADU application is accepted, and per the county's cited 2024 IRC Appendix BC standard, the owner must reside in either the primary dwelling unit or the ADU as of the date of permit approval.

In Unincorporated Laramie County, the published Building Permit Fee — same valuation-based table as new construction is: Varies by project valuation — see Laramie County 2022 Building and Plan Review Fee Schedule. Additional published fees: Plan Review Fee — 65% of the Building Permit Fee. These are the jurisdiction's own published figures — see the fee schedule table and source citations on this page.

Unincorporated Laramie County's published plan-review target for an accessory dwelling unit (adu) permit is 7–10 business days.

You'll need: Non-Traditional Housing Approval Permit Application (Planning and Zoning); Building Permit Application (SmartGov portal); Plot Plan; Building Plans. Depending on your project, Unincorporated Laramie County may also ask for: IRC Letter for Modular Homes; Accessory Dwelling Unit Guide (county handout). See the required-documents checklist on this page for details on each.

Unincorporated Laramie County requires 3 inspection(s) for an accessory dwelling unit (adu) permit, in order: Foundation, Rough Framing / Rough MEP, Final. Schedule each through Laramie County Planning and Development Department — Building Division ((307) 633-4303).

Apply through Laramie County Planning and Development Department — Building Division at 3966 Archer Parkway, Cheyenne, WY 82009. Phone: (307) 633-4303, email: building@laramiecountywy.gov. Office hours: Monday–Friday 7:00 AM–5:30 PM (closed Saturday/Sunday); Building Inspection line (307) 633-4615; fax (307) 633-4519. Official information: https://www.laramiecountywy.gov/County-Government/County-Departments/Planning-Development/Laramie-County-Building.

Per the county's Accessory Dwelling Unit Guide and Guidance for Residential Projects handout, an ADU may not exceed 50% of the floor area of the principal dwelling, with an absolute maximum of 1,200 square feet (and, per the 2024 IRC Appendix BC construction standard the county applies, a minimum of 190 square feet). In the LU and RRH rural zoning districts, an ADU may be up to the same size as the principal dwelling.

In the LU (rural) and RRH zoning districts, an ADU requires a minimum lot size of 10.5 acres, per Laramie County Land Use Regulations Section 3-1-107 Part E.

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

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Accessory Dwelling Unit (ADU) Permit in other cities

Casper, WyomingCheyenne, WyomingEvanston, WyomingGillette, WyomingGreen River, WyomingJackson, WyomingLaramie, WyomingRiverton, Wyoming

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