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Accessory Dwelling Unit (ADU) Permit in Unincorporated Washoe County, Nevada

Required for construction of an attached, detached, or minor accessory dwelling unit (ADU) on a residential property in unincorporated Washoe County. Washoe County (population ≥100,000) is subject to NRS 278.257 (effective July 1, 2026), which mandates a county ordinance authorizing ADUs and, as a condition of approval, prohibits barring separate kitchen facilities, requiring more than one added parking space where existing parking is adequate, imposing stricter side/rear setbacks than the main residence, requiring most public-street improvements, and (except for transient/short-term lodging) prohibiting the owner from renting the ADU as long-term housing (NRS 278.257(2)(a)-(e)). The statute does not address owner-occupancy, and Washoe County's ADU standards (WCC §110.306.20-.25) do not impose an owner-occupancy requirement either.

Verified 2026-06-30 · Source

When you need this permit

  • A main residential dwelling unit must exist on the parcel
  • Only one ADU or guest quarters is permitted per parcel
  • ADUs are permitted in General Rural (GR), General Rural Agricultural (GRA), and Residential Regulatory Zones (WCC Development Code §110.306.20–110.306.25)
  • Attached ADU: minimum 5,000 sq ft lot; size limit is 80% of main dwelling or 1,500 sq ft (whichever is smaller) in most zones; 1,200 sq ft cap in MDS/HDS and urban zones
  • Detached ADU: minimum 12,000 sq ft lot; size limit is 80% of main dwelling or 1,500 sq ft (whichever is smaller) in most zones; 1,200 sq ft in MDS zone
  • Minor ADU (detached, <500 sq ft): if 12 ft or less in height, may be placed as close as 5 ft from side/rear property lines; no off-street parking required on parcels >½ acre
  • Detached ADUs on parcels ≤½ acre require administrative review (Article 809) and one additional off-street parking space
  • Compliance with 2024 IRC and all applicable setback, height, and lot coverage standards (Article 406)
  • Submit Residential Application (2023) via ONe NV permit portal; contact Planning Division (775-328-6100) to confirm zoning eligibility before applying

Required documents

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Fee schedule

Building Permit — valuation-based per Table 1WCC Chapter 100, Appendix A, Table 1 and Building Valuation Data. Example: a 500 sq ft minor ADU (Type VB, utility/misc. occupancy at $36.91–$64.30/sf) would typically fall in the $25,000–$50,000 valuation range: $443.62 + $10.90 per $1,000 over $25,000.
Varies — valuation-based (same tiered table as new residential construction)
Plan Review FeeWCC Chapter 100, Appendix A, Table 9 — accessory buildings / other permits
65% of building permit fee

Review timeline

Plan reviewTypical estimate — confirm current times with the Unincorporated Washoe County building department
~10–45 business days

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

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

Inspection process

  1. 1

    Foundation

    Footings and foundation before concrete pour; setback certification required

  2. 2

    Framing

    Structural framing, egress windows, fire separation

  3. 3

    MEP Rough-In

    Mechanical, electrical, plumbing rough-ins before walls closed

  4. 4

    Final

    All work complete, smoke/CO detectors, address posted

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

Tips

  • NRS 278.257 (effective July 1, 2026): As a county with population ≥100,000, Washoe County must authorize ADUs by ordinance. As a condition of ADU approval, the ordinance may not: bar separate kitchen facilities; require more than one added parking space where existing parking is adequate; impose stricter setbacks than the main residence; require most public-street improvements; or (except for transient/short-term lodging) prohibit the owner from renting the ADU as long-term housing (NRS 278.257(2)(a)-(e)). The statute does not mention owner-occupancy, and Washoe County's ADU standards (WCC §110.306.20-.25) do not impose an owner-occupancy requirement either — so there is no known local rule for the statute to override. (2026-07-18: an earlier version of this note asserted a local owner-occupancy requirement was 'superseded' by NRS 278.257; that claim was unsourced and has been removed.) Short-term rentals (under 28 days) may still be restricted per county regulations.
  • Washoe County maintains an ADU Hub (csd.washoecounty.gov/adu-hub/) with pre-approved plan designs that can accelerate the permitting timeline.
  • Contact the Planning Division (775-328-6100) FIRST to confirm your parcel's regulatory zone, lot size eligibility, and whether administrative review (Article 809) is required.
  • A detached ADU proposed to connect to a potable water supply or sewer system requires a deed restriction be filed prior to permit issuance if not yet legally converted — contact the Planning and Building Division.
  • Minor ADUs (under 500 sq ft) have more relaxed setback rules and may not require additional off-street parking if on parcels larger than ½ acre.
  • Trade sub-permits (electrical, plumbing, mechanical) are required separately for ADU construction.

Frequently asked questions

Unincorporated Washoe County requires an accessory dwelling unit (adu) permit for: A main residential dwelling unit must exist on the parcel; Only one ADU or guest quarters is permitted per parcel; ADUs are permitted in General Rural (GR), General Rural Agricultural (GRA), and Residential Regulatory Zones (WCC Development Code §110.306.20–110.306.25); Attached ADU: minimum 5,000 sq ft lot; size limit is 80% of main dwelling or 1,500 sq ft (whichever is smaller) in most zones; 1,200 sq ft cap in MDS/HDS and urban zones; Detached ADU: minimum 12,000 sq ft lot; size limit is 80% of main dwelling or 1,500 sq ft (whichever is smaller) in most zones; 1,200 sq ft in MDS zone; Minor ADU (detached, <500 sq ft): if 12 ft or less in height, may be placed as close as 5 ft from side/rear property lines; no off-street parking required on parcels >½ acre; Detached ADUs on parcels ≤½ acre require administrative review (Article 809) and one additional off-street parking space; Compliance with 2024 IRC and all applicable setback, height, and lot coverage standards (Article 406); Submit Residential Application (2023) via ONe NV permit portal; contact Planning Division (775-328-6100) to confirm zoning eligibility before applying. If your project isn't listed, confirm with Washoe County Building Program at (775) 328-2020 before starting work.

In Unincorporated Washoe County, the published Building Permit — valuation-based per Table 1 is: Varies — valuation-based (same tiered table as new residential construction). Additional published fees: Plan Review Fee — 65% of building permit fee. 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 Unincorporated Washoe County typically runs 10–45 business days. This is an estimate, not a published figure — confirm current review times with Washoe County Building Program at (775) 328-2020.

You'll need: Residential Building Permit Application (2023); Site Plan Checklist (2025). See the required-documents checklist on this page for details on each.

Unincorporated Washoe County requires 4 inspection(s) for an accessory dwelling unit (adu) permit, in order: Foundation, Framing, MEP Rough-In, Final. Schedule each through Washoe County Building Program ((775) 328-2020).

Apply through Washoe County Building Program at 1001 E. Ninth Street, Building A, Reno, NV 89512. Phone: (775) 328-2020, email: building@washoecounty.gov. Office hours: Monday–Friday 8:00 AM – 4:00 PM. Official information: https://www.washoecounty.gov/building/.

Yes, in most residential and General Rural zones. Attached ADUs require a minimum 5,000 sq ft lot; detached ADUs require 12,000 sq ft. Only one ADU or guest quarters is allowed per parcel. Contact the Planning Division at (775) 328-6100 to confirm your zone eligibility before applying. As of July 1, 2026, NRS 278.257(2) prohibits an ADU ordinance from, among other things, barring separate kitchens, requiring more than one added parking space where existing parking is adequate, imposing stricter setbacks than the main residence, requiring most street improvements, or (except for transient lodging) prohibiting the owner from renting the ADU as long-term housing. The statute does not address owner-occupancy, and Washoe County's ADU standards (WCC §110.306.20-.25) do not impose an owner-occupancy requirement.

A Minor ADU is a detached ADU under 500 square feet (WCC §110.304.15(c)(3)). If 12 feet or less in height, it can be placed as close as 5 feet from side and rear property lines. No additional off-street parking is required if the parcel is larger than ½ acre. It is permitted in the same zones as detached ADUs.

Sources & verification

Verified against official sources. Last reviewed 2026-06-30.

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 Washoe 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

Carson City, NevadaDouglas County, NevadaHenderson, NevadaLas Vegas, NevadaMesquite, NevadaNorth Las Vegas, NevadaReno, NevadaSparks, Nevada

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