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 prohibits the county from requiring the owner to live on the property as a condition of renting the ADU.
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
- Req
Residential Building Permit Application (2023)
Used for ADU construction; available at washoecounty.gov/building
- Req
Site Plan Checklist (2025)
Engineering checklist required for all new construction including ADUs
Fee schedule
| Fee type | Amount | Notes |
|---|---|---|
| Building Permit — valuation-based per Table 1 | Varies — valuation-based (same tiered table as new residential construction) | WCC 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. |
| Plan Review Fee | 65% of building permit fee | WCC Chapter 100, Appendix A, Table 9 — accessory buildings / other permits |
Review timeline
~10–45 business days
Typical estimate — confirm current times with the Unincorporated Washoe County building department
Inspection process
- 1
Foundation
Footings and foundation before concrete pour; setback certification required
- 2
Framing
Structural framing, egress windows, fire separation
- 3
MEP Rough-In
Mechanical, electrical, plumbing rough-ins before walls closed
- 4
Final
All work complete, smoke/CO detectors, address posted
Tips
- NRS 278.257 (effective July 1, 2026): As a county with population ≥100,000, Washoe County must authorize ADUs by ordinance and may NOT prohibit the owner from renting the ADU as a long-term rental — any local ordinance provision requiring owner-occupancy as a condition of long-term rental is superseded by NRS 278.257 as of 7/1/2026. 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
- Can I build an ADU on my property in unincorporated Washoe County?
- 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 prohibits Washoe County from requiring owner-occupancy as a condition of renting an ADU as long-term housing.
- What is a Minor ADU and how does it differ from a regular detached ADU?
- 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.
- Washoe County Building Program — official building department
- Washoe County Development Code Division Three — Regulation of Uses (§110.306.20–110.306.25, effective January 23, 2026)
- Washoe County ADU Hub
- NRS 278.257 — Accessory Dwelling Units (effective July 1, 2026)
- Washoe County Code Chapter 100, Appendix A — Fee Tables
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.
Other permits in Unincorporated Washoe County
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