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Washoe County, NV Accessory Structures: ADU Rules (2026)

Some Restrictions

Compiled from the official code textEditor Martyn O'NeillLast verified July 2026

ADU rules in Washoe County, NV, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.

Key Facts

ADUs per parcel: One (1) maximum
Attached ADU lot min: 5,000 sq ft
Detached ADU lot min: 12,000 sq ft
Detached size cap: 1,500 sq ft (800 in MDS)
Applies to: Unincorporated county only

ADU Eligibility Quick-Check

An Accessory Dwelling Unit (ADU) is a smaller, independent living unit on the same lot as a single-family home: converted garages, detached cottages, basement or attic conversions, and attached additions all qualify. Most states have streamlined ADU permitting since 2020, but local rules still control size, height, and setback.

Is your lot zoned single-family or multi-family residential?
Does your lot have at least 1,200 sq ft of buildable space?
Is your existing home owner-occupied (in most states this is not required, but some require it for ADU permits)?
Will the ADU stay under your state's size cap (commonly 850-1,200 sq ft for detached)?
Can you provide one off-street parking space (waived in many states within 0.5 mi of transit)?

If you answered 'yes' to most of these, you likely qualify in Nevada under recent ADU streamlining laws. The Washoe County, NV rules below cover local size, height, and setback requirements.

Summary

In unincorporated Washoe County, one ADU is allowed per parcel. Attached ADUs need a 5,000 sq ft lot; detached need 12,000 sq ft. Detached units are capped at 1,500 sq ft (800 in Medium Density Suburban).

City-specific rules exist: Reno has its own adu rules rules that differ from Washoe County's county-level regulations. If you live in Reno, check the city-specific page instead.

The detached accessory dwelling unit shall not exceed fifteen hundred (1,500) square feet, or fifty (50) percent of the total square footage of the main dwelling unit, whichever is smaller. In the Medium Density Suburban (MDS) Regulatory Zone, the detached accessory dwelling unit shall not exceed eight hundred (800) square feet.

View official code

Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 20 Update 2).

Full Breakdown

The Washoe County Development Code (WCC Ch. 110, Article 306) permits attached accessory dwellings in General Rural, General Rural Agricultural, and Residential zones once a main residence exists and no other ADU has been established (Sec. 110.306.20). Attached units are limited to 40% of the main dwelling or 1,000 sq ft, whichever is smaller. Detached accessory dwellings (Sec. 110.306.25) are allowed in GR/GRA and rural/LDS zones by administrative review, and in MDS by special use permit. Only one ADU or guest quarters per parcel. One extra off-street parking space is required. This governs unincorporated county land only; Reno and Sparks set their own city ADU rules.

Violations & Fines

Building/zoning enforcement under Article 910; unpermitted units may be cited as violations and must be removed or brought into compliance before permits issue.

Frequently Asked Questions

Can I put an ADU on any lot?

Only where zoning allows. Attached ADUs need at least 5,000 sq ft; detached need 12,000 sq ft, plus a main residence and one added off-street parking space.

How big can a detached ADU be?

Up to 1,500 sq ft or 50% of the main dwelling, whichever is smaller (800 sq ft in the Medium Density Suburban regulatory zone).

Sources & Official References

Other rules in Washoe County

Parking Rules: Overnight ParkingSome Restrictions Parking Rules: Street Parking LimitsSome Restrictions Shed & Carport RulesSome Restrictions Tiny HomesSome Restrictions Garage ConversionsSome Restrictions Parking Rules: EV ChargingSome Restrictions Fence Regulations: Fence Permit RequirementsSome Restrictions Animal Ordinances: Pet LimitsSignificant Restrictions Animal Ordinances: Wildlife FeedingSome Restrictions

All Washoe County rules

How Washoe County compares: Easiest Cities to Build an ADU·Compare Washoe County to another location·View the Nevada accessory structures overview

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ADU Rules in Cities Across Washoe County

Reno, NV