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ADU rules in Nevada

Representative cities: Las Vegas, Reno.

Verify locally. Nevada has NO mandatory statewide residential building code — each city and county adopts its own edition of the IRC/IBC (Southern Nevada or Northern Nevada amendments). Clark County (Las Vegas) and Washoe County / City of Reno set the rules that affect most homeowners. Always check the specific city/county code for your property. ADU rules below are drawn from official sources — always confirm with the issuing building department before designing or building.

ADU permit rule

Permit requiredRestrictedcity authority
Fee basis
Valuation-based building + plan-check fees; no flat ADU fee published. Clark County fees scale with valuation.
Typical timeline
Clark County (unincorporated) typically administrative approval under recent state ADU law; City of Las Vegas requires a special-use permit (entitlement ~2–4 months) before a building permit.
Setback
Clark County: 5 ft rear setback for detached Accessory Living Quarters; setbacks follow the underlying zoning district.
Area threshold
Clark County allows one ADU per lot with a single-family residence; size tied to a % of the primary dwelling (state law).
Exempt if
None — an ADU/casita always requires a building permit (and, in Las Vegas, a zoning entitlement).
Go / no-go
restricted
Nevada has NO statewide ADU mandate. Clark County (unincorporated) permits "Accessory Living Quarters" largely by right under Nevada’s 2025 ADU law (SB 396), but the City of Las Vegas treats ADUs as a conditional/special-use permit under LVMC Title 19. Verify the exact entitlement path for your jurisdiction.
ADU official sources: Clark County — Building & Fire Prevention (Do I Need a Permit?) · City of Reno — Building Permits (ADU Guide) · AWC — Nevada Building Code Adoption Profile
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Frequently asked questions

Do I need a permit to build an ADU in Nevada?

Per Nevada rules, an ADU is "yes" for a permit and the authority is "city". Nevada has NO statewide ADU mandate. Clark County (unincorporated) permits "Accessory Living Quarters" largely by right under Nevada’s 2025 ADU law (SB 396), but the City of Las Vegas treats ADUs as a conditional/special-use permit under LVMC Title 19. Verify the exact entitlement path for your jurisdiction. Always confirm with the issuing building department.

How big can an ADU be in Nevada?

Area threshold: Clark County allows one ADU per lot with a single-family residence; size tied to a % of the primary dwelling (state law).

What are the ADU setbacks in Nevada?

Setback: Clark County: 5 ft rear setback for detached Accessory Living Quarters; setbacks follow the underlying zoning district.

How much does an ADU permit cost in Nevada?

Fee basis: Valuation-based building + plan-check fees; no flat ADU fee published. Clark County fees scale with valuation.

State-wide sources: Clark County — Building & Fire Prevention Department · City of Reno — Development Services / Building Permits · City of Las Vegas — Building & Safety · Southern Nevada Building Officials — Current Adopted Codes · AWC — Nevada Building Code Adoption Profile

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