ADU rules in Douglas County

A detached accessory dwelling is allowed only in five residential districts (SFR-1/2, SFR-1, SFR-2, RA-5 and RA-10) plus the agricultural and forest and range districts (A-19, FR-19/40); the residential use table marks it 'X' (prohibited) in SFR-8,000, SFR-12,000, every SFR-T townhouse district and MFR, which rules out most platted Carson Valley subdivision lots. The parcel must contain at least one-half net acre, must already hold an owner-occupied single-family detached home, and must not already contain two or more dwelling units. Only one accessory dwelling is allowed per parcel outside the agricultural and forest and range districts. A detached unit may sit in a rear or side yard; front or street-side yard placement is allowed only on parcels of at least one net acre in a district with a one-acre minimum, and only if it does not block the front of the primary residence as seen from the street and covers no more than 20 percent of that yard. Separately, chapter 20.560 requires a growth-management building permit allocation before the building permit can issue, and the county's own submittal guide puts that duty on the applicant.

The code's own definition is 'an attached or detached dwelling unit,' so an attached wing, an addition or an internal conversion qualifies and runs through exactly the same review as a detached unit. The same gates therefore bite: eligible zoning district only, at least one-half net acre, an owner-occupied single-family main dwelling, and one accessory dwelling per parcel. Where the unit is attached, a separate entrance is allowed but only one entrance may be visible from the front property line. The county's January 2026 submittal guide adds an important line-drawing rule: an attached living area without kitchen facilities that has direct, heated access from a common area inside the primary dwelling is not an accessory dwelling at all, so a kitchen-free in-law suite is simply part of the house and needs no design review.

The 800 square foot cap is the number that applies to almost every eligible residential lot; only parcels of two net acres or larger in SFR-2, RA-5 or RA-10 get 1,000 square feet. Two other caps exist outside ordinary residential zoning: an accessory dwelling in the agricultural or forest and range districts that houses people significantly employed in open agricultural work on the property may reach 2,500 square feet of livable area, and an accessory dwelling in a non-residential district is capped at 1,000 square feet. An existing residential structure in a non-residential district may be used as an accessory dwelling regardless of size if at least 25 percent of the total floor area is put to a use permitted in that district. Inside the Lake Tahoe Basin, Table 20.702.3 applies section 20.664.010 in R-prefix and M-prefix Tahoe districts but expressly excepts the subsection C.5 size limitation where the parcel is larger than one acre. The code sets no separate height cap for accessory dwellings; the zoning district's height standard governs.

Owner occupancy is required both at approval and on an ongoing basis, and it is stated three separate times. An accessory dwelling may only be permitted on a parcel that has an owner-occupied single-family detached main dwelling; either the principal dwelling or the accessory dwelling must be occupied by the owner of the parcel; and the property owner must live on the property and maintain one of the units as the primary residence. The owner may choose which of the two units to live in. Nevada's 2025 ADU statute, NRS 278.257, does not preempt this: its mandate reaches only counties of 100,000 or more and cities of 60,000 or more, and Douglas County's certified July 1, 2025 population was 57,149 with no incorporated cities.

The accessory dwelling must be provided with one off-street parking space in addition to whatever the main dwelling requires, and the parking table repeats the same rule ('One in addition to that which is required for the main dwelling'). No variance or minor exception may be filed to put that space inside a required front or side yard setback, which on the deep 30-foot front yards typical of SFR-1, SFR-2, RA-5 and RA-10 can constrain driveway layouts. Note a divergence between the code and the county handout: the January 2026 submittal guide says the added space must be a 'covered' space, while the current text of section 20.664.010.C.7 and the parking table require only an off-street space. For comparison, the main single-family dwelling itself is required to have two covered spaces.

Accessory dwellings carry a 'D' (requires design review) in the residential use table, and the design review chapter puts accessory dwelling units in the minor design review category. Minor design review is administrative: the community development director is the final decision-maker, applications are not set for a public hearing, and the director must approve, deny or conditionally approve within 15 working days of submittal. In practice the county folds the planning design review into the building permit review. Two wrinkles keep it from being purely ministerial: the director may in his sole discretion refer any design review to the planning commission for a noticed hearing instead of deciding it, and the design review findings include neighborhood compatibility. On A-19, FR-19 and FR-40 parcels actively in open agricultural use the accessory dwelling is permitted by right with no design review at all; design review returns if the use is non-agricultural. Separately, a growth-management allocation under chapter 20.560 is a condition precedent to the building permit, released quarterly on a first-come basis (or on demand within ten working days whenever excess allocations exist).

Renting an accessory dwelling long term is squarely contemplated: the code defines it as a unit 'intended for occupation by paying or non-paying guests, members of the family, or person employed on the premises.' The catch is that the owner must keep living on the property in one of the two units, so the main house and the accessory dwelling cannot both be rented out. The accessory dwelling may also be used only as approved through design review, and any change in how it is used terminates the accessory dwelling use. Short-term rental is a different regime: it is unlawful to rent any dwelling unit or bedroom for 28 consecutive days or less without a Douglas County Vacation Home Rental permit, and by ordinance all VHRs are limited to the Lake Tahoe Township, so short-term rental is not available anywhere in the Carson Valley part of the county (Minden, Gardnerville, Genoa, the Gardnerville Ranchos, Johnson Lane, Topaz). Even at Tahoe, permits are capped at 600 county-wide with a 15 percent VHR density ceiling per residential community (40 percent in Tahoe Village), no new permits at all in Cave Rock Cove, Logan Creek, Shakespeare Point, Uppaway and non-affiliated Glenbrook parcels, and a waitlist. There is no separate-sale path: the accessory dwelling must remain on the same parcel as the main dwelling, and the State Engineer's domestic-well approval form is rescinded if it ever ceases to be.