ADU rules in Oklahoma County

No ordinary residential district allows a detached accessory dwelling. The Land Use Chart lists Accessory Dwelling only in the R-5 Agriculture and Rural Residential District (P-2: accessory quarters in the house, in a detached garage or in a separate structure) and in the C-R Commercial-Rural District (P-3, a unit for the owner or manager of the business). R-5 is a voluntary district with a 5-acre minimum lot and rezoning area; the 2021 regulations state that no property was zoned R-5 when they took effect, and none of the roughly 55 county rezoning, PUD and SUP resolutions put before the Board of County Commissioners from June 2021 to October 2026 created any R-5 land. So a homeowner in R-2, R-1, R-0 or R-M can get one only by rezoning to R-5 through Planning Commission and County Commission hearings. Single-Family Residential is defined as a dwelling on a lot 'unoccupied by any other dwelling unit'. Narrow alternatives are a tiny house on wheels (up to 400 sq ft) by Specific Use Permit and a temporary manufactured home by medical-hardship special exception.

No ordinary residential district allows an attached or internal accessory dwelling either. R-5 condition 2 allows 'accessory quarters located in the principal building', but R-5 has no land and requires a voluntary rezoning of at least 5 acres; C-R allows a unit only for the owner or manager of the commercial use. The only by-right attached second-unit route is Two-Family Residential (a duplex), permitted only in the R-M Multi-Family Residential District, which is a multi-family district covering very little unincorporated land (4 of 652 mapped zoning polygons in the county's last public zoning layer), not a route open to single-family homeowners without rezoning; it is therefore not counted as an ordinary residential duplex route.

Because no ordinary residential district allows an accessory dwelling, no size cap applies in practice. Where the R-5 district is obtained by rezoning, 'the Accessory Dwelling living area shall not exceed fifty (50) percent of the principal building square footage', and only one accessory building may be used as living quarters per lot; the C-R condition sets no unit size cap. Every detached accessory building is also limited by Table 22: all of them combined may not occupy more than 30 percent of the rear yard, height is 18 ft on lots up to 20,000 sq ft and 25 ft on lots of 20,000 sq ft to 1 acre (or the main building's height if taller) and not applicable on lots over 1 acre, and side and rear setbacks are 7 ft if no taller than 20 ft. A tiny house is by definition up to 400 sq ft excluding lofts.

Not applicable because no ordinary residential district allows an accessory dwelling. For reference, the R-5 condition contains no owner-occupancy rule, while a C-R residential unit 'shall be the primary residence of the owner(s) or primary manager(s) of the commercial use on the property'. Oklahoma has no state owner-occupancy rule for accessory dwellings.

The Land Use Chart's parking column requires '1 : dwelling unit' for Accessory Dwelling (and for Tiny House), in addition to the 2 spaces per single-family dwelling. Article III, Section 5 makes the chart the minimum, requires all parking on the lot, and lets single-family, duplex, triplex and fourplex structures count a paved driveway toward the minimum (each space 9 by 18 ft); parking on lots under 1 acre must be hard-surfaced.

Not applicable because no ordinary residential district allows an accessory dwelling. The path to one is discretionary: a Zoning Map Amendment to R-5 (5-acre minimum; Planning Commission recommendation, then a Board of County Commissioners decision after published notice and public hearings under 19 O.S. 868.16), after which the R-5 accessory dwelling is 'P-2' and needs only a building permit from the County Engineer with a site plan and an ODEQ water and sewage certificate. A tiny house needs a Specific Use Permit through the same hearing process, and a temporary hardship manufactured home needs a Board of Adjustment special exception.

The 2021 regulations contain no rental, licensing or short-term-rental provision for accessory dwellings (no 'short-term' text anywhere; lodging is regulated only as hotels, motels and campgrounds in commercial districts), so an R-5 accessory dwelling carries no rental restriction in county zoning. A C-R residential unit may house only the owner or primary manager of the commercial use and their family, which excludes renting it to others. A medical-hardship manufactured home must be occupied by a relative of the main home's occupants. Oklahoma has no state short-term-rental preemption or registry; lodging taxes apply under state law.