ADU rules in Owasso

Owasso's zoning code, rewritten by Ordinance 1249 in June 2026, lists an accessory dwelling unit as a permitted accessory use in every residential district (RE, RS-1 to RS-3, RD, RNX, RM and the legacy RMH district). The definition expressly includes units detached from the house, such as tiny homes and garage apartments. A detached unit follows the general accessory structure rules of Section 4.6.2 plus the ADU conditions of Section 4.6.8: one unit per lot of record, current Building Code compliance, a principal home already on the lot, one off-street parking space, and nothing on a utility easement or right-of-way.

The code's definition covers a unit "incorporated within, attached to, or detached from" a single-family home and names guest suites and accessory apartments, so internal conversions and attached additions are ADUs in every R district on the same terms. The unit must have its own sleeping and sanitation facilities. The Section 4.6.8 conditions (one per lot, Building Code, one parking space) apply to attached units as well.

Owasso has no ADU-specific size number. A detached ADU is an accessory structure, and Section 4.6.2(e) caps the combined footprint of every accessory structure on an RS, RD, RNX, RM or RMH lot (detached garage, shed and ADU together) at 1,000 square feet; Ordinance 1249 (June 2026) raised that cap from 500 square feet. Anything over 1,000 square feet needs a special exception from the Board of Adjustment after a hearing. Height is managed through setbacks rather than a cap: 5 feet from the property line up to 15 feet at the roof peak, 10 feet between 15 and 20 feet, and 15 feet above 20 feet; in RE the district setbacks apply in full. An attached or internal unit is part of the house and has no stated size limit beyond the district's bulk rules.

Neither Section 4.6.8 nor the definition requires the owner to live on the property, at application or afterward. The definition does bar separate ownership: the ADU "shall not be otherwise segregated in ownership from the principal residential unit," so it cannot be sold off on its own (no condominium split). Oklahoma has no state ADU statute, so this is purely local.

Section 4.6.8(c) requires one off-street parking space for an accessory dwelling unit. The parking chapter separately requires two off-street spaces (a garage counts) for a single-family home, so a lot with an ADU needs three spaces in total. There is no transit or lot-size exception, and Oklahoma has no parking preemption (2025 SB 347 and HB 1050 died).

An ADU is a by-right accessory use in all residential districts under Section 4.6.1 and Table 4.11. Approval is a building permit, issued only when a principal home already exists on the lot (Section 4.6.8(d)). No specific use permit or public hearing is required unless the lot's total accessory footprint would exceed 1,000 square feet or a setback needs relief; either of those goes to the Board of Adjustment as a special exception or variance after notice and a hearing.

Neither the zoning code nor the Code of Ordinances says anything about renting an ADU. With no owner-occupancy rule, a long-term rental is allowed, but the unit stays under the same ownership as the main house. Owasso has no short-term rental ordinance, license or registry. Section 4.6.2 says accessory structures in residential districts "shall not be used for commercial purposes" other than home occupations, and Section 4.6.4 excludes bed and breakfasts and an "inn or tourist home" from home occupations. So renting a detached ADU nightly is a gray area the code does not settle. The city's 5 percent hotel tax (Code Sec. 7-601 and 7-602) reaches only lodging with five or more rooms.