Burien, WA Accessory Structures: ADU Rental Restrictions (2026)

The Burien City Council wrote ADUs into two places in the Rental Housing Inspection Program. First, BMC 5.62.030(1) defines the term and ties it to BMC 19.10.120, the section that carries the ADU requirements themselves. Second, BMC 5.62.030(17) counts accessory dwelling units inside the definition of a residential housing unit, in the same list as duplexes, triplexes, fourplexes, townhouses, multifamily dwellings and apartment buildings.

The exemption sits in BMC 5.62.040(1)(f). Alongside accessory dwelling units, the chapter exempts single-family residences, units unavailable for rent, mobile and manufactured homes, condominiums and townhomes, rental units owned or operated by a government unit, and living arrangements exempted under RCW 59.18.040. An ADU therefore stays off the three-year certificate of inspection cycle described in BMC 5.62.070.

Two points keep the exemption from being a complete answer. The business license rule in BMC 5.62.040(2) speaks of each owner or landlord renting or leasing a residential housing unit within the city limits, and that defined term includes ADUs. The penalty clause in BMC 5.62.040(2)(b) likewise refers to a residential housing unit operating without a business license. The text read here does not say how those clauses fit with the ADU exemption. Separately, BMC 5.62.040(2)(a) says short-term rentals such as AirBNB and VRBO fall under a different Burien Municipal Code and can require a Burien business license there, and BMC 5.62.020 makes the more restrictive provision control when two code provisions conflict. Burien Community Development, the department that runs the program, administers all of it.