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  Service Detail

Service Name: Accessory Dwelling Units (mother-in-law apartments)
Service Phone: 206-296-6600
Service Fax: 206-296-6644
Service Mail Stop: OAK-DE-0100
Group Name: DPER/BFSD - Planning/Customer Services Section - Permit Intake

Accessory dwelling units are commonly referred to as mother-in-law apartments. Accessory dwelling units (ADUs) are a second dwelling on a piece of property where a primary residence already exists.

Instructions: For more information about building an Accessory Dwelling Unit in unincorporated King County, please see Accessory Dwelling Units under Department of Development and Environmental Services (DPER) Frequently Asked Questions, or the main DPER FAQ Web link below.

Please note that DPER processes building and land use permits for property in unincorporated King County only. If your property is within city limits, you will need to contact your city for its own permit regulations.

Contact Name: DLS - Permitting Customer Service DLS - General Information
Contact Phone: 206-296-6600
Contact Fax: 206-296-6644
Service TTY: 206-296-7217
Web Link:
Keywords: DPER, ADU, ADUs, MIL, MILs, accessory dwelling unit, accessory dwelling units, accessory dwelling, accessory dwellings, mother-in-law, mother-in-laws, mother-in-law apt, mother-in-law apartment, mother in law, mother in laws, mother in law apartment
Groups That Provide This Service
Group Name Phone
DPER/BFSD - Planning/Customer Services Section - Permit Intake (206) 296-6600
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Places To Find This Service
Place Name Phone
Blackriver Community Service Center (206) 296-7810
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