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Accessory Dwelling UnitsDEPARTMENT OF COMMUNITY AND ECONOMIC DEVELOPMENT 1 H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\Accessory Dwelling Units.doc Rev: 02/2020 Customer Information Bulletin ACCESSORY DWELLING UNITS Planning Division 1055 South Grady Way-Renton, WA 98057 Phone: 425-430-7200 | www.rentonwa.gov What is an Accessory Dwelling Unit (ADU)? Commonly known as mother-in-law units, backyard cottages, or granny flats, Accessory Dwelling Units (ADUs) are independent units located on a lot that has a single-family home. Renton Municipal Code (RMC) defines an ADU as “An independent subordinate dwelling unit that is located on the same lot, but not within a single family dwelling. This may include units over detached garages.” Attached ADUs , units within a single-family dwelling, are not permitted. ADUs are intended to create affordable, flexible housing opportunities tha t take advantage of the City’s existing infrastructure while addressing the need for increased housing choices that reflect changing lifestyles and environmental concerns. How is Maximum ADU Size Determined? Maximum ADU size depends on several factors, including the sizes of the lot and primary residence and maximum impervious surface coverage allowed in the zone where the property is located. Maximum Unit Size* Lot Area Maximum ADU Size 3,000 sq. ft. or less 600 sq. ft. 3,001 - 4,999 sq. ft. 700 sq. ft. 5,000 - 6,999 sq. ft. 800 sq. ft. 7,000 - 8,999 sq. ft. 900 sq. ft. Greater than 9,000 sq. ft. 1,000 sq. ft. *The total square footage of the ADU shall not exceed the size allowed based on lot size or 75% of the total square footage of the primary residence, whichever is smaller. ADUs do count toward the maximum impervious surface area allowed on site. However, ADUs do not count toward maximum building coverage/lot coverage. 2 H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\Accessory Dwelling Units.doc Rev: 02/02/2020 Where are ADUs Allowed? Most residential zones in Renton allow you the opportunity to build an onsite ADU, including properties zoned RC, R-1, R-4, R-6, R-8, R-10, and R-14. ADUs must be a minimum of 6 feet from the primary residence. ADUs shall not be permitted between the primary structure and the street u nless approved in the Conditional Use Permit process. See RMC 4-2-110C, Development Standards for Residential Development (Accessory Dwelling Units), for more information. The minimum rear yard setback in all zones is 5 feet. The minimum side yard setbac k varies by zone and is included in the Development Standards for Residential Development (Accessory Dwelling Units) at the end of this document. Is Owner Occupancy Required? Owner occupancy is required unless the applicant applies for and is granted a Conditional Use Permit (CUP). Proposals must meet the criteria outlined in RMC 4-9-030D and meet the decision criteria for ADU owner occupancy exemption in RMC 4-9-030H. Are Permits Required? Yes, you will need to apply for permits from the Building Division in order to ensure that you meet the requirements of the International Residential Code and other safety -related requirements. Building plans are required at the time of application submittal. Additionally, a Conditional Use Permit (CUP) is required in each of the following scenarios: 1. The proposal includes locating the ADU between the primary residence and street; or 2. The property owner does not plan to live on site. 1 Do ADUs Require Additional Parking? In most cases, ADUs will require a minimum of one additional parking space and a maximum of two is allowed. However, ADUs located within a ¼ mile of a mass transit facility shall be exempt from off-street parking requirements. If the primary structure on a site where an ADU is proposed does not meet the City’s minimum parking standards, one additional off-street parking space is required. What Other Requirements Are Necessary for ADU Approval?  Architectural Character to be Consistent: The ADU must be consistent with the architectural character of the pri mary structure and shall be required to meet the ADU Residential Design Standards. If the primary structure where the ADU is proposed does not comply with the adopted architectural detailing standards, the primary structure shall be brought to compliance p rior to the issuance of ADU building permits. 1 Only proposals that meet the criteria of RMC 4-9-030D and RMC 4-9-030H are eligible for non-owner occupancy. 3 H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\Accessory Dwelling Units.doc Rev: 02/02/2020  Owner Occupancy Affidavit Required: The property owner shall file an affidavit affirming that the owner will occupy the principal dwelling or the Accessory Dwelling Unit.  Notice on Title Required: Additionally, prior to the issuance of building permits the owner shall record a notice on the property title. The notice shall bear the notarized signature of all property owners listed on the property title and include the legal description of the property, a copy of the approved plans, and the applicable City restrictions and conditions of approval. Does the City Allow Garage to ADU Conversions? Conversion of accessory buildings, including detached garages are permitted. If the existing structure was built prior to January 1, 2020, the ADU will be exempt from select development standards, such as maximum ADU size, location, and setbacks. If your project proposal is for an accessory building to ADU conversion, it will still be required to meet relevant building and energy code. How Do I Apply? If you are interested in ADU construction, please do the following: 1. Fill out the Roadway and Drainage Determination form on our website. This request is intended to help applicants better understand what is expected with regard to roadway and drainage improvements when preparing for ADU permit application review and approval. Please remember to include staff’s Roadway and Drainage Determinatio n analysis with other submittal documents at the time of application. 2. Download the application, submittal requirements, and electronic file standards Please read the submittal requirements carefully so that you know what is required for project submittal. 3. Contact the Permit Center at (425) 430-7200 to schedule an appointment to review your plan submittals with a Permit Technician. If we find that the application is incomplete, we will ask that you schedule another appointment once you have all the required documents. Please note: Some fees will be collected at the intake appointment. 4. Pay your permit fees. Payments are to be made in person on the 1st floor in the Finance Department. Payments may be made by Visa, MasterCard, cash or check. Please note: We do not accept payment over the phone or online. 5. Pick up your permits! Your project manager will notify you when your permit is approved and ready for pick up.There may be additional items needed, so please review the email for any further instructions. This email will also include the invoice for the remaining balance; please print the invoice and bring it to the Finance Department on the 1st floor. 4 H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\Accessory Dwelling Units.doc Rev: 02/02/2020 Prior to submitting your building permit application to Development Services, we strongly encourage you to meet with a Planner during walk-in customer service hours (8:00 a.m. to 4:00 p.m.) for site plan review. You may also submit your site plan for r eview to planningcustomerservice@rentonwa.gov. Development Standards for Residential Development (Accessory Dwelling Units) MAXIMUM NUMBER AND SIZE General 2 RC, R-1, R-4, R-6, R-8, R- 10, and R-14 1 ADU is permitted per legal lot in association with a detached single - family home. Unit size shall be determined by lot size and the size of the primary structure; the total square footage of the ADU shall not exceed the size stated in the Maximum Unit Size section of this table or 75% of the total square footage of the primary structure, whichever is smaller.4 Maximum Unit Size Lot Area: Maximum ADU Size 3,4 3,000 sq. ft. or less 600 sq. ft. 3,001 - 4,999 sq. ft. 700 sq. ft. 5,000 - 6,999 sq. ft. 800 sq. ft. 7,000 - 8,999 sq. ft. 900 sq. ft. Greater than 9,000 sq. ft. 1,000 sq. ft. MAXIMUM WALL PLATE HEIGHT 4 RC, R-1, R-4, R-6, R-8, R- 10 and R-14 ADUs are subject to the maximum wall plate height of RMC 4-2-110A, and associated conditions, except that the ADU shall not be taller than the primary structure. LOCATION 4 General RC, R-1, R-4, R-6, R-8, R- 10 and R-14 ADUs shall be located at least 6 ft. from any residential structure. MINIMUM SETBACKS 4 Front Yard and Secondary Front Yard 2 The lot coverage of accessory dwelling units shall not be calculated towards maximum building/lot coverage. 3 The square foot calculation shall not include porches or exterior stairs. Garages attached to accessory dwellings shall be included in the square foot calculation, except for when the accessory dwelling is located above a garage. 4 Conversion of accessory buildings to ADUs shall be exempt if the accessory building was constructed prior to January 1, 2020. 5 H:\CED\Data\Forms-Templates\Self-Help Handouts\Planning\Accessory Dwelling Units.doc Rev: 02/02/2020 RC, R-1, R-4, R-6, R-8, R- 10 and R-14 The ADU shall be setback an additional 5 ft. parallel to and measured from the front façade of the primary structure and shall comply with the setbacks applied to the primary structure, as identified in RMC 4-2- 110A, Development Standards for Residential Zoning Designations. Side Yard RC and R-1 25 ft. R-4, R-6 and R-8 5 ft. R-10 and R-14 4 ft. Rear Yard RC, R-1, R-4, R-6, R-8, R- 10 and R-14 5 ft. When located within 10 ft. of the rear property line, at least 25% of the lineal length of the rear yard shall remain unoccupied from accessory dwellings, except when the rear property line abuts an alley. Clear Vision Area RC, R-1, R-4, R-6, R-8, R- 10 and R-14 In no case shall a structure over 42 in. in height intrude into the 20 ft. clear vision area defined in RMC 4-11-030. CRITICAL AREAS General RC, R-1, R-4, R-6, R-8, R- 10 and R-14 See RMC 4-3-050, Critical Areas Regulations, and 4-3-090, Shoreline Master Program Regulations.