HomeMy WebLinkAboutD_Williams_ADU_Garage_SSDP_FINALDEPARTMENT OF COMMUNITY
AND ECONOMIC DEVELOPMENT
SHORELINE MANAGEMENT ACT OF 1971
PERMIT FOR SHORELINE MANAGEMENT
EVALUATION FORM & DECISION
DATE OF PERMIT ISSUANCE: April 2, 2025
LAND USE ACTION FILE NO.: LUA25-000025, ECF, SSDP, MOD
DATE RECEIVED January 28, 2025
DATE OF PUBLIC NOTICE: January 30, 2025
Pursuant to Chapter 90.58 RCW, staff recommends that the City of Renton grant a Shoreline Substantial
Development Permit. This action is proposed on the following application:
PROJECT NAME: Williams ADU/Garage
PROJECT MANAGER: Jill Ding, Senior Planner
OWNER/APPLICANT:
CONTACT:
Jamie Williams
13411 SE 151st St
Renton, WA 98058
Patty Thumann
13411 SE 151st St
Renton, WA 98058
PROJECT LOCATION: 13411 SE 151st St (APN 2223059112)
LEGAL DESCRIPTION:
(Per King County Assessors Records)
POR OF SW 1/4 OF NW 1/4 & OF NW 1/4 OF SW 1/4 - BAAP S 1490.96
FT & E 88.67 FT FROM NW CORNER OF NW 1/4 TH S 61-09-00 E 595
FT TH S 28-51-00 W 350.04 FT TH S 04-34-00 W 546.25 FT TH N 63-05-
36 E 92.31 FT TO POB TH N 63-05-36 E 106.94 FT TH S 17-51-20 E
114.03 FT TH N 63-05-36 E 10 FT TH S 17-51-20 E 184 FT M/L TO NLY
BANK OF CEDAR RIVER TH SWLY ALG RIVER TAP S 15-27-20 E FROM
POB TH N 15-27-20 W 350 FT M/L TO POB
SEC-TWN-R: SEC22-TWN23-R5
PROJECT WITHIN THE SHORELINE OF: Cedar River, Reach CR-C
APPLICABLE MASTER PROGRAM: City of Renton
PROPOSAL DESCRIPTION: The applicant is requesting a Shoreline Substantial Development Permit,
Environmental (SEPA) Review, and a Height Modification for the construction of a two-story, 1,012 square foot
detached accessory dwelling unit (ADU). The project site is a 37,744 square foot lot within the Residential-4 (R-4)
zone that is currently developed with a single-family home and associated accessory structures. The site is
currently accessed via a residential driveway off of SE 151st St. A Height Modification is requested to allow the
proposed ADU to exceed the height of the existing single-family residence. According to the City of Renton Maps
Docusign Envelope ID: 27BE356D-C4D4-4690-AD70-16B8CCBE7A53
City of Renton Department of Community & Economic Development Shoreline Management Permit
Williams ADU/Garage LUA25-000025, ECF, SSDP, MOD
Report of April 2, 2025 Page 2 of 16
(COR Maps), the project site is mapped with a Wellhead Protection Area Zone (Zone 2, Maplewood Wellfield),
Special Flood Hazard Areas (100 year flood, FEMA Zone-AE), Moderate to Severe Channel Migration Zone Hazards,
Regulated Shoreline High Intensity Environmental Designation, Regulated Shoreline: CR-C Cedar River Reaches
Jurisdiction, High Seismic Hazards, Regulated Slopes, and High Erosion Hazards.
An Environmental (SEPA) Review Determination of Non-Significance-Mitigated (DNS-M) was issued for this project
on March 17, 2025. The appeal period of the determination ended on March 31, 2025.
FINDINGS OF FACT (FOF):
1. The applicant is requesting a Shoreline Substantial Development Permit and a Height Modification for the
construction of a two-story, 1,012 square foot detached accessory dwelling unit (ADU).
2. The landward portion of the site currently is developed with an existing single-family residence.
3. The proposed ADU would be constructed approximately 180 feet (180’) from the ordinary high water mark
(OHWM) of the Cedar River.
4. The proposed ADU would have a wall plate height of twenty-four feet (24’) and a maximum height of thirty
feet (30’).
5. The proposed detached ADU is an outright permitted use within the R-4 zone and Shoreline High Intensity
Environmental Designation per RMC Table 4-3-090E.1 Shoreline Use Table.
6. The subject site has priority habitat and is located in areas regulated by the City of Renton Shoreline Master
Program for the Cedar River.
7. The project site is mapped with a Wellhead Protection Area Zone (Zone 2, Maplewood Wellfield), Special
Flood Hazard Areas (100 year flood, FEMA Zone-AE), Moderate to Severe Channel Migration Zone Hazards,
Regulated Shoreline High Intensity Environmental Designation, Regulated Shoreline: CR-C Cedar River
Reaches Jurisdiction, High Seismic Hazards, slopes with grades of less than twenty-five percent (25%), and
High Erosion Hazards.
8. There are four (4) significant trees located on the project site, of which two (2) trees would be removed as
a result of the proposed ADU construction (Exhibit 17).
9. Comments were received from the Duwamish Tribe (Exhibit 6) during the thirty (30) day public comment
period. Comments from the Duwamish were addressed as part of the Environmental Review Committee
(ERC) Report (Exhibits 1 and 7) and as further discussed below under Archaeological, Historical, and
Cultural Resources.
10. Representatives from various city departments have reviewed the application materials to identify and
address issues raised by the proposed development. These comments are contained in the official file,
and the essence of the comments have been incorporated into the appropriate sections of this report, the
Environmental (SEPA) Review Report, and the Departmental Recommendation at the end of this report
(Exhibit 9).
11. An Environmental (SEPA) Review Determination of Non-Significance-Mitigated (DNS-M) was issued for this
project on March 17, 2025. The appeal period of the determination ended on March 31, 2025. No appeals
of the threshold determination were filed.
12. Based on an analysis of probable impacts from the proposal, the Environmental Review Committee (ERC)
issued the following mitigation measures with the Determination of Non-Significance – Mitigated:
Docusign Envelope ID: 27BE356D-C4D4-4690-AD70-16B8CCBE7A53
City of Renton Department of Community & Economic Development Shoreline Management Permit
Williams ADU/Garage LUA25-000025, ECF, SSDP, MOD
Report of April 2, 2025 Page 3 of 16
a. The applicant shall submit an Inadvertent Discovery Plan prepared by a qualified professional with the
building permit for review and approval by the Current Planning Project Manager prior to permit
issuance.
13. A Channel Migration Study, prepared by DCG Watershed, dated October 18, 2023 (Exhibit 4) and a Wetland
and Stream Assessment, prepared by J. S. Jones and Associates, Inc., dated November 20, 2021 (Exhibit 5)
were submitted with the project application. The Channel Migration Study concluded that the proposed
ADU location would not be in an area subject to surface erosion or channel migration following major
floods. The new construction proposed within this area would be unlikely to require new shoreline
stabilization or other structural flood hazard reduction measures. The Wetland and Stream Assessment
concluded that there were no wetlands present on the subject property. The Cedar River is classified as a
Shoreline of the State and would be subject to the city’s adopted Shoreline Master Program and would not
be subject to the city’s Critical Areas Regulations. No net loss of ecological functions are anticipated as no
work is proposed within the 65-foot (65’) combined vegetation conservation buffer and building setback.
14. The following table contains project elements intended to comply with the Shoreline Master Program
standards and policies, as outlined in RMC 4-3-090:
Shoreline Master Program Criteria:
A. Comprehensive Plan Compliance and consistency, Shoreline Element:
The site is located in the Shoreline Residential and Aquatic Overlay Districts. The objective of the
Residential Shoreline Overlay District is to accommodate residential development and appurtenant
structures that are consistent with this chapter. The objective of the Aquatic designation is to protect,
restore, and manage the unique characteristics and resources of the areas waterward of the ordinary
high water mark. The proposal is compliant with the following Shoreline policies:
✓
Objective SH-B. Provide that the policies, regulations, and administration of the
Shoreline Master Program ensure that new uses, development, and redevelopment
within the shoreline jurisdiction do not cause a net loss of shoreline ecological functions.
✓ Policy SH-7. Existing and future activities on all Shorelines of the State regulated by the
City of Renton should be designed to ensure no net loss of ecological functions.
✓
Policy SH-14. Shoreline use and development should be carried out in a manner that
prevents or mitigates adverse impacts so that the resulting ecological condition does
not become worse than the current condition. This means ensuring no net loss of
ecological functions and processes in all development and use. Permitted uses should
be designed and conducted to minimize, in so far as practical, any resultant damage to
the ecology and environment (RCW 90.58.020). Shoreline ecological functions that
should be protected include, but are not limited to, fish and wildlife habitat, food chain
support, and water temperature maintenance. Shoreline processes that shall be
protected include, but are not limited to, water flow; littoral drift; erosion and accretion;
infiltration; ground water recharge and discharge; sediment delivery, transport, and
storage; large woody debris recruitment; organic matter input; nutrient and pathogen
removal; and stream channel formation/maintenance.
B. Development Standards:
The subject site where the ADU would be located is classified as Shoreline High Intensity on the City of
Renton Shoreline Overlay Map. The following development standards are applicable to the proposal:
1. No Net Loss of Ecological Functions:
Docusign Envelope ID: 27BE356D-C4D4-4690-AD70-16B8CCBE7A53
City of Renton Department of Community & Economic Development Shoreline Management Permit
Williams ADU/Garage LUA25-000025, ECF, SSDP, MOD
Report of April 2, 2025 Page 4 of 16
✓
Shoreline use and development shall be carried out in a manner that prevents or
mitigates adverse impacts to ensure no net loss of ecological functions and processes
in all development and use. Permitted uses are designed and conducted to minimize, in
so far as practical, any resultant damage to the ecology and environment (RCW
90.58.020). Shoreline ecological functions that shall be protected include, but are not
limited to, fish and wildlife habitat, food chain support, and water temperature
maintenance. Shoreline processes that shall be protected include, but are not limited
to, water flow; erosion and accretion; infiltration; groundwater recharge and discharge;
sediment delivery, transport, and storage; large woody debris recruitment; organic
matter input; nutrient and pathogen removal; and stream channel
formation/maintenance.
Impact Evaluation Required: In assessing the potential for net loss of ecological
functions or processes, project-specific and cumulative impacts shall be considered
and mitigated on- or off-site.
Evaluation of Mitigation Sequencing Required: An application for any permit or approval
shall demonstrate all reasonable efforts have been taken to provide sufficient mitigation
such that the activity does not result in net loss of ecological functions. Mitigation shall
occur in the following prioritized order:
(a) Avoiding the adverse impact altogether by not taking a certain action or parts of an
action, or moving the action.
(b) Minimizing adverse impacts by limiting the degree or magnitude of the action and its
implementation by using appropriate technology and engineering, or by taking
affirmative steps to avoid or reduce adverse impacts.
(c) Rectifying the adverse impact by repairing, rehabilitating, or restoring the affected
environment.
(d) Reducing or eliminating the adverse impact over time by preservation and
maintenance operations during the life of the action.
(e) Compensating for the adverse impact by replacing, enhancing, or providing similar
substitute resources or environments and monitoring the adverse impact and taking
appropriate corrective measures.
Staff comment: The applicant submitted a Channel Migration Study, prepared by DCG
Watershed, dated October 18, 2023 (Exhibit 4) and a Wetland and Stream Assessment,
prepared by J. S. Jones and Associates, Inc., dated November 20, 2021 (Exhibit 5) with
the project application materials. The proposed ADU would be constructed within the
designated moderate channel migration zone. The moderate hazard area is located
between the outer boundary of severe hazard and the maximum probable limits of future
migration. Work within the severe channel migration zone would be limited to the
installation of a new septic system. Work proposed within the 100-year flood plain would
be limited to the installation of a new septic system as well as posts for an upper level
deck (Exhibit 15).
The Channel Migration Study concluded that the proposed ADU location would not be in
an area subject to surface erosion or channel migration following major floods. The new
construction proposed within this area would be unlikely to require new shoreline
stabilization or other structural flood hazard reduction measures.
Docusign Envelope ID: 27BE356D-C4D4-4690-AD70-16B8CCBE7A53
City of Renton Department of Community & Economic Development Shoreline Management Permit
Williams ADU/Garage LUA25-000025, ECF, SSDP, MOD
Report of April 2, 2025 Page 5 of 16
The Wetland and Stream Assessment concluded that there were no wetlands present on
the subject property.
According to the Shoreline Master Program, residential lots with a lot depth greater than
170 feet (170’) would be required to provide a 50-foot (50’) vegetation conservation buffer
and a 15-foot (15’) building setback. The subject property has a lot depth of
approximately 345 feet (345’). The proposed ADU would be constructed approximately
180 feet (180’) from the ordinary high water mark (OHWM) of the Cedar River, and the
proposed septic system would be installed approximately 100 feet (100’) from the
OHWM of the Cedar River, which would exceed the 65-foot (65’) combined vegetation
conservation buffer and building setback required. No net loss of ecological functions
are anticipated as all proposed work would occur outside of the combined vegetation
conservation buffer and building setback areas.
2. Burden on Applicant:
✓
Applicants for permits have the burden of proving that the proposed development is
consistent with the criteria set forth in the Shoreline Master Program and the Shoreline
Management Act, including demonstrating all reasonable efforts have been taken to
provide sufficient mitigation such that the activity does not result in net loss of ecological
functions.
Staff Comment: The applicant has submitted a Channel Migration Zone Study (Exhibit 4)
and a Wetland and Stream Assessment (Exhibit 5) that demonstrates that the proposed
ADU would not require new shoreline stabilization and would not result in a net loss of
ecological functions and values on the project site, which is consistent with the City of
Renton’s Shoreline Master Program and the Shoreline Management Act.
3. View Obstruction and Visual Quality:
N/A
View Corridors Required: Where commercial, industrial, multiple use, multi-family
and/or multi-lot developments are proposed, primary structures shall provide for view
corridors between buildings where views of the shoreline are available from public right-
of-way or trails.
Staff comment: Not applicable. The proposal does not include commercial, industrial,
multiple use, multi-family and/or multi-lot developments.
✓
Maximum Building Height: Buildings shall be limited to a height of no more than 35 feet
above average finished grade level except at specific locations.
Staff comment: The proposed ADU would have a wall plate height of twenty-four feet
(24’) and a maximum height of approximately thirty feet (30’), which is less than the thirty-
two-foot (32’) maximum wall plate height permitted within the R-4 zone and the
maximum thirty-five-foot (35’) height limit permitted by the Shoreline Management Act.
N/A
Minimum Setbacks for Commercial Development Adjacent to Residential or Park
Uses: All new or expanded commercial development adjacent to residential use and
public parks shall provide fifteen feet setbacks from adjacent properties to attenuate
proximity impacts such as noise, light and glare, and may address scale and aesthetic
impacts. Fencing or landscape areas may be required to provide a visual screen.
N/A Lighting Requirements: Display and other exterior lighting shall be designed and
operated so as to prevent glare, to avoid illuminating nearby properties used for
noncommercial purposes, and to prevent hazards for public traffic. Methods of
Docusign Envelope ID: 27BE356D-C4D4-4690-AD70-16B8CCBE7A53
City of Renton Department of Community & Economic Development Shoreline Management Permit
Williams ADU/Garage LUA25-000025, ECF, SSDP, MOD
Report of April 2, 2025 Page 6 of 16
controlling spillover light include, but are not limited to, limits on the height of light
structure, limits on light levels of fixtures, light shields, and screening.
Staff comment: Not applicable. No lighting is proposed as part of this project.
N/A
Reflected Lights to Be Limited: Building surfaces on or adjacent to the water shall
employ materials that limit reflected light.
Staff comment: Not applicable. No buildings are proposed on or adjacent to the water.
N/A
Integration and Screening of Mechanical Equipment: Building mechanical equipment
shall be incorporated into building architectural features, such as pitched roofs, to the
maximum extent feasible. Where mechanical equipment cannot be incorporated into
architectural features, a visual screen shall be provided consistent with building exterior
materials that obstructs views of such equipment.
Staff comment: Not applicable. No mechanical equipment is proposed as part of this
project.
✓
Visual Prominence of Freestanding Structures to Be Minimized: Facilities not
incorporated into buildings including fences, piers, poles, wires, lights, and other
freestanding structures shall be designed to minimize visual prominence.
Staff comment: The proposed ADU plans do not include fences, piers, poles, wires,
lighting, or other structures that would impact views of the Cedar River from neighboring
homes.
✓
Maximum Stair and Walkway Width: Stairs and walkways located within shoreline
vegetated buffers shall not exceed four feet in width; provided, that where ADA
requirements apply, such facilities may be increased to six feet in width. Stairways shall
conform to the existing topography to the extent feasible.
Staff comment: No stairs or walkways are proposed within the vegetation conservation
buffer as part of this project. The only stairs proposed would be located on the proposed
ADU to provide access to the second story.
4. Community Disturbances:
✓
Noise, odors, night lighting, water and land traffic, and other structures and activities
shall be considered in the design plans and their impacts avoided or mitigated.
Staff comment: The project is not anticipated to generate noise, odors, lighting issues, or
other water and land traffic disturbances. All proposed work would be outside of the
combined 65-foot (65’) vegetation conservation buffer and building setback.
5. Public Access:
Physical or visual access to shorelines shall be incorporated in all new development when the
development would either generate a demand for one or more forms of such access, would impair
existing legal access opportunities or rights, or is required to meet the specific policies and regulations
of the Shoreline Master Program.
N/A
Cedar River Reach C: Public/community access along the waterfront should be
provided as private lands on the north side of the river redevelop, considered along with
the goal of restoration of ecological functions. Public or community access shall be
provided when residential development occurs consistent with standards of the
Shoreline Master Program.
Docusign Envelope ID: 27BE356D-C4D4-4690-AD70-16B8CCBE7A53
City of Renton Department of Community & Economic Development Shoreline Management Permit
Williams ADU/Garage LUA25-000025, ECF, SSDP, MOD
Report of April 2, 2025 Page 7 of 16
Staff comment: The project proposal includes the construction of a new ADU on an
existing residential lot. No subdivision or nonresidential development is proposed;
therefore the public access requirement is not applicable.
6. Building and Development Location – Shoreline Orientation:
Shoreline developments shall locate the water-dependent, water-related, and water-enjoyment
portions of their developments along the shoreline. Development and use shall be designed in a manner
that directs land alteration to the least sensitive portions of the site to maximize vegetation conservation;
minimize impervious surfaces and runoff; protect riparian, nearshore and wetland habitats; protect
wildlife and habitats; protect archaeological, historic and cultural resources; and preserve aesthetic
values.
Compliant if
conditions
of approval
are met
Minimization of Site Alteration: Development shall minimize site alteration in sites with
substantial unaltered natural features by applying the following criteria:
(a) Vehicle and pedestrian circulation systems shall be designed to limit clearing,
grading, and alteration of topography and natural features.
(b) Impervious surfacing for parking lot/space areas shall be limited through the use of
under-building parking or permeable surfaces where feasible.
(c) Utilities shall share roadway and driveway corridors and rights-of-way wherever
feasible.
(d) Development shall be located and designed to avoid the need for structural shoreline
stabilization over the life of the development. Exceptions may be made for the limited
instances where stabilization is necessary to protect allowed uses, particularly water-
dependent uses, where no alternative locations are available and no net loss of
ecological functions will result.
Staff comment: The site is already developed with a single-family residence. The
proposed ADU would be located on the northern portion of the project site, close to the
existing residence and away from the Cedar River. As previously discussed, the
proposed ADU would be set back approximately 180 feet (180’) from the Cedar River. No
shoreline stabilization is anticipated as a result of the proposed construction of the ADU.
As shown on the submitted Septic Design Plan (Exhibit 14), the proposed septic system
would be located within the 100-year flood plain. Prior to permitting the proposed septic
system within the 100-year flood plain, staff recommends, as a condition of approval,
that the applicant demonstrate that the proposed septic system would comply with the
adopted flood plain regulations as found in RMC 4-3-050, including the compensatory
storage requirements. Necessary plans and/or reports demonstrating compliance with
the flood plain requirements shall be submitted to the Current Planning Project Manager
for review and approval at the time of Building Permit review.
Access to the proposed ADU would be via a new twenty-foot (20’) wide driveway. Per
RMC 4-4-080I.3.b the maximum width of single loaded garage driveways shall not
exceed nine feet (9') and double loaded garage driveways shall not exceed sixteen feet
(16'). The proposed ADU would include a double loaded garage and be permitted a
maximum driveway width of sixteen feet (16’). Staff recommends, as a condition of
approval, that a revised site plan be submitted at the time of Building Permit review. The
revised site plan shall include a driveway with a maximum width of sixteen feet (16’). The
Docusign Envelope ID: 27BE356D-C4D4-4690-AD70-16B8CCBE7A53
City of Renton Department of Community & Economic Development Shoreline Management Permit
Williams ADU/Garage LUA25-000025, ECF, SSDP, MOD
Report of April 2, 2025 Page 8 of 16
revised site plan shall be submitted to the Current Planning Project Manager for review
and approval.
N/A
Location for Accessory Development: Accessory development or use that does not
require a shoreline location shall be located outside of shoreline jurisdiction unless such
development is required to serve approved water-oriented uses and/or developments or
unless otherwise allowed in a High Intensity designation. When sited within shoreline
jurisdiction, uses and/or developments such as parking, service buildings or areas,
access roads, utilities, signs and storage of materials shall be located inland away from
the land/water interface and landward of water-oriented developments and/or other
approved uses unless a location closer to the water is reasonably necessary.
✓
Navigation and Recreation to Be Preserved: Shoreline uses shall not deprive other
uses of reasonable access to navigable waters. Existing water-related recreation shall
be preserved.
Staff comment: The proposed ADU would not deprive abutting property owners access
to the Cedar River.
7. Archaeological, Historical, and Cultural Resources:
Compliant if
SEPA
Mitigation
Measure is
met
Detailed Cultural Assessments May Be Required: The City will work with tribal, State,
Federal, and other local governments as appropriate to identify significant local
historical, cultural, and archaeological sites in observance of applicable State and
Federal laws protecting such information from general public disclosure. Detailed
cultural assessments may be required in areas with undocumented resources based on
the probability of the presence of cultural resources.
Staff comment: The project proposal and notice of application were provided to
reviewing agencies including the State Department of Archaeology & Historic
Preservation (DAHP), and the Duwamish and Muckleshoot Tribes as part of the SEPA
review process. Comments were received from the Duwamish Tribe (Exhibit 6)
requesting that an Inadvertent Discovery Plan be followed in the case that archeological
deposits are discovered during construction activities. To ensure that any archeological
deposits are managed appropriately, the ERC imposed a SEPA mitigation measure
requiring that the applicant submit an Inadvertent Discovery Plan prepared by a qualified
professional with the building permit for review and approval by the Current Planning
Project Manger prior to permit issuance (Exhibits 1 and 11).
✓
Coordination Encouraged: Owners of property containing identified or probable
historical, cultural, or archaeological sites are encouraged to coordinate well in advance
of application for development to assure that appropriate agencies such as the
Washington State Department of Archaeology and Historic Preservation, affected tribes,
and historic preservation groups have ample time to assess the site and identify the
potential for cultural resources.
Staff comment: See comment above.
✓
Detailed Cultural Assessments Required: Upon receipt of application for a
development in an area of known or probable cultural resources, the City shall require a
site assessment by a qualified professional archaeologist or historic preservation
professional and ensure review by qualified parties including the Washington State
Department of Archaeology and Historic Preservation, affected tribes, and historic
preservation groups.
Docusign Envelope ID: 27BE356D-C4D4-4690-AD70-16B8CCBE7A53
City of Renton Department of Community & Economic Development Shoreline Management Permit
Williams ADU/Garage LUA25-000025, ECF, SSDP, MOD
Report of April 2, 2025 Page 9 of 16
Staff comment: See comment above.
✓
Work to Stop Upon Discovery: If historical, cultural, or archaeological sites or artifacts
are discovered in the process of development, work on that portion of the site shall be
stopped immediately, the site secured, and the find reported as soon as possible to the
Administrator of the Department of Community and Economic Development or
designee. Upon notification of such find, the property owner shall notify the Washington
State Department of Archaeology and Historic Preservation and affected tribes. The
Administrator of the Department of Community and Economic Development or designee
shall provide for a site investigation by a qualified professional and may provide for
avoidance, or conservation of the resources, in coordination with appropriate agencies.
Staff comment: See comment above.
✓
Access for Educational Purposes Encouraged: Land owners are encouraged to
provide access to qualified professionals and the general public if appropriate for the
purpose of public education related to a cultural resource identified on a property.
Staff comment: See comment above.
8. Standards for Density, Setbacks, and Height:
The proposed ADU construction would be subject to the following buffer, setback, and height
requirements.
✓
Single Family Residential Uses: Front Yard, Side Yard, and Rear Yard Setbacks shall be
governed by underlying zoning except in cases where specific shoreline performance
standards provide otherwise. A zoning variance from the front and side yard standards
may be granted administratively if needed to meet the established shoreline buffer or
setback from OHWM, as specified in this Section and if the variance criteria of RMC 4-9-
250 are met.
The ADU shall be set back 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. The R-4 development standards require the following setbacks: a
front yard setback of thirty feet (30’), a rear setback of twenty-five feet (25’), the minimum
side yard setback is a combined twenty-foot (20’) setback not less than seven-and-a-
half feet (7.5’) on either side.
ADUs shall be located at least 4 ft. from any residential structure.
Staff comment: The proposed ADU would have a front yard setback of approximately 114
feet (114’), a side yard setback of seven and one-half feet (7.5’) along the west property
line and an approximately 73-foot (73’) setback along the east property line, and a rear
setback of approximately 180 feet (180’). The proposed ADU would be set back
approximately 45 feet (45’) from the front of the primary structure.
✓
Vegetation Conservation Buffer for Single Family Residential Uses: For lots more
than 170 feet in depth, the vegetation conservation buffer is 50 feet. If the buffer is less
than one hundred feet (100') from the OHWM the building setback is established as the
common line setback or fifteen feet (15') landward from the minimum buffer, whichever
is greater.
Staff comment: The subject property has a lot depth of approximately 345 feet (345’).
According to the Shoreline Master Program, residential lots with a lot depth greater than
170 feet (170’) would be required to provide a 50-foot (50’) vegetation conservation buffer
Docusign Envelope ID: 27BE356D-C4D4-4690-AD70-16B8CCBE7A53
City of Renton Department of Community & Economic Development Shoreline Management Permit
Williams ADU/Garage LUA25-000025, ECF, SSDP, MOD
Report of April 2, 2025 Page 10 of 16
and a 15-foot (15’) building setback. The proposed ADU would be constructed
approximately 180 feet (180’) from the ordinary high water mark (OHWM) of the Cedar
River, which would exceed the 65-foot (65’) combined vegetation conservation buffer
and building setback requirement
✓
Building Height – Maximum, for accessory buildings more than 100 ft. from the
OHWM, the maximum height permitted per the Shoreline Master Program is 35 feet.
Within the R-4 zone, the maximum height permitted is limited to a maximum wall plate
height of 32 feet. Wall plates supporting a primary roof surface that has only one sloping
plane (e.g., shed roof) may exceed the stated maximum if the average of wall plate
heights is equal to or less than the maximum wall plate height allowed. ADUs shall not
be taller than the primary structure. Additional ADU height allowances may be permitted
upon application and approval of a modification pursuant to RMC 4-9-250.
Staff comment: The proposed ADU would have a wall plate height of twenty-four feet
(24’) and a maximum height of approximately thirty feet (30’), which is less than the thirty-
two-foot (32’) maximum wall plate height permitted within the R-4 zone and the
maximum thirty-five-foot (35’) height limit permitted by the Shoreline Management Act.
The proposed ADU would be two-stories and would be taller than the existing single-story
primary residence. A modification was submitted with the project application materials
to permit the proposed ADU to exceed the height of the existing primary single-family
residence, see further discussion below under FOF 16.
✓
Coverage Standards: The maximum lot coverage for buildings within the Shoreline High
Intensity Designation and more than 100 ft. from the OHWM are governed by the
underlying zoning standards. The R-4 zone permits a maximum building coverage of
thirty-five percent (35%) of the lot area and a maximum impervious surface coverage of
fifty percent (50%) of the lot area.
Staff comment: The existing development and proposed ADU would be located
approximately 180 feet (180’) from the OHWM of the Cedar River. The existing single-
family residence has a building footprint that totals 1,846 sq. ft. The addition of the
proposed 1,012 sq. ft. ADU footprint would result in a total building coverage of 2,858 sq.
ft. or 7.57% on the 37,744 sq. ft. project site. The proposed 7.57% building coverage
would be less than the 35% permitted within the R-4 zone for development located more
than 100 feet (100’) from the OHWM of the Cedar River.
The project site has a total of 5,896 sq. ft. of impervious surfaces. The proposed ADU
would result in the addition of 2,883 sq. ft. of new impervious surfaces, which would
result in a total impervious surface coverage of 8,779 sq. ft. or 23.25%. The proposed
23.25% impervious surface coverage would be less than the 50% impervious surface
coverage permitted within the R-4 zone for development located more than 100 feet
(100’) from the OHWM of the Cedar River.
9. Use Regulations
Within the Shoreline High Intensity Designation, land uses allowed in the underlying zoning in RMC 4-2-
060 are allowed in this overlay district, subject to the preference for water-oriented uses.
Accessory Dwelling Units (ADUs):
Docusign Envelope ID: 27BE356D-C4D4-4690-AD70-16B8CCBE7A53
City of Renton Department of Community & Economic Development Shoreline Management Permit
Williams ADU/Garage LUA25-000025, ECF, SSDP, MOD
Report of April 2, 2025 Page 11 of 16
Compliance Accessory Dwelling Unit Design Standards R-4 and Analysis
✓
Scale, Bulk, and Character: The ADU shall be architecturally compatible with
significant architectural details of the primary structure, dominating forms, and design
elements, such as eaves, roof pitch, roof form, porches, principal dormers, materials,
and other significant architectural features.
Staff Comment: The proposed ADU would be architecturally compatible with the
primary structure. The proposed ADU would have a pitched roof that slopes to the rear
of the structure that is compatible with the slope of the primary residence. In addition,
the proposed ADU would include lap siding, which is the same siding material used on
the primary residence (Exhibit 3).
✓
Eaves: Both of the following are required:
1. Eaves projecting from the roof of the entire building at least twelve inches (12") with
horizontal fascia or fascia gutter at least five inches (5") deep on the face of all eaves,
and
2. Rakes on gable ends must extend a minimum of two inches (2") from the surface of
exterior siding materials.
Compliant if
condition of
approval is
met
Accessory dwelling units (ADUs) may be allowed as an accessory use to a detached
single-family dwelling within the R-4 zone. ADUs shall be consistent with the
architectural character of the primary residential structure.
Prior to the issuance of building permits the property owner shall (a) file an affidavit with
the City affirming that the owner will live on site, occupying the primary dwelling or ADU;
and (b) record a notice on the property title that the owner will occupy the site, and
bearing the notarized signature of all property owners listed on the property title and
which includes at a minimum: the legal description of the property, a copy of the
approved site/floor plan, and the applicability of the restrictions and limitations
regarding ADUs in RMC Title IV.
Staff comment: The proposed detached ADU is permitted as an accessory use within the
R-4 zone, provided either the ADU or primary dwelling unit is owner occupied. Staff
recommends, as a condition of approval, that the property owner (a) file an affidavit with
the city affirming that the owner will live on site, occupying the primary dwelling or the
ADU; and (b) record a notice on the property title that the owner will occupy the site, and
bearing the notarized signature of all property owners listed on the property title and
which includes at a minimum: the legal description of the property, a copy of the
approved site/floor plan, and the applicability of the restrictions and limitations
regarding ADUs in RMC Title IV. The affidavit and notice on the title shall be submitted to
the Current Planning Project Manager for review and approval at the time of Building
Permit review and the notice on title shall be recorded prior to the issuance of the
Building Permit.
15. Accessory Dwelling Unit Residential Design Standards: Accessory Dwelling Unit Residential Design
Standards (RMC 4-2-116) are applicable to in the R-4 zone. The Standards implement policies established
in the Land Use Element of the Comprehensive Plan. Compliance with Residential Design Standards would
be verified prior to issuance of the building permit for the new ADU. The proposal is consistent with the
following design standards, unless noted otherwise:
Docusign Envelope ID: 27BE356D-C4D4-4690-AD70-16B8CCBE7A53
City of Renton Department of Community & Economic Development Shoreline Management Permit
Williams ADU/Garage LUA25-000025, ECF, SSDP, MOD
Report of April 2, 2025 Page 12 of 16
Staff Comment: As shown on the submitted building plans (Exhibit 3), the proposed
ADU would include eaves and fascia that extend over the proposed facades.
✓
Architectural Detailing: If one siding material is used on any side of the dwelling that
is two (2) stories or greater in height, a horizontal band that measures at least eight
inches (8") is required between the first and second story.
Additionally, one of the following is required:
1. Three and one-half inches (3 1/2") minimum trim surrounds all windows and details
all doors; or
2. A combination of shutters and three and one-half inches (3 1/2") minimum trim
details all windows, and three and one-half inches (3 1/2") minimum trim details on all
doors.
Staff Comment: As shown on the submitted building plans (Exhibit 3), trim is shown
around all windows and doors and a horizontal band is shown between the first and
second story.
Compliant if
condition of
approval is
met
Materials and Color: The ADU shall be of the same building material and color as the
primary structure.
Where masonry siding is proposed at the edge of a facade, it shall also extend along
the adjoining facade no less than twenty four inches (24"), measured horizontally from
the corner of the structure.
Additionally, one of the following is required:
1. A minimum of two (2) colors (body with different color trim is acceptable), or
2. A minimum of two (2) differing siding materials (horizontal siding and shingles, siding
and masonry or masonry-like material, etc.). One alternative siding material must
comprise a minimum of thirty percent (30%) of the street-facing facade.
Staff Comment: As shown on the submitted building plans (Exhibit 3), the proposed
ADU would be sided with lap siding, which would match the siding material used on the
primary residence. A color palette for the proposed ADU was not included with the
project application materials. Staff recommends, as a condition of approval, that the
applicant submit paint chips demonstrating that the proposed ADU would be painted
the same color as the primary structure. The paint chips shall be submitted to the
Current Planning Project Manager at the time of Building Permit review for review and
approval.
✓
Garages: To ensure adequate vehicular maneuvering area, ADUs that incorporate a
garage/carport shall have an obstruction-free area (inclusive of an alley) for a length
based on the width of the garage doors:
1. Nine-foot (9’) garage doors shall be at least twenty-six feet (26’) from the adjacent
property line; or
2. Sixteen-foot (16’) garage doors shall be at least twenty-four feet (24’) from the
adjacent property line.
Staff Comment: The proposed ADU would be set back approximately 114 feet (114’)
from the front property line and would exceed this requirement.
Docusign Envelope ID: 27BE356D-C4D4-4690-AD70-16B8CCBE7A53
City of Renton Department of Community & Economic Development Shoreline Management Permit
Williams ADU/Garage LUA25-000025, ECF, SSDP, MOD
Report of April 2, 2025 Page 13 of 16
Compliant if
condition of
approval is
met
Garages: If an attached garage is wider than twenty six feet (26'), at least one garage
door shall be recessed a minimum of four feet (4') from the other garage door.
The garage doors contain a minimum of thirty percent (30%) glazing, architectural
detailing (e.g., trim and hardware), and are recessed from the front facade a minimum
of five feet (5'), and from the front porch a minimum of seven feet (7').
Staff Comment: As shown on the submitted building plans (Exhibit 3), the proposed
garage would have a total width of approximately twenty-eight feet (28’) and would
contain one hundred percent (100%) glazing. One (1) of the garage doors is proposed
to be recessed two feet (2’) behind the other door, which is less than the minimum four-
foot (4’) recess that is required. Staff recommends, as a condition of approval, that
revised building plans be submitted at the time of Building Permit review showing one
(1) garage door recessed at a minimum of four feet (4’) from the other garage door. The
revised building plans shall be submitted to the Current Planning Project Manager for
review and approval.
16. Modification Analysis: The applicant is requesting a modification from RMC 4-2-110C Development
Standards for Residential Development (Accessory Dwelling Units) in order to permit the proposed ADU to
exceed the height of the existing single-family residence. The existing residence is a single-story residence
and the proposed ADU would have two-stories and a maximum height of thirty feet (30’). The proposal is
compliant with the following modification criteria, pursuant to RMC 4-9-250D.2, if all conditions of approval
are met. Therefore, staff is recommending approval of the requested modification, subject to conditions as
noted below:
Compliance Modification Criteria and Analysis
✓
a. Substantially implements the policy direction of the policies and objectives of the
Comprehensive Plan Land Use Element and the Community Design Element and the
proposed modification is the minimum adjustment necessary to implement these
policies and objectives.
Staff Comment: As previously discussed above, See FOF 14, the proposed ADU would
comply with the Shoreline Element Policies as adopted in the City’s Comprehensive Plan.
In addition, the proposed ADU would also comply with the following Land Use Element
Policies:
Policy LU-3: Encourage infill development with a variety of housing types to meet growth
targets and provide a greater variety of housing options.
Goal LU-V: Protect the natural functions of 100-year floodplains, floodways, and channel
migration zones to prevent threats to life, property, and public safety associated with
flooding hazards.
Policy LU-33: Ensure buildings, roads, and other built features are located on less
sensitive portions of a site when sensitive areas are present.
Goal LU-BB: Ensure new development supports a high quality of life with design that is
functional and attractive.
✓
b. Will meet the objectives and safety, function, appearance, environmental protection
and maintainability intended by the Code requirements, based upon sound
engineering judgment.
Docusign Envelope ID: 27BE356D-C4D4-4690-AD70-16B8CCBE7A53
City of Renton Department of Community & Economic Development Shoreline Management Permit
Williams ADU/Garage LUA25-000025, ECF, SSDP, MOD
Report of April 2, 2025 Page 14 of 16
Staff Comment: The applicant contends that the proposed ADU has been sited as far
away from the Cedar River and 100-year floodplain as possible while still providing
adequate space for the applicant’s family, and would meet the objectives, safety,
function, and appearance intended by code requirements (Exhibit 12).
Staff has reviewed the request and concurs that the proposed height modification would
meet the objectives intended by code requirements. The approval of a two-story ADU that
would exceed the height of the primary structure would allow for a more compact building
footprint, that could be accommodated with a single-story ADU. The more compact
building footprint would allow for the ADU to remain outside of the mapped 100-year
floodplain of the Cedar River and would allow for the ADU to be constructed as far away
from the Cedar River as possible, while still remaining to the rear of the existing residence
as is preferred by the location requirements specified in RMC 4-2-110C.
✓
c. Will not create adverse impacts to other property(ies) in the vicinity.
Staff Comment: The applicant contends that the proposed modification to allow the
proposed ADU to exceed the height of the existing structure would not create adverse
impacts to other properties in the vicinity. The applicant contends that the proposed ADU
would have a wall plate height of twenty-four feet (24’) and a total maximum height of
thirty feet (30’), which is less than the maximum height requirement within the R-4 zone.
The applicant also contends that the proposed ADU would not impact views of the Cedar
River from abutting properties to the east and west as the ADU has been sited as far north
on the project site as possible.
Staff has reviewed the requested modification and concurs that the proposal to allow the
proposed ADU to exceed the height of the existing primary residence would not adversely
impact other properties in the vicinity. As shown on City of Renton (COR) Maps (Exhibit
18), the proposed location of the ADU would be to the north of the abutting properties to
the east and west of the project site and would not impede their views of the Cedar River.
✓
d. Conforms to the intent and purpose of the Code; and
Staff Comment: See comments under criterion ‘b’.
✓
e. Can be shown to be justified and required for the use and situation intended.
Staff Comment: See comments under criterion ‘b’.
This Permit is granted pursuant to the Shoreline Management Action of 1971 and pursuant to the following:
1. The issuance of a license under the Shoreline Management Act of 1971 shall not release the applicant
from compliance with federal, state, and other permit requirements.
2. This permit may be rescinded pursuant to Section 14(7) of the Shoreline Management Act of 1971 in the
event the permittee fails to comply with any condition(s) hereof.
3. Construction permits shall not be issued until 21 days after approval by the Washington State
Department of Ecology or until any review proceedings initiated within this twenty-one (21)-day review
period have been completed.
4. The proposed Accessory Dwelling Unit may require additional permits from other state and federal
agencies. It is the applicant’s repsonsiblity to obtain all necessary permits.
Docusign Envelope ID: 27BE356D-C4D4-4690-AD70-16B8CCBE7A53
City of Renton Department of Community & Economic Development Shoreline Management Permit
Williams ADU/Garage LUA25-000025, ECF, SSDP, MOD
Report of April 2, 2025 Page 15 of 16
5. The applicant shall comply with the mitigation measure issued as part of the Determination of Non-
Significance – Mitigated (DNS-M), dated March 17, 2025.
6. The applicant shall demonstrate that the proposed septic system would comply with the adopted flood
plain regulations as found in RMC 4-3-050, including the compensatory storage requirements.
Necessary plans and/or reports demonstrating compliance with the flood plain requirements shall be
submitted to the Current Planning Project Manager for review and approval at the time of Building
Permit review.
7. A revised site plan shall be submitted at the time of Building Permit review. The revised site plan shall
include a driveway with a maximum width of sixteen feet (16’). The revised site plan shall be submitted
to the Current Planning Project Manager for review and approval.
8. The property owner shall (a) file an affidavit with the city affirming that the owner will live on site,
occupying the primary dwelling or the ADU; and (b) record a notice on the property title that the owner
will occupy the site, and bearing the notarized signature of all property owners listed on the property
title and which includes at a minimum: the legal description of the property, a copy of the approved
site/floor plan, and the applicability of the restrictions and limitations regarding ADUs in RMC Title IV.
The affidavit and notice on the title shall be submitted to the Current Planning Project Manager for
review and approval at the time of Building Permit review and the notice on title shall be recorded prior
to the issuance of the Building Permit.
9. The applicant shall submit paint chips demonstrating that the proposed ADU would be painted the
same color as the primary structure. The paint chips shall be submitted to the Current Planning Project
Manager at the time of Building Permit review for review and approval.
10. Revised building plans shall be submitted at the time of Building Permit review showing one (1) garage
door recessed at a minimum of four feet (4’) from the other garage door. The revised building plans shall
be submitted to the Current Planning Project Manager for review and approval.
DATE OF DECISION ON LAND USE ACTION:
SIGNATURE:
Matthew Herrera, Planning Director Date
APPEALS: Appeals of Shoreline Substantial Development Permit issuance must be made directly to the
Shorelines Hearings Board. Appeals are made by filing a request in writing within the 21 days of receipt of the final
order and concurrently filing copies of such request with the Washington State Department of Ecology and the
Attorney General’s office as provided in section 18(1) of the Shorelines Management Act of 1971. All copies of
appeal notices shall also be filed with the City of Renton Planning Division and the City Clerk’s office.
RECONSIDERATION: Within 14 days of the decision date, any party may request that the decision be reopened
by the approval body. The approval body may modify his decision if material evidence not readily discoverable
prior to the original decision is found or if he finds there was misrepresentation of fact. After review of the
reconsideration request, if the approval body finds sufficient evidence to amend the original decision, there will
be no further extension of the appeal period. Any person wishing to take further action must file a formal appeal
within the 14-day appeal time frame.
EXPIRATION: Unless a different time period is specified in the shoreline permit as authorized by RCW 90.58.143
and subsection J1 of RMC 4-9-190, construction activities, or a use or activity, for which a permit has been
granted pursuant to this Master Program must be commenced within two (2) years of the effective date of a
Docusign Envelope ID: 27BE356D-C4D4-4690-AD70-16B8CCBE7A53
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City of Renton Department of Community & Economic Development Shoreline Management Permit
Williams ADU/Garage LUA25-000025, ECF, SSDP, MOD
Report of April 2, 2025 Page 16 of 16
shoreline permit, or the shoreline permit shall terminate, and a new permit shall be necessary. However, the
Planning Division may authorize a single extension for a period not to exceed one year based on reasonable
factors, if a request for extension has been filed with the Planning Division before the expiration date, and notice
of the proposed extension is given to parties of record and the Washington State Department of Ecology.
DEFINITION OF COMMENCEMENT OF CONSTRUCTION ACTIVITIES: the construction applications must be
submitted, permits must be issued, and foundation inspections must be completed before the end of the two (2)
year period.
EXHIBITS:
Exhibits 1-9: ERC Report and Exhibits
Exhibit 10: Shoreline Substantial Development Permit
Exhibit 11: Environmental (SEPA) Determination of Non-Significance – Mitigated (DNS-M)
Exhibit 12: Height Modification Justification
Exhibit 13: Comparison of Primary Structure and ADU Design
Exhibit 14: Septic Design Plan
Exhibit 15: Technical Information Report, prepared by Donna Breske and Associates, dated
December 19, 2024
Exhibit 16: Geotechnical Engineering Study, prepared by Pacific Geo Engineering, dated June 28, 2024
Exhibit 17: Arborist Report, prepared by Arborist Solutions, dated March 28, 2024
Exhibit 18: COR Maps Aerial Photo
cc: Office of Attorney General
Clark Close, Current Planning Manager
Nathan Janders, Development Engineering Manager
Docusign Envelope ID: 27BE356D-C4D4-4690-AD70-16B8CCBE7A53