HomeMy WebLinkAboutPlanning 2024-05-23 Item 7.2 - Public Hearing - Zoning Code Amendments for Accessory Dwelling Units (ADUs)City of Tukwila
Thomas McLeod, Mayor
Staff Report to the Planning Commission
Prepared May 9, 2024
HEARING DATE: May 23'd, 2024
FILE NUMBERS: L24-0051
APPLICANT: City of Tukwila
REQUEST: Planning Commission Public Hearing regarding minor housekeeping
amendments to TMC Title 18 regarding Accessory Dwelling Units
LOCATION: The action would result in a change to the zoning code that would affect
areas throughout the City of Tukwila.
NOTIFICATION: Hearing notice was published in the Seattle Times and posted on the City of
Tukwila website on May 9`h, 2024.
SEPA: Staff will review the proposed changes for compliance with SEPA should the
Planning Commission move to advance this topic to the City Council for
review.
STAFF: Isaac Gloor, Associate Planner
BACKGROUND
In 2023, the Planning Commission recommended that the City Council consider zoning code
amendments that would alter the development standards for Accessory Dwelling Units (ADUs).
These changes were proposed by staff to bring Tukwila's code into compliance with a newly passed
State Law that was known during development as HB 1337. The City Council approved those
changes in November of last year.
Because of those changes, Tukwila's zoning code now allows all parcels that permit Single -Family
Homes (SFH) to develop up to two ADUs, in either attached or detached form, without owner
occupancy and, if near frequent transit, without additional parking. Parking standards for SFHs
were not changed, and ADUs are still subject to most of the same development standards as
single-family homes are, including setbacks and impervious surface limits. While most of the
changes made were amendments to TMC 18.50 (the chapter containing `Supplemental
Development Standards'), additional non -compliant code sections were identified since
Ordinance 2716 was ratified and must be addressed.
FINDINGS
Below is a summary of the identified code sections and proposed changes:
• TMC Table 18-6: Land Uses Allowed by District
o Issue: State law requires that Tukwila permit ADUs anywhere that the City permits
SFHs. Most of Tukwila's SFHs are located within Tukwila's three residential zoning
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Staff Report to the Planning Commission: Title 18 Housekeeping
May23rd Public Hearing
districts: Low -Density Residential, Medium -Density Residential, and High -Density
Residential. The land use table currently permits ADUs within those districts.
However, Tukwila also permits single-family homes within several other districts,
including the Mixed Use Office (MUO), Office (0), Residential Commercial Center
(RCC), Neighborhood Commercial Center (NCC), Tukwila Valley South (TVS), and
Tukwila South Overlay (TSO) districts. As Table 18-6 does not show that ADUs are
permitted within those districts, Tukwila could not allow a new ADU to be
established within them. This leaves Tukwila out of compliance with the
requirements of State Law.
o Suggested Change: Staff proposes to amend TMC Table 18-6 to include ADUs as
permitted accessory uses within the MUO, 0, RCC, NCC, TVS, and TSO zoning
districts. While this would permit ADUs within 6 additional zoning districts than
what is currently permitted, this is expected to result in minor changes, as these
districts do not currently contain many eligible properties and are unlikely to gain
more in the future.
• TMC 18.50.220(6)(3): Accessory Dwelling Unit (ADU) Standards; General Standards
o Issue: This code section establishes the maximum size of detached ADUs, which,
as required by the State, is set at 1000 square feet. However, it also states that if an
ADU is built over a detached garage, the department will not count the square
footage of the detached garage toward the maximum size of an ADU. While this is
accurate, it implies that in other scenarios, the department would count the square
footage of a garage and use that to limit the size of ADUs. This implicit meaning is
unintentional, and if enforced, would violate state requirements.
o Suggested Change: Staff proposes to amend TMC 18.50.220(6)(3) to remove the
sentence "If built over a detached garage, the detached garage would not count
toward the area limit for the ADU". This sentence is unnecessary, as garages are not
habitable and would not count toward an ADUs floor area in any circumstance.
This change would remove the implication that other types of garages may count
toward ADU area limits.
• TMC 18.50.055(C): Single -Family Dwelling Design Standard Exceptions
o Issue: Washington State allows cities to establish design standards for ADUs,
provided that those standards are no more restrictive than the standards for single-
family dwellings. The TMC does this by establishing design standards for all new
single-family dwellings, as well as accessory dwelling units and other accessory
structures that require a building permit. These standards, as they are equally
applied, comply with State requirements. Prior to the November code update by
Council, Tukwila's Accessory Dwelling Unit standards contained design
requirements that were more restrictive than those for single-family homes. While
those requirements were removed from the code specifically referencing ADUs,
Tukwila's single-family design standards still contain a reference to that now
defunct code section.
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Staff Report to the Planning Commission: Title 18 Housekeeping
May23rd Public Hearing
o Suggested Change: Staff proposes to correct this scrivener's error and remove TMC
18.50.055(C).
CONCLUSIONS
Staff has determined that these changes are required to comply with Washington State law. The
changes will correct errors in the TMC and represent a minor change to Tukwila's development
regulations.
REQUESTED ACTION
Staff requests that the Planning Commission forward a recommendation for adoption of these
amendments to Title 18 -Zoning to the City Council for further consideration.
ATTACHMENTS
Exhibit A: Title 18 Housekeeping
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City of Tukwila
Thomas McLeod, Mayor
Department of Community Development - Nora Gierloff,, A!CP, Director
Title 18 Housekeeping
Exhibit A:
Accessory Dwelling Units
This document shows all relevant code sections
with proposed changes.
Text in red and with a strikethrough is proposed
for removal.
Text in green that is bolded and underlined is
proposed for addition.
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CHAPTER 18.50
SUPPLEMENTAL
DEVELOPMENT STANDARDS
Sections:
18.50.050 Single -Family Dwelling Design Standards
18.50.055 Single -Family Design Standard Exceptions
18.50.220 Accessory Dwelling Unit (ADU) Standards
18.50.050 Single -Family Dwelling Design Standards
All new single-family dwellings, as well as accessory dwelling
units and other accessory structures that require a building permit,
must:
1. Be set upon a permanent concrete perimeter
foundation, with the space from the bottom of the home to the
ground enclosed by concrete or an approved concrete product that
can be either load bearing or decorative.
2. If a manufactured home, be comprised of at least two
fully -enclosed parallel sections, each of not less than 12 feet wide
by 36 feet long.
3. Be thermally equivalent to the current edition of the
Washington State Energy Code with amendments.
4. Have exterior siding that is residential in appearance
including, but not limited to, wood clapboards, shingles or shakes,
brick, conventional vinyl siding, fiber -cement siding, wood -
composite panels, aluminum siding or similar materials. Materials
such as smooth, ribbed or corrugated metal or plastic panels are
not acceptable.
5. Have the front door facing the front or second front
yard, if the lot is at least 40 feet wide. This requirement does not
apply to ADUs or accessory structures.
6. Have a roofing material that is residential in
appearance including, but not limited to, wood shakes or shingles,
standing seam metal, asphalt composition shingles or tile.
(Ord. 2678 §13, 2022; Ord. 2581 §9, 2018;
Ord. 2500 §23, 2016; Ord. 2098 §2, 2005)
18.50.055 Single -Family Design Standard Exceptions
A. The design standards required in TMC Section 18.50.050
(4), (5) and (6) may be modified by the Community Development
Director as part of the building permit approval process.
1. The criteria for approval of use of unconventional
exterior siding are as follows:
a. The structure exhibits a high degree of design
quality, including a mix of exterior materials, detailing, articulation
and modulation; and
b. The proposed siding material is durable with an
expected life span similar to the structure; and
c. The siding material enhances a unique
architectural design.
2. The criteria for approval of a house with a front door
that faces the side or rear yard are as follows:
a. The topography of the lot is such that pedestrian
access is safer or more convenient from the side or rear yard;
b. The entrance is oriented to take advantage of a
site condition such as a significant view; or
c. The entry feature is integral to a unique
architectural design.
B. The design standards required in TMC Section 18.50.050
(5) and (6) may also be modified by the Community Development
Director as part of the building permit approval process if the
proposal includes a replacement of a single wide manufactured
home with a double wide and newer manufactured home. The
property owner can apply for this waiver only one time per property
starting from the date of adoption of this ordinance. Additionally,
the proposal should result in aesthetic improvement to the
neighborhood.
C. The design standards required in TMC Section
18.50.220.A (4) may be modified by the Community Development
Director as part of the building permit approval proccsc. The
design of an attached ADU that does not reflect the design
vocabulary of the existing primary residence may be approved if
the new portion of the structure exhibits a high degree of design
quality, including a mix of durable exterior materials, detailing,
articulation and modulation.
(Ord. 2678 §14, 2022; Ord. 2581 §10, 2018;
Ord. 2368 §52, 2012; Ord. 2098 §3, 2005)
18.50.220 Accessory Dwelling Unit (ADU) Standards
A. For the purposes of this section, terms shall be defined
as follows:
1. "Major transit stop" means a stop on a high -capacity
transportation system funded or expanded under the provisions of
chapter 81.104 RCW, including but not limited to: commuter rail
stops, stops on rail or fixed guideway systems, including
transitways, stops on bus rapid transit routes, or routes that run on
high -occupancy vehicle lanes, stops for a bus or other transit
mode providing actual fixed route service at intervals of at least
fifteen minutes for at least five hours during the peak hours of
operation on weekdays.
2. "Principal Unit" means the single-family housing unit,
duplex, triplex, townhome, or other housing unit located on the
same lot as an accessory dwelling unit.
B. General Standards.
1. Two (2) ADUs may be created per lot. The lot shall
contain one (1) principal unit and a maximum of two (2) ADUs.
These ADUs may be either attached or detached.
2. Attached ADUs may occupy a maximum of 40% of
the square footage of the principal unit (excluding the area of any
attached garage) or up to 1,000 square feet, whichever is greater.
3. Detached ADUs may be a maximum of 1,000 square
feet. If built over a detached garage, the detached garage would
not count toward the area limit for the ADU.
4. Detached ADUs may be up to 25 feet in height.
5. ADUs are subject to the development standards of
the zoning district they are located within. Development standards
relating to setbacks and development coverage do not apply to
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conversions of existing non -conforming structures that are
proposed for ADU conversion. New ADUs are not subject to rear
yard setbacks on parcels where the rear yard abuts an alley.
6. ADUs may not be rented for periods of less than 30
days.
C. Parking.
1. See Figure 18-7 for parking requirements.
2. Tandem spaces are permitted.
(Ord. 2716 §5, 2023; Ord. 2581 §11, 2018)
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ADU Housekeeping Amendments:
TMC Title 18-6 Land Uses Allowed by District
P = Permitted outright; A = Accessory (customarily appurtenant and
incidental to a permitted use) ;
C = Conditional (subject to TMC 18.64); U = Unclassified (subject to
TMC 18.66); S = Special Permission (Administrative approval by the
LDR
MDR
HDR
MUO
0
RCC
NCC
RC
RCM
C/L
LI
HI
MICAMIC/H
TVS
TSO
PRO
Contractor storage yards
PPP
p
p
P
Continuing care retirement facility
C
C
C
C
C
C
C
P
Convalescent & nursing homes & assisted living facility for not
more than twelve patients
C
P
P
P
C
P
P
P
P
P
P
Convalescent & nursing homes & assisted living facility for more
than twelve patients
C
C
C
C
C
C
C
P
Convention facilities
P
P
PPP
P
P
Correctional institutes
U11
U
U
U
Daycare Centers (not home -based)
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
Daycare Family Home (Family Child Care Home)12
A
A
A
A
A
A
A
A
A
A
A
Diversion facilities and diversion interim services facilities south of
Strander Blvd
U
Domestic Shelter
P
P
P
P
P
Dormitory
C
C
C
A13
A13
A13
A13
A13
A13
A13
A13
A13
A13
A13
Drive-in theatres
C
C
C
C
C
C
Dwelling — Detached single family (Includes site built, modular home
or new manufactured home). One detached single family dwelling
per existing lot permitted in MUO, 0, RCC, NCC, TVS.
P
P
P
P
P
P
P
P
P
Dwelling- Detached Zero -Lot Line Units
P
Dwelling- Duplex, triplex or fourplex or townhouse up to four attached
P
P
Dwelling- Townhouses
P
P
Dwelling —Multi-family
P
P14
p
Dwelling — Multi -family units above office and retail uses
p
p
p
p
C15
22/
ar
P
Dwelling — Senior citizen housing, including assisted living facility for
seniors
*see purpose section of chapter, uses sections, and development
standards
P
meeting
density and
all other
MDR
standards
P
60/ac
p
60/ac
P
60/
ac
P
60/ac
P
60/ac
C15
100/
ac
p
Dwelling unit — Accessory 16
A
A
A
A
A
A
A
A
A
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