HomeMy WebLinkAboutCDN 2018-05-29 Item 2D - Discussion - Accessory Dwelling Unit (ADU) RegulationsCity of Tukwila
Allan Ekberg, Mayor
INFORMATIONAL MEMORANDUM
TO: Community Development and Neighborhoods Committee
FROM: Jack Pace, Community Development Director
BY: Nora Gierloff, Deputy DCD Director
CC: Mayor Ekberg
DATE: May 23, 2018
SUBJECT: Accessory Dwelling Unit Code Amendments
ISSUE
How should development regulations for Accessory Dwelling Units be changed to allow more
flexibility and encourage the development of this housing type?
BACKGROUND
After the City Council's public hearing on the proposed Accessory Dwelling Unit (mother-in-law
apartment and backyard cottage) ordinance on May 14th the Council sent the issue back to the
Community Development and Neighborhood Committee. The topics they identified for further
discussion include:
• Number of parking spaces required;
• Minimum lot size required to qualify for an ADU;
• Maximum size of attached and detached ADUs;
• Whether lots with ADUs should be required to subscribe to curbside garbage pickup;
and
• How the ADU requirements will be enforced.
DISCUSSION
Each of the topics identified for further discussion is listed below with options for change.
Staff's recommendation is listed first in each group.
1. The proposed ordinance requires ADUs to have one on-site parking space per bedroom
in addition to the parking required for the main house. Single family houses with up to
3 bedrooms are required to have 2 parking spaces. Other options include:
a. Reinstate the PC recommended waiver of the second space if the ADU is
accessed from a block with on -street parking.
b. Retain the current requirement that ADUs up to 600 SF are required to have 1
off-street parking space while units over 600 SF are required to have 2 spaces.
c. Select a different parking standard.
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INFORMATIONAL MEMO
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2. The proposed ordinance would reduce the lot area requirement from 7,200 square feet
to the minimum lot size required in the LDR zone, currently 6,500 square feet, for both
attached and detached ADUs. This standard is not proposed to be waived under the
amnesty program. Other options include:
a. Applying the minimum lot size to detached ADUs only and allowing attached
ADUs as part of a house on any legal LDR lot.
b. Allowing ADUs to be built on lots as small as 6,000 or 5,500 square feet because
there are areas of the City that were platted with smaller lots. There are 137 LDR
lots between 5,000 and 5,999 square feet and 251 lots between 6,000 and 6,499
square feet.
c. Retaining the current 7,200 square foot requirement.
3. The proposed ordinance would increase the percentage of a house that can be occupied
by an attached ADU from 33% to 40% up to a maximum of 1,000 SF, whichever is less.
At the March 13 CDN meeting the maximum unit size was flagged for further
discussion. Other options include:
a. Return to the 800 square foot maximum in Tukwila's current code.
b. Select a different percentage and/or maximum size.
4. The proposed ordinance would allow detached ADUs up to 1,000 square feet if they
could meet other existing standards for total building footprint and impervious surface
on the lot. Other options include:
a. Set an 800 square foot maximum.
b. Allow detached ADUs to be 12% of the lot size up to a maximum of 1,000 square
feet. A 6,500 square foot lot would be eligible for a 780 square foot ADU.
c. Select a different percentage and/or maximum size.
5. There are no specific requirements for single family garbage collection in the zoning
code. Solid waste and recycling are governed by TMC Chapter 22 and the current
franchise agreement with Waste Management (contract 12-027) negotiated through
the Public Works Department. Options include:
a. Do not single out ADUs for special garbage requirements.
b. Work with the Public Works Department to develop an amendment to Chapter
22 that implements a universal garbage requirement with an opt out provision.
c. Work with the Public Works Department to develop an amendment to Chapter
22 that addresses ADU garbage collection only.
Rental ADUs are required to obtain a Residential Rental Business License before occupancy by a
tenant under the same requirements as any other rental unit. Failure to license, register and
maintain the ADU would be enforced under TMC 5.06 Residential Rental Business License and
Inspection Program and TMC 8.45 Enforcement.
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In the over 20 years that Tukwila has allowed ADUs only a handful have been legally developed.
While there is growing interest in this housing type the current standards are very limiting and
few properties qualify. If the final ordinance doesn't add a significant amount of flexibility it is
unlikely that Tukwila will see many new ADUs developed.
FINANCIAL IMPACT
Construction of additional dwelling units would result in modest increases to permit revenue,
sales tax, rental license revenue and property taxes. Establishing an ADU registry and
conducting enforcement and inspections for ADUs will require building, planning and code
enforcement staff time.
RECOMMENDATION
The Council is being asked to identify any amendments to the draft ordinance and return it to
the June 25, 2018 Committee of the Whole meeting and subsequent July 2, 2018 Regular
Meeting.
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