HomeMy WebLinkAbout11-07-16 CC Mtg - FYI1. UDC Update and Policy Framework Preparation Memo
Commission Memorandum
REPORT TO: Honorable Mayor and City Commission
FROM: Tom Rogers, Senior Planner Martin Matsen, Director of Community Development
SUBJECT: Unified Development Code update progress report and infill policy
framework preparation
MEETING DATE: November 7, 2016
AGENDA ITEM TYPE: For your information
RECOMMENDATION: Not applicable
Project summary The City is revising the development code. The purpose of this project is to review and update
as needed the Unified Development Code (UDC) for the City of Bozeman. Primary objectives
of the revisions are to improve and enhance the code to, in part, create more:
• Consistency (with other policies/standards/plans),
• Clarity,
• Compatibility/appropriateness (with transition areas),
• User-friendliness,
• Flexibility, and
• Predictability
The update will be completed in a two-step process. Step one focused on the North Seventh
Avenue corridor (“Midtown”) and urban renewal/tax increment district (TIF); and creating a new more user friendly organization and presentation of the development code that will carry through the entire chapter 38. This step entailed preparing text/graphic zoning concepts for Midtown that
focus on mixed-use infill that fulfills the goals of the urban renewal district. The intent was also
to create a design handbook, image catalog, or visual representation of what the Midtown code
provisions will do and will allow, or not allow.
Step two is to continue the evaluation of the Unified Development Code, Chapter 38, BMC, make recommendations on the organization, presentation and create revised code for adoption.
Staff and others have identified 15 broad issues and more than 150 specific code revisions this
update intends to address. In addition, the Community Development Department will integrate
current code updates in process including cash-in-lieu of parkland, subdivision review process, Neighborhood Conservation Overlay District (NCOD) demolition, and others into the overall code update.
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Progress to date
Step one is complete
Creation of two new zoning districts; B2-M and R-5 to address the Midtown corridor plan
Revisions to the extent of the Entryway Corridors to reflect the block frontage approach
for B2-M and R-5
Creation and adoption of a streamlined site plan review process
Modifications to the review process and of the Wetlands Review Board
Zone map modifications to implement the Midtown corridor plan
Step two completed tasks
Reorganization and re-numbering is complete
Revised subdivision review processes accepted by City Commission
Adopted and in effect Cottage Housing ordinance
Revisions to the cash-in-lieu of parkland dedication accepted by City Commission
Cash-in-lieu of infrastructure – to be effective Dec. 7th
Intersection level of service standard – to be effective Dec. 7th
Maintenance of property and process revisions for demolition of historic properties (partial with final revisions to return to the Commission)
Step two tasks to complete include (see attached adoption schedule; web link HERE)
Revised covenants and condominium amendments. First public hearing was held on
October 24, 2016. Revisions per Commission direction being developed.
Determine best alternative to integrate the City’s Design Objectives Plan into base
development code. Current proposal was presented and discussed at a number of city
wide open houses related to the code update project. For draft information please refer to
the Community Design Framework Overview Map found under the UDC Update web
site.
Water adequacy, quality and quality provisions (part one will brought before the
Commission shortly, part two is expected early winter)
Detailed amendments to correct and improve known issues listed on the comprehensive
code correction list. The correction list is hosted on the City web site and will be updated
to include the expected amendment that will address the line item.
Develop in-fill provisions alternatives for discussion (see below for more detail). In fill
provisions may include:
o Modifications to accessory dwelling units standards (attached and detached)
o Density and dimensional standards. Changes made may mean modifications to
the adopted Affordable Housing Ordinance (Ordinance No. 1922). o Small lot provisions
o Revisions to existing in-fill programs
o Arterial and Collector street setback back requirements
Water related amendments to address water quality and quantity
Changes to definitions
Revise permitted uses in zoning districts to address conditional and non-conditional
review process
Develop and integrate enhanced visual graphics to describe and clarify code language
Possible modifications to the City Zone Map to fully implement the amendments
Final repeal and replace of all amendments
Numerous other revisions have been identified through the process. Those amendments
determined as critical for the UDC update will be addressed through this project. Specifically,
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staff identified a number of minor of code revisions omitted in the step one amendments. Four
code amendments will be brought before the Commission on November 21, 2016 under
Ordinance No. 1962, 1963, 1964, and 1965. Other identified amendments will be addressed
through ongoing text amendments handled by City staff as permitted.
Upcoming Infill Discussion and Draft Amendments – December 5, 2016
The next set of amendments and revisions revolve around “infill.” Infill has many definitions
depending on one’s perspective. Significant discussion has occurred on the subject including the creation of a policy work session and City Commission tour held on September 23, 2013.
Excerpts from this memo include a general description of infill along with some illustrative
examples of circumstances in which infill would occur. Please click HERE for the information.
These are working descriptions and subject to change as the infill policy develops.
Generalized definition: Infill is either the intensification of development or redevelopment on a site which was previously developed for urban use; or the initial development of vacant
property located with historically developed neighborhoods.
Infill Circumstances 1) Addition or provision of infrastructure to previously underserved areas within the outermost boundaries of the City without an immediate increase in intensity or change in
type of development. Example of Western Drive.
2) Reinvestment in existing properties and buildings to enhance their functionality and to
increase their value and improve their appearance while not materially increasing the intensity of use. Ex. Red Barn at 15th & Main Street.
3) Significant intensification of use, often including new building construction, on sites
previously developed but which are substantially underutilized within the limitations of
development standards. Ex. Brownfields like Idaho Pole, redevelopment like Northside
PUD on Rouse Ave., or intensification like the Etha Hotel.
4) Development on proportionately small previously undeveloped areas located within
neighborhoods which have been developed for at least 25 years. Ex. the field between the
Fairgrounds and N. Fifth Avenue; or the lot at West Babcock and Meagher Avenue.
Outreach Staff continues outreach to the community to determine the palatability of proposed
alternatives. All proposals continue to be brought before the UDC Advisory Committee for
consideration. Staff is going before the Inter Neighborhood Council (INC) on November 10,
2016 to discuss attached and detached ADU’s and other possible “in-fill” provisions and will
report back to the Commission on the discussion.
General Discussion Points
There are common infill challenges including (not an exhaustive list):
1. difficulty of land assembly to create sites suitable for current needs, reluctance of
lending sources for more complex, non-greenfield sites, uncertainty of costs for environmental clean up or structural conditions,
2. Conflict with regulatory standards with non-conforming sites or buildings,
3. Need to work within established ownership and physical boundaries requires
creativity and may increase costs for things like staging areas,
4. Perceived or real conflict with adjacent owners and occupants who may resist change, and
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5. More challenging coordination for infrastructure upgrades with existing conditions
and users.
Setting aside those challenges the City has limited ability to address, staff will propose a number of amendments to alter existing code to further the goals and objectives of the
Bozeman Community Plan to achieve more viable regulatory framework to facilitate those
goals.
Proposal one Generally, staff is proposing fundamental changes in how we administer standards for front
yards. We will propose the elimination of Entryway Corridors, special Arterial and
Collector yard requirements for non-residential districts and replacing those with standard
commercial and industrial minimum and/or maximum front yards, Block Frontage
framework (see UDC update web site), and integrating the intent of the existing standards from the DOP as simple site and building standards (see the B-2M District as an example).
Proposal two
Modifications to dimension and design standards associated with accessory dwelling units.
To more fully understand issues and show other examples of ADU’s Staff has attached a “general ADU issues” sheet for reference. In addition, our consultant team prepared a ADU
comparison chart to assist in developing best practice for Bozeman. Based on these analysis
possible changes to Bozeman’s ADU provisions include decreasing lot coverage maximums,
parcel size requirements, sidewall height limitations, and allowing ground floor detached
ADUs.
All ADU proposed changes are for discussion only and require additional design
requirements to insure the development of ADU do not materially harm adjacent property
owner’s enjoyment of their property.
Proposal three
Proposal three includes various adjustments to further the Bozeman Community Plan and
address known issues of our development code. These revisions may include clarification of
double frontage lots, transitions between zoning districts and individual developments;
minimum and maximum parcel size, and augmenting review criteria associated with 38.19.100.A.4, BMC.
Staff will be back before the Commission on December 5, 2016 to present detailed options
addressing the infill provisions the City currently utilizes and proposed modifications and additions to fully implement the City’s effort to fulfill its goals and objectives of the Bozeman
Community Plan. The aforementioned proposals necessitate a holistic approach for review
because they are interrelated and dependent on one another. Due to the many elements involved
with infill development I would anticipate some amendments may be complex and require
follow up discussion.
ALTERNATIVES: As identified by the Commission
Attachments: Adoption Schedule, General ADU Issues, ADU Comparison Chart
Report compiled on: October 26, 2016
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Bozeman UDC Code Update Review & Adoption Schedule November 2, 2016
Component & Sub-category Ref #
%
Compt. Lead 2nd Ord #
Notice
dates
Other
Advisors
Advisory
Committee
Zoning
Commission
Planning
Board CC
Effective
Date
Midtown area zoning provisions (ZCA) 100% TR CS 1942 June 8
Midtown Zoning district changes (ZMA) 100% TR CS 1943 June 8
Entryway corridor revisions 100% TR CS 1946 June 8
Site plan process changes (concept review, etc.) 100% TR CS 1944 June 8
Wetland Review Board revisions 100% TR CS 1945 June 8
Cottage Housing ordinance 100% CS 1952 May 9 June 21 June 27 Aug 10
Chapter 38 reorganization 92% Makers TR June 14 Aug 2 Aug June 27
& Aug 15 Aug 15
Chapter 38 reorganization numbering plan 100% Makers TR Legal June 14 Aug 2 Aug 2 June 27
& Aug 15 Aug 15
Parks – general procedures& guidance & cash-in-lieu 2A 90% CS CP Aug 9 Sept 6 Sept 6 Sept 26
Maintenance of property & Demolition of Historic
Structures 2C 85% CS TR Aug 9 Sept 6 Sept 6 Sept 26
Subdivision Process Changes 2F 95% CS Legal Sept 13 Oct 4 Oct 4 Oct 24
Cash-in-lieu of Infrastructure 97% MW CS 1915 Sept 13 Oct 4 Oct 4 Oct 24
Intersection level of service modification 97% MW CS 1959 Sept 13 Oct 4 Oct 4 Oct 24
Covenants / Condos 2I 98% MR CS 1916 Sept 13 Oct 4 Oct 4 Nov 7
Nov 21
Water (part 1) 2D 95% RO BK Oct 16 Nov 1 Nov 1 Nov 21
Misc corrections Nov 1 Nov 1 Nov 21
B2-M & R-5 sign code application MR TR 1962 Nov 1 Nov 1 Nov 21
R-5 group living MR TR 1963 Nov 1 Nov 1 Nov 21
B1 note MR TR 1964 Nov 1 Nov 1 Nov 21
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Bozeman UDC Code Update Review & Adoption Schedule November 2, 2016
Component & Sub-category Ref #
%
Compt. Lead 2nd Ord #
Notice
dates
Other
Advisors
Advisory
Committee
Zoning
Commission
Planning
Board CC
Effective
Date
Parks as allowed use MR TR 1965 Nov 1 Nov 1 Nov 21
Residential Open Space requirements 2H 10% BK MW Dec 13 Dec 20 Dec 20 Jan 9
Infill Provisions – Missing Middle
Accessory Dwelling Units 2J.1 MR MW Dec 13 Dec 20 Dec 20 Jan 9
Density & dimensional standards 2J.2
Small lot provisions 2J.3
Vacant lot incentives 2J.4
Other 2J.5
Arterial setbacks and Entryway application 2K 25% MR RO Dec 13 Jan 3 Jan 3 Jan 23
Definition modifications 2L BB TR Nov 8** Dec 6 Dec 6 Dec 19
Transit language improvement 2M 5% BK
Water Part 2 - Adequacy
Water Part 3 – Conservation effort (irrigation,
consumption, management, etc.)
2N 12% RO BK Feb 14 March 7 March 7 March 20
DOP & NCOD integration 2Q 3% Multiple Feb 14 March 7 March 7 March 20
Map Amendments (if necessary) 2R 0 TR
Revised uses in districts and creation of SUP 2O 25% CS BK Jan 10 Feb 7 Feb 7 Feb 27
Signs (legal requirements only, no substantive changes) KS GS
Final comprehensive edit revisions (see sheet) 2S 5% TR CS Feb 14 March 7 March 7 March 20
Floodplain Regulation changes & amendments 2T BH TR
Final Adoption Makers TR Feb 14 Mar 7 Mar 7 Mar 27 Apr 10
346
Bozeman UDC Code Update Review & Adoption Schedule November 2, 2016
Component & Sub-category Ref #
%
Compt. Lead 2nd Ord #
Notice
dates
Other
Advisors
Advisory
Committee
Zoning
Commission
Planning
Board CC
Effective
Date
Notes:
* Excluding noticing, public meetings, and adoption.
Legend:
BB Bob Bengford, Makers Architecture
BK Brian Krueger
CP Carolyn Poissant
CS Chris Saunders
GS Greg Sullivan
KS Karen Stambaugh
MR Mayana Rice
MW Mitch WerBell
RO Rebecca Owens
TR Tom Rogers
347
Bozeman UDC Code Update Review & Adoption Schedule November 2, 2016
Component & Sub-category Ref #
Advisory
Committee ZC PB Amend
Other
Advisors CC Revised CC
Midtown area zoning provisions (ZCA)
Midtown Zoning district changes (ZMA)
Entryway corridor revisions
Site plan process changes (concept review, etc.)
Wetland Review Board revisions
Cottage Housing ordinance
Chapter 38 reorganization
Chapter 38 reorganization numbering plan
Parks – general procedures& guidance & cash-in-lieu 2A
Maintenance of property & Demolition of Historic
Structures 2C
Subdivision Process Changes 2F N/A 4:1 No 5:0
Cash-in-lieu of Infrastructure 3:0 4:1 No 5:0
Intersection level of service modification 3:0 5:0 No 5:0
Covenants / Condos 2I 3:0 4:1 No 2:3
Water (part 1) 2D
Misc corrections
B2-M & R-5 sign code application
R-5 group living
B1 note
Parks as allowed use
348
Bozeman UDC Code Update Review & Adoption Schedule November 2, 2016
Component & Sub-category Ref #
Advisory
Committee ZC PB Amend
Other
Advisors CC Revised CC
Residential Open Space requirements 2H
Infill Provisions – Missing Middle
Accessory Dwelling Units
Density & dimensional standards
Small lot provisions
Vacant lot incentives
Other
Arterial setbacks and Entryway application 2K
Definition modifications 2L
Transit language improvement 2M
Water Part 2 - Adequacy
Water Part 3 – Conservation effort (irrigation,
consumption, management, etc.)
2N
DOP & NCOD integration 2Q
Map Amendments (if necessary) 2R
Revised uses in districts and creation of SUP 2O
Signs (legal requirements only, no substantive
changes)
Final comprehensive edit revisions (see sheet) 2S
Floodplain Regulation changes & amendments 2T
Final Adoption
349
Bozeman UDC Code Update Review & Adoption Schedule November 2, 2016
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GENERAL ADU ISSUES AND STANDARDS
Owner Occupancy
Either the primary residence or the accessory dwelling unit must be occupied by an
owner of the property. (Bel.)
Either the principal dwelling unit or the accessory dwelling unit must be occupied by
an owner of the property or an immediate family member of the property owner.
(MI)
Owners shall sign an affidavit attesting to their occupancy every five years. (Tac.)
Definition
Property owner, as reflected in the title records, makes his or her legal residence
at the site, as evidenced by voter registration, vehicle registration, or similar
means, and actually resides at the site more than six months out of any given
year, [and at no time receives rent for the owner-occupied unit.] (Bel)
Limitation on occupancy
The total number of occupants in both the primary residence and accessory
dwelling unit combined may not exceed the maximum number established by the
definition of family in Section (Bel)
(Note: Bellevue debated the tradeoffs of limiting the scale of individual units by
either limiting the size, or limiting the number of occupants. They eventually
decided that they were essentially controlling the number of occupants by
controlling the size of accessory units, and therefore did not need to explicitly
address limiting the number of residents in ADUs.)
* Resident must be an immediate family member of the owner of the primary
home.
Limitation on size
The ADU shall contain not less than 300 sq. ft. and not more than 800 sq. ft.,
excluding any related garage area. (Note: the minimum was based on using
minimum room sizes outlined by the Code.)
The square footage of the accessory dwelling unit shall be a minimum of 220 square
feet and a maximum of 900 square feet, excluding any garage area; provided, the
square footage of the accessory dwelling unit shall not exceed 40 percent of the total
square footage of the primary dwelling unit, excluding the garage area, as it exists or
as it may be modified. (MI)
The square footage of the ADU, excluding garage area, shall not exceed 40% of
the primary residence and ADU combined, excluding garage area. (Bel)
The total square footage of a detached ADU shall not exceed 40 percent of the total
square footage of the primary dwelling unit and the accessory dwelling unit
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combined excluding any garage area, and in no case shall it exceed 1,000 square feet.
The square footage of the ADU shall not exceed forty (40) percent of the total square
footage of the primary residence and ADU combined, excluding any non-living areas
such as garage area, storage sheds, or decks, unless the excluded area is the location
of the proposed ADU. (Issaq)
If the accessory unit is completely located on a single floor [of a multistory
structure], the Planning Director may allow increased size in order to efficiently use
all floor area. (Kirk)
o reason for discretion, i s the presumption that for daylight basements, s q. ft.
limitation could be arbitrary
The square footage shall not be less than 300 sq. ft. nor more than 800 sq. ft.
The maximum square footage for the ADU may be exceeded for two story
structures provided other criteria are met and the intent of the ordinance is
maintained. (Tac)
ADU does not exceed 50% of the combined total area of the principal residence
and the ADU. (K.C.) (Note: This may not be appropriate if want to ensure that
the ADU is'secondary' to primary residence, unless include some other types of
restrictions. The King County ordinance does not do that.)
Detached accessory dwelling units shall not exceed 800 square feet of gross floor
area. The gross floor area shall not include area with less than five (5) feet of ceiling
height, as measured between the finished floor and the supporting members for the
roof. When calculating the square footage of the ADU (see KZC 5.10.340, definition
of “gross floor area”), covered exterior elements such as decks and porches will not
be included; provided, the total size of all such covered exterior elements does not
exceed 200 square feet. (Kirk)
No ADU may have more than one bedroom, nor be more than 700 sq. ft.
o No ADU shall be more than 30% of the total floor area, excluding garage. (WC)
* Must have at least 1,400 sq. ft. of floor area exclusively for the primary unit.
(Note: Portland has revised this provision. There are probably more appropriate
and less arbitrary means to accomplish the underlying objective of this
provision.).
New or Existing
Silent on issue which would imply allowed in new or existing homes.
An ADU may be developed in either an existing or new residence.
Only permitted in existing units defined as construction of the principal dwelling
was completed (occupancy approved) at least three years prior to application for
accessory dwelling unit. (Bel)
Density of accessory units? {e.g. #of accessory units allowed in a community)
Do not address. (Bel.)
* The number of accessory units shall not exceed 3% of total units within a Census
Tract. (WC) (Note: Cities that have permitted ADU's have not had a problem
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with an overa bundance, or an over concentration of units.)
Home Occupation and Accessory units (Note: To appropriately address this issue, should
first evaluate in what circumstances Home Occupation Permits are required.)
A site may not contain both an accessory dwelling unit and a business subject to
the regulations in 20.30N for a Class A or Class B Home Occupation Permit (Bel)
(Note: These are businesses that generally have customer traffic.)
"No home occupations, day care home or mini child care facility shall be allowed
in an ADU." (Tac.) (Note. Different from Bellevue in that it appears to only
limit the ADU, not the primary residence.)
Miscellaneous
An ADU shall not be subdivided or otherwise segregated in ownership from the
primary dwelling unit. (Red)
There shall be no more than 1 accessory unit per parcel. (Evt)
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DESIGN ISSUES
The first step is to develop a sense of your community's existing housing. For example,
what physical forms of housing exist in your community, and which ones might best lend
themselves to accommodating ADUs such as houses with:
1) Detached garages
2) Daylight basements
3) Larger homes
4) Two story homes
5) Access off of alleys 6) Traditional basements
If your housing does not easily lend itself to adding ADU's then it is more likely that
ADUs would be done through additions. If so, does this lead to concerns with privacy?
Entrances
Shall have only one entrance on the front of the house. Additional entrances
permitted on the side and rear of the house. (Bel.)
The primary entrance to the accessory dwelling unit shall be located in such a manner
as to be clearly secondary to the main entrance to the principal unit and shall not
detract from or alter the single-family character of the principal unit. (Kirk)
The single-family dwelling containing the accessory dwelling unit shall have only one
entrance on each front or street side of the residence except where more than one
entrance existed on or before January 17, 1995. (MI)
One ADU door may be constructed on the front or street side of the residence;
provided, that it is screened from the street or the visual impact is otherwise mitigated
(Issaq)
* Unit can only be accessed through the main unit. (No separate entrance) (Not
really a fully separate unit) Additions
Silent on issue, which means must meet setbacks etc. of single family zoning. (Bel)
(Note: Bellevue Commission concluded that it would be ineffective or appropriate
to have design criteria more stringent than that used for normal additions. What
would prevent someone from getting a permit for an addition, and then afterward
come back for a permit for an ADU?)
Additions to an existing structure or newly constructed detached structures created for
the purpose of developing an accessory dwelling unit, shall be designed consistent
with the existing roof pitch, siding, and windows of the principal dwelling unit. (MI)
Garages
Silent on issue. Implies that can convert garage, so long as meet building code and
provide necessary amount of parking. City has no provision that required parking
for the primary residence or ADU be covered. (Bel)
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* Garage space may be converted only if the same numbers of covered
parking spaces are provided elsewhere on the property. (KC)
Privacy
The location and orientation of a ADU shall not materially reduce the privacy of
residents of adjoining properties. The Zoning Administrator shall consider
placement of windows, decks and balconies, landscape screening, and height/number
of stories, in determining if privacy will be materially reduced. (WC) (Note; This
may apply only to attached structures. Reason to apply on to detached structures is
that detached structures would normally not be used for living quarters other than
as an ADU, whereas, for the primary residence additions, etc could occur without
an ADU.) Parking
One off-street space for the ADU, which is in addition to any off-street spaces
required for the primary residence. (Bel) (Note: Bellevue used this language instead of requiring 3 off-street spaces. This is because some older houses are required to provide
only one off-street space, and they did not want to trigger a requirement for 2
additional spaces. Also, if a house already has 3 parking spaces, it does not need to
provide an additional spot. Therefore most houses can meet this requirement with
existing parking areas (garages and driveways).)
One off-street parking space is required for an ADU in addition to the parking required for
the primary dwelling unit. [Parking spaces must be paved and may include private
driveways, garages, carports, or off-street areas reserved for vehicles.] (Red)
Total of 3 off-street spaces.
Parking must be provided in the rear of the lot when alley access is available. (Tac)
All single-family dwellings with an accessory dwelling unit shall meet the parking
requirements applicable to the dwelling if it did not have such an accessory dwelling unit.
(MI). NOTE: City already required so much parking did not feel needed extra, and
requirement varied in a few areas.
Tandem parking can be used to fulfill this requirement. (Issaq)
Do not require additional off street parking. (Ptl) (Using this approach would be
dependent on evaluating current parking situation in a community.)
Attached vs. Detached
Only in the same building as the principal residence unless the lot is at least 10,000 sq. ft. [and the allowable density of the zone is not exceeded]. (KC)
ADU shall not be permitted in structures detached from the primary residence. (Bel)
ADU permitted as a second dwelling added to, created within, or detached from the
main building. Detached ADUs should be located in the rear of the lot. (Tac)
An accessory dwelling unit will be considered to be “detached” from the principal unit if it has any of the following characteristics (Kirk):
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a. It does not share a common roof structure with the principal unit.
b. It is not integrated into the footprint of the principal unit.
c. The design is inconsistent with the existing roof pitch, siding treatment, and window style
of the principal unit.
Abbreviations for Referenced Ordinances * Provisions not recommended to be incorporated into local ordinances.
Bel. Bellevue
EC El Cerrito, California
Evt. Everett KC King County Ptl. Portland, Oregon
Red. Redmond Tac. Tacoma WA Washington DCD Ordinance recommendations WC Walnut Creek, California
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PERMITTING/ENFORCEMENT
Permitting process
Allow as outright permitted use. No special permit or application or covenant. (KC) (Note: Doesn't allow for ability to track units/may be harder to enforce owner
occupancy)
Building permit process with requirement to sign a covenant. Do an inspection of the
unit to ensure meet accessory unit requirements. (Tac)
The property owner shall apply for an accessory dwelling unit permit with the Building Department. The application shall include an affidavit signed by the property owner
agreeing to all the general requirements outlined in this section. (Kirk)
After receipt of a complete application and prior to approval of an accessory dwelling unit,
the city shall inspect the property to confirm that all applicable requirements of this code
and other codes are met. (MI)
The registration form as required by the City shall include a property covenant. The
covenant must be filed by the property owner with the City for recording with the King
County Department of Records and Elections to indicate the presence of the accessory
dwelling unit, and reference to other standards outlined in this section. The covenant shall
run with the land as long as the accessory dwelling unit is maintained on the property. (Kirk)
Approval of the accessory dwelling unit shall be subject to the applicant recording a
document with the King County department of records and elections which runs with the
land and identifies the address of the property, states that the owner(s) resides in either the
principal dwelling unit or the accessory dwelling unit, includes a statement that the owner(s)
will notify any prospective purchasers of the limitations of this section, and provides for the removal of the accessory dwelling unit if any of the requirements of this chapter are
violated. (MI)
File a registration application (includes mailing labels for residents w/in 200') Property
inspection to ensure meets standards. Separate building permit if necessary. Covenant
recorded against the property. After approval notice to neighbors informing of enforcement procedures. (Bel)
Permit process which requires a public hearing prior to permitting. (WC)
The fee for an application for an ADU shall be the same as the fee required in a Home
Occupation Level 1 Review. (Issaq)
* Permit is only good for x years, or is voided upon sale of the property. (Note: Places
a severe restriction on the use of accessory units. Also, eliminates ability for
accessory unit to be considered by a lender.)
* Applicant must have lived in house for 2 years, and permit cannot be assumed at
time of sale.
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Meeting Building Code(s)
The ADU shall meet all technical code standards including building, electrical, fire and
plumbing code requirements). (Bel)
In order to encourage the development of housing for people with disabilities, the (building official) may allow reasonable deviation from the stated requirements to install
features that facilitate accessibility. Such facilities shall be in conformance with the
UBC. (WA.) (To what extent is this a moot point because ADU's are not required to
meet accessibility requirements (less than 4 units)?)
The portion of a single-family dwelling in which an accessory dwelling unit is proposed must comply with all standards for health and safety contained in all applicable codes, with the following exception for ceiling height. Space need not meet current International
Building Code (IBC) ceiling height requirements if it was legally constructed as habitable
space. (Kirk)
The accessory dwelling unit shall comply with all standards for health and safety in the Uniform Building Code, Uniform Plumbing Code, Uniform Electrical Code, Uniform Mechanical Code, Uniform Fire Code and any other applicable codes, except as provided in
this chapter. The ADU shall comply with all development code provisions for single-family
dwellings including height and setbacks, and the ADU shall be included as part of the
impervious surface and floor area limitations for a building site. (MI)
All existing accessory dwelling units that are located within a single-family dwelling which was legally constructed but does not now comply with current ceiling height requirements of
the Uniform Building Code, shall be allowed to continue in their present form. (MI)
Vancouver B.C. has special codes to ensure meeting safety standards without exorbitant
costs to bring to full code.
Administrative Discretion
The Land Use Administrator may allow variances to the stated general requirements
pursuant to Section 13.06.408 of Tacoma's Land Use Regulatory Code. (Tac)
Tracking Process
Annual report to Council re: ADU applications, distribution, complaints, etc. (Tac)
What to do about existing 'illegal' units
ADU's existing prior to enactment of these general requirements may be found to be
legal, if the property owner applies for a building permit for the ADU and complies with all required standards and provisions. (Tac)
Silent on issue, which implies same as Tacoma. (Bel)
If an ADU was or is created without being part of a project for which a building permit was
or is finaled, an ADU inspection will be required for issuance of an ADU permit. The ADU
inspection fee will cover a physical inspection of the ADU. This fee will be waived if the ADU existed on January 1, 1995, and the ADU permit is applied for by December 31, 1995. (Kirk)
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If an ADU was created without being part of a project for which a building permit was
finalized, the City shall require a building inspection to determine if the structure is sound,
will not pose a hazard to people or property, and meets the requirements of this section and
building code. The ADU inspection fee will cover the building inspection of the ADU. This fee will be waived if the ADU permit is applied for within two years of the effective date of
the ordinance codified in this section. (Issaq)
That portion of a single family residence which meets the definition of accessory dwelling
unit, may be legally established, and not subject to zoning violation fines, if the following
requirements are met: (1) An application for an ADU permit is filed within two (2) years of the effective date of the ordinance codified in this section; (2) The ADU is determined to
meet the requirements of this section as well as any other applicable Code requirements.
(Issaq)
Existing legally nonconforming structures may be used for the locating of an ADU if the
Building Official determines that the structure is sound, will not pose a hazard to people or property, and meets the requirements of this section and building code requirements.
Portions of buildings that undergo a change of use are required to meet building codes for
new construction in compliance with the current building code. (Issaq)
Those created prior to 1953 shall be permitted upon registration and evidence of date of
establishment, evidence of use of the unit for the 6 month period prior to registration.
Those created after 1953 can be permitted through administrative use permit if the unit
does not otherwise conform with requirements. Must apply within 180 days of adoption
of the ordinance. Those that do not meet requirements for size and parking will be
referred to the Planning Commission. (EC)
Enforcement
Cancellation of the covenant.
Civil violation, for which a monetary penalty may be assessed and abatement may be required. (Bel.)
The city retains the right with reasonable notice to inspect the ADU for compliance with the
provisions of this section. (MI)
The owner shall file an Owner's Certificate of Occupancy in a form acceptable to the
City Attorney no later than April 1st of each year. (Evt.)
In addition to all other penalties provided in the Redmond Municipal Code ...owner shall
be subject to a civil penalty of $100 per day, for each day the violation is allowed to
persist after receiving notice thereof from the Code Administrator. (Red.)
(Note: If the solution is to move out a renter, may place an undo hardship on the renter
to move out immediately. May want a phased penalty to give renter a reasonable time to move out.)
Utility hook-ups
Do not require separate utility hook-ups. Only one electric and one water meter shall
359
10
be allowed for the entire building, serving both the principal and accessory dwelling
unit. (Evt.) (Note: may want to leave some discretion for administrator to waive this
requirement).
* Require separate metering (This could place a large cost burden on creating ADUs and appears contrary to the general concept of the ADU being a secondary use.)
How to deal with local CC&R's
CC&R's are a private contract, and do not need to be considered by cities when issuing
permits. Cities evaluate permits based on their codes. Enforcement of CC&R's done
outside of city procedures.
Source: Art Sullivan, Program Manager, ARCH – A Regional Coalition for Housing,
Redmond, WA 98052. http://www.archhousing.org/index.html.
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Location Where
Permitted
Minimum
Site Size Unit Size Maximum
Height Density Parking Setbacks Open Space Design
Standards Other
Bozeman,
MT
• In R-S and R-1 zones, ADUs are
permitted above garages in
subdivisions with preliminary plat
approval after Jan 1. 1997, or as a
dwelling unit within detached
single-household dwelling
• 6,000SF
(except 4800SF
in REMU zone)
Min. lot widths
•R-S, R-1: 50ft
•REMU: 40ft
Lot widths
•R-S: 50ft
•R-1: 50ft, but
can be reduced
10ft, when lot
is adjacent to
an alley, and
vehicular
access is taken
only from that
alley.
• R-S, R-1 zones: <800sf,
or <1/3 of total area of
principal structure, and
not >1 bedroom
• R-2, R-3, R-4, R-O,
REMU (res. single
household lots only):
<600sf, and not >1
bedroom, and <footprint
of principal building
• Same as primary
structure
• Only one ADU may
be created per lot
• One additional paved
off-street parking space
provided for the
exclusive use of the
accessory of the dwelling
unit
• n/a; Same as primary
structure
n/a • 2nd story additional only approved if compatible with
neighborhood character/fabric
• Entrance for ADU, if separate from entrance of principal
structure, to only be located in rear/side yards
• 2 person occupancy limit for ADU
• Garages shall not be converted for
use as ADUs
• No deviations in lot area or parking
reqs and no more than two total
deviations total shall be granted to
allow establishment of ADU,
• In R-S, or R-1 zones owner
occupancy requirements for either
primary or accessory dwelling
Max lot coverage by principal and
accessory buildings shall be:
• in R-S dist. (new lots): determined
through PUD review procedures
• in R-S dist. (existing lots) <25% lot
area
• R-1. R-2, R-3. RMH: <40% for all
uses except townhouses
• R-1. R-2, R-3. RMH: <50% for
townhouses
• R-4 Zones: <50%
• R-O: <50% residential uses, 60% for
neighborhood/non-residential
Missoula, MT
Internal ADUs are allowed In
R215, R80, R40, R20, RT10, R8,
R5.4 RT5.4, R3, RT2.7, RM2.7,
RM1, RM1.5 RM0.5, RMH, B, C
and M1R zoning districts,
Internal Addition ADUs are
allowed as a conditional use in
the zones above, and allowed
outright in RT5.4, RT2.7, RM2.7,
RM1, RM1.5 RM0.5, RMH, B, C
and M1R zoning districts
No additional
land area
required for
ADU beyond
minimum
parcel size
required for
detached
house in
subject zoning
district
Attached
Internal ADU (no
footprint increase): floor
area <600 SF, and
>350SF, and also <40%
of gross floor area excl.
attached garage
Internal addition: No
increase in floor area of
primary dwelling unit by
>600SF, or exceed 40%
of gross floor area
n/a Not included in min.
parcel area/unit
calculations
No more than one
ADU per parcel
At least 1 paved off-
street parking space
provided, in addition to
off-street parking reqs
for principal unit. For
parcels abutting alley,
access to parking for
ADU must come from
the alley.
n/a n/a Exterior finish materials, roof pitch, and trim of any
additions must be same as principal detached house.
Only one entrance to detached house containing ADU
may be located on street frontage, unless door was pre-
existing to creation of ADU
Annual permit required, subject to no
substantial alterations, no change in
provision of required off-street
parking spaces, and meeting owner-
occupancy requirements
Connection of ADU to city sewer
required
Boulder, CO
Allowed, with approval, in RL-1,
RL-2, RE, RR-1, RR-2, A or P zoning
districts, where no more than
10% of single family lots/parcels
contain an ADU within a 300 foot
(RL-1, RL-2, P) or 600 foot (RE, RR-
1, RR-2) radius from perimeter of
any lot line.
Owner’s Accessory Units can be
established either as unit within
principal structure, or within
accessory structure, on a lot in
RR, RE, and RMX-1 zones
Only to be
created
through
internal
conversion of
single-family
detached
dwelling unit
on a lot >6000
SF
Min. 300SF, and does
not exceed lesser of 1/3
total floor area of
principal structure, or
1000SF, with minor
exterior changes
allowable on building if
added SF is <5% of
principal structure’s
existing foundation area
n/a n/a One additional off-street
parking space
Front: 55’
Side: 0-25’ depending
on zone and location
of lot line
From other buildings:
6’
n/a Additional entrances may only face street-fronting
property line if adequately and appropriately screened
• Subject to Administrative Review
• 2 person occupancy limit for ADU
•Owner must occupy one of the
permitted dwelling units on the site
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Location Where
Permitted
Minimum
Site Size Unit Size Maximum
Height Density Parking Setbacks Open Space Design
Standards Other
Bellingham
•Attached are permitted in
residential single zones, except
within the Lake Whatcom
watershed (unless allowed per
BMC 16.80.060.A.).
n/a •Must not exceed 40%
of the sq. footage of the
conditioned floor area
measured from the
outside of the exterior
walls of the SF
residence, excluding
garages, and shall
contain a minimum sq.
footage as required by
the building code and a
max. of 800 sq. ft.
•Height must be
less than or equal
to the primary
structure, and no
higher than 25 feet.
•The parcel may not
contain more than
one primary dwelling.
•The total number of
persons who may
occupy the ADU shall
not exceed 3,
regardless of
relationship.
•One additional parking
space on private
property shall be
provided for each
bedroom located w/in
the ADU. Each ADU shall
provide a min. of one
parking space.
n/a n/a •No more than 2 bedrooms shall be located within the
ADU.
•Only one entrance for the entire structure may be visible
from the front street.
• Any additions must have similar roof pitch, siding and
windows so that the addition is architecturally compatible
with the existing home.
•At least one of the dwelling units
must be owner occupied (affidavit
reqd).
•Purchasers of homes with an ADU
must register with the department of
planning and community
development within 30 days of
purchase.
Everett
Prohibited on lots within an
easement access short sub
division
• Otherwise, allowed in single
family dwelling units on lots
>5000sf, using one or a
combination of methods:
a. Alteration of interior space of
the dwelling;
b. Conversion of an attic,
basement, attached garage, or
other previously uninhabited
portion of a dwelling or attached
accessory structure; or
c. Addition of attached living
area onto an existing dwelling.
Residential
zones- A-1, R-S,
R-1, R-2, R-
1(A), R-2(A).
A-1=5 Acres, R-
S= 9,000 SF, all
others=5,000
SF.
•The floor area of the
ADU shall not exceed
40% of the total floor
area of the structure, or
800 sq. ft, whichever is
less.
•Attached
accessory buildings
may be
constructed to the
max. height
allowed by the
zone in which it is
located; provided
that the attached
accessory building
meets all setbacks
required for the
principal building.
•Only one electric
and one water meter
shall be allowed for
the entire building,
serving both the
principal and ADU.
•The total number of
persons who may
occupy the principal
and ADU combined
shall not exceed the
number of persons
that are defined by
this title as a "family."
•3 off-street parking
spaces shall be provided
for the principal and
ADU. When the
property abuts an alley,
the off-street parking
space for the ADU shall
gain access from the
alley, unless topography
makes such access
impossible.
•Attached or detached
accessory buildings
may be located within
the principal buildings
rear setback provided
that the accessory
building meets all side
setback requirements;
and a min setback of 5
ft is provided from the
rear lot line,
n/a • The single-family appearance and character of the
dwelling shall be maintained when viewed from the
surrounding neighborhood.
•Only one entrance to the residential structure may be
located on any street side of the structure.
•At least one of the dwelling units
shall be occupied by one or more
owners of the property as the
owner's permanent and principal
residence.
Portland
•An ADU may be added to a
house, attached house, or
manufactured home in an R zone,
except for attached houses in the
R20-R5 zones that were built
using the regulations of Duplexes
and Attached Houses on Corners.
n/a •The size of the
accessory dwelling unit
may be no more than 75
percent of the living area
of the primary dwelling
unit or 800 square feet,
whichever is less.
Base zone
development
standards.
•In the single-
dwelling zones, ADUs
are not included in
the min. or max.
density calculations
for a site. In all
aother zones, ADUs
are included in the
min. density
calculations, but are
not included in the
max. density
calculations.
•No additional parking is
required. Existing
parking must be
maintained or replaced
on-site.
Base zone
development
standards.
n/a •The exterior finish material, roof pitch, trim, and
windows must be the same or visually match in type, size
and placement, the exterior finish material of the house,
attached house, or manufactured home.
•Only one entrance may be located on the façade of the
principal structure facing the street, unless the principal
structure contained additional entrances before the ADU
was created. Entrances that do not have access from the
ground are an exception.
•ADUs in “d” Design overlays (33.420), or some historic
designations (33.445) may be subject to additional design
reqs. These ADUs must meet the Community Design
Standards (33.218), where allowed to use Community
Design Standards, or be approved through Design review
or Historic Resource review.
•The total number of individuals that
reside in both units may not exceed
the number that is allowed for a
household.
Seattle Ch.23.44
•single-family or lowrise zone n/a •Attached accessory
dwelling units are
limited to 1,000 square
feet,in a single family
structure, and up to 650
square feet in a
rowhouse or townhosue.
?? •One per single
family dwelling.
• Except for rowhouses
or townhouses on lots
within areas defined as
an urban center or urban
village in the City's
Comp. Plan, one off-
street parking space is
required for the ADU
and may be provided as
??
•Only one entrance to the structure may be located on
each street-facing facade of the dwelling unit.
•An owner with at least 50% interest
in the property must occupy either
dwelling unit for >6 months year as
the owner's permanent residence.
•No limit for related persons
occupying unit in a single-family
dwelling unit with an accessory
dwelling unit; provided that, if
unrelated persons occupy either unit,
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Location Where
Permitted
Minimum
Site Size Unit Size Maximum
Height Density Parking Setbacks Open Space Design
Standards Other
tandem parking with the
parking space provided
for the principal dwelling
unit.
the total number of persons in both
units may not exceed 8.
Vancouver,
BC
Within RS (one-family), RM
(multiple-dwelling), and RT (two-
family) zones
n/a ? ? 2 ADUs total (1 AADU
and 1 DADU) per lot
1 additional parking
(depending on when
house was built)
? ? ? Also called secondary suites
Mountlake
Terrace, WA
Within RS or RM zones 5000 sf 200sf min to 800sf max
(excl. garage areas), and
must be <40% of sf of
primary dwelling
Compliant with
dev’t stds (height)
for all SF dwellings
Total # of occupants
in both units shall not
exceed six unrelated
persons
No addl parking reqs,
except if legal on-street
parking n/a immediately
abutting site, one addl
parking space req’d on-
site
Comply with dev’t stds
(setbacks) for all SF
dwellings
? ADUs shall be designed and built to be consistent with
existing roof pitch, siding and windows of primary
dwelling unit
Owner occupancy reqs (either unit)
for min. of 3 consecutive
month/year. Both units cannot be
simultaneously leased
ADUs shall not be subdivided
Tacoma, WA
All areas, except in industrial M-2
and PMI districts
In R-1, R-2, R-2SRD and HMR-SRD
districts, only AADUs allowed
n/a for AADUs
fitting within
existing bldg
envelope
Floor area max equal to
lesser of 40% of main
home and ADU sf
combined or 1,000 sf
(2/3 of main building)
AADUs – same as
main home
1 ADU/res. lot
Up to 4 ppl may live
in an ADU; also see
minimum housing
code standards
Not required for ADU Same as for main
dwelling
AADUs must maintain appearance of single family
residence, and only one entrance door allowed in front
façade of dwelling
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Location Where Permitted Minimum
Site Size Unit Size Maximum Height Density Parking Setbacks Open Space Design Standards Other
Bozeman, MT
• Permitted if ADU located
above detached garage in
R-2, R-3. R-4, R-O, REMU
zones.
• In R-S and R-1 zones,
ADUs are permitted above
garages in subdivisions
with preliminary plat
approval after Jan 1. 1997,
and are also allowed as
dwelling unit within
detached single-
household dwelling
•6,000SF (except
4800SF in REMU
zone)
Min. lot widths
• R-2, R-3, R-4, R-O:
60ft
• R-S, R-1: 50 feet
• REMU: 40ft
•Lot widths can be 10
feet less (except for
R-S zones), when lot
is adjacent to an
alley, and vehicular
access is taken only
from that alley.
•R-S, R-1 zones: <800sf, or
<1/3 of total area of
principal structure, and not
>1 bedroom
•R-2, R-3, R-4, R-O, REMU
(res. single household lots
only): <600sf, and not >1
bedroom, and <footprint of
principal building
• Detached: 1 ½
stories for accessory
buildings, where floor
to floor height <12
feet, and “where a ½
story is established by
a side wall, under a
sloped roof, of 3 ft in
height or less above
the floor level within
space allowed to be
occupied by persons
by the IBC”
• Only one ADU may
be created per lot
• One additional paved
off-street parking space
provided for the
exclusive use of the
accessory of the
dwelling unit
Detached structure
not allowed in
front/side or corner-
side yard, must
occupy <20% of lot
area located to rear
of principal building,
AND
• <120SF: min 3ft
from rear ppty line
• 120-600SF: min 6 ft
from rear ppty line,
or if parking is b/t
structure and rear
property line, 20 ft,
except when parking
spaces require
greater setback for
backup
maneuverability
• >600SF: provision of
adequate back-up
maneuverability for
required parking
spaces
• Structure not
allowed in
front/side or
corner-side
yard, must
occupy <20% of
lot area located
to rear of
principal
building
• 2nd story additional only approved if
compatible with neighborhood character/fabric
• Entrance for ADU, if separate from entrance
of principal structure, to only be located in
rear/side yards
• 2 person occupancy limit for ADU
• Garages shall not be converted for use
as ADUs
• No deviations in lot area or parking reqs
and no more than two total deviations
total shall be granted to allow
establishment of ADU,
• In R-S, or R-1 zones owner occupancy
requirements for either primary or
accessory dwelling
Max lot coverage by principal and
accessory buildings shall be:
• in R-S dist. (new lots): determined
through PUD review procedures
• in R-S dist. (existing lots) <25% lot area
R-1. R-2, R-3. RMH: <40% for all uses
except townhouses
• R-1. R-2, R-3. RMH: <50% for
townhouses
• R-4 Zones: <50%
• R-O: <50% residential uses, 60% for
neighborhood/non-residential
Missoula, MT (20.45.060)
Detached ADUs are
allowed in RT5.4, RT2.7,
RM2.7, RM1, RM1.5
RM0.5, RMH, B, C and
M1R zoning districts, and
allowed as a conditional
use in R215, R80, R40,
R20, RT10, R8, R5.4 RT5.4,
R3, RT2.7, RM2.7, RM1,
RM1.5 RM0.5, RMH, B, C
and M1R zoning districts,
No additional land
area required for
ADU beyond
minimum parcel size
required for detached
house in subject
zoning district
Detached
New DADU: floor area <600
SF, and >350SF, except for
conversions of existing
accessory structures built
before June 5, 2013, in
which case there is no limit
to floor area unless the
conversion adds to the
floor area.
Lesser of 22 feet or
height of primary
building
Not included in min.
parcel area/unit
calculations
No more than one
ADU per parcel
At least 1 paved off-
street parking space
provided, in addition to
off-street parking reqs
for principal unit. For
parcels abutting alley,
access to parking for
ADU must come from
the alley.
DADU must be
located at least 10
feet behind detached
house, with the
separation open from
ground to the sky,
although it may
include walkways,
patios, decks, or
similar structures <30
inches in height
above finished grade
Exterior finish materials, roof pitch, and trim
must be same as principal detached house.
Building entrances to DADUs may not face the
nearest side/rear property line unless there is
an alley abutting that property line
Building coverage for DADU may not exceed
that of detached house, and combined
coverage of all detached accessory buildings
may not exceed 50% of actual rear yard area
Annual permit required, subject to no
substantial alterations, no change in
provision of required off-street parking
spaces, and meeting owner-occupancy
requirements
Connection of ADU to city sewer required
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Location Where Permitted Minimum
Site Size Unit Size Maximum Height Density Parking Setbacks Open Space Design Standards Other
Boulder, CO
Limited Accessory Units,
through conversion of
existing nonconforming
duplex or two detached
dwelling units on the
same R-1 lot. (Note: Only
applicable to dwelling
units legally existing and
actively used as multiple
dwelling units, with a valid
rental license on Jan 1,
2005.
9-7-12 of the Boulder
Municipal code allows two
detached dwellings on a
single lot in RM-2, RM-3,
RH-1, RH-2, RH-5 zones,
although they are both
treated as principal
buildings
Owner’s Accessory Units
can be established either
as unit within principal
structure, or within
accessory structure, on a
lot in RR, RE, and RMX-1
zones
>6000sf, where there
is only one detached
single-family dwelling
in RMX zone.
See 9-7-12 for two
detached dwellings
provisions
See 9-7-12 for two
detached dwellings
provisions
See 9-7-12 for two
detached dwellings
provisions
One additional off-street
parking space
See 9-7-12 for two
detached dwellings
provisions
See 9-7-12 for
two detached
dwellings
provisions
See 9-7-12 for two detached dwellings
provisions
See 9-7-12 for two detached dwellings
provisions
Bellingham
(Chapter
20.28.100 BMC)
•Detached ADUs are not
permitted in residential
single zones, neighb.
commercial zones or
property regulated by
Chapter 16.80 BMC, Lake
Whatcom Reservoir
Regulatory Provisions.
•Detached ADUs are
permitted in all other
zones that allow
residential, including
specifically designated
areas of urban villages.
• > 10,000 sq ft,
unless parcel has
alley access,or access
to more than one
public street
• The DADU is limited to
the lesser of 800 sq. ft or
40% of the primary
structure.
•Single floor area limited to
500 sq ft.
•Max FAR of 0.5 including
primary structure.
•Height must be less
than or equal to the
primary structure,
and no higher than 25
feet.
Detached:
•Only one DADU shall
be allowed per lot.
•The DADU is exempt
from density
limitations.
•One stall is reqd. for
the DADU.
•If parcel abuts an alley,
parking shall be
accessed from the alley
except when the
planning director
determines that alley
access is impractical or
environmentally
constrained. •Parking
accessed from the public
street/lane shall be
limited to 1 driveway
per street or lane with a
max. width of 20 ft.
•Front and side street
setbacks shall comply
with the underlying
zone for the main
building.
•Garage/Carport
setbacks shall provide
a 20ft backup
distance (incl. alley
width)
•Min. 6 feet of
separation is required
between the primary
residence and the
DADU.
n/a •The DADU shall have similar roof pitch, siding
and windows as the primary structure, or have
other similar features that satisfy the design
guidelines.
•Proportions and size of DADU to give
appearance it is secondary to primary structure
on site.
•Stagger windows to not align with those in
adjacent properties
•Provide small stoop/covered step associated
with separate DADU entrance
•It shall have an entrance with direct access to
a public street, lane or alley via a pedestrian
path or driveway.
•Both single-family residence and DADU entries
should be oriented to the street.
•At least one of the dwelling units must be
owner occupied.
•Purchasers of homes with an ADU must
register with the department of planning
and community development within 30
days of purchase.
•The DADU may not be divided from the
property ownership of the primary
dwelling.
•The parcel may not contain more than
one primary dwelling.
•The total number of persons who may
occupy the ADU shall not exceed 3,
regardless of relationship.
Everett
n/a (detached not
allowed)
n/a n/a n/a n/a n/a n/a n/a n/a n/a
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Location Where Permitted Minimum
Site Size Unit Size Maximum Height Density Parking Setbacks Open Space Design Standards Other
Portland
•An ADU may be added to
a house, attached house,
or manufactured home in
an R zone, except for
attached houses in the
R20-R5 zones that were
built using the regulations
of Duplexes and Attached
Houses on Corners.
n/a •The size of the accessory
dwelling unit may be no
more than 75
percent of the living area of
the primary dwelling unit
or 800 square feet,
whichever is less.
Detached:
The building coverage for
the DADU may not be
larger than the building
coverage of the house,
attached house, or
manufactured home. The
combined building
coverage of all detached
accessory structures may
not exceed 15% of the total
area of the site.
20’ when located
outside of required
setbacks for the zone,
15’ when an ADU is
allowed to be
located within
required setbacks for
the zone
•In the single-
dwelling zones, ADUs
are not included in
the min. or max.
density calculations
for a site. In all
aother zones, ADUs
are included in the
min. density
calculations, but are
not included in the
max. density
calculations.
•No additional parking is
required. Existing
parking must be
maintained or replaced
on-site.
•40 ft from the front
lot line; or behind the
rear wall of the
house, attached
house, or
manufactured home.
n/a For detached units >15’ high additional
standards apply
•The exterior finish material, roof pitch, trim,
and windows must be the same or visually
match in type, size and placement, the exterior
finish material of the house, attached house, or
manufactured home OR finish must be made
from wood, composite boards, vinyl or
aluminum products composed in a shingle
pattern, or in a horizontal clapboard or shiplap
pattern with boards 6 inches or less in width.
ADUs in “d” Design overlays (33.420), or some
historic designations (33.445) may be subject to
additional design reqs. These ADUs must meet
the Community Design Standards (33.218),
where allowed to use Community Design
Standards, or be approved through Design
review or Historic Resource review.
•The building coverage for the detached
ADU may not be larger than the building
coverage of the house, attached house or
manufactured home. The combined
building coverage of all detached
accessory structures may not exceed 15
percent of the total area of the site.
•The total number of individuals that
reside in both units may not exceed the
number that is allowed for a household.
Seattle
Ch.23.44
• Single-family or lowrise
zone, except any lots that
are within the Shoreline
district, in the rear yard
• 4,000 sq ft in single-
family zones
• min lot width 25ft,
• min lot depth 70ft.
•Detached accessory
dwelling units are limited
to 800 square feet in single
family zones, including any
garage and storage area
provided in the same
structure as the accessory
dwelling unit, but excluding
areas below grade and
covered porches/decks less
than 25 sf in area.
• In lowrise zones, 650
square feet
•12'-16' depending
on lot width; plus an
additional 3-7' above
base height if roof is
pitched and/or a
shed/butterfly roof.*
•One per single
family dwelling.
• Except on lots located
within areas that are
defined as either an
urban center or urban
village in the City's
Comp. Plan, one off-
street parking space is
required for the ADU
and may be provided as
tandem parking with the
parking space provided
for the principal
dwelling unit.
• May be in the rear
yard if the ADU is 5 ft
of any lot line, unless
the lot line is adjacent
to an alley, in which
case a detached
DADU may be located
at that lot line.
• Min. 5 ft.
separation from any
structure.
• A DADU, and
any other
accessory
structures and
other portions
of the principal
structure is
limited to 40%
of the rear yard
•Entrances to DADUs may not be located on
facades facing the nearest side lot line or the
rear lot line unless the nearest side lot line or
rear lot line abuts an alley or other public right-
of-way.
•An owner with at least 50% interest in
the property must occupy either the
principal dwelling unit or the ADU for six
or more months of each calendar year as
the owner's permanent residence.
•Any number of related persons may
occupy each unit in a single-family
dwelling unit with an accessory dwelling
unit; provided that, if unrelated persons
occupy either unit, the total number of
persons occupying both units may not
altogether exceed 8.
Vancouver, BC
Within RS (1-family), RM
(multiple-dwelling), and
RT (2-family) zones 9.8m (32 ft) in width
Lesser of 16% of site area,
or 83.6 m2 (899 sf)
Also subject to stds for bldg
width in certain zones
One-story: 3.7m (12
feet) if flat roof or to
mean height level b/t
eaves and ridge of
gable/hip roof,
except that no part of
house may be >4.6m
(15ft)
Partial two-story:19-
20 ft depending on
roof type
2 ADUs total (1 AADU
and 1 DADU) per lot
1 additional parking
(depending on when
house was built)
Within 9.8m (32 ft) of
rear pty line
At least 0.9m (2.95 ft)
from rear pty line
Distance from each
side pty line of at
least 10% of lot width
At least 4.9 (16
ft) from one-
family dwelling
to provide for
open space
Requirements for entry canopies, trim around
doors/windows, entry locations in relation to
the street, landscaping, wall cladding
Mountlake
Terrace, WA
Within RS or RM zones 5000 sf 200sf min to 800sf max
(excl. garage areas), and
must be <40% of sf of
primary dwelling
Compliant with dev’t
stds (height) for
accessory buildings
Total # of occupants
in both units shall not
exceed six unrelated
persons
No addl parking reqs,
except if legal on-street
parking n/a immediately
abutting site, one addl
parking space req’d on-
site
Compliant with dev’t
stds (setbacks) for all
accessory buildings
? ADUs shall be designed and built to be
consistent with existing roof pitch, siding and
windows of primary dwelling unit
Owner occupancy reqs (either unit) for
min. of 3 consecutive month/year. Both
units cannot be simultaneously leased
ADUs shall not be subdivided
Tacoma, WA
All areas, except in
industrial M-2 and PMI
districts
In R-1, R-2, R-2SRD and
HMR-SRD districts, only
AADUs allowed
DADUs must meet
min. lot areas and
min. lot width reqs of
zoning district
Floor area max equal to
lesser of 40% of main home
and ADU sf combined or
1,000 sf
(2/3 of main building)
DADUs must also meet
standards in TMC
13.06.100F
DADUs – up to 18ft,
subject to
13.06.150.D.3, and no
taller than main
house
1 ADU/res. lot
Up to 4 ppl may live
in an ADU; also see
minimum housing
code standards
Not required for ADU Same as for main
dwelling
DADUs must be
located in rear yard,
w/ 5 ft min from pty
lines, except along
alley
Design for DADU must be consistent with
architectural style, appearance and character of
main home
Entrance door shall not face same property line
as entrance to main building
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Comparison of Detached ADU Regulations across PNW Jurisdictions, Mid 2016
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