Chapter 17.30


17.30.010    Intent.

17.30.020    Types of accessory dwelling units.

17.30.030    Eligibility.

17.30.040    Preexisting accessory dwelling units.

17.30.050    No subdivision.

17.30.060    Development and design standards.

17.30.070    Accessibility.

17.30.080    Uses.

17.30.090    Permit issuance, renewal, recording, expiration and cancellation.

17.30.100    Appeal.

17.30.110    No transferability.

17.30.120    Enforcement.

17.30.130    Conflict.

17.30.010 Intent.

The intent of this chapter is to:

A.    Comply with RCW 43.63A.215, which requires cities with populations greater than twenty thousand to include provisions for accessory dwelling units in their development regulations.

B.    Protect the integrity of single-family residential neighborhoods while allowing accessory dwelling units to be located in single-family residential zoning districts.

C.    Diversify the housing options and increase the supply of affordable housing in the city.

D.    Enhance neighborhood stability by providing extra income that potentially could allow homeowners to live in their houses longer and maintain their property better. (Ord. 1219 § 5 (Exh. E) (part), 2009)

17.30.020 Types of accessory dwelling units.

A.    Interior. Accessory dwelling unit is located entirely within the footprint of the principal dwelling unit.

B.    Attached. Accessory dwelling unit shares a common wall or roof line with the principal dwelling unit but some or all of the accessory dwelling unit is outside the footprint of the principal dwelling unit.

C.    Detached. Accessory dwelling units that are neither interior nor attached. (Ord. 1219 § 5 (Exh. E) (part), 2009)

17.30.030 Eligibility.

Accessory dwelling units shall only be allowed:

A.    If it is a permitted use for the underlying zoning district pursuant to Chapter 17.16.

B.    The lot where the proposed accessory dwelling unit is to be located is at least:

1.    Five thousand square feet for interior and attached units; or

2.    Ten thousand square feet for detached units.

C.    The property owner (title holder or contract purchaser) resides in either the principal unit or the accessory dwelling unit as the permanent residence for at least six months of each calendar year. At no time may the property owner receive rent for whichever unit is owner-occupied.

D.    There are at least two off-street parking spaces serving the principal dwelling unit and at least one space is within a garage or carport.

E.    If any of the following uses are located on the lot, then an accessory dwelling unit shall not be allowed:

1.    Existing accessory dwelling unit.

2.    Extended family dwelling unit.

3.    Family day care home.

4.    Housing for people with functional disabilities.

5.    Rooming and boarding. (Ord. 1219 § 5 (Exh. E) (part), 2009)

17.30.040 Preexisting accessory dwelling units.

A.    Legal nonconforming accessory dwelling units and extended family dwelling units approved with a conditional use permit in existence prior to January 1, 2009, shall be allowed to continue as a conforming use.

1.    Property owners who are residents in either the principal or accessory dwelling unit may apply for an accessory dwelling unit permit and the permit shall be issued even if the provisions of this chapter cannot be met provided application is made within eighteen months of enactment of this chapter. However, an accessory dwelling unit permit shall only be approved if at least one off-street parking space for the accessory unit is provided. If an accessory dwelling unit permit is approved, then the accessory dwelling unit shall become a conforming use.

2.    The accessory dwelling unit permit may be renewed as allowed under Section 17.30.090 provided the provisions of this chapter that were met when the permit was issued are still met.

B.    Illegal accessory dwelling units and units built without benefit of a permit, in existence prior to the effective date of the ordinance codified in this chapter, may become legal conforming uses if property owners are residents in either the principal or accessory dwelling unit, all required permits are obtained, all of the requirements of this chapter, including but not limited to parking requirements, are met and application for an accessory dwelling unit permit is made and approved. (Ord. 1219 § 5 (Exh. E) (part), 2009)

17.30.050 No subdivision.

Lots with accessory dwelling units shall not be subdivided or otherwise segregated in a manner that distinguishes between the accessory dwelling unit and the principal dwelling unit. (Ord. 1219 § 5 (Exh. E) (part), 2009)

17.30.060 Development and design standards.

A.    All accessory dwelling units shall comply with all applicable codes and standards, including but not limited to the:

1.    International Building Code.

2.    International Residential Code.

3.    International Fire Code.

B.    Structure Exterior Standards. New exterior construction associated with creating an accessory dwelling unit shall be similar to the exterior appearance of the principal dwelling unit.

1.    Exterior finish materials shall be the same or visually match in type, size and placement the exterior finish material of the principal dwelling unit.

2.    The roof pitch shall be similar to the predominant roof pitch of the principal dwelling unit.

3.    Trim must be the same in type, style, design, size, and location as the trim used on the principal dwelling.

4.    Windows shall be similar to those in the principal dwelling in proportion (relationship of width to height) and orientation (horizontal or vertical). This standard shall not apply when in conflict with building code regulations.

Examples of Units Meeting Structure Exterior Standards

C.    Location in Relation to Principal Residence.

1.    Interior accessory dwelling units shall be completely within the principal dwelling unit footprint.

2.    Attached accessory units shall:

a.    Comply with the standard unmodified setback requirements of the underlying zoning district.

b.    Not be closer to the front property line than the front of the principal unit.

3.    Detached accessory dwelling units shall:

a.    Comply with the standard unmodified setback requirements of the underlying zoning district.

b.    Be at least twenty feet further from the front property line than the front of the principal unit.

Location and Height Illustration (C3 and D)

D.    Height. Accessory dwelling units shall:

1.    Comply with the maximum building heights allowed for the underlying zoning district;

2.    Not exceed the height of the principal dwelling unit if a detached unit;

3.    Be a maximum of two floors/stories; or

4.    A maximum of one floor/story if a detached unit located above a garage or storage area or habitable area.

E.    Setbacks. All accessory dwelling units shall conform to the front, rear and side yard setbacks for the underlying zoning district.

F.    Pedestrian Entrances.

1.    Shall have direct access to the exterior completely independent of the principal unit.

2.    Shall be subordinate to the principal dwelling unit entrance.

3.    Shall not face the public street or roadway from which the principal unit takes primary access. If the ADU is a detached unit located behind the principal unit, then the entrance may face the public street or roadway.

4.    If access is by stairway, the stairway shall either be internal, or if external, not on the front facade.

5.    If a lot is adjacent to an open alley, then the ADU entrance shall be provided off the alley unless the city finds there is a compelling reason to the contrary.

6.    Shall be connected to the street or alley by an unobstructed hard surface pedestrian walkway with a minimum vertical clearance of seven feet.

Pedestrian Entrance and Parking Illustration (F and I)

Pedestrian Entrance, External Stairway and Privacy Screening Illustration (F and G)

G.    Privacy. The privacy of dwelling units on adjacent lots and accessory dwelling units shall be protected to the maximum extent practical by:

1.    Orienting the accessory dwelling unit to not directly face dwelling units on adjacent lots.

2.    Using landscape screening, fencing, and window and door placement to maintain the privacy of residents in dwellings on adjacent lots as determined by the physical characteristics surrounding the accessory dwelling unit.

3.    Windows, doors, and balconies shall be designed and located to maintain the privacy of both the new unit and dwellings on adjacent lots.

4.    Interior ADUs are exempted from the privacy design standard requirements.

H.    Floor Area.

1.    The accessory dwelling unit shall have a gross floor area of no more than seven hundred square feet or sixty percent of the floor area of the principal dwelling unit, whichever is less.

2.    The accessory dwelling unit shall have no more than one bedroom.

I.    Parking.

1.    At least two off-street parking spaces shall be provided for the accessory dwelling unit, in addition to the parking required for the principal dwelling unit. The parking space(s):

a.    Shall be dedicated solely for use by the accessory dwelling unit residents.

b.    Shall have a defined hardened surface such as, but not limited to, pavement, concrete (pervious or impervious) or gravel.

c.    May be located in a garage, carport, or in an off-street area reserved for vehicle parking.

d.    Shall be independent of the principal unit’s parking spaces, which means access to the accessory dwelling unit’s parking spaces shall not require crossing over any part of a parking space serving the principal unit nor may the accessory unit’s parking spaces be located in tandem to the principal unit’s spaces.

e.    May encroach into a side yard setback area only if no structures are within thirteen feet of the property line.

2.    When an accessory dwelling unit is located on a lot adjacent to an alley, access to the parking space(s) shall be from the alley unless topography makes such access infeasible.

Entrance, Privacy and Parking Illustration (F, G and I)

J.    Addressing. The address for the accessory dwelling unit shall be different than the address for the principal dwelling unit unless required otherwise by the United States Postal Service. (Ord. 1219 § 5 (Exh. E) (part), 2009)

17.30.070 Accessibility.

A.    In order to encourage the development of housing units suitable for people with disabilities, the director may allow reasonable deviations from the requirements of this chapter and this title to install features or facilities that facilitate accessibility. Potential deviations include, but are not limited to:

1.    Increase in floor area (both total and as a percentage of the principal unit’s floor area) to accommodate larger doorways, restrooms and other ADA accessibility requirements.

2.    Encroachments into setbacks to accommodate steps and ramps.

B.    Deviations that do not comply with building or fire codes shall be prohibited.

C.    Deviations pursuant to this section shall not require a variance. (Ord. 1219 § 5 (Exh. E) (part), 2009)

17.30.080 Uses.

A.    The following uses are prohibited on lots with an accessory dwelling unit:

1.    SFR cottages.

2.    Townhouse.

3.    Multifamily.

4.    Extended family dwelling unit.

5.    Family day care home.

6.    Group care facility.

7.    Housing for people with functional disabilities.

8.    Retirement apartments and/or housing.

9.    Rooming and boarding.

B.    No more than one home occupation may be located on a lot where an accessory dwelling unit is located. (Ord. 1219 § 5 (Exh. E) (part), 2009)

17.30.090 Permit issuance, renewal, recording, expiration and cancellation.

A.    Application Process. Application, review and approval of an accessory dwelling unit permit shall be pursuant to Chapter 17.13, Project Permit Review Procedures.

B.    Permit Issuance.

1.    No construction permit for any improvements or occupancy permit for an accessory dwelling unit shall be issued until an accessory dwelling unit permit for the unit is approved pursuant to this chapter.

2.    Permits issued pursuant to this chapter shall be issued only to the resident property owner and shall be valid only so long as the permit holder owns the property in title or as a contract purchaser and is a resident of one of the dwelling units on the property.

C.    Ownership Verification. Prior to the issuance of an accessory dwelling unit permit, and annually by April 1st each year thereafter, the owner of the property shall file an owner’s certificate of occupancy in a form acceptable to the director. Any person who falsely certifies that he or she resides in a dwelling unit at the stated address to satisfy the requirements of this section shall be subject to the violation and penalty provisions of Title 18.

D.    Expiration. Accessory dwelling unit permits shall expire automatically if:

1.    An approved owner’s certificate of occupancy is not submitted as required in subsection C of this section each year by April 1st.

2.    The accessory dwelling unit is altered such that it no longer conforms with the intent of the plans approved by the director.

3.    The required off-street parking spaces for both the accessory and principal dwelling units are no longer provided in conformance with the requirements of this chapter.

4.    The applicant ceases to own the property and reside in either the principal or the accessory dwelling unit.

5.    City access to inspect the property is not provided within fourteen days of a request for inspection being mailed to the property owner.

E.    Effect of Property Sale.

1.    If the original applicant for an existing accessory dwelling unit permit sells the property where the unit is located, a permit application shall be submitted by the new contract purchaser or new property owner. The application shall be reviewed pursuant to Chapter 17.13, except submittal of construction drawings and/or site plans is not required if no physical modifications to the existing accessory dwelling unit are proposed.

2.    If property with an occupied accessory dwelling unit is sold, tenants may continue to reside at the property for the remainder of any lease, or up to ninety calendar days, whichever is shorter. A single additional continuation of up to ninety calendar days may be granted by the director, upon written request by both the tenant and the (new) property owner, if it is determined termination of residency by the tenants would impose a substantial and unusual hardship on the tenants. For continued occupancy by the tenants, the new property owner must obtain an accessory dwelling unit permit.

F.    Cancellation. An accessory dwelling unit permit may be cancelled by the property owner by filing with the city an affidavit that the owner is relinquishing an approved accessory dwelling unit permit and recording the certificate at the county.

G.    Revocation. A permit for an accessory dwelling unit may be revoked by the city for violation of the requirements of this chapter or if the city discovers fraudulent activity in obtaining the permit.

H.    Recording Requirements. Any permit approved under this section shall not become effective until evidence is provided to the director that a land use permit binder and other documents as required by the director have been recorded with the Snohomish County auditor’s office. The recorded document(s), in a format approved by the director, shall contain, but not be limited to, the following information:

1.    Identify the parcel where the accessory dwelling unit is located;

2.    State the accessory dwelling unit permit is only valid for the identified parcel;

3.    State any changes to the recorded documents must be approved by the city of Mukilteo;

4.    State the owner of the property lives in one of the dwelling units;

5.    Notify future owners or long-term lessors of the subject property that the existence of the accessory dwelling unit is predicated upon the occupancy of either the accessory dwelling unit or the principal dwelling by the property owner;

6.    Notify prospective buyers of the limitations of this section and to provide for the removal of improvements that created the accessory dwelling unit and restoration of the site to a single-family dwelling with no additional dwelling units in the event that any condition of approval is violated. (Ord. 1219 § 5 (Exh. E) (part), 2009)

17.30.100 Appeal.

Decisions by the director may be appealed by the applicant pursuant to the provisions in Chapter 17.13. (Ord. 1219 § 5 (Exh. E) (part), 2009)

17.30.110 No transferability.

A permit for an accessory dwelling unit shall not be transferable to any lot other than the lot described in the application nor may it be transferred to different owners of the lot. (Ord. 1219 § 5 (Exh. E) (part), 2009)

17.30.120 Enforcement.

Violations of this chapter are punishable under Title 18, Land Use Enforcement, and as otherwise provided by law, and are subject to injunctive and other forms of civil relief which the city may seek. (Ord. 1219 § 5 (Exh. E) (part), 2009)

17.30.130 Conflict.

In the event that there is a conflict between the provisions of this chapter and those in any other chapter of the Mukilteo Municipal Code enacted prior to the enactment of this chapter, the provisions of this chapter shall control. (Ord. 1219 § 5 (Exh. E) (part), 2009)