Chapter 19.02
RESIDENTIAL Revised 8/18

Sections:

19.02.005    Purpose and applicability.

19.02.010    Single-family.

19.02.020    Development standards. Revised 8/18

19.02.030    Accessory dwelling units.

19.02.040    Garages, other accessory buildings and accessory structures.

19.02.050    Fences, retaining walls and rockeries. Revised 8/18

19.02.060    Lot coverage – Regulated improvements.

19.02.070    Swimming pools.

19.02.005 Purpose and applicability.

A. Purpose. The purpose of the residential chapter is to identify land uses and to establish development standards that are appropriate within the residential zoning designations. The development standards provide a framework for a site to be developed consistent with the policy direction of the adopted Mercer Island Comprehensive Plan.

B. Applicability.

1. The provisions of this chapter shall apply to all development proposals in the R-8.4, R-9.6, R-12, and R-15 zoning designations.

2. Unless otherwise indicated in this chapter, the applicant shall be responsible for the initiation, preparation, and submission of all required plans or other documents prepared in support of or necessary to obtain a permit and to determine compliance with this chapter. (Ord. 17C-15 § 1 (Att. A).

19.02.010 Single-family.

A use not permitted by this section is prohibited. Please refer to MICC 19.06.010 for other prohibited uses.

A. Uses Permitted in Zones R-8.4, R-9.6, R-12, and R-15.

1. Single-family dwelling.

2. Accessory buildings incidental to the main building.

3. Private recreational areas.

4. Public schools accredited or approved by the state for compulsory school attendance, subject to design commission review and all of the following conditions:

a. All structures shall be located at least 35 feet from any abutting property and at least 45 feet from any public right-of-way.

b. Off-street parking shall be established and maintained at a minimum ratio of one parking space per classroom with high schools providing an additional one parking space per 10 students.

c. A one-fourth acre or larger playfield shall be provided in one usable unit abutting or adjacent to the site.

5. Home business as an accessory use to the residential use, subject to all of the following conditions:

a. The home business may make those improvements to the home business normally allowed for single-family residences. For a day care, play equipment and play areas are not allowed in front yards.

b. Only those persons who reside on the premises and one other person shall be permitted to engage in the business on the premises at any one time; provided, that a day care or preschool may have up to three nonresident employees on the premises at any one time. This limitation applies to all owners, managers, staff or volunteers who operate the business.

c. There shall be no exterior storage or display of materials except as otherwise allowed for single-family residences, and no sign advertising the home business located on the premises except as specifically allowed by MICC 19.12.080(B).

d. No offensive noise, vibration, smoke, dust, odor, heat or glare or excessive traffic to and from the premises shall be produced or generated by the home business.

e. The home business shall not involve the use of more than 30 percent of the gross floor area of the residence, not including the allowed basement exclusion area consistent with subsection E of this section and MICC 19.16.010(G). However, a day care or preschool may use up to 75 percent of said gross floor area.

f. No home business shall be permitted that generates parking demand that cannot be accommodated on the lots consistent with the applicable maximum impervious surface coverage limits of MICC 19.02.060. Parking shall be provided to handle the expected parking demand. In the case of a day care or preschool, parking for residents and employees shall occur on site; resident and employee parking shall not occur on an adjacent street.

g. The business shall not provide healthcare services, personal services, automobile repairs; serve as a restaurant, commercial stable, kennel, or place of instruction licensed as a school under state law and which will operate with more than three students at a time; or serve as a bed and breakfast without a conditional use permit as set out in subsection (C)(7) of this section. Nothing contained in this subsection (A)(5)(g) shall be interpreted to prohibit a day care.

h. A day care shall be limited to 18 children maximum (not including dependents) at a time.

6. Public park subject to the following conditions:

a. Access to local and/or arterial thoroughfares shall be reasonably provided.

b. Outdoor lighting shall be located to minimize glare upon abutting property and streets.

c. Major structures, ballfields and sport courts shall be located at least 20 feet from any abutting property.

d. If a permit is required for a proposed improvement, a plot, landscape and building plan showing compliance with these conditions shall be filed with the city development services group (DSG) for its approval.

7. Semi-private waterfront recreation areas for use by 10 or fewer families, subject to the conditions set out in MICC 19.07.080.

8. One accessory dwelling unit (ADU) per single-family dwelling subject to conditions set out in MICC 19.02.030.

9. Special needs group housing as provided in MICC 19.06.080.

10. Social service transitional housing, as provided in MICC 19.06.080.

11. A state-licensed day care or preschool as an accessory use, when situated at and subordinate to a legally established place of worship, public school, private school, or public facility, meeting the following requirements:

a. The number of children in attendance at any given time shall be no more than 20 percent of the legal occupancy capacity of the buildings on the site, in the aggregate.

b. Signage shall be consistent with the provisions of MICC 19.12.080(B)(3).

c. Off-street parking provided by the primary use shall be deemed sufficient for the accessory day care or preschool if at least one space per employee is provided, and either:

i. One additional parking space is provided for every five children in attendance, or

ii. Adequate pick-up and drop-off space is provided as determined by the code official.

12. Places of worship may have a stage theater program as an accessory use. Stage theater programs are defined as productions of live presentations involving the performances of actors or actresses, singers, dancers, musical groups, or artists. Stage theater programs also include related classes and instructional workshops. Adequate parking must be provided, as determined by the code official.

B. Additional Use Permitted in Zones R-9.6, R-12, and R-15. One accessory building for the housing of domestic animals and fowl, having a floor area not to exceed 36 square feet for each lot and located not less than 65 feet from any place of habitation other than the owners’; provided, the roaming area shall be fenced and located not less than 35 feet from any adjacent place of human habitation.

C. Conditional Uses. The following uses are permitted when authorized by the issuance of a conditional use permit when the applicable conditions set forth in this section and in MICC 19.15.020(G)(3) have been met:

1. Government services, public facilities, utilities, and museums and art exhibitions, subject to the following conditions:

a. All structures shall be located at least 20 feet from any abutting property;

b. Off-street parking shall be established and maintained at a minimum ratio of one parking space for each 200 square feet of gross floor area; and

c. Utilities shall be shielded from abutting properties and streets by a sight obscuring protective strip of trees or shrubs.

2. Private schools accredited or approved by the state for compulsory school attendance, subject to conditions set out in subsection (A)(4) of this section.

3. Places of worship subject to the following conditions:

a. All structures shall be located at least 35 feet from any abutting property.

b. Off-street parking shall be established and maintained at a ratio of one parking space for each five seats in the chapel, nave, sanctuary, or similar worship area.

4. Noncommercial recreational areas, subject to the conditions contained in subsection (A)(6) of this section.

5. Semi-private waterfront recreation areas for use by more than 10 families, subject to conditions set out in MICC 19.07.080.

6. Retirement homes located on property used primarily for a place of worship subject to the following conditions:

a. Retirement home structures shall not occupy more than 20 percent of the lot; provided, the total lot coverage for the retirement home, the place of worship, and all other structures shall not exceed the lot coverage specified in MICC 19.02.060.

b. A plot, landscape and building plan shall be filed with the design commission for its approval, and the construction and maintenance of buildings and structures and the establishment and continuation of uses shall comply with the approved plot, landscape and building plan. Alterations to the project are permitted only upon approval by the design commission of a new or amended plan.

c. The number of dwelling units shall be determined by the planning commission upon examination of the following factors:

i. Demonstrated need;

ii. Location, size, shape and extent of existing development on the subject property;

iii. Nature of the surrounding neighborhood; and

iv. Legal assurances that the entire property remains contiguous, and that the retirement home is owned and controlled by the applicant religious organization.

d. The retirement home shall be located at least 35 feet from all abutting property.

e. Off-street parking shall be established and maintained at a ratio of one-half parking space for each dwelling unit.

7. The use of a single-family dwelling as a bed and breakfast subject to the following conditions:

a. The bed and breakfast facility shall meet all applicable health, fire, and building codes.

b. Not more than four rooms shall be offered to the public for lodging.

c. There shall be no external modification of any structure that alters the residential nature of the premises.

d. The bed and breakfast shall be the primary residence of the operator.

e. In addition to the parking required set out in MICC 19.02.020(G), one off-street parking space, not located in the lot setbacks, shall be provided for each rental room.

f. Meals shall be made available only to guests, and not to the general public.

8. Nonschool uses of school buildings, subject to the following conditions:

a. No use or proposed use shall be more intensive than the school activity it replaced. Consideration shall be given to quantifiable data, such as, but not limited to, traffic generation, parking demand, noise, hours of operation;

b. All activities, with the exception of outdoor recreation shall be confined to the interior of the building(s);

c. Exterior modification of the building(s) shall not be permitted if such a modification would result in an increase in the usable area of the building(s);

d. Minor changes in the building exterior, landscaping, signs, and parking may be permitted subject to the review and approval of the design commission; and

e. Off-street parking for all activities at the site shall be provided in existing school parking lots.

f. Termination. Conditional use permits for nonschool uses shall terminate and the use of the site shall conform to the requirements of the zone in which the school building is located on the day of the termination under the following conditions:

i. The school building is demolished or sold by the Mercer Island school district.

ii. The city council revokes the permit on the recommendation of the planning commission. Revocation shall be based on a finding that the authorized use constitutes a nuisance or is harmful to the public welfare, or the applicant has failed to meet the conditions imposed by the city.

g. Revision. Any modification to a nonschool conditional use permit shall be approved by the planning commission; however, the code official may approve minor modifications that are consistent with the above stated conditions.

9. A state-licensed day care or preschool not meeting the requirements of subsection (A)(11) of this section, subject to the following conditions:

a. Off-street parking and passenger loading shall be sufficient to meet the needs of the proposed day care or preschool without causing overflow impacts onto adjacent streets.

b. Signage shall be consistent with the provisions of MICC 19.12.080(B)(3). (Ord. 17C-15 § 1 (Att. A); Ord. 15C-03 § 1; Ord. 09C-04 §§ 1, 2; Ord. 08C-01 § 1; Ord. 05C-16 § 1; Ord. 04C-08 § 9; Ord. 03C-08 § 3; Ord. 01C-06 § 1; Ord. 99C-13 § 1).

19.02.020 Development standards. Revised 8/18

A. Minimum Net Lot Area.

R-8.4:

The net lot area shall be at least 8,400 square feet. Lot width shall be at least 60 feet and lot depth shall be at least 80 feet.

R-9.6:

The net lot area shall be at least 9,600 square feet. Lot width shall be at least 75 feet and lot depth shall be at least 80 feet.

R-12:

The net lot area shall be at least 12,000 square feet. Lot width shall be at least 75 feet and lot depth shall be at least 80 feet.

R-15:

The net lot area shall be at least 15,000 square feet. Lot width shall be at least 90 feet and lot depth shall be at least 80 feet.

1. Minimum net lot area requirements do not apply to any lot that came into existence before September 28, 1960. In order to be used as a building site, lots that do not meet minimum net lot area requirements shall comply with MICC 19.01.050(G)(3).

2. In determining whether a lot complies with the minimum net lot area requirements, the following shall be excluded: the area between lateral lines of any such lot and any part of such lot which is part of a street.

B. Street Frontage. No building will be permitted on a lot that does not front onto a street acceptable to the city as substantially complying with the standards established for streets.

C. Yard Requirements.

1. Minimum. Except as otherwise provided in this section, each lot shall have front, rear, and side yards not less than the depths or widths following:

a. Front yard depth: 20 feet or more.

b. Rear yard depth: 25 feet or more.

c. Side yards shall be provided as follows:

i. Total Depth.

(a) For lots with a lot width of 90 feet or less, the sum of the side yards’ depth shall be at least 15 feet.

(b) For lots with a lot width of more than 90 feet, the sum of the side yards’ depth shall be a width that is equal to at least 17 percent of the lot width.

ii. Minimum Side Yard Depth.

(a) The minimum side yard depth abutting an interior lot line is five feet or 33 percent of the aggregate side yard total depth, whichever is greater.

(b) The minimum side yard depth abutting a street is five feet.

iii. Variable Side Yard Depth Requirement. For lots with an area of 6,000 square feet or more, the minimum side yard depth abutting an interior lot line shall be the greater of the minimum side yard depth required under subsection (C)(1)(c)(ii) of this section, or as follows:

(a) Single-family dwellings shall provide a minimum side yard depth of seven and one-half feet if the building:

(1) For nongabled roof end buildings, the height is more than 15 feet measured from existing or finished grade, whichever is lower, to the top of the exterior wall facade adjoining the side yard; or

(2) For gabled roof end buildings, the height is more than 18 feet measured from existing or finished grade, whichever is lower, to the top of the gabled roof end adjoining the side yard.

(b) Single-family dwellings with a height of more than 25 feet measured from the existing or finished grade, whichever is lower, to the top of the exterior wall facade adjoining the side yard shall provide a minimum side yard depth of 10 feet.

2. Yard Determination.

a. Front Yard. The front yard is the yard abutting an improved street from which the lot gains primary access or the yard abutting the entrance to a building and extending the full width of the lot. If this definition does not establish a front yard setback, the code official shall establish the front yard based upon orientation of the lot to surrounding lots and the means of access to the lot.

i. Waterfront Lot. On a waterfront lot, regardless of the location of access to the lot, the front yard may be measured from the property line opposite and generally parallel to the ordinary high water line.

b. Rear Yard. The rear yard is the yard opposite the front yard. The rear yard shall extend across the full width of the rear of the lot, and shall be measured between the rear line of the lot and the nearest point of the main building including an enclosed or covered porch. If this definition does not establish a rear yard setback for irregularly shaped lots, the code official may establish the rear yard based on the following method: The rear yard shall be measured from a line or lines drawn from side lot line(s) to side lot line(s), at least 10 feet in length, parallel to and at a maximum distance from the front lot line.

c. Corner Lots. On corner lots the front yard shall be measured from the narrowest dimension of the lot abutting a street. The yard adjacent to the widest dimension of the lot abutting a street shall be a side yard. If a setback equivalent to or greater than required for a front yard is provided along the property lines abutting both streets, then only one of the remaining setbacks must be a rear yard. This code section shall apply except as provided for in MICC 19.08.030(F)(1).

d. Side Yard. Any yards not designated as a front or rear yard shall be defined as a side yard.

3. Intrusions into Required Yards.

a. Minor Building Elements.

i. Except as provided in subsection (C)(3)(a)(ii) of this section, porches, chimney(s) and fireplace extensions, window wells, and unroofed, unenclosed outside stairways and decks shall not project more than three feet into any required yard. Eaves shall not protrude more than 18 inches into any required yard.

ii. No penetration shall be allowed into the minimum side yard setback abutting an interior lot line except where an existing flat-roofed house has been built to the interior side yard setback line and the roof is changed to a pitched roof with a minimum pitch of 4:12, the eaves may penetrate up to 18 inches into the side yard setback.

b. Hardscape and Driveways. Hardscape and driveways not more than 30 inches above existing grade or finished grade, whichever is lower, may be located in any required yard.

c. Fences, Retaining Walls and Rockeries. Fences, retaining walls and rockeries are allowed in required yards as provided in MICC 19.02.050.

d. Garages and Other Accessory Buildings. Garages and other accessory buildings are not allowed in required yards, except as provided in MICC 19.02.040.

e. Heat Pumps, Air Compressors, Air Conditioning Units, and Other Similar Mechanical Equipment. Heat pumps, air compressors, air conditioning units, and other similar mechanical equipment may be located within any required yard provided they will not exceed the maximum permissible noise levels set forth in WAC 173-60-040, which is hereby incorporated as though fully set forth herein. Any such equipment shall not be located within three feet of any lot line.

f. Architectural Features. Detached, freestanding architectural features such as columns or pedestals that designate an entrance to a walkway or driveway and do not exceed 42 inches in height are allowed in required yards.

g. Other Structures. Except as otherwise allowed in this subsection (C)(3), structures over 30 inches in height from existing grade or finished grade, whichever is lower, may not be constructed in or otherwise intrude into a required yard.

4. Setback Deviation. The code official may approve a deviation to front, side, and rear setbacks pursuant to MICC 19.15.020.

D. Gross Floor Area.

1. Except as provided in subsection (D)(3) of this section, the gross floor area shall not exceed:

a. R-8.4: 5,000 square feet or 40 percent of the lot area, whichever is less.

b. R-9.6: 8,000 square feet or 40 percent of the lot area, whichever is less.

c. R-12: 10,000 square feet or 40 percent of the lot area, whichever is less.

d. R-15: 12,000 square feet or 40 percent of the lot area, whichever is less.

2. Gross Floor Area Calculation. The gross floor area is the sum of the floor area(s) bounded by the exterior faces of each building on a residential lot, provided:

a. The gross floor area shall be 150 percent of the floor area of that portion of a room(s) with a ceiling height of 12 feet to 16 feet, measured from the floor surface to the ceiling.

b. The gross floor area shall be 200 percent of the floor area of that portion of a room(s) with a ceiling height of more than 16 feet, measured from the floor surface to the ceiling.

c. Staircases shall be counted as a single floor for the first two stories accessed by the staircase. For each additional story above two stories, the staircase shall count as a single floor area. For example, a staircase with a 10-foot by 10-foot dimension that accesses three stories shall be accounted as 200 square feet (100 square feet for the first two stories, and 100 square feet for the third story).

d. For the purposes of calculating allowable gross floor area, lots created in a subdivision through MICC 19.08.030(G), Optional Standards for Development, may apply the square footage from the open space tract to the lot area not to exceed the minimum square footage of the zone in which the lot is located.

3. Allowances.

a. The gross floor area for lots with an area of 7,500 square feet or less may be the lesser of 3,000 square feet or 45 percent of the lot area; or

b. If an accessory dwelling unit is proposed, the 40 percent allowed gross floor area may be increased by the lesser of five percentage points or the actual floor area of the proposed accessory dwelling unit, provided:

i. The allowed gross floor area of accessory buildings that are not partially or entirely used for an accessory dwelling unit shall not be increased through the use of this provision;

ii. The lot will contain an accessory dwelling unit associated with the application for a new or remodeled single-family home; and

iii. The total gross floor area shall not exceed 4,500 square feet or 45 percent of the lot area, whichever is less.

E. Building Height Limit.

1. Maximum Building Height. No building shall exceed 30 feet in height above the average building elevation to the highest point of the roof.

2. Maximum Building Height on Downhill Building Facade. The maximum building facade height on the downhill side of a sloping lot shall not exceed 30 feet in height. The building facade height shall be measured from the existing grade or finished grade, whichever is lower, at the furthest downhill extent of the proposed building, to the top of the exterior wall facade supporting the roof framing, rafters, trusses, etc.

3. Antennas, lightning rods, plumbing stacks, flagpoles, electrical service leads, chimneys and fireplaces and other similar appurtenances may extend to a maximum of five feet above the height allowed for the main structure in subsections (E)(1) and (2) of this section.

4. The formula for calculating average building elevation is as follows:

Formula:

Average Building Elevation = (Weighted Sum of the Mid-point Elevations) ÷ (Total Length of Wall Segments)

Where:

Weighted Sum of the Mid-point Elevations = The sum of: ((Mid-point Elevation of Each Individual Wall Segment) x (Length of Each Individual Wall Segment))

For example for a house with 10 wall segments:

(Axa) + (Bxb) + (Cxc) + (Dxd) + (Exe) + (Fxf) + (Gxg) + (Hxh) + (Ixi) + (Jxj)

a + b + c + d + e + f + g + h + i + j

Where:

A, B, C, D… = The existing or finished ground elevation, whichever is lower, at midpoint of wall segment.

And:

a, b, c, d… = The length of wall segment measured on outside of wall.

F. Lot Coverage – Single-Family Dwellings.

1. Applicability. This section shall apply to the development of single-family dwellings including, but not limited to, the remodeling of existing single-family dwellings and construction of new single-family dwellings. This section does not apply to regulated improvements.

2. Landscaping Objective.

a. To ensure that landscape design reinforces the natural and wooded character of Mercer Island, complements the site, the architecture of site structures and paved areas, while maintaining the visual appearance of the neighborhood.

b. To ensure that landscape design is based on a strong, unified, coherent, and aesthetically pleasing landscape concept.

c. To ensure that landscape plantings, earth forms, and outdoor spaces are designed to provide a transition between each other and between the built and natural environment.

d. To ensure suitable natural vegetation and landforms, particularly mature trees and topography, are preserved where feasible and integrated into the overall landscape design. Large trees and tree stands should be maintained in lieu of using new plantings.

e. To ensure planting designs include a suitable combination of trees, shrubs, groundcovers, vines, and herbaceous material; include a combination of deciduous and evergreen plant material; emphasize native plant material; provide drought-tolerant species; and exclude invasive species.

3. Lot Coverage – Landscaping Required.

a. Minimum Area Required. Development proposals for single-family dwellings shall comply with the following standards based on the net lot area:

Lot Slope

Maximum Lot Coverage (house, driving surfaces, and accessory buildings)

Required Landscaping Area

Less than 15%

40%

60%

15% to less than 30%

35%

65%

30% to 50%

30%

70%

Greater than 50% slope

20%

80%

b. Hardscape.

i. A maximum of nine percent of the net lot area may consist of hardscape improvements including, but not limited to, walkways, decks, etc., and provided:

(a) The hardscape for lots with a net lot area of 8,400 square feet or less may be the lesser of 755 square feet or 12 percent of the net lot area.

ii. Hardscape improvements are also permitted in the maximum lot coverage area established in subsection (F)(3)(a) of this section.

c. Softscape and Driveways.

i. The required landscaping area in subsection (F)(3)(a) of this section shall consist of softscape improvements, except where used for hardscape improvements pursuant to section (F)(3)(b) of this section.

ii. Driveways and other driving surfaces are prohibited within the landscaping area.

For example, a flat lot with a net area of 10,000 square feet shall provide a minimum 6,000 square feet of landscaped area. Up to 900 square feet of the landscaped area may be used for a walkway, patio, or deck or other hardscape area. The remainder of the area shall be used for softscape improvements, such as landscaping, tree retention, etc.

d. Development proposals for a new single-family home shall remove Japanese knotweed (Polygonum cuspidatum) and Regulated Class A, Regulated Class B, and Regulated Class C weeds identified on the King County Noxious Weed list, as amended, from required landscaping areas established pursuant to subsection (F)(3)(a) of this section. New landscaping associated with new single-family home shall not incorporate any weeds identified on the King County Noxious Weed list, as amended. Provided, that removal shall not be required if the removal will result in increased slope instability or risk of landslide or erosion.

e. Allowed Adjustments. A one-time reduction in required landscaping area and an increase in the maximum lot coverage are allowed, provided:

i. The total reduction in the required landscaping area shall not exceed five percentage points, and the total increase in the maximum lot coverage shall not exceed five percentage points; and

ii. The reduction in required landscaping area and increase in maximum lot coverage are associated with:

(a) A development proposal that will result in a single-story single-family dwelling with a wheelchair accessible entry path, and may also include a single-story accessory building; or

(b) A development proposal on a flag lot that, after optimizing driveway routing and minimizing driveway width, requires a driveway that occupies more than 25 percent of the otherwise allowed lot coverage area. The allowed reduction in the required landscaping area and increase in maximum lot coverage shall not exceed five percent, or the area of the driveway in excess of 25 percent of the lot coverage, whichever is less.

For example, a development proposal with a driveway that occupies 27 percent of the otherwise allowed lot coverage may increase the total lot coverage by two percent; and

iii. A recorded notice on title, covenant, easement, or other documentation in a form approved by the city shall be required. The notice on title or other documentation shall describe the basis for the reduced landscaping area and increased lot coverage.

G. Parking.

1. Applicability. Subsection (G)(2) of this section shall apply to all new construction and remodels where more than 40 percent of the length of the structure’s external walls have been intentionally structurally altered.

2. Parking Required.

a. Each single-family dwelling with a gross floor area of 3,000 square feet or more shall have at least three parking spaces sufficient in size to park a passenger automobile; provided, at least two of the stalls shall be covered stalls.

b. Each single-family dwelling with a gross floor area of less than 3,000 square feet shall have at least two parking spaces sufficient in size to park a passenger automobile; provided, at least one of the stalls shall be a covered stall.

3. No construction or remodel shall reduce the number of parking spaces on the lot below the number existing prior to the project unless the reduced parking still satisfies the requirements set out above.

4. Except as otherwise provided in this chapter, each lot shall provide parking deemed sufficient by the code official for the use occurring on the lot; provided, any lot that contains 10 or more parking spaces shall also meet the parking lot requirements set out in Appendix A of this development code.

H. Easements. Easements shall remain unobstructed.

1. Vehicular Access Easements. No structures shall be constructed on or over any vehicular access easement. A minimum five-foot yard setback from the edge of any easement that affords or could afford vehicular access to a property is required for all structures; provided, that improvements such as gates, fences, rockeries, retaining walls and landscaping may be installed within the five-foot yard setback so long as such improvements do not interfere with emergency vehicle access or sight distance for vehicles and pedestrians.

2. Utility and Other Easements. No structure shall be constructed on or over any easement for water, sewer, storm drainage, utilities, trail or other public purposes unless it is permitted within the language of the easement or is mutually agreed in writing between the grantee and grantor of the easement.

I. Large Lots. The intent of this section is to ensure that the construction of a single-family dwelling on a large lot does not preclude compliance with applicable standards related to subdivision or short subdivision of the large lot. Prior to approval of a new single-family dwelling and associated site improvements, accessory buildings, and accessory structures on large lots, the applicant shall complete one of the following:

1. Design for Future Subdivision. The proposed site design that shall accommodate potential future subdivision of the lot as follows:

a. The proposed site design shall comply with the applicable design requirements of Chapters 19.08, Subdivision, 19.09, Development, and 19.10, Trees, MICC.

b. The proposed site design shall not result in a circumstance that would require the removal of trees identified for retention, as part of a future subdivision.

c. The proposed site design shall not result in a circumstance that would require modifications to wetlands, watercourses, and associated buffers as part of a future subdivision.

d. Approval of a site design that could accommodate a potential future subdivision does not guarantee approval of such future subdivision, nor does it confer or vest any rights to a future subdivision.

2. Subdivide. Prior to application for a new single-family dwelling, the property is subdivided or short platted to create all potential lots and building pads permitted by zoning. The proposed single-family dwelling shall be located on a lot and within a building pad resulting from a recorded final plat.

3. Limit Subdivision. Record a notice on title, or execute a covenant, easement, or other documentation approved by the city, prohibiting further subdivision of the large lot for a period of five years from the date of final inspection or certificate of occupancy.

J. Building Pad. New buildings shall be located within a building pad established pursuant to Chapter 19.09 MICC. Intrusions into yard setbacks authorized pursuant to MICC 19.02.020(C)(3) may be located outside of the boundaries of the building pad. (Ord. 18C-05 § 1 (Att. A); Ord. 17C-15 § 1 (Att. A); Ord. 17C-02 § 1; Ord. 10C-07 § 1; Ord. 09C-17 § 1; Ord. 08C-01 § 1; Ord. 06C-05 § 1; Ord. 05C-12 § 7; Ord. 03C-01 § 3; Ord. 02C-09 § 4; Ord. 01C-06 § 1; Ord. 99C-13 § 1).

19.02.030 Accessory dwelling units.

A. Purpose. It is the purpose of this legislation to implement the policy provisions of the housing element of the city’s comprehensive plan by eliminating barriers to accessory dwelling units in single-family residential neighborhoods and provide for affordable housing. Also, to provide homeowners with a means of obtaining rental income, companionship, security and services through tenants in either the accessory dwelling unit or principal unit of the single-family dwelling.

B. Requirements for Accessory Dwelling Units. One accessory dwelling unit is permitted as subordinate to an existing single-family dwelling; provided, the following requirements are met:

1. Owner Occupancy. 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. Owner occupancy is defined as a property owner, as reflected in title records, who 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.

2. Number of Occupants. The total number of occupants in both the principal dwelling unit and accessory dwelling unit combined shall not exceed the maximum number established for a family as defined in MICC 19.16.010 plus any live-in household employees of such family.

3. Subdivision. Accessory dwelling units shall not be subdivided or otherwise segregated in ownership from the principal dwelling unit.

4. Size and Scale. 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 80 percent of the total square footage of the primary dwelling unit, excluding the garage area, as it exists or as it may be modified.

5. Location. The accessory dwelling unit may be added to or included within the principal unit, or located in a detached structure.

6. Entrances. 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.

7. Additions. 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.

8. Detached Structures. Accessory dwelling units shall be permitted in a detached structure.

9. Parking. All single-family dwellings with an accessory dwelling unit shall meet the parking requirements pursuant to MICC 19.02.020(G) applicable to the dwelling if it did not have such an accessory dwelling unit.

C. Exceptions – Ceiling Height. 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 construction codes set forth in MICC Title 17, shall be allowed to continue in their present form.

D. Permitting and Enforcement.

1. Application. The property owner shall apply for an accessory dwelling unit permit with the development services group. The application shall include an affidavit signed by the property owner affirming that the owner or an immediate family member will occupy the principal dwelling unit or accessory dwelling unit for more than six months per year.

2. Notice. The city shall provide notice of the intent to issue a permit for an accessory dwelling unit as required by MICC 19.15.020(D) and (E).

3. Applicable Codes. The accessory dwelling unit shall comply with all construction codes set forth in MICC Title 17 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.

4. Inspection. 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.

5. Recording Requirements – Permits. 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.

6. Permit. Upon compliance with the provisions of this section, a permit for an accessory dwelling unit will be issued.

7. Enforcement. The city retains the right with reasonable notice to inspect the ADU for compliance with the provisions of this section.

E. Elimination/Expiration. Elimination of an accessory dwelling unit may be accomplished by the owner recording a certificate with the King County department of records and elections and development services stating that the accessory dwelling unit no longer exists on the property.

F. Variance. Variances to this chapter shall require variance approval as outlined in MICC 19.15.020(G)(4).

G. Violations. Any violation of any provision hereof is a criminal violation under MICC 19.15.030. (Ord. 08C-01 § 1; Ord. 04C-12 § 10; Ord. 99C-13 § 1).

19.02.040 Garages, other accessory buildings and accessory structures.

A. Accessory buildings, including garages, are not allowed in required yards except as herein provided.

B. Attached Accessory Building. An attached accessory building shall comply with the requirements of this code applicable to the main building.

C. Detached Accessory Buildings and Accessory Structures.

1. Gross Floor Area.

a. The combined total gross floor area for one or more accessory building(s) shall not exceed 25 percent of the total gross floor area allowed on a lot within applicable zoning designations pursuant to MICC 19.02.020. For example, on a lot where the total allowed gross floor area is 4,000 square feet, the combined total gross floor area for all accessory buildings is 1,000 square feet.

b. The gross floor area for a detached accessory building that is entirely or partially used for an accessory dwelling unit may be increased by the additional floor area authorized pursuant to MICC 19.02.020(D)(3)(b).

2. Height.

a. Detached accessory buildings, except for buildings that contain an accessory dwelling unit, are limited to a single story and shall not exceed 17 feet in height above the average building elevation computed from existing grade or finished grade, whichever is lower, to the highest point of the roof. Average building elevation is calculated using the methodology established in MICC 19.02.020(E)(4).

b. Detached accessory buildings that are entirely or partially used for an accessory dwelling unit shall meet the height limits established for the primary building.

3. Detached accessory buildings are not allowed in required yard setbacks; provided, one detached accessory building with a gross floor area of 200 square feet or less and a height of 12 feet or less may be erected in the rear yard setback. If such an accessory building is to be located less than five feet from any property line, a joint agreement with the adjoining property owner(s) must be executed and recorded with the King County department of records and thereafter filed with the city.

4. Accessory Structures. The maximum height of an accessory structure that is not also an accessory building shall not exceed 17 feet. The height of an accessory structure is measured from the top of the structure to the existing grade or finished grade, whichever is lower, directly below the section of the structure being measured.

D. Garages and Carports. Garages and carports may be built to within 10 feet of the front property line if the front yard of the lot, measured at the midpoint of the wall of the garage closest to the front yard property line, is more than four feet above or below the existing grade or finished grade, whichever is lower, at the point on the front property line closest to the midpoint of the wall of the garage at its proposed location. The height of such garage shall not exceed 12 feet from existing grade for that portion built within the front yard.

E. Pedestrian Walkways. Enclosed or covered pedestrian walkways may be used to connect the main building to a garage or carport. Enclosed pedestrian walkways shall not exceed six feet in width and 12 feet in height calculated from finished grade or 30 feet above average building elevation, whichever is less. (Ord. 17C-15 § 1 (Att. A); Ord. 08C-01 § 1; Ord. 01C-06 § 1; Ord. 99C-13 § 1).

19.02.050 Fences, retaining walls and rockeries. Revised 8/18

A. Location in Required Yard. Fences, retaining walls and rockeries may be located within any required yard as specified below.

B. Location in Street.

1. Fences. No fence shall be located in any improved street. Fences may be allowed in unimproved public streets subject to approval of the city engineer and the granting of an encroachment agreement as required by MICC 19.06.060.

2. Retaining Walls and Rockeries. Retaining walls and rockeries may be allowed in any street subject to the approval of the city engineer and the granting of an encroachment agreement covering any public street as required by MICC 19.06.060.

C. Height Measurement.

1. Fences/Gates. The height of a fence or gate is measured from the top of the fence or gate, including posts, to the existing grade or finished grade, whichever is lower, directly below the section of the fence or gate being measured.

2. Retaining Walls and Rockeries. The height of a retaining wall or rockery is measured from the top of the retaining wall or rockery to the existing grade or finished grade, whichever is lower, directly below the retaining wall or rockery.

D. Retaining Walls and Rockeries – Requirements.

1. Building Permit. A building permit is required for retaining walls or rockeries not exempted from permit by Section 105.2 of the Construction Administrative Code, Chapter 17.14 MICC.

2. Engineer. Any rockery requiring a building permit shall be designed and inspected by a licensed geotechnical engineer.

3. Drainage Control. Drainage control of the area behind the rockery shall be provided for all rockeries.

4. Maximum Height in Required YardCut Slopes.

a. No retaining walls or rockeries, or any combination of retaining walls or rockeries, to the extent used to protect a cut or cuts into existing grade within any required yard, shall exceed a total of 144 inches in height.

b. All retaining walls and/or rockeries within a required yard shall be included in calculating the maximum height of 144 inches.

c. Retaining walls or rockeries may be topped by a fence as provided in subsection E of this section.

5. Maximum Height in Required YardFill Slopes.

a. No retaining walls or rockeries, or any combination of retaining walls or rockeries, to the extent used to raise grade and protect a fill slope, shall result in an increase in the finished grade by more than 72 inches at any point.

b. All retaining walls and/or rockeries within a required yard shall be included in calculating the maximum height of 72 inches.

c. Retaining walls or rockeries may be topped by a fence as provided in subsection E of this section.

E. Fences and Gates.

1. Fences or Gates in Required Yard.

a. Height Limits.

i. Side and Rear Yards. Fences and gates are allowed to a maximum height of 72 inches within required side or rear yards, provided the combined height of a fence and retaining wall or rockery for a fill slope authorized pursuant to subsection (D)(5) of this section shall not exceed a total height of 72 inches.

ii. Front Yards. Fences, gates, or any combination of retaining walls, rockeries and fences are allowed to a maximum height of 42 inches within required front yards.

b. Exceptions to Height Limits.

i. Fences within front yards may be designed to incorporate an open latticework or similar architectural feature at the entrance of a walkway, provided the total height of the entryway feature shall not exceed 90 inches. The open latticework or architectural feature shall be designed such that at least 50 percent of its total surface area consists of evenly distributed open spaces.

ii. Fences or gates located within the front yard may have a maximum height of 72 inches, provided:

(a) The proposed fence or gate is located along a property line contiguous to either: Island Crest Way north of SE 53rd Place, or SE 40th Street between 92nd Avenue SE and 78th Avenue SE; and

(b) The proposed fence or gate is located a minimum of five feet from the street property line and will be screened by landscaping designed to soften the presence of the fence; and

(c) The proposed fence or gate will not create a traffic, pedestrian, or public safety hazard.

2. Fill/Berms. No person shall place fill upon which to build a fence unless the total height of the fill plus the fence does not exceed the maximum height allowable for the fence without the fill.

3. Shorelines. Fences, rockeries and retaining walls located within any shoreland shall also comply with Chapter 19.07 MICC.

F. Electric and Barbed Wire Fences. Electric fences, barbed wire fences, or similar fences that could pose a safety risk are not allowed.

G. Exceptions. These provisions do not apply to fences required by state law to enclose public utilities, or to chain link fences enclosing school grounds or public playgrounds, or to screens used for safety measures in public recreation areas such as ballfields. (Ord. 18C-05 § 1 (Att. A); Ord. 17C-15 § 1 (Att. A); Ord. 04C-12 § 11; Ord. 02C-09 § 2).

19.02.060 Lot coverage – Regulated improvements.

A. Applicability. This section shall only apply to regulated improvements (for example, schools or religious buildings) in the residential zoning designations of R-8.4, R-9.6, R-12, and R-15.

B. Maximum Impervious Surface Limits for Lots. The total percentage of a lot that can be covered by impervious surfaces (including buildings) is limited by the slope of the lot for all single-family zones as follows:

Lot Slope

Lot Coverage

(limit for impervious surfaces)

Less than 15%

40%*

15% to less than 30%

35%

30% to 50%

30%

Greater than 50% slope

20%

*    Public and private schools, religious institutions, private clubs and public facilities (excluding public parks or designated open space) in single-family zones with slopes of less than 15 percent may be covered by the percentage of legally existing impervious surface that existed on May 1, 2006, as determined by the code official.

C. Exemptions. The following improvements will be exempt from the calculation of the maximum impervious surface limits set forth in subsection B of this section:

1. Decks/Platforms. Decks and platforms constructed with gaps measuring one-eighth inch or greater between the boards which provide free drainage between the boards as determined by the code official shall be exempt from the calculation of maximum impervious surface limits so long as the surface below the deck or platform is not impervious.

2. Pavers. Pavers installed with a slope of five percent or less and covering no more than 10 percent of the total lot area will be calculated as only 75 percent impervious. Provided, however, that all pavers placed in driveways, private streets, access easements, parking areas and critical areas shall be considered 100 percent impervious.

3. Pedestrian-Oriented Walkways. Uncovered pedestrian walkways constructed with gravel or pavers not to exceed 60 inches in width shall be exempt from the maximum impervious surface limits.

4. Public Improvements. Open storm water retention/detention facilities, public rights-of-way and public pedestrian trails shall be exempt from the maximum impervious surface limits.

5. Rockeries/Retaining Walls. Rockeries and retaining walls shall be exempt from the maximum impervious surface limits.

6. Residences for Religious Leaders Located on Properties Used by Places of Worship.

a. A structure primarily used as a residence for a religious leader provided by its congregation and located on the same lot or lots as the improvements for a church, synagogue, mosque, or other place of worship shall be exempt from the maximum impervious surface limits, subject to the limitations under subsection (C)(6)(b) of this section. All impervious surface areas directly and commonly associated with the residence such as, but not limited to, the footprint of the residence, an attached or detached garage, a patio and/or deck not otherwise exempted by subsections (C)(1) and (3) of this section, and a driveway not otherwise used for general access to the place of worship, shall be exempt.

b. A residence and its associated impervious improvements, as described above, may only be exempted if 4,999 square feet or less or up to 20 percent of lot area, whichever is less. For these purposes, lot area means the lot or lots on which the place of worship is located.

c. Impervious surface lot coverage exceeding 60 percent shall not be allowed whether by variance to this section or by this exemption.

D. Variance. Regulated improvements in the R-8.4, R-9.6, R-12, and R-15 zoning designations may request a variance to increase impervious surface pursuant to MICC 19.15.020(G). (Ord. 17C-15 § 1 (Att. A)).

19.02.070 Swimming pools.1

A. A swimming pool is not allowed in any front yard.

B. A swimming pool is not allowed closer than five feet from any adjacent property measured from the edge of the water to the property line.

C. A swimming pool located in a public park or noncommercial recreation area shall conform to the setback regulations governing such areas.

D. All fences surrounding outdoor swimming pools shall conform to the requirements of MICC Title 17. (Ord. 04C-12 § 12; Ord. 99C-13 § 1. Formerly 19.02.060).


1

Code reviser’s note: Ord. 17C-15 added a new Section 19.02.060 (Lot coverage – Regulated improvements). This section has been editorially renumbered to 19.02.070 in order to accommodate the addition of the new section.