The provisions and standards in this chapter apply to all uses and structures in all zone districts. (Ord. 2009-702 § 2 (Exh. C); Ord. 2005-609 § 2)

All lots and developments shall be generously landscaped, consistent with the natural environment of Mill Creek and appropriate to the planned use. Retention and enhancement of natural landscaping is encouraged. Landscaping design objectives and standards are contained in Chapter 17.34 MCMC. (Ord. 2009-702 § 2 (Exh. C); Ord. 2005-609 § 2)

A. No yard setback shall be reduced in size or area below the minimum dimensions required by this title except:

1. As permitted through the variance process in Chapter 17.30 MCMC;

2. Under the provisions of subsection C of this section;

3. Through approval of a permitted modification as a component of a planned area development in accordance with MCMC Title 16; or

4. As allowed by MCMC 17.22.040, 17.22.050, or 17.22.130.

B. No portion of any principal building or structure over 30 inches above the finished grade shall extend into a required yard setback except as specifically provided elsewhere in this title. Eaves, bay windows, chimneys, flue chases, and the like may extend a maximum of 18 inches into a required yard setback.

C. Yard setback requirements may be reduced by the director up to 50 percent of the required dimensions if necessary for the reasonable use of the property, and upon a showing of unusual circumstances because of topography, vegetation or irregular lot shape. (Ord. 2025-933 § 2 (Exh. A); Ord. 2022-884 § 2; Ord. 2009-702 § 2 (Exh. C); Ord. 2006-633 § 2; Ord. 2005-609 § 2)

A. Natural evergreen screening is encouraged. Temporary fencing may be approved if erected simultaneously with permanent plantings.

B. A permit shall be required prior to the erection of any permanent fence within the city. All permanent fencing in residential zones shall be of ornamental metal, wood, masonry, or some combination of the three. Exceptions: (1) black vinyl chain link fencing is permitted on the side and rear yard property lines in residential zones adjacent to open space tracts, if supported on wood rail-type fences; (2) fencing around critical areas, designated open space areas, and detention ponds in residential zones may be constructed of black vinyl chain link and can be supported on black metal posts and rails or wooden posts and rails.

C. No fence shall be permitted in any roadway buffer/cutting preserve. No fence or structure over 42 inches in height shall be permitted in any required front yard setback area within residential zones. Hedges within the front yard setback that are parallel or substantially parallel to the street shall not exceed 42 inches in height.

D. On corner lots with two or more front yards, fences over 42 inches in height may be constructed no closer than five feet to the front lot line along the street side where there is no driveway access. If there is no sidewalk on the street side with no driveway access, the director has the discretion to authorize fences to be built no closer than two feet from the front lot line if it is determined that the city is unlikely to construct a sidewalk along the property line in the future.

E. In nonresidential zones wood or black vinyl chain link fencing shall be permitted.

F. No fence or boundary structure shall exceed 78 inches in height from the finished grade. Arbors, trellises and other gate treatments may extend up to 90 inches from finished grade, provided such arbor, gate or trellis width does not exceed six feet.

G. At street intersections, driveways, corner or radius lots or other potential traffic conflict points, no visually obstructive plantings or structures shall exceed 30 inches in height from grade in an area that would obstruct the required sight distance as set forth in the current edition of the AASHTO Geometric Design Manual as determined by the city engineer.

H.  Property Buffer. Fences, decks and other accessory structures that do not require tree removal may be allowed in property buffers after review and approval by the director.

I. Roadway Buffer/Cutting Preserve. Vegetation removal and clearing is generally prohibited in roadway buffers/cutting preserves, except where necessary for residential access roads or minor encroachments for necessary public improvements such as sidewalks. In areas where native vegetation is sparse or nonexistent, supplemental landscaping may be allowed upon review and approval by the design review board in accordance with Chapter 17.34 MCMC.

J. Noise Attenuation Walls and Highway Screening Fences. Walls and fences constructed adjacent to SR 527 and SR 96 shall have a maximum height of 15 feet. In order to provide visual relief, said fences and walls shall incorporate the following features, subject to design review board approval:

1. Use of cut-outs or breaks in the continuous wall plane with landscaping separating the wall sections.

2. Where possible, articulation of planes every 100 linear feet of continuous wall plane should occur through the use of landscaped recesses being approximately eight feet in length with a depth of four feet.

3. Planting of street trees or landscaping approximately every 30 feet on center or adjusted as needed for species or available site.

4. Combinations of materials, colors and textures.

5. Incorporation of trellises and other architectural features.

6. Provision of pilasters, columns, or other vertical or horizontal features at every change in direction, and on the average of every 25 feet of contiguous wall.

7. Approval of the design review board is required pursuant to Chapter 17.34 MCMC. (Ord. 2022-884 § 2; Ord. 2013-763 § 2; Ord. 2009-702 § 2 (Exh. C); Ord. 2008-682 § 2; Ord. 2005-609 § 2)

A. No accessory building shall be located in any front setback area.

B. In zones where accessory buildings are allowed, accessory buildings may be located within the side or rear setback. However, no accessory building shall be located closer than five feet to any side or rear lot line.

C. No accessory building within a side or rear setback area shall have a gross floor area greater than 400 square feet, or a height greater than 12 feet. Accessory buildings meeting the setback requirements for principal buildings shall not have a gross floor area greater than the principal building and shall be limited to the maximum height of the underlying zone.

D. If an accessory building is within a setback area, any walls facing a neighboring residential property shall not have windows higher than 78 inches above grade.

E. Accessory dwelling units shall comply with the size limitations in MCMC 17.22.130(B).

F. No accessory building housing livestock or for storage of malodorous substances shall be located within 40 feet of a lot line or principal building. (Ord. 2022-884 § 2; Ord. 2021-872 § (2)(a); Ord. 2009-702 § 2 (Exh. C); Ord. 2005-609 § 2)

On-site open space and recreational facilities are required in an amount adequate to meet the recreational, health, environmental and safety needs of the residents, occupants, guests and visitors of the development. That determination shall be made in accordance with the following standards and criteria:

A. The amount of open space and type of recreational facilities shall meet the specific needs of the residents, guests and visitors.

B. The amount of open space and recreational facilities should be proportional to the density of the development (i.e., as density increases and/or as lots become smaller, there is a greater need for common open space available to all of the residents, guests and visitors to the development). In multi-unit dwelling developments without individual yards, total common open space should be equivalent to 250 square feet per dwelling unit. Single-unit dwelling developments located more than one-quarter of a mile from a public park shall provide mini-parks and/or open space proportional to serve the density of the development and the need of the local residents.

C. The amount of open space and recreational facilities should meet the purpose and intent of the zone district in which the development is located.

D. The open space and recreational facilities should be readily accessible to all dwelling units in the development.

E. The open space and recreational facilities shall be appropriately screened from parking areas.

F. The length of the open space area shall be no more than twice the width.

G. The open space area may be located in any required setback area, except street setbacks, so long as the uses thereof are compatible and permissible.

H. The open space shall not have more than five percent grade. (Ord. 2024-928 § 2 (Exh. A); Ord. 2010-718 § 18 (Exh. R); Ord. 2009-702 § 2 (Exh. C); Ord. 2005-609 § 2)

A. No outside storage, including garbage cans, firewood, construction materials, fuel or other tanks or any other materials not permanently affixed to the ground or buildings, is permitted in any street setback area.

B. All outside storage, when permitted elsewhere in the code, shall be enclosed by a sight-obscuring screen at least 78 inches high measured from the nearest street grade elevation. MCMC 15.16.100 provides additional requirements for screening storage of materials and equipment. Fences required for screening shall be landscaped at the base for a minimum of 18 inches horizontally from any portion of the fence. Fences and hedges required for screening may exceed the height limitations of other fences and hedges except at street intersections and within required setback areas. Fences shall require a building permit.

C. When permitted elsewhere in the code, outside sales, display and eating/drinking establishment seating shall comply with the following performance standards:

1. Maximum display height shall be six feet;

2. Maximum display depth shall be four feet (depth of one wood pallet);

3. Minimum pedestrian access shall be four feet clear access at all times on designated pedestrian surfaces. Minimum ADA access requirements shall be maintained at all times;

4. Display areas shall be located immediately adjacent to an authorized retail/commercial/business use;

5. Temporary displays or sales located within parking lot areas shall require administrative approval by the director of community development.

The application of these performance standards is depicted on the accompanying illustration.

Outside Display and Sales Performance Standards

(Ord. 2009-702 § 2 (Exh. C); Ord. 2008-682 § 2; Ord. 2005-609 § 2)

Repealed by Ord. 2025-933. (Ord. 2019-846 §§ 3, 4; Ord. 2010-717 § 2 (Exh. B); Ord. 2005-609 § 2)

A. Television Antennas. No outside television antennas, except as allowed elsewhere in this code, shall be permitted in areas served by community television cable. In such cases, antennas shall be fully screened from the right-of-way.

B. Satellite Dish Antennas.

1. Residential Districts. Satellite dish antennas four feet or more in diameter require approval of a conditional use permit. Satellite dish antennas less than four feet in diameter are not regulated in accordance with the Federal Telecommunications Act.

2. Commercial Districts. Satellite dish antennas over four feet in diameter require a conditional use permit. (Ord. 2005-609 § 2)

All development shall comply with Chapter 70.92 RCW and Washington State Rules and Regulations for Barrier-Free Design, as now or hereafter amended. (Ord. 2005-609 § 2)

A. For any private development that includes new construction typically associated with a binding site plan, plat, short plat, or a conditional use permit subject to the provisions of the development code, the developer shall place underground all new and existing wiring and related facilities for all utilities, including but not limited to electrical, cable television and communication, unless otherwise provided in this section.

B. This section shall not apply to electrical distribution substations or to electrical lines of greater than 50 KV capacity unless the director determines that undergrounding of such lines has become economically feasible.

C. Wiring and/or related facilities for existing above ground utilities may remain above ground only when the directors of community development and public works determine all of the following circumstances are present:

1. Existing utility service is within the public right-of-way or utility easements.

2. One or more of the following site conditions are present:

a. Subsurface soil or water conditions exist that may make undergrounding technically unpractical, or

b. The utilities are located along the following roadways:

i. SR 527 (Bothell-Everett Highway).

ii. SR 96 (132nd /128th Street Southeast).

iii. 35th Avenue Southeast.

iv. 164th Street Southeast.

v. Mill Creek Road.

vi. Seattle Hill Road.

vii. 9th Avenue Southeast.

D. Utility cabinets and boxes may be placed or remain above ground when the directors of community development and public works determine all of the following conditions are met:

1. The above ground utility cabinets and/or boxes are used in conjunction with and/or are ancillary to existing or new underground utilities; and

2. The above ground utility cabinets and/or boxes are located, designed, and/or otherwise screened to minimize visual impacts to the public view.

E. Repair, maintenance or upgrading of existing underground service shall not be relocated overhead.

F. Any deviation from the requirements of this section shall require a variance under Chapter 17.30 MCMC. (Ord. 2012-743 § 3; Ord. 2005-609 § 2)

All new developments within the city shall be consistent with the provisions of the comprehensive plan, including but not limited to the following:

A. All developments within the city shall be consistent with the land use plan map as adopted in the land use element of the comprehensive plan.

B. All developments within the city shall be consistent with the applicable goals and policies of the comprehensive plan.

C. Developments shall not cause a reduction in the level of service for transportation and/or neighborhood park facilities below the minimum standards established within the comprehensive plan and capital facilities plan, unless improvements or strategies to accommodate the impacts of the development are made concurrent with the development.

For the purpose of this section, “concurrent with the development” is defined as the required improvements or strategies are in place at the time of occupancy, or that a financial commitment is in place to complete the improvements or strategies within six years of occupancy.

D. Site design and frontage improvements shall be consistent with the streetscape plans as established in the streetscape element of the comprehensive plan. A roadway buffer/cutting preserve is required adjacent to all arterial and collector roads as identified in the transportation element of the comprehensive plan, with the exception of North Creek Drive between Trillium Boulevard and Dumas Road. The minimum width of a roadway buffer/cutting preserve widths adjacent to commercial uses is 35 feet. The minimum width of a roadway buffer/cutting preserve adjacent to residential uses is 50 feet.

E. If concurrency cannot be met in accordance with the comprehensive plan and adopted development regulations, the city has the right to disapprove the proposed development application. (Ord. 2015-803 § 9 (Exh. A); Ord. 2005-609 § 2)

A. Application. The owner of a lot or residence intending to develop an accessory dwelling unit shall make application to the department of community development on forms provided by the department. The department shall maintain a file of all approved accessory units and shall submit a periodic report to the city council on the number of accessory units permitted.

B. Size. The gross floor area of accessory dwelling units must not be less than 400 square feet nor more than 1,000 square feet. For the purpose of this subsection, “gross floor area” means the interior habitable area of a dwelling unit including basements and attics but not including a garage or accessory structure.

C. Number. No more than two accessory dwelling units are allowed per lot.

D. Public Alley Setbacks. Accessory dwelling units may be sited at a lot line if the lot line abuts a public alley.

E. Existing Structure Conversions. Accessory dwelling units may be established in existing structures, including but not limited to detached garages, even if they do not meet setback or lot coverage requirements.

F. Public Improvements. The city may not require public street improvements as a condition of permitting accessory dwelling units.

G. Compliance with Standards. An accessory dwelling unit shall comply with all zoning and building code requirements.

H. Water and Sewer. When submitting an accessory dwelling unit application, the applicant must provide documentation from the local water and sewer district that the water supply is potable and of adequate flow and that the existing or proposed sewage system is capable of handling the additional demand placed upon it by the accessory dwelling unit. (Ord. 2025-933 § 2 (Exh. A); Ord. 2024-928 § 2 (Exh. A); Ord. 2021-872 § (2)(b); Ord. 2011-723 § 2 (Exh. B); Ord. 2006-633 § 2; Ord. 2005-609 § 2)

No person or entity may produce, grow, manufacture, process, accept donations for, or sell marijuana or marijuana infused products within the city. (Ord. 2014-782 § 1)

A. Residential Density Calculation. The number of dwelling units allowed per lot must comply with the zoning district’s minimum and maximum density requirements. The number of dwelling units allowed per lot is calculated as follows:

1. Determine the net developable area by subtracting all unbuildable area as defined in MCMC 14.01.030(U) from the gross lot area.

2. Multiply the net developable area in acres by the number of dwelling units per acre required by the underlying zone.

B. Exceptions. Exceptions to the residential density calculation include:

1. The maximum number of dwelling units allowed per lot in residential zones is never less than two.

2. Lots where the only principal dwelling is a single-unit dwelling are allowed two accessory dwelling units.

3. Boarding house sleeping units are treated as one-quarter of a dwelling unit when calculating residential density.

4. The maximum number of allowed dwelling units is increased by 50 percent when new dwelling units are added entirely within the existing building envelope of a building located in a commercial zone or the MU/HDR zone. For the purpose of this subsection, “existing building” means a building that received a certificate of occupancy at least three years prior to the permit application to add dwelling units. (Ord. 2025-933 § 2 (Exh. A))