Urban Form Overlay District

The Urban Form Overlay District applies throughout the eligible areas. It establishes design and development standards that help ensure redevelopment creates a connected, walkable, and active district.

The Overlay District works alongside the underlying zoning district. It guides building placement, parking, open space, building form, ground-floor design, streetscapes, and connections to streets, sidewalks, trails, and transit. Where overlay standards conflict with underlying zoning, the Overlay District requirements apply.

Active Commercial Corridors

Designated active commercial corridors are designations that are intended to support pedestrian activity, storefront businesses, and a more vibrant public realm.

Development along active commercial corridors must include active commercial uses and pedestrian-oriented building frontages. Required active commercial uses may include retail, restaurants, personal services, lodging, recreation and assembly uses, and other comparable uses approved by the City.

Development Standards

The following table summarizes key Urban Form Overlay District standards. Applicants should consult Mill Creek Municipal Code Chapter 17.08 for complete requirements.

Topic	Development Standard
Applicability	Applies to development within the South Town Center Subarea
Active commercial corridors	Parts of Main Street and Mill Creek Boulevard
Active commercial frontage	Active commercial uses are required along designated active commercial corridors
Middle housing	Limited to no more than 20 percent of dwelling units within new subdivisions, short subdivisions, and binding site plans
Parking	Off-street parking must meet applicable City standards
Surface parking	Surface parking lots are limited to 100 spaces
Front setback	Minimum 0 feet; maximum 10 feet
Side and rear setbacks	Minimum 0 feet; no maximum
Open space	At least 100 square feet per dwelling unit, up to 25 percent of the total development site
Alternative open space	Usable common indoor amenities, rooftops, balconies, and stepbacks may count toward open-space requirements
Outdoor open-space dimensions	Minimum 800 square feet, with each side at least 15 feet
Building articulation	Buildings must use changes in wall plane, setbacks, distinct building volumes, balconies, bays, recesses, material changes, or similar features to reduce perceived bulk
Building length	Maximum 180 feet along the primary façade plane above the ground floor
Active-corridor stepbacks	Minimum 8-foot stepback above the second or third story adjacent to active commercial corridors
Transition zones	Additional standards apply to building portions above the base height adjacent to SR 527, 164th Street SE, and the northern subarea boundary
Transition-zone options	Reduced building massing or a minimum 10-foot stepback
Building frontage	At least 70 percent of frontage along active commercial corridors must be occupied by building frontage
Ground-floor height	Nonresidential ground floors must be at least 18 feet floor-to-floor
Ground-level transparency	At least 75 percent for nonresidential uses and 30 percent for residential uses
Residential entries	Residential stoops must generally be at least 18 inches above adjacent sidewalk grade
Blank walls	Maximum 30 feet generally and 20 feet along active commercial corridors
Parking and service frontage	Maximum 60 feet generally; not allowed along active commercial corridors
Primary entries	At least one entrance every 75 feet
Weather protection	Required along nonresidential frontage, with greater coverage required on active commercial corridors and at public entries

Building Form and Design

The Overlay District requires buildings to contribute to attractive streets and pedestrian spaces. Building massing must be broken into smaller visual elements through upper-level setbacks, changes in wall plane, distinct building volumes, balconies, bays, recesses, and material changes.

Along active commercial corridors, buildings must provide street-facing frontage, windows, entrances, weather protection, and limits on blank walls. Parking, loading, and service areas must be located and screened to reduce their impact on sidewalks, storefronts, and public spaces.

Open Space and Streetscapes

Each development must provide usable open space for residents. Open-space requirements may be met through qualifying outdoor areas as well as common indoor amenity spaces, rooftop areas, balconies, and stepbacks when they are accessible and functional for building occupants.

The Overlay District also supports pedestrian-oriented streetscapes through landscaping, street-facing buildings, weather protection, active ground-floor uses, lighting, and high-quality building materials. Together, these standards help create a district that is comfortable to walk through, active throughout the day, and connected to parks, trails, transit, and nearby businesses.