i. At the scale of the pedestrian (i.e. within the ground floor portion of the façade), a base treatment should be created at a height between nine inches and six feet.

ii. At the scale of the building, the façade of the entire ground floor (or up to the second floor, depending on the height of the building) should be designed to read as a base that “anchors” the building (i.e., the portion of the façade above) to the ground.

i. A horizontal projection (or visible thickening) of the wall surface, which may be accompanied by a change of material and/or color; this may be an exterior version of a “wainscot.”

ii. A “heavier” design treatment, such as a darker color and/or stronger, more permanent material, for the base portion of the façade than for the portions above.

iii. A horizontal architectural line or feature at or below the top of the first story, such as a belt course or secondary cornice (related to or repeating the pattern of an upper cornice) separating the first two floors.

iv. A ground level arcade with columns may be used, except within the Downtown Special Review Area. Column spacing should be regular and related to the structural bay of the building.

i. A visibly thicker and continuous base portion of the wall along the ground, where the wall above the base sets back.

ii. A material and/or color change of the base wall relative to the building wall above. The base material should generally be heavier (e.g. of darker color and/or a heavier or more permanent material) than portions of the building above.

iii. A horizontal architectural feature at or below the top of the first story, such as an intermediate cornice line or protruding horizontal band.

i. Buildings should be “four-sided”, meaning that all façades including side and rear façades should be considered visible (unless facing “blind” onto an adjacent party wall) and should be treated with an architectural façade composition.

ii. Distinctive building elements such as, for example, a corner tower are encouraged to accent terminating views within the Plan Area. The exception will be within the Downtown Special Review Area, where “sameness, symmetry and balance” will be encouraged (see the Historic Resources Guidelines section).

iii. Covered outdoor spaces such as arcades and galleries are encouraged to protect pedestrians from summer heat and winter rain, except within the Downtown Special Review Area surrounding Main Street.

i. Unifying architectural approaches should be used to lay out a window pattern across a façade, such as aligning windows by using common sill or header lines.

ii. At attached residential dwellings, façades of attached residences within the same project should be distinct and even different, but also should maintain unifying compositional elements such as a common window header or sill line, and/or aligned vertical centerlines of windows and doors between upper and lower floors.

iii. Horizontal ornament such as awnings or belt courses, string courses or cornice lines should be carried across adjacent façades to unify various building masses and convey the sense of a consistent building wall. In the Downtown Special Review Area, such features should be made compatible among neighboring buildings in alignment and character to the degree possible.

i. Window Bay Projections are encouraged at upper stories as they create architectural interest and a regional architectural context, except within the Downtown Special Review Area. They also serve to increase usable internal floor space for upper story tenants.

ii. Permitted alcoves and balconies are encouraged at upper stories to create architectural interest, a regional architectural context, and to provide outdoor spaces for upper story tenants – except within the Downtown Special Review Area.

iii. Storefront Awnings and canopies: Colored fabric mounted awnings supported by a metal structural frame are recommended. See BMC 12.64.501 for illustrations. The form of storefront awnings should not dominate or obscure the storefront or façade – i.e., a straight sloping profile is recommended and a bulbous quarter-round profile is strongly discouraged. Internally illuminated fabric awnings should not be used. For a sequence of storefronts or windows, a sequence of discrete awnings or canopies for each storefront or building bay should be used, rather than one continuous run-on awning. Awnings should not cover up intermediate piers, pilasters, or other vertical architectural features.

iv. Trellises, Marquees and Architectural Canopies: Materials, colors, and form should be derived from the building architecture, e.g. a trellis painted the same color as a building’s trim scheme is appropriate.

v. Ornamental wall-mounted outdoor lighting (sconces) may be used to accent entries, mark a sequence of repeating pilasters, or serve as a “centerpiece” for a façade panel. Style and material should be consistent with that of the building.

vi. Protrusions such as balconies and porches may be used on second and higher stories if the overall projection and encroachment into the public right-of-way and/or required setbacks conforms to the regulations established in BMC 12.64.207 Front Yard Setback, except within the Downtown Special Review Area. Protrusions of this type should extend no greater than two feet from the face of the building. Alcoves used in conjunction with these elements increases the usability of this element, while providing shadow and visual interest to the façade composition.

vii. Barrier railings of balconies that project from the wall surface of the building should use a visually open design made of pickets or bars rather than solid wall panels.

viii. Balconies or alcoves that are recessed into the building façade may use a curb wall with open railing at top.

ix. Balconies and porches should be constructed of materials and proportions related to the overall façade composition. A contrasting material to the wall surface should be used.

i. Brick: Red brick is the characteristic brick color in Bothell and its region, although yellows and tans are occasionally used as well. Full size brick is preferable to thin veneer brick. When used, brick veneers should be mortared to give the appearance of full-depth brick. Detailing should avoid the exposure of sides of veneer tiles; wrap-around corner and bullnose pieces should be used to further minimize the appearance of veneer. Brick wall cladding is frequently complemented by light-colored (white, off-white, light gray) accent materials such as limestone, glazed terra cotta tile, precast concrete, and/or glass fiber reinforced concrete (GFRC). Accent materials are typically used at window and door frames, wall bases, cornices, and as decorative elements. Other accent materials such as granite, river rock or colored glazed terra cotta are also occasionally used.

ii. Ceramic tile: Glazed and unglazed tile should be limited in use to a façade cladding or decorative wall accent material. Simple color palettes and design motifs should be used.

iii. Fiber-Cement or Cementitious Siding: An exterior siding product available in planks, panels and shingles and composed of portland cement, ground sand, cellulose fiber and sometimes clay, mixed with water and cured in an autoclave. They may be an acceptable substitute for wood siding when used in the formats described below under “Wood” (except in the Downtown Special Review Area). Extra care and training must be taken to ensure properly installation, proper tools are used for cutting, and non-rusting hardware is used for fastening. Earlier generation wood siding substitute products such as hardboard, oriented-strand board and asbestos board should not be used.

iv. Fiber-reinforced plastics (FRP), cast glass fiber composites (“fiberglass”): These materials are often used in molded reproductions of carved wooden or cast metal architectural ornamentation such as architectural columns, capitals and bases, cornices, and other trim. They may be used if their appearance closely approximates the type of painted wood element they are simulating, and are coordinated in color and composition with the selected architectural style. They should only be used at locations above the reach of pedestrians.

v. Profile, Corrugated, and Other Sheet, Rolled and Extruded Metal Surfaces: Where used, sheet metal should be detailed with adequate thickness to resist dents and impacts, and should have trim elements to protect edges.

vi. Stone (including river stone), stone veneers, cast stone, terra cotta, precast concrete, glass fiber reinforced concrete (GFRC): As well as wall cladding, these materials should be used as a wall base or wainscot materials and for copings, trim, and special decorative elements. Riverstone should not be used in the Downtown Special Review Area. Improperly simulated or contradictory finishes (i.e. use of panelized concrete to simulate a riverstone wall appearance with visible straight-line joints cutting across individual stones) should not be used.

vii. Stucco or EIFS (Exterior Insulating and Finish Systems): Stucco or EIFS materials are not recommended for Downtown Special Review Area buildings. For other locations, close attention should be paid to detail and trim elements for a high quality installation; for EIFS, high-density versions should be specified at ground floor level to resist impacts. Very stylized or highly textured surfaces are strongly discouraged. Joint patterns should be architecturally coordinated with overall façade composition. Ground floor level window and door trim elements should not be made from stucco, cement plaster or EIFS; they should instead be made of wood, metal, precast concrete or other contrasting durable materials.

viii. Wood: Horizontal sidings such as clapboard and tongue-in-groove; vertical siding such as board and batten; and other horizontal sidings such as smaller wood shingles may be suitable. The larger, more rustic styles of shakes should not be used. Trim elements should be used for all wood siding types. Timber detailing and exposed bracing may be appropriate. “T1-11” plywood panel siding is not recommended unless detailed with additional trim to emulate a board and batten style and must be of a smooth grade to avoid a rustic, textured appearance.

ix. Precast Concrete: The location and spacing of panel and expansion joints should be incorporated into the façade composition. Castings should be shaped to form architectural profiles that create bases, cornices, pilasters, panel frames, and other elements contributing to façade composition and human scale. Cement type, mineral pigments, special aggregates and surface textures may be exploited in precast concrete to achieve architectural texture and variety.

x. Poured-in-Place Concrete: Long surfaces of uninterrupted flat concrete walls should not be used. The use of textured form liners, pigments, stains, and/or special aggregates should be used to create visually interesting surfaces. At a minimum, the design of exposed concrete walls should incorporate the location and spacing of formwork tie-holes, expansion joints and control joints into the façade composition. To the degree possible, formwork should shape architectural profiles of walls that create bases, cornices, pilasters, panel frames, and other elements contributing to façade composition and human scale. Concrete walls may also be clad with other finish materials such as stucco and patterned to match other building walls. The architectural treatment of poured concrete that is used as a building architectural base should be extended to concrete used elsewhere in the project for sitework material.

xi. Concrete Block: Where concrete blocks are used, creativity in selecting block sizes, surface textures, stacking/bonding patterns, and block and grout colors should be used. In the case of a building base, façade composition should be coordinated with the architecture of primary building walls above. To avoid an institutional (i.e. “project” or “prison”) appearance, a plain stack-bond block pattern of standard size blocks should not be used. Decorative treatments such as alternating block courses of differing heights, contrasting grout colors, alternating surface textures (e.g. precision face and split face) and/or compositions of colored blocks should be used, along with matching cap and trim pieces.

i. Materials used should be appropriate to the architectural style and building type. Authentic materials and methods of construction should be used to the degree possible. Where simulated cladding materials (e.g. artificial stone to substitute for real stone, or painted fiber reinforced plastics to substitute for painted wood) are used for reasons of economy, they should be durable and closely match proportions, surface finishes, and colors of original materials.

ii. Wall cladding materials on additions and accessory buildings should be carried over from the primary building where possible. For historic buildings, please refer to the specific requirements and guidelines for historic buildings.

iii. If the building massing and pattern of windows and doors is complex, a simple palette of wall materials, textures and/or colors should be used. If the building volume and the pattern of wall openings are simple, additional wall materials, textures and articulation may be utilized.

iv. For individual buildings or portions of buildings intended to appear as individual buildings, materials used as primary cladding should be limited in number – one or two maximum in most cases.

v. Grout and sealant colors should be coordinated with colors of abutting materials as well as other building colors.

vi. An anti-graffiti coating should be applied at the ground floor level and wherever exposed façade surfaces may be accessible from upper floors through wall openings. A clear matte finish is generally recommended for such coatings.

vii. Primary Commercial Building Wall Materials.

viii. Primary Residential Building Wall Materials.

ix. Wall Accent Materials: are recommended to add interest and variety, for example, at architectural elements such as cornices and on portions of buildings or walls. Materials recommended for use as accents include brick, wood, stone, Fiber Reinforced Plastic, ceramic tile as listed above, in keeping with the architectural style of the building.

x. Building Base, Parking Podium or Above Ground Parking Structure Materials: may be clad, built with materials that extend down from portions of the building above, or built with contrasting materials of a more substantial character. Visible façades of Parking Structures, if not clad, should display quality materials of a substantial character that are complementary to surrounding architecture such as Precast Concrete, Poured-in-Place Concrete, and Concrete Block.

i. Window openings, operating types (single-hung, casement, etc.) and proportions of window frames and members should be designed in accordance with the building’s architectural style.

ii. Where greater privacy is desired for ground floor restaurants or professional services, large storefront windows should be divided into smaller units or panes. An “industrial sash” type of multi-pane window may be used where appropriate with the building’s architectural style.

iii. A vertical proportion of window openings (e.g., 3:2 to 2:1 height: width ratio) should typically be used. Openings may be composed of a series of vertically proportioned panes or frames.

iv. Commercial clerestory windows are a recommended feature in storefront glazing to provide natural light in conjunction with required height for shopfront.

v. Windows should generally maintain consistency in shape and in location across a façade. Unifying patterns should include a common window header line or sill line, and/or aligned vertical centerlines of windows and doors. The overall effect should create a harmonious pattern across the street wall.

vi. Windows on the upper floors should be smaller in size than storefront windows on the first floor, and should encompass a smaller proportion of the façade wall surface area. Exceptions to this may occur when large window openings are used as “penthouse” glazing (top floor of a four or more story building).

vii. At freestanding parking structures, long-span façade openings with a height: width ratio that is more horizontal than 1:3 should not be used. Vertically proportioned window-like openings (3:2 to 2:1 ratio) are strongly encouraged, to continue the pattern of pedestrian-scaled building façades. If horizontally proportioned openings are used, vertical pilasters, columns, or other elements should be applied to subdivide the horizontal proportion into smaller vertically proportioned openings.

i. Where multi-pane windows are utilized, “true divided light” windows or sectional windows should be used. “Snap-in” muntins (i.e. detachable vertical or horizontal glass plane dividers or glass pane dividers sandwiched between layers of glass) are discouraged.

ii. Window trim: Expressed window frames and sills should be used to enhance openings and add additional relief. They should be proportional to the glass area framed, as where a larger window should have wider framing members. Upper story windows and parking structure “window” openings should be detailed with architectural elements such as projecting “lug” sills, and/or lintels.

iii. Window accessories such as window boxes for plants, fabric awnings, etc., should be considered for additional articulation and interest, in coordination with the selected architectural style. Decorative grillework is recommended for parking structure openings, to add detail and help “break down” the scale.

iv. At additions and accessory buildings: windows should be of the same architectural style as the main building, including opening mechanisms and trim.

v. An average glazing inset of three inches from the surface of the exterior wall should be achieved through the use of thicker cladding materials, like masonry, on some sections of façades.

i. If horizontal or vertical aluminum sliding windows are used, assemblies with extrusions and frame members of minimum one and one-half inches exterior width dimension should be used, to avoid an insubstantial appearance common to aluminum sliding windows.

ii. Clear glass should be used. If tinted glazing is used, light tints and green, gray or blue hues should be used.

iii. If solar or heat control is desired, reflective glazing and/or reflective adhesive films should not be used. Nonreflective types should be selected instead. Low emissivity glass and external and internal shade devices are other options that should be used as well.

iv. “Lug sills” (protruding window sills – see glossary) should not be formed of rigid foam or other substrates sprayed with stucco or other wall finish material. They should be instead constructed with a permanent material such as painted wood, painted FRP, metal, precast concrete, GFRC, terra cotta, or stone.

i. Marked by a taller mass above, such as a modest tower, or within a volume that protrudes from the rest of building surface (except at the Downtown Special Review Area).

ii. Accented by special architectural elements, such as columns, overhanging roofs, awnings, and ornamental light fixtures (except at the Downtown Special Review Area).

iii. Indicated by a recessed entry or recessed bay in the façade. Recommended treatments include special paving materials such as ceramic tile; ornamental ceiling treatments, such as coffering; decorative light fixtures; and attractive decorative door pulls, escutcheons, hinges, and other hardware.

iv. Sheltered by a projecting canvas or fabric awning, or as a permanent architectural canopy utilizing materials from the primary building.

i. Located in the center of the façade between storefronts, as part of a symmetrical composition.

ii. Aligned with prominent façade elements of upper stories, such as an expressed or embedded entrance tower (except at the Downtown Special Review Area).

iii. Accented by architectural elements such as clerestory windows, sidelights, and ornamental light fixtures, and identified by signage and/or address numbering.

iv. Indicated by a recessed entrance, vestibule or lobby distinguishable from storefronts.

i. Mansard roofs shall not be permitted along Main Street within the Downtown Special Review Area.

ii. The height of a building with a mansard roof shall be as defined in BMC 12.64.202 Building Height.

iii. The maximum slope shall be no steeper than three feet of rise for every two feet of run (3:2).

iv. The minimum height of mansard roofs (from eave to roof peak) shall be one typical building story height or 30% of the building façade height as measured to the eave, whichever is smaller.

v. Mansard roofs shall fully enclose the perimeter of a building. Where a break in the horizontal run of mansard roof occurs, an architectural termination is required (e. g. the roof intersects into a tower).

vi. Mansard roofs shall include a cornice at the eave line where the roof overhang depth is less than two feet, and an edge termination at the peak.

vii. Mansard roofs shall have functioning or decorative dormer windows or vents to add visual interest.

i. The primary cornice should be decorated or bracketed with parapets, finials, or simple decorative panels or molding.

ii. An architecturally profiled cornice and/or expressed parapet cap should be used to terminate the top of the parapet wall.

iii. Surface mounted cornices, continuous shading elements, or trellises should be used to strengthen a parapet wall design.

iv. Sheet metal parapet caps or coping should provide a formed (compound folded) overhanging edge termination and a heavy gage sheet metal thickness selected to avoid “oilcanning” distortion. Single layer, flush sheet metal parapet caps should not be used. Finish should either be of an unpainted ornamental metal such as copper or painted to match adjacent wall surface. Unpainted galvanized metal should not be used in the Downtown Core or Downtown Neighborhood Districts.

i. At roof overhangs, vertical roof edge fascia over eighteen inches in height are recommended to be subdivided or accented by additional horizontal layers, stepbacks, trim, and other detailing.

ii. Brackets and corbels (i.e. decorative supporting pieces designed to bear the weight of projected overhangs), or other expressed roof overhang supports (whether structural or nonstructural) are encouraged to add richness to detailing. The spacing module of repeating supports should relate to the building’s structural bay spacing or window mullion spacing.

iii. The soffit (i.e. the underside surface of the roof overhang) should be designed as a visible feature and incorporated into the overall architectural composition. Soffit beams, coffers, light fixtures and other design articulation are encouraged.

i. At stair and/or elevator towers, special roof forms such as sloped or curved roofs are encouraged.

ii. Along parapet edges, cornices, shading elements, and/or trellises are encouraged to provide additional visual interest. The height of parapet walls and/or guard railings may be varied in coordination with the overall façade composition but should be tall enough to conceal vehicles.

iii. Due to their highly visible location, light poles and fixtures at roof parking decks should be specified or designed as decorative fixtures, architecturally coordinated with the style of the building.

i. Metal Seam Roofing: Finishes should be painted or coated. Copper, zinc, and other exposable metal roofs should be natural or oxidized.

ii. Slate or slate-like materials such as concrete tile: For simulated materials, exaggerated high-relief surface textures should not be used.

iii. Sheet metal shingles, such as copper, zinc, and alloys.

iv. Tar and Gravel, Composition, or Elastomeric Roofs (at flat roof locations): Light, reflective colors are recommended to minimize heat gain within the buildings. Roof surfaces utilizing these materials should be screened from view from adjacent buildings and sites by parapet walls.

v. Asphalt shingles: Projects using asphalt shingles should use the highest quality commercial grade materials, and be provided with adequate trim elements. Lightweight asphalt shingles should not be used.

vi. Solar (or photovoltaic) roof shingles: Where solar and non-solar shingles are combined in the same roof plane, shingles should be configured to match the visible size and layout of solar and non-solar roof shingles for an unobtrusive appearance.

i. Corrugated sheet metal, unless used as an accent roofing material.

ii. Stamped sheet metal used to simulate Mediterranean or Spanish roof tiles.

iii. Wood shakes or shingles in Downtown Core and Downtown Neighborhood District Requirements.

i. Materials, architectural styles, colors and/or other elements from the façade composition shall be used to integrate the screening into the building’s architecture.

ii. In the design of screening enclosures, use dimensional increments of window spacing, mullion spacing, or structural bay spacing taken from the façade composition.

iii. Solar panels if not completely concealed should be architecturally integrated into the roof.

iv. Wind equipment need not be screened, but should be architecturally integrated into the building design and located to avoid blocking views.