Building on an Existing Structure

The existing garage below Director Park placed a number of constraints on the project. The site’s eleven-foot grade change coupled with a need to maintain six inches of undisturbed gravel over the uneven garage lid (to help ensure the integrity of the existing waterproofing) required innovative solutions to incorporate sub-surface utilities and accommodate the maximum ADA-allowed cross slope of two percent. While the finish grades are nine feet above the lid at the south end of the site, they literally are on top of it along the north edge. The fact that the existing garage was designed to support a 375-pound-per-square-foot maximum plaza load meant that areas requiring more than 36 inches of fill had to utilize a combination of rigid foam block and a lightweight soil mix to stay within limits. Finding a lightweight soil mix that would also support trees added a layer of complexity to the project’s design.

The garage portion of Director Park was completed by TVA Architects under a separate contract. To ensure both projects would ultimately come together as one, ZGF and TVA collaborated on the placement and material selection for the two shafts supporting the garage’s stair and elevator access.

Canopy & Art

The dramatic glass canopy is an organizational element that realizes a number of conceptual and programmatic functions.

By providing shelter for two outdoor terraces fronting the café, the canopy unifies the café with these seating zones and extends their use into Portland’s rainy season. Additionally, the canopy helps the park fit within its surrounding context by providing an intermediate scale between the horizontality of the plaza and the vertical proportions of surrounding buildings. At night, the canopy subtly attracts attention via the light-art installation integrated into the underside of the structure. The installation created by Seattle artist Dan Corson, titled “Mercurial Sky Dance,” displays a series of patterns derived from natural phenomena and movements on an array of LED light tubes that run the entire 110 feet of the canopy.

The glass canopy is supported by a steel post and beam structure topped with a series of purlins. The purlins are a composite assembly of back-to-back wood glulam beams sandwiched around a series of steel boxes. The patterning created within the purlins emulates the pattern created in the plaza stonework and provides a zone to mount and conceal the LED light fixtures and their associated wiring and drivers. The decision to use wood for the purlins was driven by a desire to reflect the regional architecture of the Pacific Northwest.

Café

Open from breakfast through after-dinner drinks and desserts, the café activates the park from early morning well into the evening, seven days a week. The 1,000 SF café provides both indoor and outdoor seating and features a walk-up window for “grab-and-go” drinks and snacks. Outdoor seating consists of a series of fixed benches crafted from Ipe hardwood along with a number of loose tables and chairs that park patrons can configure as desired.

The café is constructed from an exposed, beadblasted stainless steel structural frame. At the seating area, the frame is clad with clear glass, while the area surrounding the kitchen and support zone is clad with limestone and glass of varying degrees of transparency.

The composition of transparencies around the kitchen provides passersby with glimpses of the workers’ activities without completely displaying the less aesthetically appealing components of a commercial kitchen.

Detailing is accomplished with an unobtrusive style that completely showcases the building’s materiality and assembly. The glazing detail, for example, eliminates the typical window mullion and uses the structural frame to support the glass panels. Structural silicon sealant, hidden from view, is the only attachment between the two.

A number of creative solutions were required to maintain the high percentage of glass at the café’s facades. To meet energy code, cooling is not provided within the building; a combination of passive ventilation and a perimeter rooftop misting system keeps the space comfortable during warmer seasons. During the cooler seasons, a heat pump utilizes waste heat from the parking garage exhaust to warm the space. A perimeter radiant slab and operable windows keep the kitchen functions and the Portland weather from creating condensation on the interior of the glass facades.

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