Winning Project of the Chicago Architecture Biennial 2015 Lakefront Kiosk Competition.
How much kiosk can you get for $75,000? Chicago Horizon probes this question through a quest to build the largest flat wood roof possible. Using Cross-Laminated Timber, a new carbon-negative engineered lumber product, in the largest dimensions commercially available, the kiosk aims to provide an excess of public space for the Architecture Biennial and Chicago beach-goers. The generous 56-foot square offers an architectural lending library and shelter from the elements during its time in Millennium Park, and later becomes a large shading canopy overlooking Lake Michigan with space for commercial vending within. Chicago Horizon expresses lightness at a variety of scales, from the 8-foot hovering roof plane to the viewing platform and vending kiosk, which are suspended from the roof using chain-link fencing without any additional supports. The lateral reach of the roof recalibrates the experience of two extremes of the Chicago landscape: at ground level, the Lake Michigan horizon dominates, forming a line of symmetry between ground and canopy. From the viewing platform, the roof becomes a new artificial horizon, shutting out the foreground and emphasizing the floating vertical Chicago skyline above an abstract floating plane.
The program of the kiosk is formulated around its multiple contexts: the Chicago Architecture Biennial, the Lake Michigan beach, and, of course, the city of Chicago. During the Biennial, it will house an architectural lending library, designed both to facilitate the free exchange of books and as a venue for the exchange of new ideas: the large canopy extends well beyond the library enclosure, offering space for talks, events, and discussion, and for fair-goers to take refuge from the elements. Once the kiosk has been relocated to the Lake Michigan beach, the library transforms into a space for commercial vending, and the roof offers as much protection from the summer sun as it does from rain and snow. The lockable fence enclosures provide a secure environment for the library and commercial vendor alike, while also offering the potential for chair storage beneath the viewing platform.
At night the chain-link enclosures double as a lighting installation, each outfitted with a plane of programmable LED lighting and glowing with a different color temperature. The two pulsate in dialogue with each other throughout the night, alternating between the two poles of experience that the design sets up: ceiling and floor, day and night. LED strip lighting integrated into the fencing is used as signage for both library and commercial vendor.
Chicago Horizon is constructed almost entirely out of engineered timber products, including CLT for the roof canopy and glulam columns, making its total carbon impact negative due to the ability of wood to sequester atmospheric carbon. The canopy is to be fully protected by a roof membrane and an exterior grade plywood deck, ensuring its longevity. Interior enclosures are made from galvanized steel chain-link fencing, with steel grating for the viewing platform and wood shelving in the library enclosure. The fencing is suspended in tension from the canopy, providing the sole means of support for the platform and shelving. The kiosk emphasizes ease of construction, with most components fabricated off site and installation complete within a matter of days. The roof is constructed from the largest CLT panels commercially shippable in North America, and is assembled on the ground and hoisted up on glulam columns set on temporary helical pile foundations. Once the Biennial is complete, the roof can be lowered again and transported as a single piece the short distance to its final home on Lake Michigan.
The pavilion roof structure represents the application of the principles of flat plate (typical to concrete construction) to the material of wood. Two layers of CLT panels—one layer oriented in each principal direction, and each outer layer oriented lengthwise to the 8-foot-wide by 56-foot-long panels—combine to form a two-way spanning plate supported at points by columns. Each layer carries bending in the direction of the panel, with the layer above or below providing shear transfer between adjacent panels (and vice versa in the other direction). The result is a surprisingly thin 8.25-inch roof structure that spans upward of 30 feet between columns.
The columns connect to the roof plate using steel tongue plate bolted to the columns, which passes up through a slot in the CLT to a horizontal plate that connects to the CLT panels from above, hidden below the roofing and waterproofing. The columns themselves are simple glued laminated sections, held off the ground by a similar tongue plate at the base. The observation platform is supported by a chain-link fence held in tension along the edge of the opening to the roof using tack welds to structural steel angle framing the opening. The overall system is simple in its detailing, use of materials, and conception of its performance as a two-way plate, and this underlying simplicity complements the efficiency of the system.