by Zach Mortice
Associate Editor

How do you . . . minimize the footprint of a library addition to maintain public amenity and green space?

Summary: The South Pavilion addition to the Berkeley School of Law Library, Berkeley, Calif., offers a rooftop garden and screening system to replace the public amenity and green space consumed by its construction. Similarly, most of the building is placed underground to reduce the footprint of the building. From bottom to top, the building becomes lighter and more open, eventually becoming an ephemeral pavilion that steps gently on its site.

When the University of California-Berkeley School of Law needed to expand their law library facilities, they were faced with two less-than-ideal options. They could disrupt the operations of their main law library, Boalt Hall, for years, or they could tear up a public courtyard in front of Boalt and build there. The law school, which had expanded their law school faculty by 25 percent in the past four years alone, weighted their options and let their architects, Ratcliff of Emeryville, Calif., decide. Joseph Nicola, Ratcliff’s director of academic practice, and his team decided to dig up the courtyard—removing a public gathering space and sorely needed foliage from a dense, urban campus.

But, through attentive material choices and thoughtful programming, Ratcliff’s design preserves these spaces as much as it can and creates new public amenities where it must, all by sitting lightly on its site and minimizing its footprint.

Underground, in the hills
The 54,000-square-foot, $90 million South Pavilion addition law library broke ground in October and is expected to be completed in two and a half years. It is a modest, glass-walled rectangular pavilion with an overhanging roof, placed in what was a disused and overgrown courtyard just south of Boalt Hall. To minimize the footprint of the addition, Ratcliff put two of the building’s three levels below grade, thereby not obscuring views of Boalt Hall and maintaining courtyards to the east and west of the addition. Nicola and his team replaced the courtyard space their design consumed by adding a park-like rooftop garden. This garden connects to both Boalt Hall to the north and Steinhart Courtyard to the east via skywalks. An 18-foot gap between the South Pavilion addition and Boalt Hall is encased in glass that becomes a skylight peering down two levels into the building’s first basement reading room. This is the only visual clue that most of the building lies underground. Ratcliff’s building is never fussy or attention-seeking about its below-grade design. “We wanted to be subtle as far as that’s concerned,” he says. “We didn’t want to be overbearing and say, ‘Hey! Look at us!’”

Adjacent to this gap is a rainwater collection system trough that delivers storm water to a cistern that will store water for landscape irrigation. Other sustainability features will include low-flow faucets and toilets, low-VOC materials, and Forest Stewardship Council-certified woods. Ratcliff is targeting LEED® Gold certification for the project.

The most expressive features of the otherwise staid and rational Modernist glass pavilion are its topographically rich patches of green roof. Planted with trees and grasses, they run across the roof in thick, irregular strips, hemmed in by concrete and cast-stone retaining walls that match their topographic contours. These artificial hills, developed in conjunction with the project’s landscape architects, Hargreaves Associates of San Francisco, will rise up several feet, and create a welcome disruption to the urban campus. Nicola says this rooftop topography was inspired by the hills that surround Berkeley. The rooftop garden terminates at a glass handrail and zinc-paneled overhanging roof.

Giving back green
The east and west elevations of the addition are moveable glass walls that open to courtyards. Thin steel and concrete columns just inside the glass walls support the structure and contribute to its light touch on the land by leaving open the visual exchange between the inside of the building and the public life surrounding it. The south elevation is lined with a series of vertical wire mesh “green screens,” as Nicola calls them. In addition to adding green space back to the site with the rooftop garden, these 4-foot by 8-foot vertical louvers will be woven with a plant material that is still to be determined. The screens, placed every nine feet, give a consistent rhythm to the building. “We needed to put something back on that green edge,” Nicola says.

Behind the screens will be a dual-skinned system of rods (Nicola calls them “terra cotta baguettes”) and glass. This system is similar to AIA Gold Medal recipient Renzo Piano’s New York Times Building, where horizontal ceramic rods outside a glass curtain wall diffuse light and provide solar shading. The middle section of the south façade will be clad in solid terra cotta panels. From a textural standpoint, these panels and “baguettes” will match the terra cotta roof of the vaguely Spanish Mission-style Boalt Hall, though the addition’s materials will be much paler in color. From the law library complex’s south street-facing elevation, the squat profile of the South Pavilion addition also fits in as another tier in Boalt Hall’s subtly terraced massing.

The evaporating building
The new addition to the law library will house stacks from Boalt Hall, freeing it for more seminar rooms and study areas. Programmatically and formally, the South Pavilion addition becomes more open, ephemeral, and public as it rises from floor to floor—from the natural light-shielded bottom-most level filled with stacks, to the skylighted first basement level with staff offices, reference desks, reading rooms, and conference spaces, to the glass-walled top level’s lobby and café. By the time visitor reaches its rooftop garden, the building has entirely evaporated into a constructed landscape meant for recreation. Any building can’t occupy a site much lighter than that.