The University of California, Berkeley (UC Berkeley), School of Law (Berkeley Law) consistently ranks among the top 10 law schools in the country, one of the few public schools in a list of Ivy Leaguers. Until recently, though, Berkeley Law’s facilities were outdated and didn’t project the school’s identity as a world-class educational institution. The school not only needed upgraded classrooms and more storage for expanding collections, but it also sought new communal spaces for students and professors.

Since 1951, the law school has occupied Boalt Hall, a heavy concrete structure that has been expanded through multiple additions over the years to form a horseshoe-shaped complex framing a courtyard. The school administrators weighed their options: tear down the complex and start over with a blank slate, or work within its confines. The latter proved the more economical and sustainable choice.

Berkeley Law engaged Ratcliff, an architecture firm in Emeryville, Calif., to renovate 49,000 square feet throughout Boalt Hall and to design a new addition. Beyond classroom upgrades, the renovations in Boalt, which were phased over several years to avoid disrupting the academic calendar, include a new moot courtroom, meeting areas for student groups, law journal offices, faculty offices, conference rooms, and three distance-learning facilities.

The designers also faced the challenge of squeezing 55,000 square feet of new programmatic space—including collections storage, reading rooms, study space, staff offices, and a café—within the existing courtyard. Since there was no way to build up without blocking the view of Boalt Hall, Ratcliff chose to submerge most of the new addition. “We started digging before we even had a design,” recalls Kathleen Vanden Heuvel, the associate dean and director of the law library. Building below grade allowed the designers to preserve portions of the existing courtyard and create a new front door for the southeast section of campus. “Green space on the UC Berkeley campus is a really precious commodity,” explains Joseph Nicola, associate principal of Ratcliff Architects.

The centerpiece of the project, and the only visible portion from the street, is a glass pavilion, which contains the café, student lounge, and classrooms. Its simplicity calls to mind Mies van der Rohe’s Barcelona Pavilion, contrasting the weightiness of Boalt Hall. “It doesn’t sit heavily upon the earth,” Vanden Heuvel observes. Movable furniture allows the space that is the coffee shop by day to transform into an elegant venue for evening functions. Glass panels slide open and interior activities spill out into the courtyard. Besides glass, the subdued exterior palette includes a terra-cotta screen for solar shading, solid terra-cotta panels, and zinc panels. These materials bleed to the interior; for example, the western red cedar soffit at the roof overhang continues inside as an acoustical ceiling, and its staggered slats emphasize the east–west movement through the building and site.

A rooftop garden sits on top of the pavilion, connected to Boalt Hall by a new glass-enclosed bridge. Ratcliff collaborated with Hargreaves Associates on the design (the firm also designed the east and west courtyards flanking the pavilion and reconfigured nearby College Plaza, a major entry point for the campus), which features rounded, raised planters filled with succulents, reflecting the topography of the surrounding Berkeley Hills. On a clear day, the Golden Gate Bridge is visible in the distance. The rooftop provides a place for students to have lunch and doubles as a platform for fundraising events.

Below the roof garden and airy pavilion, the subterranean levels transition from public to increasingly private spaces. The first of the two lower levels—which are referred to as LL1 and LL2 instead of the basement—houses reading rooms, study areas, and offices for library staff, which were consolidated from previous locations. Skylights installed between the pavilion and Boalt Hall, along with walkable glass pavers in the courtyards, filter sunlight below. The main stair, enclosed in glass, also allows light to penetrate deeply into the lower floors, and it glows like a lantern at night.

The lowest level accommodates the stacks and protects books from damaging light. The collections, which are open to the public, are stored in space-saving compact shelving units that respond to the touch of a button. The designers aimed to draw students down to the lower level, so they carved out study spaces furnished with 100-year-old mahogany study carrels from the original law school building, Durant Hall. Another piece of the past is revealed: Boalt Hall’s split-face Indiana limestone foundation wall. Light rakes down this textured surface, which contrasts with the softer materials that line the lower levels. Cork flooring and acoustical wood ceilings and wall panels add warmth while improving acoustics.

Berkeley Law’s new addition is a subtle gesture that allows old and new to coexist in harmony, while reinforcing the school’s identity. It also reflects UC Berkeley’s commitment to sustainability, including the school’s goal to reduce potable water use significantly by 2020. The designers created a rainwater harvesting system that pulls an impressive 65,000 gallons per year from the existing 15,000-square-foot roof of Boalt Hall. Thanks to the integration of such sustainable features, the renovation is anticipated to achieve LEED Silver for Commercial Interiors, and the addition is anticipated to achieve LEED Gold for New Construction.

Murrye Bernard writes about architecture from Brooklyn, N.Y.