The Pendleton West classroom building on the Wellesley College campus had been on administrators’ radar since 2010, when inspectors reported that the building was outdated and unsafe. It became a key part of a $550-million renewal plan that included a variety of other campus updates. To announce the changes and bring it in line with the campus aesthetic language, designers value-engineered the exterior to architectural precast concrete panels with a distinctive board-form finish.
The original building, built in the 1935, was not designed to make efficient use of its current functions of providing space for practices and performances for the music school and had become worn. To revive it, the existing building was gutted and a 10,000-square-foot addition was built adjacent. The addition will feature a contemporary lecture hall seating approximately 50 students and will connect via an arts courtyard and walkway to Lulu Hall next door. The project was designed to achieve LEED certification.
The initial plan to use a cast-in-place façade was changed to feature a texture mimicking weathered boards. This was achieved by creating molds using hemlock boards selected by the architect to pour against, creating the desired wood grain. “Another benefit was the sugar from the wood leached into the panel, replicating the hemlock texture that was the architect’s design intent,” says Gerald Grassby, business development manager at Strescon, the precaster. Some of the panels received a sandblasted finish instead to provide contrast.
A base and foundation walls were created with cast-in-place concrete, and matching those elements to the precast concrete wall panels provided the biggest challenge for the façade, explains Eric Thiboutot, project manager at Garrick Construction. “Their strength requirements are different, so the mix colors we were getting didn’t match,” he explains.
The cast-in-place concrete was a Type 1 mix, while the precast concrete was a faster-setting Type 3. The team cast approximately 70 2- by 3-foot “tombstone” samples to find the best approach for matching the mixes. “We wanted to maintain the color consistency but still vary the tone to allow it to be a realistic appearance,” Thiboutot says. “It worked well and looks great. You can’t tell the difference between the two materials. But it took a lot of work to make it happen.”
The site sits on a hill, complicating delivery and erection of the panels, he notes. That made coordination of embeds and connections more difficult, especially in areas where through-bolts were required but access was restricted. “About 95% of the erection was very easy, but the rest required adapting to conditions and working through challenges.”
The erection moved quickly and was completed in less than three weeks using one crane. The renovations wrapped up in the fall of 2016, with classes set to return to the facility for the spring 2017 semester.