In designing a music rehearsal hall for an addition to Wellesley College’s Neo-Gothic Pendleton West arts building, in Massachusetts, Philadelphia-based KieranTimberlake was inspired by the wooden sounding box of violins and other instruments. Naturally lit from clerestory windows, the double-height space is wrapped almost entirely in a custom wood acoustical wall system, developed in collaboration with Cambridge, Mass.–based Acentech.
The 1,625-square-foot rehearsal hall is the main programmatic element to the 10,000-square-foot jewel-box concrete addition that connects Pendleton West, built in 1934 and renovated as part of the project, to Paul Rudolph’s 1958 Jewett Arts Center via a series of bridges.
In such a sylvan and storied setting, the architect’s job is that of a doctor’s: Primum non nocere. First, do no harm. “That’s sort of a primary goal,” says KieranTimberlake principal Tim Peters, AIA. “So the work tends to be deferential in a lot of ways, but it’s not trying to match, it’s not trying to mimic.”
In tone and materiality, the addition takes cues both from Rudolph’s exposed-aggregate concrete columns and the natural landscape, using concrete and red oak to create a quietly contemporary, high-performance building. Wood serves as a unifying element, visible not just in the interiors and curtainwall but also in the contours of the board-formed concrete. “The making of a concrete building involves an incredible amount of wood,” Peters says. “So why not imprint the wood as evidence of that making?”
Although the building’s concrete shell is mostly exposed, the design team knew the rehearsal hall’s walls would need to absorb and contain sound. At the same time, Peters says, “we were extremely strapped for space. Every inch counted. So we didn’t have the luxury of shaping that room in a way that would’ve been a little bit more acoustically beneficial.”
The acoustical wall system the team developed essentially creates a “box within a box” that helps prevent sound transfer. From the outside in, the building’s 10-inch-thick concrete shear walls support an insulated metal-stud frame sheathed with gypsum wallboard. Affixed to the gypsum wallboard are vertical furring members and 2-inch-thick, fabric-wrapped fiberglass panels, the latter of which attach with aluminum panel cleats. The furring members are crossed with horizontal nailers, spaced 24 inches on center, creating a 2.25-inch airspace between 3.5-inch-wide, quarter-sawn white oak slats and the sound-absorbing panels.
The system is tunable, incorporating 19 bifold panels that increase the absorption of sound when opened. The acoustic wall system also conceals utilities, including plenums for the building’s displacement ventilation system, which helped the rehearsal space become more zen-like. “We had this incredible desire to create a serene space, one that, when everything was in its place, was more like a chapel than a music practice room,” Peters says.
Using hand calculations and 3D modeling, KieranTimberlake built a prototype of the wall system that it then took to Acentech’s office for acoustic modeling and experimentation with variables such as airspace depth, acoustical panel thickness, and wood-slat width and spacing. Finding the right combination of parameters that would perform the best acoustically is “a little bit of a dark art,” Peters says.
The testing proved invaluable. The designers learned that the assembly, configured as it is now built, balanced the absorption of the correct sound frequencies as equally well as a layout that varied slat widths and spacing. “Because of our desire for serenity in the space, we chose the regular wood slat dimension and layout over the randomized version,” Peters explains. The testing also revealed that the upper volume of the rehearsal hall needed to reflect more sound; as a result, in that area, the designers closed the 1-inch gaps between slats with a solid plywood backer in the walls, eliminating the need for the fabric-wrapped acoustical panels.
Although the panelized wall system was designed to be prefabricated off-site, CDD Custom Millwork, in Norwich, N.Y., assembled the system in situ using parts that workers had prefinished in the shop. By completing the system on-site, Peters says, the carpenters could better align the system with adjacent conditions, such as doors and windows, and coordinate with other trades on integrated components, such as airflow plenums and utility enclosures. “At the end of the day, it really worked out,” he says. “The stars aligned, and we had very few hiccups.”
The project took two years to complete, with the renovated Pendleton West and the addition opening in spring 2017. While the new building deftly marries its adjacent buildings, finding commonalities across 80 years of campus building, Peters is most pleased with the activities the arts center now hosts. “It’s been extremely gratifying to see students engage with the building,” he says. He has seen students documenting the architecture or mounting small art installations that acknowledge the building’s materiality. “How does light filter across a board-formed concrete wall? How do certain textures reveal themselves? Students are engaging very literally with those things,” he notes. “And that’s the best thing that could possibly come of it—that the building is actually a pedagogical tool."