Vinyl Roof Gives Art Museum Cool Looks, Reliable Performance

An architect's work is typically grounded in a certain philosophy or vision of how lines, shapes and forms interact with each other to create a defined structure. Just as often, it may reflect an institution's mission. As in, for instance, "see, explore and make art" - the motto of Bellevue Art Museum in Bellevue, Wash.

When the museum embarked on its campaign to create a distinct building that would reflect its mission, it found an architect who took that vision to another level. Steven Holl, a native of the area who now heads Steven Holl Architects in New York City, welcomed the challenge. The architect decided to build a structure that would be a visible, palpable expression of the museum's goal to describe itself in terms of three - a reflection of Bellevue's "tripleness" in seeing, exploring and making art. One of the very vivid examples of Holl's concept is the museum's vinyl roof, whose three different types of slopes help achieve three different light qualities - fragmented, changing and linear.

Sclater Partners Architects, P.C., the local firm that carried out Holl's design, had to make sure that the quality of the 20,000-square-foot roof was as good as its "cool" looks. After considering various roofing materials and their appropriateness for the project, Brad Smith, an architect with Seattle-based Sclater Partners, decided to use vinyl. "We carried EPDM for a while in the general spec but we switched to PVC for several reasons," Smith said.

During discussions with a contractor, Pacific Rainier Roofing, also of Seattle, the architects discovered that vinyl - unlike EPDM - was available in the right custom color that complemented the aluminum used in the museum design. Scott Nicholson, vice president with Pacific Rainier Roofing, pointed to maintenance issues. "EPDM, though traditionally less expensive than PVC, would have to be systematically re-coated with paint," he said. And that would mean additional expenses for the museum in the long run, whereas vinyl's long lifecycle - often as long as 35 years - would eventually prove very cost effective.

Mechanical concerns were taken into consideration as well. "We felt vinyl would bond much better to metal flashing at the exterior joint. At the edge-roof condition, we wanted a really, really solid bond with metal at the exterior wall so we could have as minimal a downturn on the flashing as possible," said Smith. The vinyl membrane, ideal for that purpose, was heat-welded and mechanically fastened to the construction. "Such thermal bonding never comes apart," added Nicholson.  

To reflect Steven Holl's architectural philosophy, which emphasizes clean transitions and smooth intersections of different materials, the roof needed to keep as low a profile as possible, for which a single-ply vinyl membrane proved the right type of material. In the end, aesthetics drove the choice of materials for the whole project - and vinyl proved a better selection not only for appearance but for performance as well.