Preserving a Historic Facade

Environmental and socio-economic benefits of sustainable preservation have become apparent most recently in the restoration of the historic former May Company department store, now renamed the Saban Building: the future home of the Academy Museum of Motion Pictures in Los Angeles.

Preservation of this building included seismic strengthening of its structure as well as its facade cladding. The potential falling hazard of historic facades is a major component of ensuring adequate life-safety performance when retrofitting historic structures. Such work involves challenges as older facade material properties are often poorly understood.

The Saban Building, a City-designated Streamline Modernestructure from 1939, presented this exact challenge. Large limestone panels supported on unpainted, mild-steel, shelf angles cast-in-place with the exterior concrete wall form this unique facade. As the shelf angles corroded over time, the panels cracked and spalled, requiring rehabilitation as a crucial part of the overall seismic strengthening and adaptive reuse of the property. The facade retrofit utilized countersunk, asymmetrical, helical, friction anchors to avoid alteration of its historic character and appearance. Drilled in pilot holes, through the existing limestone panels and backing grout, the anchors secured the panels to the concrete wall. With panels stabilized, stone Dutchmen and mortar patch repairs completed the work over new continuous flashings installed to protect the original steel box windows and frames.

Since helical anchors had not been permitted for this application in Los Angeles, there being no published engineering data for such anchors in limestone, the devices were tested by innovative means to obtain a one-time approval. Test data helped determine the required number of anchors for each panel. The retrofit scheme resulted in the successful preservation of the historic facade in lieu of complete replacement, while mitigating the falling hazard from the damaged limestone panels and reducing the project’s carbon footprint and cost.