Preserving a Historic Facade
Repairs to Extend Cladding Life
Presented on August 26, 2020 at Facade Tectonics 2020 World Congress
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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.
Commencing in the fall of 2016, a project team lead by John Fidler Presentation Technology with engineers Structural Focus sought to investigate the deterioration, causes and possible treatments to stabilize
Properties of the Cordova Texas Shelly Limestone panels in façade application were not well documented. The material has an open-pored, shelly, outward appearance not dissimilar to that of Travertine, though
The historic May Company building exterior walls consist of steel beams and columns encased in reinforced concrete and infilled with reinforced concrete walls. The façade consists of 3” thick limestone
The testing procedure mimicked the installation of helical anchors into existing configuration of the limestone panels with grout backing on the concrete wall. Although the project team observed some tenacious
Once the tensile and shear capacities of the helical anchors were determined, helical anchor patterns were designed for the weight and seismic load of each panel. The patterns were selected
Conclusion and Future Work
As the limestone façade of the historic May Company building was part of the most prominent feature of the building, the preservation of the façade in lieu of full replacement
Scott M. Pons P.E., Preservation Engineers assisted field testing of helical anchors
John Walsh, Highbridge Materials Consulting Inc., stone testing
Tim Foster P.E., Specialized Testing Inc., engineering laboratory testing
Client: Academy Museum of Motion Pictures
Project Management: Paratus Group
General Contractor: MATT Construction
Masonry Contractors: Western Specialty