Preserving a Historic Facade

Repairs to Extend Cladding Life

Overview

Authors

Photo of Maria Mohammed, S.E.

Maria Mohammed, S.E.

Design Engineer

Structural Focus

mmohammed@structuralfocus.com

Photo of John Fidler, RIBA, Intl Assoc AIA, FRICS, FSA, FRSA, FIIC, FAPT

John Fidler, RIBA, Intl Assoc AIA, FRICS, FSA, FRSA, FIIC, FAPT

President

johnfidler@jf-pt.com


Keywords


Abstract

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 façade 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 façade 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 façade. 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.

Introduction

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

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Background

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

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Case Study

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

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Data

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

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Explanation

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

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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

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Acknowledgements

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