A San Francisco Treat: Restoring the Historic Ghirardelli Square Clock Tower
Rising more than 100 feet above San Francisco’s waterfront, the 1916 French Gothic-style Ghirardelli Square Clock Tower is defined by its steep-slope slate roof and ornate sheet-metal detailing. Decades of exposure to the harsh marine environment and chronic water intrusion prompted a comprehensive investigation, which revealed widespread corrosion of ornamental sheet metal, deteriorated underlayment, and missing flashing components. These findings led the project team to reevaluate how to reconstruct the historic assemblies to preserve their original appearance while providing reliable long-term waterproofing performance for the rehabilitated structure.
In this webinar, we will explore the collaborative design process between the consultant team, preservation architect, roofing contractor, and sheet metal fabricator to refine details and address constructability challenges. Through extensive mockups and shop drawings, the team developed innovative solutions for transitions, flashings, attachments, and fastening systems to integrate modern waterproofing membranes and replicate the tower’s historic appearance. We will also discuss reconstructing the tower’s roofing system, including evaluating the existing slate, matching historic colors and patterns, and coordinating interfaces. Attendees will learn how historic preservation and modern performance requirements can successfully coexist in a complex restoration project.
LEARNING OBJECTIVES
After attending this webinar, participants will be able to:
- Understand how forensic investigation can inform restoration strategies for historic roofing and building enclosure systems.
- Examine the development of architectural sheet metal assemblies from historic documentation and conceptual details through fabrication-ready shop drawings.
- Identify constructability challenges commonly encountered while rehabilitating historic landmark structures and discuss strategies to resolve them.
- Explore the coordination of slate roofing, sheet metal detailing, and modern waterproofing systems within a preservation-focused restoration project.
Participants will earn 1 AIA CES Learning Unit (LU/HSW) for attending the seminar. Registration is free. Please note that space is limited – email events@sgh.com to join our waitlist if the session is closed when you register.
About the Speaker
Lauren DiCenzo has on-the-job experience designing, investigating, and rehabilitating contemporary and historic building facades. She values partnership and collaboration, and consults with architects, contractors, and building owners to deliver technically sound projects that maintain the architectural intent of the building enclosure. She has published on preservation technology and roofing through associations such as APT and Western States Roofing Contractors Association.
James Mendygral has extensive industry experience and a diverse background in building enclosure and structural engineering. His expertise covers a full range of engineering services, including assessments, design, and construction administration to assist clients with the successful delivery of their most challenging projects. His recent projects range from contemporary building enclosure design for various Silicon Valley technology companies to the award-winning restoration of PG&E’s historic headquarters in downtown San Francisco, CA. In addition to private consulting, Jim has served as an industry advisor to the Architectural Engineering Department at Pennsylvania State University.
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