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Exterior Envelope Renovation of Philadelphia City Hall
Date:  Tuesday, May 11th
Time:  9:00am-12:00pm 
Offers: 2 AIA/CES LUs    
Cost:   $35

City Hall Before Renovation		City Hall After Renovation

Presenters/Project Team:

VITETTA:  Nan R. Gutterman & Hyman Myers		Nan R. Gutterman
Kelly Maiello:     Vincent Maiello & Robert Glick		Robert Glick
Marianna Thomas Architects:  Marianna Thomas		Marianna Thomas
Keast & Hood Co.:   Carl Baumert		Carl Baumert
Steve McLaughlin Roofing Consultant: Steve McLaughlin		Steve McLaughlin

                                                                                                        More about the Presenters 
                         
Philadelphia City Hall is one of the City’s greatest architectural treasures. The building sits at the very center of the City’s original grid of streets, planned by William Penn in 1681. The building, designed by John McArthur, Jr., was constructed over a thirty-year period starting in 1871. It is now designated a National Historic Landmark, arguably the finest example of French Second Empire architecture in the United States, and it is the tallest masonry bearing wall building in the world. Almost square in plan with a center exterior courtyard and two major lightwells, the building contains over one million square feet of interior space, and about 700 rooms making it the largest city hall in the country. Its richly ornamented perimeter facades extend nearly 500 feet along each side and the masonry on the tower rises to three hundred thirty-seven feet with the top of William Penn’s hat topping the tower at five hundred forty-eight feet and weighing in at almost 27 tons. The facades, the fifty-story clock tower and the four portal entries are adorned throughout with a fantastic array of monumental marble and bronze sculptures as well as ornamental motifs designed and executed under the direction of the renowned sculptor Alexander Milne Calder.

The Philadelphia City Hall Envelope Renovation is a multi-phase project. The project includes the exterior renovation of all the exterior facades of the building facing both the street and the courtyard. The project includes the exterior rehabilitation of over 700,000 square feet of masonry - granite and marble; the rehabilitation of the cast iron cresting and ornament - including lead abatement, painting and repair, the rehabilitation of over 1000 original mahogany windows; the installation of new window air conditioners and frames; repairs to the slate roofs and the installation of over 100,000 square feet of new flat roofing. The Phase 4 project is scheduled to start in the 2010.

The project team included the Capital Program Office, as the Owner, C.B. Development as the Owner’s representative, and a team of professional consultants. VITETTA was the lead designer historical architect and project manager for Phase 1 and 2. They were also responsible for documenting repairs to the masonry and copper dormers for all phases of the project. Kelly Maiello Inc. was the project manager for Phase 3 and 4 and were responsible for documenting repairs to the windows, roof and gutter systems for all phases of the project. Marianna Thomas Architects documented repairs to distinctive ornamental cast iron roof components. Other consultants included Keast & Hood Co. as the structural engineers for the entire team, Norton Art Conservation as the sculpture conservator work and Vinokur Pace Engineering for the related mechanical and electrical engineering work.

Design and Craftsmanship
The original building was constructed of the finest of building materials: two types of granite at the base, Massachusetts Lee marble for the facades and sculptures, cast iron for the crestings and ornaments on the mansards, solid mahogany windows, copper dormers and flat roofing systems modified bituminous membrane. The quality of the original construction set the standard for the restoration work. Daniel J. Keating Co., the general contractor for all the work completed to date selected sub-contractors who could complete quality work for each of the trades required to restore the building envelope to its original condition when construction was completed in 1901, and the original high craftmanship standards set by John McArthur Jr., the original architect.

Excellence in Project Teamwork
Daniel J. Keating Co. organized their sub-contractors and submitted a project schedule that took into account the restoration of the cast iron, which was the one critical path item for the project that would control how quickly the project could be completed. Even though the initial cast iron survey was completed from a high-reach as part of the design documentation phase, each piece of cast iron was re-surveyed after the many layers of paint coatings were removed in order to determine the level of deterioration hidden under the paint coatings and identified the nature of repair required on each cast iron piece. The three levels of repair on the cast iron were 1) minor repairs completed in the field, 2) shop repairs and 3) total replacement. The cast iron was replaced in-kind where required with new cast iron pieces fabricated from new molds. The subcontractor completing the repairs to the cast iron in Phases 1-3 was Crescent Iron Works, who has maintained the standards set by the original cast iron fabricators.

A similar re-inspection process of the building façade was completed on the masonry which is resurveyed by the architect after the marble and granite has been cleaned with a combination of water misting and low-pressure micro abrasive system. This work in Phases 1-3 was completed by the masonry sub-contractor Lepore-Mark. A majority of this work has temperature limitations and therefore these requirements need to be factored into the project schedule. This project was significant because of the scale of the building and the extensive work required to overcome more than fifty years of minimal maintenance in order to return the building to its original pristine appearance and to protect the interior. The original copper dormers were repaired rather than replaced. The work was completed by Hamada Roofing in phases 1-3 who also installed the new flat roofing systems, new gutter liners and repairs to the slate mansard roofs.

Innovation in Construction Techniques or Materials
Where any new or replacement materials were installed, they were the same materials that were used when the building was constructed over one-hundred years ago and the project has set a new standard for level of care. For example, prior to starting the cleaning of the masonry, the City funded a study in 1995 that was completed by VITETTA, a team of conservators and the USGS. The objective of this study was to determine the balance between the safest and best way to clean the Massachusetts Lee marble on Philadelphia City Hall facades including the array of sculptures thereon.

Excellence In Client Service and Customer Satisfaction
The building was continuously occupied throughout the construction period. In addition, construction started in the courtyard prior to the Republican National Convention in Philadelphia in August 2000. Public safety and public image were always important on this very prominent City building. The client, the Capital Project Office and the owner’s representative C.B. Development were extremely pleased with the results of the project. The north facade and the tower of Philadelphia's City Hall were completed in the fall of 2003 and the majority of the west façade was completed in October 2004. The work on Phase 3 which included the South façade and one half of the East Façade was completed in late 2008. The current view from North Broad Street and the Benjamin Franklin Parkway shows that the city has properly reinvested in its primary governmental symbol and is the greatest symbol of American Victorian architecture.

Philadelphia's City Hall is recognized nationally as an extraordinary piece of Victorian architecture, but it is also important locally to the citizens of Philadelphia as the symbolic and physical center at the crossroads' of our city. The purpose of presenting this project is to show how to approach the exterior renovation of a high municipal building without lowering preservation standards.
 
The Philadelphia City Hall Facts:
>Built over 30 years: 1871-1901
>Largest & tallest masonry building in the world
>Footprint: 4.5 acres (4 city blocks)
>Over 250 Sculptures
>William Penn statue at 37ft. is the tallest on any building in the world and was set on the tower in 1894