Assessment and analysis of the plaster exhibit hall ceiling at the wagner free institute of science, philadelphia, pa

1.0 Introduction

In December of 2003, a portion of the plaster Exhibit Hall ceiling at the Wagner Free Institute of Science fell two stories, causing concern as to the stability of the remaining plaster. Replacement of the entire plaster ceiling was suggested as a response to the fallen piece and the extent of cracking.

While plaster, as a finish material, is often considered replaceable and may not be considered a high priority for conservation, the Exhibit Hall ceiling is historically significant and worth preserving. For a site of historic significance such as the Wagner, total replacement should only be considered if the ceiling is in imminent danger of falling and if the current conditions cannot be successfully mitigated by more sensitive conservation methods such as reattachment. In 2007, an assessment of the problem was undertaken by Building Conservation Associates, Inc. in conjunction with summer interns employed by the University of Pennsylvania’s Architectural Conservation Laboratory. Visual observations do reveal that the plaster has experienced severe cracking and staining, but the ceiling appears to be sound and is not causing stress to the rest of the building. There has not been any additional loss since 2003. A structural engineer deemed the truss system structurally sufficient, and repairs only to the masonry walls were recommended as preventative maintenance. The assessment employed traditional diagnostic methods of assessing damage as well as Geographic Information Systems (GIS) analyses tools to determine the extent of damage, document the current conditions, and develop recommendations regarding treatment or replacement of the Exhibit Hall ceiling. A report on the observations and recommendations of this study was issued in January of 2008.

There are two objectives for this thesis: examination of the general utility of GIS as a diagnostic tool for the conservation field and exploration of the cause and effect relationship of the cracking plaster of the Wagner ceiling with the primary goal being preservation of the original fabric wherever possible. In order to better understand these relationships, a comprehensive review of the available information about the plaster ceiling was critical to the research and has also proven critical for better understanding of GIS as a diagnostic tool. GIS, while powerful, is one of only several tools necessary to execute a comprehensive and hopefully complete assessment of the plaster and its associated conditions of the ceiling at the Wagner Free Institute of Science.

2.0 The Wagner Free Institute of Science

The Wagner Free Institute of Science was established in 1855 by the amateur scientist, William Wagner, to provide free lectures for adults on scientific topics. Wagner first began offering lectures in 1847 at his home before moving to a larger space at the Municipal Hall near Thirteenth and Spring Garden Streets in 1855. The need for a larger building where Wagner could both offer lectures and store his growing collection of scientific specimens soon became apparent. Planning for the construction of the current building began in 1859 with its opening just after the end of the Civil War, in 1865. The dual function of the building as lecture hall and museum space continues today.