Extending the Service Life of Historic Terra Cotta Roofing with Fluid-Applied Waterproofing Membranes

摘要

Many historic buildings from the late 19th and early 20th century have terra cotta roofs that are in need of repair or replacement, but their stewards find it difficult to mobilize financial resources for the full replacement of the terra cotta tiles. The application of fluid-applied waterproofing membranes on the exterior of the terra cotta tiles can extend the service life of historic terra cotta tiles and provide waterproofing protection for the building. Although these membranes are not "historic" material, if appropriately applied, they can provide a cost-effective and aesthetically appropriate alternate to full replacement of the terra cotta tiles. The selection of the appropriate fluid-applied waterproofing membrane requires a deliberate process that integrates both design and construction considerations. It includes background review to develop removal techniques (if an existing membrane is present) and options for the fluid-applied waterproofing membrane; a careful evaluation of the moisture content of the terra cotta; a field investigation that includes a series of mockups to understand the existing coating removal process and fluid-applied waterproofing membrane application process; and finally, careful installation and a continued review to ensure that all the lessons learned during the mockup (sample membrane installation) are implemented in the field. This paper presents practical advice to designers and builders to assist in the selection, design, and installation of fluid-applied waterproofing membranes on historic materials. Using a case study, the Luzerne County Courthouse in Wilkes-Barre, Pennsylvania, this paper shows the step by step process required to develop the design for the application of a fluid-applied waterproofing membrane over historic terra cotta.