Deteriorating Limestone on Historic Bank Building Restored
Historic restoration experts Western Specialty Contractors, Springfield branch, recently completed a two-month project to repair the limestone base of landmark Illinois National Bank in Springfield, Ill.
Located in the city's prominent historical section, just blocks from President Abraham Lincoln's home and the Old State Capitol, the building's limestone base had deteriorated over time due to age, weathering and salts/deicers applied to the concrete sidewalks and streets adjacent to the building.
Bank owners contacted Western Specialty Contractors directly to make the needed repairs and maintain the building's historical integrity. Western consulted on the project with Cathedral Stone, a nationwide manufacturer of limestone and brick masonry restoration materials.
"After in-depth discussions with all parties about replacing the limestone pieces versus restoration patching, it was decided that the deteriorated limestone would be patched with limestone repair mortar Jahn M70 manufactured by Cathedral Stone," said Scott Haas, Western Springfield, IL Branch Manager. "This restoration technique made more sense than replacing the limestone, which would have required removal and reinstallation of some windows in order to replace some of the stones."
Before any materials were ordered for the project, restoration experts with Western and Cathedral Stone performed onsite mockups of the patch material to determine a custom-designed mix ratio to match the existing limestone as closely as possible. The craftsmen utilized on the project were Jahn Certified Installers, trained by Cathedral Stone in the use of their materials.
The first step in restoring the limestone was to remove the loose and deteriorated limestone back to a depth needed to reach a sound and solid surface. Crews used light-duty electric hammers to accomplish this task.
Western's craftsmen then custom-mixed the Jahn M70 restoration mortar and patched the cavities by hand. The limestone pieces were unique in shape and ornament, so matching the existing profile as closely as possible was of high importance.
"The repair material was over-filled, which allowed it to set to the necessary state," said Haas. "Then we shaved and carved the pieces manually to match the existing limestone."
Bank officials were pleased with Western's attention to detail and efforts to preserve the building's historical integrity.
"Our building is almost 100 years old. Over our years of ownership, we've tried to maintain its original integrity, and the work done by Western's staff helps assure we can do this going forward as well. We appreciate the tenacity of the local crew that spent many hot summer days on our sidewalks perfecting their work," said Tom Gihl, INB executive vice president and chief operating officer.
Click here to view the before and after product pictures.