Horizon Architect Michael Nolan described the need for exterior repairs on the courthouse following a study of the building.
“During my preparation of project design for the exterior repairs to the Monroe County Courthouse, I conducted a thorough survey of the building including the exterior walls and interior foundations,” said Nolan. “My observations included significant degradation of the face of the sandstone at the base of the building, partial and incomplete repointing with improper materials and temporary patching with foam materials.”
Nolan said that there are several areas of failed and missing mortar joints along the façade and large swaths of spalling face material. The dentil blocks are severely degraded along nearly 50 percent of the building. On the interior, evidence of water infiltration is evident with significant efflorescence and degraded mortar at the foundation brick structure.
The bulk water management of this building (i.e. rainwater) is accomplished on the exterior face as is common with most historic buildings,” said Nolan. “Modern buildings incorporate a drainage cavity and waterproofing behind the veneer stone but that practice was not common before the mid 20th century,” he said. “In historic masonry the stones and mortar joints are critical to the water management system.”
He said that in the case of the Monroe County Courthouse, the eroded and missing mortar joints have created direct pathways for water to penetrate the outer veneer stone and created “shelves” to retain water that either soaks the porous sandstone or simply degrades the stone through freeze/thaw cycles.
“The situation appears to be exacerbated by the application of a surface waterproofing in the past which is contributing to the lower level spalling of face material,” said. “Left unchecked, the material will continue to degrade, ultimately compromising the structure and making the building unsafe for continued use.”
In conclusion, Nolan said that by addressing the issues and proceeding with the repair, the county will ensure that every masonry joint on the building is struck and repaired with the appropriate material (lime mortar). “Mortar is intended to be a sacrificial material and should be softer than the stone or masonry,” he said. “As noted, incompatible mortars have been used in the past, leading to degradation of the surrounding stone.”
Nolan said that this project will use a compatible lime based mortar to halt this degradation and re-establish the drainage plane at the exterior of the face masonry. “Properly executed, this repair should last 40-50 years at which time weathering action and natural processes will likely require a similar project to repoint the exterior sandstone,” he said.