Deteriorating sandstone being replaced at St. John’s Church
One of Medicine Hat’s oldest churches is an getting an upgrade back to 1890s building technology, according to the “historic conservationist” tradesman doing the work.
Traditional mason Shawn Thibault has worked for several summers at St. John’s Presbyterian Church on Second Street, and since April has been replacing the sandstone accents and blocks on the historic building.
That is addressing deteriorating sandstone on the exterior, and refilling joints in the heavy stone foundation and brick walls, which show as much degradation over 130 years as would a stone building in Europe dating back to the Dark Ages.
Much of that has to do with the change in construction styles and materials used during the 20th Century.
“We’re just now learning from our mistakes,” said Thibault, whose company Ravenstone Conservation is based near Victoria, and previously performed major renovations of Medalta building and beehive kilns.
This spring, Thibault is replacing sandstone blocks that top columns along the exterior of St. John’s, technically called watershed capitals. But, he is using his own mix of mortar which he matched to samples taken from still-original portions of the building. That is mostly lime and sand, he said, opposed to Portland cement which includes gypsum.
Thibault said modern concrete, which came into use after the Second World War, is more permanent and requires less maintenance, making it more attractive to builders and owners. However, it absorbs and releases moisture at different rates than the main building material of brick or sandstone.
The result, said Thibault, is instead of the mortar wicking the water away, the water is trapped and winds up eroding the main building material.
“Repointing (mortar joints) is a pain,” he said. “But using traditional materials where applicable keeps the building healthy.”
The work is scheduled to be complete in late June.