THE SLOVAK capital’s largest church, St Martin’s Cathedral, which in its current form dates back to the 14th century, has been recently been undergoing renovation. However, it has also had to deal with an unwanted side-effect of an earlier makeover: woodworm, which was unwittingly introduced during work on the roof in the 1990s. The parasite is believed to have got in via wood which was used without having had all the bark removed. Since 1993, the woodworm has been consuming the wood in the roof, threatening to destroy the whole edifice and even spread to the cathedral’s wooden decorations and statues.
For the first time in Slovakia, a new method that has been used since last year in the Czech Republic was applied in the cathedral.
After the worm was found, the church authorities called in a company from the Czech Republic, Termo Sanace, to get rid of it. The method they used is known as thermal rescue and involves pumping hot air into the affected areas via aluminium piping. Woodworm cannot survive temperatures above 55 degrees Celsius, so the contractors heated the air in the roof to between 55 and 120 degrees Celsius. Its workers had to be careful, however, as wood can ignite at 300 degrees Celsius and all the church’s interior, and its roof, is made of wood.
“We had to drill holes in the wood and insert electronic probes one-millimetre thick. Then we had to check that the air was entering at 55 degrees Celsius everywhere, to be sure that all the worms were killed,” Jan Štěpánek of Termo Sanace told the Sme daily. “We had to check the temperature by computer, and also in person from time to time. Representatives of the archdiocese came to check, but they were able to stay for only about five minutes," he noted.
The whole process consisted of three phases, each lasting between four and ten hours. “When we later looked at the cathedral from the New Bridge through a thermal camera the whole building appeared to be luminescent,” Štěpánek said.
He refused to specify the cost of the thermal rescue procedure, only insisting that it was definitely cheaper than building a completely new roof – which was one alternative option. He criticised the ignorance of the restorers back in 1993, who he said did not check the wood properly and brought in woodworm under the bark of the lumber they had used.
5. Sep 2011 at 0:00 | Compiled by Zuzana Vilikovská