investigation - Fixed church roof: Several factors causes
A collaboration of various factors led to the collapse of the roof of the Elisabethkirche in Kassel eight months ago, according to a report by engineers Ulrich Huster and Lars Eisenhut of the HAZ firm in Kassel.
As Eisenhut explained, the supporting roof construction of the Elisabethkirche, built in 1959/1960 in the Kassel city center, consisted of rafters joined together with special longitudinal connections, called general keel zinc connections. These connections were bonded with a resin-based adhesive.
"The bonding was subpar in today's view," Eisenhut stated. It had lost its strength over time. The exact cause for this was to be determined by scientists at University of Kassel. Possible factors could be shrinkage during manufacturing or climatic influences during the service life.
Additional stresses in roof construction
Another cause, according to the engineers: The supports of the roof construction should have been larger in size, based on current technology, than what the standards of the construction period allowed. Over the years, weather- and construction-related additional stresses had developed in the roof construction. A late roof addition in the 1980s also led to a permanent increase in load, according to the engineers.
"The general keel zinc connections have been torn apart like a zipper from the bottom up," Eisenhut explained. Eventually, the roof construction collapsed.
All 26 roof beams were broken
The causes were not recognizable prior to the collapse, the engineers emphasized. "The 63-year service life without a significant load event at the time of collapse suggests that there was a damage progression during the service life. Until the load-bearing capacity was no longer sufficient," was their conclusion.
On November 6 of the previous year, the roof of the Catholic Elisabethkirche collapsed in its entire length. All 26 roof beams, which had supported it, were broken at the time. A church employee, who was in the building at the time of the collapse, remained unharmed.
Following the incident, the Diocese of Fulda also inspected its other buildings for potential issues. In the Diocese's inventory, there were no other buildings constructed similarly to the Elisabethkirche, stated Diocesan Building Master Martin Matl. However, a screening of the churches in the Diocese had identified 48 buildings in need of inspection, which has since been reduced to 31.
Given that such issues are not limited to the churches in the Diocese of Fulda, we will share the findings from the report with church building experts from other dioceses and land churches. "And of course, this ultimately applies to buildings in general," Matl added.
The collapse of the church roof in Kassel eight months ago occurred at the Elisabethkirche, a church with a unique roof construction built in the 1950s. The University of Kassel was tasked with investigating the subpar bonding of the general keel zinc connections, which were believed to have lost strength over time due to factors such as shrinkage or climatic influences. The engineers also suggested that the roof construction supports should have been larger based on current technology, leading to additional stresses over the years. Following the incident, an inspection of other buildings in the Diocese of Fulda was conducted, revealing the need for inspections of 31 buildings. This incident highlights the importance of regular inspections and maintenance of church roofs to prevent such misfortune.
