The analysis of the timber roofs of the Loreta in Prague

The Loreto of Prague is a remarkable Baroque historic monument, a place of pilgrimage with a captivating history. Behind the main façade, which is the marvelous work of the famous Dientzenhofers, there is a courtyard with a copy of the St. Mary´s Holy House of Nazareth. Since the placement of the first construction stone in 1626, the Loreto has faced many construction phases with many alterations. The majority of the works progressed between 1698 and 1748 un-der the supervision of Christoph and Kilian Ignaz Dientzenhofer. These alterations also generat-ed some changes in the configuration of the roof structure and in some parts caused even damages. Some of interventions observed on timber frames are not documented and their purpose is not always obvious. For a better understanding, a historical analysis of the Loreto complex was used recently refined by dendrochronological dating of timber roofs elements from different time periods, so the histor-ical chronology of the building could be accomplished. Afterwards, diagnostic tests were con-ducted on site for the health evaluation of the members to assess their condition. The mechanical parameters are obtained with the new diagnostic tool which is the loading jack and correlates well to the compressive strength parallel to fibers. A structural analysis is performed to evaluate the causes of the deformations on the members. Elements subjected to the diagnostic testing proved relatively good condition with small qualita-tive differences between individual members. With the structural modeling, it was possible to evaluate their safety and stability and also to assess the effectiveness of their strengthening. The possible causes of their actual deformations are assessed with a brief proposal of eliminating fu-ture problems.