Evaluating the hygrothermal performance of wooden beam heads in 19th century town houses using in-situ measurements

Abstract

Improving the energy efficiency of typical 19th century townhouses in middle Europe the focus on the wooden beam bearing´s hygrothermal performance has become more and more important during the last years. There are several issues for the risk of rotting of the wooden parts of the ceiling, because the retrofitting process of the masonry totally changes the hygrothermal conditions inside the wall. Applying an interior insulation or changing the airtightness of the building envelope as well as the introduced moisture from the retrofitting process lead to a moisture increase inside the masonry and might cause rotting of the ceilings´ wooden beam ends. This paper introduces two demonstration objects which were retrofitted during the last years. Temperature and humidity sensors have been integrated at the wooden beams´ ends to show the hygrothermal conditions during and after the retrofitting process. In the first building measurements started at the beginning of the renovation in September 2013 and are still being carried out. To compare different situations the monitored beam bearings are situated in two different retrofitted wall constructions, an inside insulated and a not insulated wall. Additionally, different indoor climates in the flats above and below the measured ceiling are monitored. In the second building 16 wooden beam heads situated in two different storeys with differing masonry thicknesses were measured. In this demonstration object the influence of building construction moisture from the renovation process as well as the drying out process were evaluated. In conclusion, the wooden beam heads´ durability will be assessed based on the measurement results and possible risk of damage influenced by the retrofitting process.