Experimental investigations of wooden beam ends in masonry with internal insulation

Abstract

Today’s stringent requirements on building energy performance and gradually increasing price of energy enforce complex refurbishment measures. Improvement of thermal insulation of building enclosure is the first logical step for climatic conditions of semi-continental climate. Refurbishment of many buildings with cultural value is possible only by accepting additional thermal insulation of external walls from interior side. Floors in such buildings are often supported by wooden beams placed in pockets embedded in brick walls. This paper deals with temperature and relative humidity in the air cavity behind wooden beam ends. To study this phenomena real scale experiments in University Center for Energy Efficient Buildings (UCEEB) of the Czech Technical University in Prague have been monitored for two years. Measured results indicated the fundamental difference between different types of joist pocket treatment. The relative humidity in open pockets approached to 100 % in cold season and corresponding mold growth index reached a maximum higher than one (germination of mold spores). Sealed pockets reached practically zero mold growth index throughout the experiment, although relative humidity in the pocket tended to exceed 80 % during cold seasons.