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This article deals with the hygrothermal performance of wooden beam ends embedded in brick masonry walls. The real-scale experiment involving three interior insulation systems with different water vapor resistances and different treatments of joist pockets was monitored for three consecutive years. The moisture load of test walls was controlled during the experiment. First, humidity of indoor air was increased in the cold season (2016–2017). Then, an artificial short-time intensive rain event brought liquid water onto the external surface of the test walls in July 2017. Despite relatively mild external climatic loads, relative humidity was unsatisfactorily high in unsealed joist pockets. Vapor and airtight sealing of the joist pockets improved the microclimate of the wooden beam ends. However, even in this case, relative humidity approached critical values for the onset of mold growth. The artificial rain load applied on the experimental walls noticeably worsened the hygrothermal conditions in the joist pockets. Relative humidity in the joist pockets further increased to a level where massive mold growth could be expected. Visual inspection of the wooden beam ends during reconstruction of the experiment, however, revealed only a small spot of mold on a single beam located in an unsealed joist pocket. Mold growth on samples of organic thermal insulation material was found by microscopic investigations. Molds were localized in small separated colonies. These in situ and laboratory investigations do not confirm the calculated values of mold growth index. In conclusion, sealing of wooden beam ends improved their hygrothermal performance in the experiment.

During the last few decades, unheated attic spaces (so-called “cold attics”) have been one of the most moisture-problematic spaces in the building practices of Europe and North America. Problems with such spaces are usually associated with condensation, frost formation, and mould growth on the lower surfaces of the roof deck. To solve these problems, a number of qualitative studies were performed. Although these studies revealed many important pieces of information, some of them are seemingly not in accordance with one another. Therefore, there has not yet been presented cold attic design which is suitable (especially moisture-safe) for the whole target region. The aim of this paper is to determine whether such a design can be determined or state the reasons why it is not possible. Based on a review of published studies, 38 cold attic designs were selected for detailed analysis. Their comparative parameters were established, quantified, and compared. The moisture-safeness of each design was evaluated using an original approach, and the designs were sorted into groups based on their similarities. Despite many uncertainties, it was found that the criteria for moisture-safe cold attic design in the target region can likely be stated.

Roof structures have been traditionally built from reed or straw in tropical climate locations. Now, traditional materials are often replaced by pure metal sheets. The roof construction is improved in terms of durability and cost effectiveness, but he roof built from pure metal sheets can cause excessive overheating of interior spaces. The aim of this paper is to compare dynamic thermal performance of different roof assemblies under real boundary conditions. For this purpose, a thermally insulated test box was built on the roof of the university. Six roof samples (0,9 m × 1,1 m) can be mounted on the roof. The roof covering made of pure steel sheet with Zn coating was the reference case. This assembly was then modified step-by-step either by change of colour, or by additional material layers of reed and earth boards, or by 2cm thick ventilated air cavity on the rear side of the sheet. In total, 18 different roof assemblies were tested in three consecutive test runs (approximately three-week periods between 07 – 09-2020). Ventilated air gap and white paint are the best adjustments to reduce heat flux. Dark colours of the metal sheet have the opposite effect. Influence of reed and earth boards was in many cases similar. One roof assembly was selected for use in real project.

Wooden floors were traditionally used in brick apartment houses built at the turn of 20th century in many European cities. Thermal renovation of such houses often involves thermal insulation at interior side of external walls. Internal insulation makes microclimate in the vicinity of wooden beam ends colder and more humid. The real-scale experiment involving a part of wooden floor connected to a 30 cm thick masonry wall was monitored for two consecutive years. Measured data were used to compare microclimate in sealed and open joist pockets. Joist pockets were either placed in the masonry wall with plaster on both sides or placed in the same masonry wall insulated on the interior side (vapour open thermal insulation system). The measured results indicate that the sealing tape alone is not sufficient to keep the relative humidity in joist pockets below 85 % in cold climate and under high internal moisture load. The paper concludes that reasonable trade-off between thermal efficiency, thermal comfort and moisture safety is difficult to reach for masonry with internal insulation and wooden floors. Sealing provisions complemented by tempering of joist pockets are considered as two key technical measures for reliable hygro-thermal performance of wooden beam ends in full-brick masonry with interior thermal insulation in cold temperate climate.