Hygrothermal behavior of window/wall connections

A detailed comparison

© Fraunhofer IBP

Investigating the hygrothermal behavior of window/wall connections with different sealing systems in the dual-chamber climate simulator.


Research on the hygrothermal behavior of window/wall connections was carried out in the dual-chamber climate simulator using two types of PU foam adhesive, without films for additional sealing. For the comparison, commercially available joint filler with caulking as well as with interior and exterior films was tested under the same climactic conditions.

For the test, two commercially available plastic windows were mounted in line with standard practice on an external single-story monolithic wall. This complete façade, consisting of the exterior wall and the two completely integrated windows, were constructed in the differentiation climate simulator. For a period of 28 days, environmental conditions in the simulator ranged from 0 °C on the cold end and 23 °C with 60-percent relative humidity on the warm end.

The aim of the research was to test the different sealing systems in regards to their hygrothermal behavior. Scientists recorded the increase in relative and absolute moisture levels by the end of the testing period as well as the mass-related moisture content on the foam samples at the end of the trial.

Their evaluation revealed a similar or slightly higher moisture increase in all joints using PU foam adhesives compared to the “standard” joints using films.


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