The aim of the project was to evaluate how the air tightness of buildings changes over time and how the sealing materials are affected during the expected life length of 50 years. The project was divided into two parts were one was laboratory tests of different products with accelerated ageing, and the other part were evaluation of older existing buildings. The laboratory test was conducted in a temporary room with lightweight construction in wood and different sealing products. The room was then heated to 80 °C and had changing relative moisture content in the air. The results showed that most products still maintained their function after accelerated ageing but some products considerably lost their ability to seal air through the building envelope.
In the testing of existing buildings, six single family houses that are between ten to twenty years old have been tested for air leakage. Test reports regarding air tightness from when the buildings where newly constructed were compared to new measurements. Three buildings had made changes to the building envelope while the other three had original structures. The results from the measurements showed that two of the tested buildings had considerably more air leakages than when they were new but that the rest had not changed. The change in air tightness for the two buildings are very likely due to changes made in the building envelope a few years after they were build.