Laboratory investigation on the durability of taped joints in exterior air barrier applications

In timber frame construction in Europe air barrier systems are typically realised at the interior side of the building envelope. Yet in some applications such as renovation projects it can be easier to provide the air barrier layer at the exterior. This way, the air barrier system – typically board materials in which the joints are sealed with tape – is exposed to outdoor weather conditions. The aim of the present article is to investigate the impact severe climatic conditions on the airtightness of typical taped joints. The airtightness of thirty two wood-fibre cement board samples have been investigated. Each specimen has a 2mm wide joint. Two different kinds of commercially available tapes were used to seal the joints. Airtightness of all specimen has been tested before and after accelerated aging procedures that mimics real exterior climate conditions. Three different aging protocols were selected: 1) temperature cycles, 2) temperature, rain and frost cycles and 3) UV exposure under high humid conditions. For the first two test conditions, the specimens had a size of 0.71m by 0.71m. Due to sample size restrictions of the UV exposure cabin, the specimens of the third test run were smaller (0.35m by 0.35m). All specimens had thickness of 12mm. The present paper will discuss the durability of the two tapes by comparing the air permeability of the specimens before and after the three accelerated aging exposures.