Wooden beam ends in combination with interior insulation: the importance of an airtight sealing

Abstract

The applicability of interior insulation when wooden beam ends are embedded in the wall is still a topic of debate, as interior insulation may imply an enlarged risk on wood decay. This paper shows the impact of convective moisture transport on the hygrothermal performance of the wooden beams. In a hot box-cold box experiment, a vapour open capillary active and two vapour tight interior insulation systems are studied together with a non-insulated reference wall. For each insulation system two configurations are analysed: one with and one without an airtight sealing between beam and insulation. The relative humidity at the beams without a sealing shows to be higher than found for those with an airtight sealing. This is especially true for the wall insulated with the capillary active system. Additionally, an overpressure is shown to influence the convective moisture transport and air flow around the wooden beams.