Adhesion of composite thermal insulation systems on woodbased panels

Failure of the adhesive bond may occur if composite thermal insulation systems are attached to wood-based panels in timber frame structures. In the past the causes of the adhesive failure have been unclear due to the lack of systematic studies. Based on experimental studies, this article describes and explains the relationship between changes in the topographical structure of wood-based panels caused by the moisture contained in the adhesive mortar and the adhesive strength of mortar as a function of mortar composition. These empirical findings were used to derive normalised adhesion curves for the expected adhesion strength on the most commonly used woodbased panels. An additional series of experiments revealed seasonal changes in the moisture content of the wood-based panels as the main problem for the adhesive bond. The results were used to derive the maximum permissible moisture content variation in wood-based panels depending on the composition of the adhesive mortar used. The findings enable scientifically sound evaluation of the adhesive bond between adhesive mortars and wood-based panels and can be used for deriving application recommendations for composite thermal insulation systems in timber frame structures.