Dimensional stability. Industry for more than that extruded board exterior insulation because poor dimensional stability due to the effects of climate led to its size deformation, resulting in facing layer coating cracking, as the EPS system. In fact, we can from the system of the three elastic modulus of the material point of view, the mortar is about 15500MPa, EPS is about 4 ~ 6MPa, XPS is approximately 7 ~ 9MPa. Although EPS XPS smaller elastic modulus ratio, but compared with the elastic modulus of mortar, EPS and XPS board belong to the same order of magnitude, the material between the constraints will be no fundamental change. Mortar does not exist on the EPS XPS constraint constraint than better argument, but many engineering examples also confirmed this effect.