The decay risk of structural timber, wood-based materials, and natural fiber insulation materials can now be assessed much more realistically than before using the newly developed prediction model based on hygrothermal simulations.

This model considers the three key influencing factors: moisture and temperature at the critical location within the material, as well as the duration of exposure to these conditions and its effect on the decay process.

Criteria used to date – especially the limiting moisture content of 18 or 20% by mass, for example according to DIN 68800 or other international standards – often lead to an early classification as decay failure because relevant influencing factors are not considered and conservative safety margins are applied. The temperature-dependent limiting moisture content according to WTA Guideline 6-8 is based only on a short exposure period and currently applies only to softwood.

In addition, WUFI® Decay accounts for material-specific decay resistance and enables an overall prediction of decay risk that is much closer to real conditions. This provides the basis for the safe, appropriate, and resource-efficient use of sustainable building materials.