**5. Conclusion**

There are several factors involved with the bio-deterioration of materials and buildings, and mathematic modelling that may help us to understand the complicated interaction of many factors. The presented numerical mould growth and decay development models are based on experimental results from several research projects. It is suitable for post-processing temperature and humidity data from any numerical simulation of hygrothermal conditions in building constructions. However, it must be kept in mind when performing the assessment that there is a great uncertainty coupled to this kind of analysis: the variation of the material sensitivities is high, estimation of a product sensitivity class is difficult without testing, the surface treatments may enhance or reduce growth potential, different mould species have different requirements for growth and the evaluation of the actual conditions in the critical material layers may include uncertainties. The best way to use the predicted mould growth and decay development as an assessment tool is to compare different solutions with each others: The solution with the lowest risk for the mould growth or decay development would most probably also have least other moisture related problems
