Abstract
For assessment of resistance of building materials against microbiological growth accordingto the so called isopleth system a special experimental set-up was developed. This set-up allows maintaining accurate controlled levels of temperature and relative humidity in special incubation chambers. Additionally, controlled lighting can be employed. The investigated materials are inoculated with well known material-relevant microorganisms. For a time of 100 days the development of growth is measured according to a scale which allows assessing both vitality and intensity of growth. Finally the results are expressed in a material specific isopleth system. In addition key conditions for the growth of certain microorganisms can be assessed. As a result each material shows its own resistance profile. Some "nutrient rich" products emonstrate an unexpected high resistance against mould. The data acquired helps planners, constructors and users to better choose the proper material for a certain application.