The aim of the paper was to provide information about defects and causes of faults on the wooden facade of ThermoWood. The examined failure is the blackening of wooden elements on the entire area of the family house facade. The family house is now in a finished form and is therefore permanently used for housing people. Current damage does not jeopardize the stability of the object. A test sample of the blackened facade from the north-east side of the building at locations available and with a predominant blackening ratio was taken to determine the cause of the failure. The evaluation was based on general technical requirements for carrying out the work related to the implementation of the facade, technological details. Local examination of the facade revealed that the blackening occurs across the surface and shows signs of fungus. For this reason, a sample of the facade was taken from the north-eastern part and the opinion of the Czech Mycological Society was requested based on the photo documentation including the description of the impregnation used. At the end of the paper, we propose a comprehensive solution to the facade failure with the provision of the disposal and elimination of possible sources supporting the mold formation.