The influence of the environment and physical properties of facade layers
The appearance of algae and mold is influenced by a number of factors:
– microclimate in the vicinity of the building, especially the proximity of vegetation, water surfaces and shady locations;
– structural exposure, such as northern facades and insufficient protection with eaves;
– rainwater drainage and the presence of capillary moisture;
– properties of the finishing layer, especially its absorbency, vapor permeability and roughness.
Infected facade/facade after renovation
A rough finishing layer offers microorganisms more opportunities for adhesion, while high absorbency allows for a longer moisture retention. Even in facades made entirely of the same materials, distinctly contaminated areas can occur due to local differences in temperature and relative humidity.
The most critical are:
– northern sides of the building,
– areas of the sub-walls,
– shaded areas under eaves or among denser vegetation,
– in some places also higher locations due to wind exposure.
Principles and phases of remediation of biologically contaminated facades
The basic guideline in remediation is the removal and destruction of microorganisms, only then does any physical or aesthetic repair of the facade follow. Mechanical cleaning at the beginning of the process is not recommended, as it could spread live spores to uninfected surfaces.
2. Mechanical cleaning after biocide application
Approximately 12 hours after application, the surface is cleaned mechanically - with a soft brush or hot water or steam under low pressure. It is crucial that the finishing layer is not damaged, as this could impair its protective function and increase absorbency.
3. Repairing damage and preparing the substrate
After complete drying, the facade is ready for repairing cracks, patching mechanical damage and leveling.
