Algae and fungus are among the oldest micro-organisms on Earth. During evolution they have adapted to life in many environments. They can be found in geysers of Iceland, and on the highest peaks of the Himalayas. They appear on almost all substrates, e.g. on stone, wood, metal, glass, and also on the facades, which create a green (algae), black (fungi) or green-black (algae and fungi together) coating.
The colonies of algae inhabit mainly the space in buildings with increased load of water, e.g. in the area of plinths. As regards the areas located near the coast and wetlands notifications relate primarily to the coating of algae on facades. Presumably, with a lower amount of moisture on the facades molds predominate and in case of higher moisture in the air or more of water on the surface – algae. It may also happen that the same faces turn green once, and once black, depending on the time of year and the related differences in humidity and temperature.
When the elevation of the building becomes green (not due to painting or air pollution), it is a sign that one need to look for the cause of external walls getting wet, since this is the basic reason for the growth of fungi and algae. Sometimes the reason for the appearance of algae is the high humidity caused by the proximity of trees and ponds. In such a situation, the only way to fight algae is washing away the layers of dirt, impregnating walls with antifungal preparations for external use and paint the façade with paints containing antifungal preparations.
After the elimination of the causes that facilitate attacking the facade by algae, plaster must be thoroughly cleaned and washed. This can be done manually, although high-pressure cleaner offers much better results After thorough drying of the walls, use one of fungicidal preparations, selected from a wide range available on the market. The measure must be richly applied to the elevation using the spray, roller or painting brush. When the substrate is soaked with preparation well, dirt which is still visible can be removed by vigorous scrubbing with a stiff brush. In the case of weak and moderate algae coating just one layer fungicide is enough. In the case of heavy contamination another layer will be necessary.
Regardless of the weather during the work walls should be protected with painting foil. One has to make sure that rain doesn’t wash off the fungicide, but it is also not advisable to dry it too fast due to the sun. Note – during the works involving the usage of fungicide liquids pay special attention, because they are toxic agents. It is worth using goggles and gloves. Avoid the liquid having contact with skin, eyes and mucous membranes of the mouth and nose.
Elevation purified and protected in this manner, after 48 hours, after complete drying of fungicides can be covered with paint. In the case of walls infested with algae, it is most recommended to use silicone paint with increased resistance to fungi and microorganisms.
Despite the use of preventive and protective measures facade sooner or later lose algae- and fungicidal properties. This means that periodically one must repeat the facade cleaning and protecting it from algae and fungi. It is difficult to predict how often, because it is affected by many factors, different for each object. Based on the experience of company usually façade should be covered with antifungal and antialgae agents not more often than every 5 years.