Biocidal products are widely used in urban areas for material protection. Their mode of action is specific against algae and fungi. Carbendazim, diuron and Irgarol 1051 are representatives for biocides in paints and plaster of facades. Similar applications of biocides are known or expected for plastic membranes on flat roofs and bitumen sheets for roof waterproofing. Pesticides used in urban and rural areas may have the same active ingredients.