7. Preventive treatments

7.1 Copper wire

One of the most common solutions for eliminating greening is the use of copper wire, usually placed at the ridge. Numerous experiments carried out by the CTTB have shown the limited effectiveness of such devices, even when the wire is replaced by copper plates, or when special ridge tiles with copper skirts are used. Close to the metal, the tiles remain "clean", but a few centimetres downstream, they turn green again. Although copper wire has no decisive effect on greening, its voltaic reactions cause rapid degradation of zinc gutters!