Rainwater is usually sufficient to keep colour coatings clean. Impurities, such as leaves from trees, however, should be cleaned off the roof, roof valleys and rainwater systems once a year. Dirt and soil cause a corrosion risk by keeping the surface of the sheet wet. A dirty roof also spoils the appearance.
Coating should be cleaned with a soft brush and water or high-pressure water. More stubborn dirt can be removed using a cleaning agent suitable for paint coatings. Difficult dirt spots can be removed with a cloth moistened in white spirit. The rinsing should be carried out from the top of the roof downwards after the cleaning agent has taken effect for a few minutes. The rainwater gutters should then finally be rinsed down with water.
It should be noted that the use of unsuitable or excessively strong cleaning agents will damage the colour coating.
It is always worthwhile to repair any damage which occurs to the coating as soon as possible. Only paints suitable for repair painting of coatings should be used. The area should be touch-up painted using as small a brush as possible. If the damage reaches down to the primer coat only, one coat of paint is sufficient. If, however, the damage reaches down to the zinc, it is recommended that a second coat of paint be applied after the first coat is dry.
Edge corrosion, in which the cut eaves edge of the sheet begins to rust, can sometimes occur, particularly on low-pitch roofs. Painting the eaves edges after the roof covering has been installed can prevent this. This is highly recommended especially in seaside conditions.
Before any decision is made to completely repaint whole surfaces it must be checked that there are no local damages and the adhesion of the coating to the base is good. If significant localised damage is found, or the coating has faded unevenly, it is best to consult an expert to establish and plan a repainting scheme.
It is difficult to give an exact time for when maintenance painting should be carried out, as the useful life of colour coatings is dependent on many factors. These are colour and type of coating, local climate conditions, slope of the roof, building method, and installation method. The strain on coating is at its greatest on the south-facing slope of a roof, when the colour of the coating is dark.