Scheduled maintenance is routine maintenance that is performed at pre-planned regular intervals. Inspection should always be an included part of scheduled maintenance.
The accumulation of deposits on a metal surface may increase the time of wetness of that surface and also increase the corrosivity of the wetness. Most exposed metal roofing will be adequately cleared of dirt by rain washing, but that is not the case with unwashed areas. Unwashed areas include all wall cladding. It is particularly applicable to areas directly sheltered from the rain, which includes all surfaces that are above a line drawn at 45° to an overhang, such as a soffit, underside of a canopy, under spouting, or garage door head.
Manual washing is required to prevent the accumulation of dirt, debris or other material not removed by rain on these surfaces, carried out at intervals as prescribed by the manufacturer.
Generally, metal wall cladding subject to some direct rain should be washed:
every 6 months in severe environments; and
every 12 months in moderate environments.
Generally, other unwashed areas should be washed:
every 3 months for severe environments; and
every 6 months for moderate environments.
Washing can be carried out with water and a sponge, soft brush or broom, or water blaster up to 20 mPa, directed away from the overlap of the sheets. Detergent will help remove deposits if it can be applied without increasing the risk of slip and fall.