When siding becomes contaminated, the bacteria not only looks unsightly but it can also wear on the surface by eating the material. When the siding becomes food for the bacteria it’s only a matter of time before the damage becomes evident in a number of ways: The color fades and then disappears first. Next the material becomes soft and weak before eventually being rotted all the way through due to failure. Often before this happens we replace the siding, but fortunately we don’t need to. All that is needed is a cleaning of the surface to kill the bacteria.