We have a disclaimer on our power wash estimates that they have to sign off on before we start the job. Power Washers depending on the age of the siding can leave tracking and bare spots. White siding is the worst. We do not use chemicals just plain pressure and occasionally a light bleach mixture for mold spots. We put in our disclaimer that if tracking does occur due to the age of the siding they are entitled to a free estimate and that we will take off the cost of the power wash from the recoating price when it is completed.:thumbup: