The process for washing a house is very similar to washing a roof, though generally less SH is used to kill the moss, mold and other growth on the surface as there is generally less build up. Following a wash is a thorough rinsing to remove debris that stuck to the house. Note that brick siding requires extra SH, but is not harmed by the process. Surfaces like aluminum and vinyl can be affected by what is known as oxidation. This build up on the surface is created by small amounts of metal in paint. This is a completely normal process of the life of the paint and can be removed in most cases. Should the oxidation be too far along, removal is no longer an option - the surface must be cleaned (soft washing) and then re-painted. This can be evaluated on-site when the technician arrives for an estimate or before they begin the cleaning process.