When cleaning your roof we remove any built up dirt, moss, mould & oxide. Oxide occurs when the tile surface becomes powdery & the surface coat of the tiles has deteriorated leaving the cement tile porous and the tile can deteriorate further. This is why resealing the tile surface with a roof paint is recommended when oxidation has occurred, as it covers the tiles with a rubbery seal that will protect & prolong the life of your tiles & roof surface. Cleaning your roof will increase its efficiency in draining off water. Keeping Gutters clean and clear of debris will prolong the life of the gutter & prevent from rusting.