Does anyone know of documentation that roof and or house cleaning adds value other than ascetics? While it is evident that restoration and maintainance of wood (decks eg) lenthens the life of that asset, I have seen very little information about roof and vinyl cleaning. Would make sense to me that removal of organic growth from asphalt shingles would lengthen life, I am not sure I have seen data that supports this premise. Looking for an additional "customer hook". Any thoughts??