Lichen –that green stuff you call moss growing on your roof is a fungus. Everyone knows that treating fungus is only done with some type of medication; it just doesn’t go away on its own. What you take for your body is real similar to what needs to happen for cleaning roofs.
Using a pressure washer on your roof is tantamount to scratching an infection and spreading it around. Without treatment these spores are now where they started from to covering your entire roof. Water propels these spores and sends them streaming and breeding along your roof line without the proper treatment after a cleaning you’re left with a bigger problem then what you started with.
An effective chemical to treat any type of moss is sodium hypochlorite at a high percentage. You can’t just go in and buy bleach at the store and spread it around as the percentage of bleach on store shelves is too low in quantity per gallon and too expensive on your pocket-book to actually do its job. On average a roof needs 35-40 gallons of roof cleaning mixture to cover and kill moss on your roof.
The effect is minimal when sodium hypochlorite isn’t given an effective herbicide (penicillin for plants) to help it last longer and kill those spores that are left, from returning.
When you decide to hire your contractor, the type of chemical he uses will give you a good idea on when you’ll have to hire him again. MOSSBEWARE and MOSSOUT are the 2 biggest retail moss killers out there. Sure they do their job but the effects only last for about 60 days before the stuff is back. On average our mixture lasts 2-3 years.