As a professional Roof Cleaning Company, we feel that the use of bleach is the most cost effective and time efficient method. It is just as "green" as some of the other methods or chemicals when used appropriately. The difference between Bleach that harms plants/surfaces and the bleach that does not, is the handler and the procedure in which it is used. Let's face it, laundry is cleaned safely everyday with bleach. But it also damges a few loads of laundry when mis-handled. Letting the teenage boy in the house handle the Laundry chores might not be such a good idea. This example just points out that while bleach can be harmful, it can also be used safely with proper process.

Instead of blanket statements of bleach being bad, the statement should be told differently. Perhaps the mis-use of bleach may cause undesirable effects. Perhaps we shouldn't be be discrediting the bleach but rather the handler. Be more picky about the knowledge of the contractor rather than skeptical of his detergents. I'd rather hire a contractor that used potentially hazardous chemicals/tools over a contractor pulling up in a non-descript truck with 4 different tires and needing a new muffler using the safest chems (which, by the way don't work the best) available.

So, think about this when looking for a Roof Cleaning Company in the future.