FL PowerWash

I know that there have been many threads regarding pricing, but unfortunately in the many that I have been through, I have yet to find one regarding roof washing. We have purchased an existing business and are trying to give a customer a price without any idea how to quote his roof. The information that I do know is that it is covered in moss and must be done for insurance reasons. Please help!

CCPC, For this particular job, I am not sure what the square footage of the house is. I know that the roof is made of wooden shingles and there is a large amount of moss on it, which the homeowner states has been there for about 5 years! I live in NY, in the Finger Lakes (hence FL Powerwash). Oneness, The house is 2 story and bleach was what we planned on using and following with a colored sealer to cover the lightened areas. The bleach would be wanded on from the roof and then we have a roof wheel to rinse. The roof has several angles and valleys. RyanH and Pam's Custom Clean, Thank you for the information, that gives me a rough idea so that I can let the customer know and then fine tune the pricing for later! Paul B, What is the difference between bleach and sodium hypochlorite for removing moss? Would it be safe to use on wood shingles? Will it discolor the shingles as we are sure that the bleach will do? I now have the original builders name and plan on contacting him for his input into this situation. I know that the homeowner has previously hired someone to do this same job, but it was not completed to the homeowner's satisfaction. Thank you all for your responses. I look forward to hearing more as we take yet another venture into entrepreneurship!