I know that alot of use new to roof cleaning dont know right off hand how to price a job,because we cant look at a roof and say it is this big or that big,so.I have had people call me and say how much would it be to have my roof clean or how much is it a foot,
I just wanted to let people know that we had a roof the other day that the owner wanted us to measure and give him a price,I could not get on the roof a measure it so I used a range finder to do it fast and it gave me a good idea at what we were looking at and because we said your roof measure at 3600 feet and he said you are right and he gave us the job!!
I hope this helps anyone else you may not have problems getting a roof measured. Or anyone else like me just getting started.
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Bayou Power Washing & Roof Cleaning  318-614-0108
best way we found is to take square footage at ground level of entire house under roof, then just use a pitch conversion chart and figure what to multiply it by. it will never be perfect but it really doesn't matter unless your actually replacing the roof.
Around here most asphalt shingles protrude about 5" If you can get a measurement on 1 shingle you are good to go. I always count the shingles going up multiply by the protrusion (usually 5") then divide by 12 and you have the highth. The width we just walk off then of course multiply the 2 together and bingo you will never get on a roof to measure it again
Beat me to the punch Bill. That's the method I usually use. A good pair of binoculars comes in handy to do a quick roof inspection to spot any potential roof damage that may allow water intrusion and addressed to home owner before any cleaning. Could save you a big headache of being blamed for any interior damage.