Opposing View #1

...and in the interest of presenting a different opinion on the subject, here is a note from Nathan (I am withholding last and company name):

Hello George Guttmann,

I recently read an article you wrote about not pressure washing roofs. You have some very valid points. However, I believe you should have done some more research before making the statement, "pressure washing only does some damage to the roofing, at worst it destroys perfectly good roofing."

The fact is, a professional that knows how to use his equipment can pressure wash a roof with as little as 200 p.s.i. and still be rinsing at 5 g.p.m. With roofs its not pressure washers that damage the roof, it's HIGH pressure. I suggest you make amendments to your article just to be on the safe side. There are MANY roof cleaning professional that use pressure washers without any granule loss. Using the same pressure as a hose only with much more flow will clean a roof in a quarter of the time a homeowner could do so. Many people make their living cleaning roofs and at this time many are being introduced to your article.

Please do some more research, it may be that the picture you took is of a person using to much pressure but I would question how you know he is using 2700 p.s.i. Just because a machine can put out say 3000 p.s.i. doesn't mean that's what is being used. The nozzles, unloader, and machine can be changed to get different pressure. I use a 3000 p.s.i. hot water washer. However, when washing roofs I use different nozzles and cold water only. I get the pressure so low I can put my hand directly in front of the nozzle while spraying and it feels like a shower. If your interested in learning all the correct techniques please let me know.

Thanks, Nathan


Thanks for taking the time to write and to present your side of the issue. I am sure that you make every effort to reduce the amount of damage to the roofing when you use a pressure washer, however, moss and lichen are very strong plants and some roofing granules are dislodged even when one removes clumps of moss by hand - let alone a tool such as a pressure washer.

In my opinion, you would do a much better job on behalf of your clients by treating their roofs with moss control agents and allowing the dead moss to release itself from the roofing. This usually takes two or three applications but it does work and it does not damage the roofing. -George

(I better go now before my wife reminds me that our roof needs some moss control work.)