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Yorkie wrote:

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I have to ask this question can anyone say hand on heart that spraying all these chemicals on roofs there is no nil nada zip damage done to roofs or underneath to roof linings etc

if you`re going to give a bully boy answer please don`t, just honest knowledge please

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  I use chemicals that have been tested in a major roofing manufacturers lab. They took 2 shingles off their line. One they soaked overnight in our chemical and one they left untreated. Both shingles were placed in separate testing ovens at 300 degrees at 100% humidity for 30 days. This is supposed to simulate 20 years shingle life. When the test was completed the shingle soaked in our chemical showed no more ageing than the one left untreated.

This test was performed by Elk Shingles who gave us hundreds of thousands of cleanings over the years.

You do have to watch for roof metals. That is why I don’t endorse maintenance agreements that treat roofs every 6 months etc. Too much exposure to chems and roof walking etc.

Hope this helps.

AC

I HAVE, and back when I was new, I caused it!  I have used straight chemical on some shingle roofs 15 years ago, before I knew any better, and came back to clean what was left of the roof years later. I have seen the loss of granules caused by excessively strong chemical solutions.

I will not name names,  but there was a large roof cleaning company here in Florida KNOWN for using pure chemicals on shingle roofs! This company had all kinds of trucks that featured an elevated tank containing pure chemical, and a seperate lower mix tank. The employees were instructed to allow the pure chemical to flow into a seperate mix tank, and dilute with water. However, a few bad employees quickly figured out that straight chemicals cleaned faster, and many roofs here were flat ruined this way.

Not to mention the almos permanent Nuking of the Yard

We use VERY weak shingle roof cleaning solutions, because they do not harm roofs. In fact, we feel if you do not have to re hit about 15 to 25 percent of the shingle roof, your solution is a bit strong.

Always remember this, the faster a roof cleaning solution cleans, the faster and better it kills plants.

And the harder the chemical works to break the granule to shingle bond.

I've been cleaning roofs here in SW Florida now since 1989. I pressure washed them until 1991, when I started chemical cleaning instead.

I do many of the same roofs - From my 22 year customer base - every 4-6 years, so some of these roofs, I have cleaned 5 times. Those who have me clean them when the algae first starts to really look bad-usually after 4 years, have the best looking roofs, in the best condition. Roofs that I get calls for, that have never been cleaned in 15 years etc, clean up fine usually, but have a large amount of granule loss in the gutters and on tile roofs, the edges don't come as brightly clean looking as the tops. Those edges are rougher and hold more moisture and even get partial shade, being on the down-facing edge. But the answer is NO. I have not seen any deterioration / damage caused by cleaning with 20-35% SH on shingles and 40-50% on tile over the years.