Rodney thank you for clarifying the real question I need answered:

Yes, we would like know for sure it will not impact the tar strips.  I don't think so, as once the SH dries, it is inert.  Yet, maybe the safe course it to rinse...

More questions than answers so far.

Thanks for responding

Thanks Mike

I appreciate you taking time to weigh in.  I appreciate the help without the negative heckling that can happen on other boards.

Have a great day!

paroofguy wrote:

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I have a problem that I need help on.  We are starting to reroof my mother's house in Oklahoma with shingles that had been purchased 2 years ago and they had gotten wet in the bundles due to inadequate tarping of the shingles.  When we opened the  packages, I have mold and algae on the fronts and evidence of it on the backs. My thought is to pre-treat both sides prior to installing the shingles with SH roof mix.  I will save one question-- we do not have the option to buy more shingles... Doug Rucker suggested the board as some roofers are on here.  Any help will be appreciated tonight, as the roof is underway as we speak.

I also would appreciate input on what strength to spray the shingles with.

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 Steve here is what I know and have experienced over the last 20 plus years.

1. In 20 years and over 50,000 roofs I have never seen any damage caused to shingle roofs from bleach based cleaners. I have seen damage from pressure washers and even some companies that used acid on roofs. Never by bleach.

2. Though I had never seen any damage doesnt mean it doesnt exist so we went another step further. Back in 1995 Elk Shingles took two shingles off the line new. One they soaked in a bleach and water solution with my duck sauce in it, with no rinsing. The other they left untreated new off the line. They then placed both shingles in a testing oven for 30 days at 300 degrees at 100% humidity. After 30 days they took the shingles and inspected them for any degragation. They found that the shingle treated with bleach and water with duck sauce had no more wear than the shingle that was left untreated. This test was to simulate 30 years of shingle life. Monier / Lifetile ran the same test on tiles from their plant as well.

3. The asphalt strip on the back is designed to seal the shingles one to another as the roof heats up in the summer. The tar strips get hot, melt and bond the shingles to one another so that wind can not get up under them during a wind storm. This strip is not normally exposed during a cleaning. Only the top of the shingles get treated because only the top of the shingles are exposed. Therefore other than the test in 1995 I have not seen these strips exposed to bleach. However this is what I do know. To break down this tar strip you would need straight bleach and many treatments of it. Remember this strip is meant to heat up, melt and bond with the top of the shingle under it. Even if you hurt the surface of this strip there would be fresh tar beneath. 

My reccomendation would be to treat the shingles top and bottom. Rinse them theroughly top and bottom with a garden hose and allow to dry out on the driveway before instalation.

I do not think you will have ANY problems at all with the cleaning process effecting the shingle.

Hope this helps,

AC