PW or no PW on asphalt shingles?

Minuteman

Minuteman

New member
I would like to get a clear concise answer regarding PW of asphalt shingles. It is my understanding that you should spray chemical on lightly, allow to dwell, then flood - NO agressive spraying... The granuals will be knocked off which shortens the life of the roof...
Then I look in Home improvement books (3) and they all show people on thier roofs spraying about 8-10 inches from the surface...
I had a customer saying a guy pressure washed two roofs with a forcefull gun on the roof with a hose to the ground in a bucket of chemical.

Soooo, Is it ever proper to pressure wash a roof while on the roof? Not just Black tipping it.
 
As a power washer and a past roofer the answer is no. Any pressure you use will wear down the integrity of the roofing. You may only wear off 3-5 years of it's life but either way, the home owner is not going to be very happy about it. I use 15% bleach when doing roofs. Spray it on and rinse it off and it works excellent.
Sodium hydroxide is made to break down oils so I'd suggest not using any chems that have it in them. It won't melt the roof but it's a lot more harmful to it than chlorine. I just finished running a test on a piece of a shingle yesterday.

I let it soak in 15% chlorine for 3 weeks, no noticeable difference in color (except it's clean) and it's just as flexible as the other piece I didn't dip.
 
Immediate results

Can you put a chemical on from the ground and rinse it from the ground and have instant results.
 
On roofs that we can safely walk we clean from the peak of the roof. When it's too steep to walk on we do it from the ground or ladders depending on the case but yes, the results happen usually within 5-10 minutes tops.
Sometimes we let it dwell for 20 minutes on really heavy mildew covered areas.
 
15% Chlorine

How do you get 15% chlorine? I have found 10% and of course 6%. I also have some 68% powder that I have diluted 8oz:5gal. I have not tried the 10% with an X-Jet yet but I am assuming that If I do not shurflow it onto the roof it will hit at about 5% or less.
 
Look around for a chemical company or distributor, they will get it in stronger concentrations which they in turn dilute and sell. 15% is as strong as I try to get it though, from what I'm told anything stronger is difficult to work with and hazerdous. Make sure all the chemicals you carry are labeled and have msds sheets in all your trucks and your office.
 
Results

When you say results in 10-15 min. What do you mean? Visable results that the customer can see?
So you are Shurflo applying 15% Chlorine when it hits the roof?
THat is the strongest concentration I have heard of so far. Most start out that high but X-Jet it on which dilutes it considerably.
 
I use a shurflow pump in conjunction with an M5. This system pumps the chlorine up to my m5 when I'm on a 2-3 story house and dilutes it at the same time. Yes the visible results usually happen in 5-10 minutes. The mildew turns brown and can easily be rinsed from the surface.
Heavy purple or black mildew may require two applications.
 
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