Thick Mold on Shingles!!

[VPW]

Ive only done a couple of roofs and so am very concerned with the liability of it. I was wondering when is a roof just too moldy to clean safely without causing leaks. I just gave an estimate on a roof that has moss growing a half inch off of the shingles. Could this moss have grown into the the shingles and by power washing it off your unplugging little holes or leaks. Maybe im too paranoid or have a big imagination. I know im a newbe but if anyone could help me out, it would be great!
When should I turn down a roof?
Thanks,
Alex

 

[Mathew Johnson]

Get ahold of Don Phelps.... I hear he knows his %$#^ when it comes to roof cleaning

 

[Don Phelps]

Thanks Mathew.

Alex,
First things first......Is it mold or moss? In your area it's probably mold (or algae). Let me know and I'll try to help ya out, if I can.

 

[VPW]

I was thinking a combination, but if its mold its pretty thick!

Mr. Phelps I hear your the best when it comes to roofs so I also have some other quick questions.
1) I use a chemical from the biggest power washer destributer in my area labeled roof bright which is a combination of Sodium Hydroxide, sodium ethylenediamina tetraacitate, sodium nitrilotriacetate, and nonylphenol poly(oxyethylene) and the brand is QwicClean. The stuff still requires me to use like 2500 psi. Is this two much?
Is it posible to just rinse with a hose with the right chems?
2) It sounds like everyone uses bleach but ive heard of major fines in our area for just having it on site. Is my distributer trying to scare me or what?

 

[squirtgun]

I was thinking a combination, but if its mold its pretty thick!

Mr. Phelps I hear your the best when it comes to roofs so I also have some other quick questions.
1) I use a chemical from the biggest power washer destributer in my area labeled roof bright which is a combination of Sodium Hydroxide, sodium ethylenediamina tetraacitate, sodium nitrilotriacetate, and nonylphenol poly(oxyethylene) and the brand is QwicClean. The stuff still requires me to use like 2500 psi. Is this two much?
Is it posible to just rinse with a hose with the right chems?
2) It sounds like everyone uses bleach but ive heard of major fines in our area for just having it on site. Is my distributer trying to scare me or what?

I'll jump in and try to give you the answer Don likely will. 2500psi is to much pressure to clean a roof.I have never heard of anyone being fined for using bleach or chlorine on a job.I bet the pool service guys just hate that if it's true,but you do live in MD the California of the east coast....lol.
Sounds like your supplier is using a scare tactic to keep you buying his product.

 

[Pete @ Sun Brite]

Scott is right

Anything more than about 300-400 PSI or so is just toooo much for roofs. Keep the pressure down, and be as gentle as possible. If you have a stubborn mold stain, I recommend a gentle scrub brush rather than more pressure. It is safer for the roof.

As for using bleach, both GAF and Johns-Manville told us that (in the event of a claim on a roof warranty) the use of bleach would void the warranty. I have never heard of "fines" for using it, though.

Since I sell cleaners, advice from me about not making your own cleaner with bleach is self-serving. All the same, think about what bleach does to your blue jeans. The same cleaning power in the form of a sodium hydroxide or potassium hydroxide won't damage those same cotton fibers. I am not opposed to using bleach if you are experienced and careful, but I have seen more damage caused by bleach than any other cleaning tool.

Good Luck!

By the way, bleach without some surfactant is useless for anything except killing mold and germs. It won't clean by itself.

 

[Don Phelps]

Arma

The Asphalt Roofing Manufacturers Association recommends chlorine for cleaning shingle roofs.

Below is a link to their info. Scroll down and click on 'Algae Discoloration of Roofs.'

http://www.asphaltroofing.org/questions_tech.html

We've always used chlorine with excellent results.

There are many out there that sell fear since they don't sell chlorine. Roofers like to do it also to try to convince homeowners that they need a $8000 new roof rather than having their current one cleaned.

It's simple.....chlorine kills algae and that is what's normally growing on most dirty roofs.

We use 45-60 psi to apply with a ShurFlo or a gas-powered diaphragm pump and rinse with the same pressure that a garden hose would produce.

 

[Pete @ Sun Brite]

Thas a great link. Short and sweet.

 

[VPW]

Exellent link! This asphalt roofing association is out of Maryland and helped me out a lot. Thanks again.
Alex
Veteran Power Wash

 

[Bleemus]

VPW,
Is it green and thick? Being from Vermont I used to see a lot of moss growing on the shady side of a roof and it can get real thick. I am not too sure I have seen mold that thick but it may exist. I imagine killing the moss with chlorine and then once it is dead it would probably rinse off with garden hose pressure once the roots have let go of the roof. In Vermont they used to just scrape it off with snow rakes but doubt that is the pro choice at all.