Roof Cleaning With Bleach?

Midwestpro · Posted: Sat Mar 08, 2008 12:19 am Post subject: Roof Cleaning With Bleach?

So are bleach based cleaners safe to use on your roof? If you’ve done any research at all about roof cleaning chances are you are more confused than ever. You may have read that bleach dries out the shingles or that it can discolor your roof. So, is this true?

Well let’s take a look at this; first of all did you notice that most all of the companies claiming these allocations happen to also be selling non bleach based roof cleaners? Companies like Roof Be Clean, Roof a Cide, and Roof Restore are just a few. Their only defense in selling their inferior roof cleaners is to scare consumers with myths and lies about bleach. Truth be told these lye and sodium hydroxide based cleaners appeared on the market a few years ago and have turned out to be very dangerous. Even at low concentrations, permanent damage could be done to the roof, possibly even dissolving the roof nails!

The bleach vs. non bleach discussion has been going back and forth for years and will probably continue far into the future. As a roofing contractor I researched and talked to many other contractors in the industry searching for a solution to my customer’s black streaked roofs. What I learned is that most of the major shingle manufacturers realize roof algae is an ongoing concern so they have their own recommendations on cleaning roof algae off of their shingles. I knew at this point that whatever their recommendations were, that’s what I was going to use on my customer’s roofs because I knew I couldn’t go wrong. Companies like GAF, Owens Corning, and the Asphalt Roofing Manufacturers Association all recommend using a mix of bleach and trisodium phosphate applied with low pressure. They also warn against the use of a pressure washer on asphalt shingles.

Most people naturally form their own opinion after reading information on any topic whether it’s wrong or right. With the Internet there is so much information out there that it can be extremely mind boggling. But as soon as I found out that the major shingle producers suggest using bleach on their own shingles it made my decision very easy in knowing what to use to clean my customer’s roofs. We have cleaned numerous roofs over the past few years and I must say when its done like recommended it is very effective. We will continue using the cleaners and methods that are recommended by the shingle producers no matter what other companies out there are saying about it.

j_bates23 · Joined: 19 Mar 2008 Posts: 2

I am going to be cleaning my roof soon and was wondering where can I purchase the trisodium phosphate? And if I use only bleach and water mixture will I get good results?

Midwestpro · Posted: Wed Mar 19, 2008 11:00 pm Post subject:

You can purchase trisodium phosphate at some hardware stores or you can find it online like at the chemistrystore.com.

I have personally cleaned roofs successfully with just bleach and water and no trisodium phosphate. But using the TSP allows for a weaker mix of bleach to be used. Anytime you can get away with using a lesser strength of bleach mix it's a good thing.

The Asphalt Roofing Manufacturers Association recommends a mix of bleach, TSP, and water. Solutions for these ingredients may vary between shingle manufacturers and depend on the amount of discoloration. Solutions range from 1 cup TSP, 1 gallon bleach, and 4 gallons of water, to 1 cup TSP and 2.5 gallons of both water and bleach. Use a low pressure method to apply, allow to dwell and rinse with no more than garden hose pressure. Never use a pressure washer on your shingles!

Extreme care must be taken when using bleach solutions around your landscaping and windows. The proper personal protection should also be worn anytime you are messing with chemicals. Safety precautions are a must when climbing around on the roof or a ladder.

You may also consider not messing with any of it and just hiring a professional to do it for you. Just make sure they use low pressure methods. If you do decide to hire, I may be able to recommend a reputable contractor in your area.

Hope this helps, if you have anymore questions or concerns please feel free to ask.

j_bates23 · Joined: 19 Mar 2008 Posts: 2

Thanks for the advice you have been a big help. My final question is how long should I let the bleach dwell on the shingles?

Midwestpro · Posted: Thu Mar 20, 2008 8:25 am Post subject:

Normally 15-20 minutes is plenty of time. Depending on the color of your roof you may also notice the black algae disappearing.