Roof Cleaning is an excellent way to enhance your properties curb appeal. That is if you have a dirty roof. It’s not really dirt though, in case you weren’t sure. It is a mold-like bacteria commonly called algae or blue-green algae. It normally forms streaks on your roof. The pattern forms streaks because that is how the moisture forms and dissipates. It needs moisture. For more info use the search term “Gloeocapsa magma”, and you can find out more.
The streaks on your usually roof form at the 4-7 year mark. At years 12-15 it can completely cover your entire roof. It can be an unsightly mess that’s for sure. There are multiple species that grow and thrive together. More so as layers are formed over the years. I have seen it get so severe that moss eventually grows. In a severe case like this you are likely to have missing patches of roof granules. This moss and underlying culprits had eaten part of the shingles. I have only seen this in isolated areas of the roof and never have seen a roof entirely ruined from this.
Different methods of roof cleaning are used. I have tried and tested all of the methods that seemed reasonable. There are a lot of roof cleaning chemicals out there. They contain herbicides, lye, peroxides, chlorine, acids, copper sulphate and more. The peroxides will work at sanitizing a virtually clean roof. The lye is dangerous and can burn your skin and plants. It can leave stains and remove paint. It is the stuff they use to make oven cleaner. Acids are dangerous and have been reported as causing explosions. Chlorine is what I use which there are more than one type. Chlorine has to be use responsibly or it can cause problems like lye does. Copper sulphate is an active ingredient in pond water clarifiers and is mostly used as a prevention method.
Another prevention method is zinc strips. These are not very effective so don’t waste your money on that. I have seen some of the worst cases where zinc strips were relied upon to prevent roof mold. 95% of the cases we deal with are moderate to severe and require an experienced professional in order to get desired results.
The only non-chemical way to clean a roof is with a pressure washer. This is not recommended. I have seen contractors and home owners on roofs with a pressure washer and cringed at the sight of debris flying from the roof. This debris contains roof granules from the shingles and is the life of the roof. You would be better of not cleaning a roof if a pressure washer is our only option.
Roof cleaning is no DIY job in my opinion because there is a steep learning curve to doing it properly. I get plenty of calls after failed attempts and you don’t want to risk injury for a failed attempt. The recommendations on the roofing manufacturers sites on how to clean a roof are how most home owners learn to do it but fail.