Have you ever had a professional roof cleaner try to talk up to you how great his services are, by telling you that he does high pressure cleaning on algae or mold or anything else on your roof? A roof pressure cleaning is always a bad idea though. So it’s a wonder that professional cleaners will still try this with potential clients. It’s a wonder that they talk about pressure cleaning in a boastful way as if they thought that it could impress.
The thing is, just because your roof is made of hard, tough materials, doesn’t mean that it’s indestructible. Especially when your roof needs to be in immaculate shape to remain waterproof. Pressure washers produce an unbelievable amount of pressure. How much pressure, you ask?
Let’s try to put this in perspective. Your garden hose is usually able to put out about 75 pounds per square inch or PSI. In comparison, the pressure washer that they use for roof pressure cleaning is 2500 psi. That’s enough to crack shingles with.
What is more, roof pressure cleaning isn’t exactly going to take the algae out. While all the high-pressure water will certainly loosen the stuff that’s attached to your roof, it is not going to wash it all off. While the roof will look great for a few days, the algae can come right back. In some cases, the high-pressure water will wash the algae off. But it’ll also push the spores there deep into any microscopic holes there may be in your roof.
You’re probably asking yourself, if something with less pressure than this might work you – like 1000 PSI. Professional roof cleaners will sometimes use something they call a Pitch witch – a little cart that has several nozzles that deliver pressurized water. The cart rolls all over your roof. But even 1000 PSI is too much. Whatever you do, you don’t want anything that’s more than 1000 PSI.
Basically, a professional roof cleaner needs to come in and use old-fashioned manual labor to clean your roof. He needs to scrub things clean with a gentle spray of water and bleach. Nothing stronger than this will do. Roofs, whether you realize it or not, are delicate things. You don’t want to do anything that could compromise the integrity of the roof. Make a mistake here, and you could be staring at a terrible leaky roof not far down the line.