Roof Cleaning Myths

Roof stains are caused by a hardy type of blue-green algae called Gloeocapsa Magma. All it takes is for one algae spore to land on your shingles and take hold and then it’s off to the races. The algae will continue to multiply and spread, its growth fed by the limestone filler in the shingles, and moisture.

Simply the presence of algae stains does not necessarily equate with needing a new roof. In many cases all a roof needs is a good professional cleaning to restore its original look and health. You might notice that roofers don’t like roof cleaners very much, and this is because we keep them honest. If a roofer tells you that you need a whole new roof just because of some algae staining tell him to take a walk and look up your local non-pressure roof cleaning company instead. You’ll save a huge amount of money.

Most people are shocked when they see how much better their home looks after a roof cleaning. I think this is because most homeowners have gotten so used to seeing the stains on their roof that they’ve completely forgotten how good it once looked. I’ve lost count of how many times I’ve cleaned the roof of a house that had been on the market for months with virtually no activity and within days of the cleaning it finally started getting serious offers. I’ve said it before and I’ll say it again that no matter how beautiful your landscaping, no matter how clean your windows, no matter how precise the painted trim, if your roof is covered in filthy algae stains then it will still ruin your curb appeal, if not in your eyes then in the eyes of your family, friends, neighbors, and potential buyers.

If not cleaned off and kept at bay roof algae has the ability to shave years off the life of your shingles. It’s important to remember that a roof alga is a living organism that needs food to continue to grow. Guess what the favorite food of roof algae is? That’s right – your shingles! Shingle makers now use limestone filler in the manufacturing process which the alga just loves to chew on. This will result in premature loss of shingle granules and general deterioration. Shingle granules are vital to the health of your roof and home because they work to deflect UV rays and heat away from your roof surface. If they are gone or covered with algae then you will have a hotter attic and higher AC bills. You’ll also have to replace the roof a lot sooner, and with the average new roof these days topping $10,000 it’s just a no-brainer to keep your shingles clean and functional for a fraction of the cost.

I’ve beaten this one to death over the years but it bears repeating that, next to positioning your home in the path of a tornado, power washing your roof to remove algae stains is the worst thing you could possibly do to it. Just because you’re concrete, deck, and siding were pressure cleaned doesn’t mean you should do it to your shingles. Don’t you have any idea how flimsy and fragile your shingles are? Don’t you realize how many thousand or tens of thousands of shingle granules will pop right off with the use of a power washing wand? It just always blows my mind that people think this is a good idea. Yes, blasting your roof with 2000 PSI will remove some of the stains, but if it removes some of your actual roof in the process then what the heck is the point? If you bought a roof algae remover and somewhere in the instructions it says that you should walk up on your roof with a power washing wand in hand and unleash hell on your shingles then it’s safe to say that you purchased the wrong product.

If you’re using the right chemicals with the proper procedures then you have nothing to fear. I’ve cleaned thousands of roofs with non-pressure chemical methods and have never once seen a situation where we caused damage to someone’s home. In some rare instances there may be some leaf burn on certain types of plants but nothing permanent, and occasionally when we screw up we cause a plant to die and we will take care of it but this is very rare. I clean most roofs with a helper present whose sole responsibility is to rinse the heck out of the grass, bushes, and perimeter landscaping so that there’s very little chance of plant damage. ARMA (the Asphalt Roofing Manufacturers Association) and GAF (North America’s largest shingle maker) both recommend that shingles be cleaned with non-pressure, chemical methods, and any home inspector worth his salt would also concur.

Just because you can’t see algae stains on certain parts of the roof doesn’t mean that it’s not already there and beginning to develop. Keep in mind that in its early stages roof algae is completely invisible to the naked eye. It’s not until the more advanced stages that it actually turns black and becomes visible. So if you can see algae on even one section of your roof that means that it’s probably already taking hold on your entire roof. I always try to explain this to my customers but occasionally I still get people who don’t believe it and demand that I only do a spot-clean to remove visible stains. I reluctantly oblige their demands but am never surprised when I drive by a year later to see the untreated areas now completely covered in black algae! Then they usually call me back with the standard, “You were right. Can you please come back and clean the whole roof as you originally recommended?”

Some roofers will tell you this but its not true, look at your warrantee or ask the roofer to show you where it states that. What it does say is that if you damage the shingles due to walking on the roof, the warrantee will not cover that damage just like it won’t cover damage from a falling limb but it will not void the warrantee. In fact the various manufactures recommend the method we use to prevent and remove algae and also recommend an inspection of your roof twice a year. All Warrantees cover defects in the manufacturing of the shingle and in certain grade shingles there is some protection for algae for a period of time.

There’s nothing easy or quick about roof cleaning. In fact, if you approach it with a cavalier attitude you run a good chance of injuring yourself. If you want to have any chance of cleaning your roof safely and effectively then you need to set out a clear plan of attack, have safety procedures in place, and, above all, take your time. Rushing through a roof cleaning only leads to trouble. Unless you’re one of these guys that absolutely have to do every home improvement job on his own I would highly recommend that you just find a qualified, non-pressure roof cleaning company in your area. Either you can hire somebody who has the equipment and experience to clean your roof in a few hours or you can spend an entire weekend doing it yourself and risking your life. That’s your choice.

I guess I’m always a little disappointed when I tell someone that it will cost 10 cents to 30 cents per sq. foot or more to clean their roof and they give me attitude and insinuate that I’m somehow ripping them off. I think people hear that word “cleaning” and they think it should be cheap like carpet cleaning or house cleaning. Think about it. Does a carpet cleaner spend three to eight hours or more at your house sweating his butt off and getting sunburned? No. Does a carpet cleaner run the possibility of paralysis or death by simply doing his job? No. Does a carpet cleaner spend $100 or more on chemicals for every single job? No. Can a carpet cleaner offer you a guarantee that the treated surface will stay clean for years to come? No. There’s so much more that goes into a professional roof cleaning than for any other kind of residential cleaning service that it’s really not even fair to lump them into the same category. As a matter of fact, I actually think that most roof cleaning companies come in too low with their prices when you consider all the variables involved. I also challenge you to name me one other home improvement service that can instantly transform a home’s curb appeal in a single day for the money spent to clean your roof. It can’t be done. And when you consider that it not only makes your home more beautiful but also extends the life of your expensive roof by a matter of years I think that having a roof cleaned is one of the smartest and most cost-effective things that a homeowner could possibly do to protect their biggest investment.