Myths & Facts

There’s a lot of misinformation about roof cleaning out there, which is to be expected because it’s still a relatively new industry, and most homeowners aren’t that familiar with it. The following should answer many of your questions:

Myth #1

Black roof stains are caused by tar, acid, dirt, or jet fuel.

Roof stains are caused by a hardy type of blue-green algae called Gloeocapsa Magma. Once algae spores land on your roof and take hold, 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.

Myth #2

Algae on roof shingles is really a signal that it’s time for a new roof.

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 healthy condition.

Myth #3

Roof algae removal will have no real impact on a home’s curb appeal.

Most people are shocked when they see how much better their home looks after a roof cleaning. 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. 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 it will still ruin your curb appeal. And, real estate agents say a nice curb appeal can add 5-10% to the value of your home!

Myth #4

Roof algae is simply an eye sore so it can be ignored.

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 roof algae is a living organism that needs food to continue to grow. Shingle makers use limestone filler in the manufacturing process which the algae thrives 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 sooner, and with the average new roof these days topping $10,000 it’s a wise investment to keep your shingles clean and functional for a fraction of the cost.

Myth #5

The best way to go about removing roof algae is with high pressure.

Just because concrete, decks and brick siding were pressure cleaned doesn’t mean you should do it to your shingles. Let the chemicals do the cleaning, then simply ‘power rinse’ the stains away. The ARMA (the Asphalt Roofing Manufacturers Association) and GAF (North America’s largest shingle maker) both recommend that shingles be cleaned with non-pressure, clean-green chemical methods, and any home inspector would concur.

Myth #6

Chemical roof cleaning will damage shingles, gutters, and landscaping.

We use sodium percarbonate (think hydrogen peroxide or Oxi Clean), the safest chemical available, with the best cleaning power. And, we promptly clean-rinse the siding, windows and perimeter plants so that there is no staining or landscape damage.

Myth #7

It’s only necessary to clean the sections of the roof that have visible stains.

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. Sometimes one side of the house (usually the north side) is really stained, while the other side seems fine. In those instances you may want to treat  the whole roof, but only power rinse the badly stained side. Let the rain rinse the good side, and save you some time – and the customer some money. This way you are killing the root causes of the stains, similar to a maintenance spray, and no rinse is needed.

Myth #8

Ambient temperature has no effect on the effectiveness of a roof algae cleaner.

If you’re using the correct chemical mixture then it will be most effective when the temperature is above 50 degrees. Below 50 and the power of the cleaning  solution drops off rapidly. If you absolutely must have the roof cleaned on a day when it’s right around 50 or a little bit lower just keep in mind that the chemicals will need to sit for a little bit longer on the roof to be effective, so instead of giving it 30 minutes to kill the algae give it a couple of hours minimum. On the flip side, if it’s an extremely hot day you may find that your chemical is evaporating before it even has a chance to kill the algae you can simply soak the roof with water to cool it down before applying the chemicals (after letting it dry off for at least 30 minutes).

Myth #9

Roof cleaning is an easy DIY project that any homeowner can do.

There’s nothing safe, easy or quick about roof cleaning. 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.

Myth #10

Roof cleaning is expensive.

People hear that word “cleaning” and they think it should be cheap like carpet cleaning or house cleaning. Think about it. We are on a roof on average for 4-8 hours braving the elements and doing somewhat dangerous work. Also consider that roof cleaning gives a home greater curb appeal, and it also extends the life of the roof by a matter of years. Roof cleaning is one of the wisest and most cost-effective things that a homeowner could possibly do to protect their biggest investment.