How to Remove Mold from Roof Shingles


Finding the best roofing contractor is a challenge and roofs are a huge personal investment. Choosing the right contractor makes all the difference to ensure you get a quality roof and peace of mind. Here are 4 simple steps to finding the best roofing contractor for you.

Without a doubt, your home’s roof is one of its most important parts of the structure. The roof provides support, climate control, and safety; it also adds value and aesthetics to your residence. It’s a major investment that will last many years if properly installed and maintained.

However, there is a silent attacker: mold on the roof.

Although most people are aware of the ruinous effects of things like loose shingles, a missing soffit, and storm damage, few are able to recognize hazards posed by mold. If you follow these guidelines you’ll learn how to identify a mold problem, how to prevent it, and how to get rid of it.


Microbial overgrowth from algae, moss, mildew, and mold are common in homes located where there is high humidity, or insufficient roof drainage.

Unfortunately, most homeowners mistakenly characterize the signs of a mold problem as a cosmetic issue or one of old age. Here’s what you should know when looking for mold on your roof:

Keep gutters clean

Know the difference between algae, moss, mildew and mold. All four organisms pose their own set of complications.

  • Algae growth is natural and is normally harmless, but excessive growth in the right conditions causes property damage. It’s distinguished by its green or black-green color that resembles a surface stain. Algae is slick and slimy to the touch.
  • Moss is normally a benign organism that grows naturally in many areas. It’s obvious by its fuzzy green appearance.
  • Mildew is a powdery residue that spreads quickly in warm wet climates. Its color varies but it’s normally a light grey-green.
  • Mold is very unattractive and often smells rancid. Mold usually grows on moist wood or drywall and is identified by the dark splotches it leaves on the materials surface.

Pay attention to odorsA vacation home that’s been closed up for a while may smell musty, but if the odor continues after you’ve aired out the space then you may be facing a mold problem. Odors originating from the attic space are a clear indication that you’re facing mold growth.

Prolonged illness can be a sign of mold on the roof. There are lots of different kinds of mold, although only a relative few are considered toxic. Despite that, even non-toxic mold can still cause significant health problems. Mold infestations have been found responsible for respiratory issues including infections, excessive runny nose and eyes, worsening of asthma and even skin rashes. Visual interior signs are evidence of an extensive outbreak.

Water intrusion through a roof leak, even a small leak, into the attic and drywall space creates an optimal environment for mold growth. And because these areas are largely enclosed you won’t notice you’ve got a problem until it’s too late.

Discoloration along the joint between the ceiling and wall is a common indication of having a leak or mold problem. You will find paint around the windows starting to peel or bubble. Roof mold affects wood in the attic and wood exposed for decorative purposes. Wood gets dark, splotchy, and will often soften.


The easiest way to deal with roof mold is to prevent it from developing at all. Take measures during your periodic roof inspection to reduce the circumstances that make your home vulnerable to mold growth.

Mold spores can easily become airborne jumping from roof to roof

Manicure shade trees. Keep branches of nearby trees trimmed about three feet from your roof line. Overhanging branches cause shade that prevents water from quickly evaporating. Trapped water is a breeding ground for microbial growth that starts generating mold on your roof.

Keep gutters clean. Remove and dispose of debris, trash, and dirt that gets lodged in your gutters. Clean gutters let water drain from the roof onto the ground. Clogged gutters trap water on the roof creating the perfect environment for mold to grow on your roof.

Apply a moisture and/or microbial barrier. Roofing materials and technology have advanced greatly within the last few decades. One of those advances is the ability to apply chemicals to your existing roof that repels water, or prevents algae and mold from developing. New roofs are often constructed of materials that have these properties impregnated into them.

Install ridge vents. Ridge vents are installed at the peak of a sloped roof. They allow warm wet air to escape the attic and roof structure. This air flow keeps those areas cooler and drier than they would without a vent, making them less hospitable to mold, mildew, and other microbes. Another alternative is to install a turbine directly on top of the roof and use wind power to suck hot and humid air out of your attic. A turbine has a series of vanes that spin as wind passes through them. Regardless of the type of attic ventilation you choose, it’s important that it’s installed correctly by a licensed roofing contractor. A roofing contractor can also help you determine the best type of attic ventilation for your home.


Despite your best intentions and preparations, your home may still succumb to mold infestation of your roof.

Apply a bleach solution. While wearing protective rubber gloves and a breathing mask, carefully pour ¼ part chlorine bleach into a clean bucket with ¾ part water. Next, put a tablespoon of trisodium phosphate into the bleach solution. Pour the bleach solution into a pump sprayer. Generously spray the moldy roof shingles with the solution. After spraying the asphalt shingles with the bleach solution, allow the bleach to sit for approximately 15 to 30 minutes, depending on the severity of the mold growth. Using a garden hose at low pressure rinse the roof shingles thoroughly to remove the bleach solution. When rinsing, start at the top affected shingle and work downwards. While wearing gloves, run your fingers across the shingles. If you still feel slime on the shingles, apply the bleach solution a second time and let it sit for an extra 10 minutes. You can then rinse the roof again. Refrain from scrubbing or using a pressure washer; both can damage asphalt shingles.

Install copper or zinc stripsThese metal strips prevent algae growth. Some asphalt shingles are manufactured to include them, but older roofs may not have them. You can install metal strips in strategic areas such as around the chimney.

Vinegar solutions work against moss and algae. A solution of equal parts apple cider vinegar and water has long been touted as an effective herbicide and pesticide. Using it does kill algae and moss, but not mold. And caution must be taken to protect nearby bushes and plants because overspray will damage them. Vinegar quickly changes the pH of the soil making it inhospitable to most plants.

Use safety precautions. Protecting your roof is important, but DIY solutions can be dangerous. If you don’t know your way around a roof it might be best to contact a roofing specialist.

your home may still succumb to mold infestation of your roof


Mold spores can easily become airborne jumping from roof to roof. That is why you might see a mold problem in a certain neighborhood. Certain conditions are more favorable for mold, such as roofs with leaks or wood rot. Oftentimes, the presence of mold is a sign that there are other roofing problems. While you may not visibly see roof damage, that does not mean that damages do not exist. When you call an experienced roofing contractor underlying problems may be found. Making these repairs can reduce the likelihood of mold growth in the future.

In addition, having a roofing contractor can also be good for your health. Not only can you avoid breathing harmful mold spores which can lead to respiratory distress, climbing onto your roof can pose significant dangers. Professional roofers use harnesses and other safety gear to ensure their safety while working. All reputable roofing contractors are also trained, certified, and insured which can provide you with peace of mind.


The roof is a vital component of your home’s structure. When properly installed and maintained it provides years of service. Regular maintenance and repairs is integral to the longevity of your roof. Mold growth on roof asphalt shingles can be a frustrating problem to deal with but you don’t have to resolve the issue on your own. For more information or to schedule a free consultation contact BB Roofing today at (843) 379-3033.

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