Home > Blog > How to Remove Roof Stains

How to Remove Roof Stains

Don’t forget about the integrity of your roof: it’s the thing that keeps you dry. It’s a piece of your home that shelters you from cold winters with protection and insulation, and it’s the piece of the puzzle that channels away heat and all outer elements.  Your roof is responsible for making your house a complete home and taking care of it means removing stains.

roof stain removal

The Deal Behind Your Roof Stains

The cause of those black stains that become more and more apparent the longer your roof is neglected may surprise you.  They aren’t caused by dirt, mold, or even mildew, and they aren’t because the shingles themselves are defective, the actual reason can be attributed to the growth of algae, specifically blue-green algae known as Gloeocapsa Magma.

green colored algae on a roof

This type of algae is the most common reason behind the black stains on an asphalt roof.

The algae don’t always start off in visible streaks running down your asphalt roof.  It begins with dark spots, and by the time you notice the lengthy stretches of black stains, the algae has likely been there for at least two months—or longer.

Interestingly enough, this species of algae is black because of its ability to form a protective outer coating that’s darkly pigmented to shield it from the sun’s harmful UV rays.

Roof Stains are Common

If you find yourself driving through neighborhoods these days and noticing an awful lot of black stains on roofs, you wouldn’t be incorrect to make the assumption that it’s more common now than ever.  Manufacturers are now configuring roofing tiles out of varying filler materials such as fiberglass and crushed limestone, both of which feed the growth of this particular algae.

Weather, too, is a factor that incites this growth, and black stains are much more excessive in the Southern United States, ranging from severe to moderate in places like the Midwest, the Pacific Northwest, and the East Coast.  A warm, humid, and preferably coastal climate encourages rapid algae growth, resulting in these unsightly black stains.

Nonetheless, algae are not harmful or dangerous, but if you don’t take care of your roof then you can certainly expect damage to arise, making your roof less effective in its functions.  When the black stains begin to appear in streak form, they erode away the protective UV granules on your shingles, weakening your roof’s integrity against the sun and UV radiation.

Removing Roof Stains

The black stains are far from a death sentence for your roof and its shingles.  Cleaning the algae off is a simple process that involves a quick roof cleaning, and the more habitual you are with a good, old fashioned roof cleaning, the less of a chance the algae has to grow and cause these damaging black streaks.

It’s going to be tempting to get up on your roof and scrub it, thereby saving you the money and effort in finding and hiring a professional. Then again, you could void any roof warranties or homeowner insurance policies that are in effect if you clean the roof yourself.  But if that doesn’t apply to you, you can whip up a homemade formula that will do the job in removing these black stains.

removing stains on an asphalt roof

Cleaning off the algae will require bleach or trisodium phosphate (TSP) mixed with water.  You can also opt to use oxygen bleach, which is less damaging to the environment.  Keep in mind that these concoctions can be harmful to humans, pets, and your surrounding vegetation, so be careful with the application.

When cleaning the roof stains in a do-it-yourself fashion, don’t use a power washer.  It may seem like a good idea to really lift those stains off the roof, but even at the lowest setting, you’ll cause major damage to your shingles, sending them flying, or blasting off their protective coating.

Getting Started on Roof Stains

Once you’ve settled on your cleaner (preferably the least corrosive roof cleaner possible), pick your day to do the chore.  You should work with weather that’s cool or overcast to allow the solution to soak into the algae, with little wind to carry the overspray.  Remove lawn furniture and cover your beloved shrubs because overspray will happen, no matter how careful you are.

If you live in an area in the United States prone to algae formation, you might want to invest in a roof cleaning rinsing tool that dislodges hard-to-remove algae colonies.  These products can be more effective than an ordinary garden hose equipped with a spray nozzle.

Wearing a safety harness, soak your shingles with your cleaner, starting from the bottom and working up towards the peak, spraying until you see a stream of runoff.  Reapply at areas that have dried out.

Preventing Roof Stains

With the right weather conditions, the black stains will, unfortunately, make their comeback in about a year.  You can prevent the algae from taking shape on your roof by installing zinc or copper strips along the ridge of the roof.  This works because rainwater will pick up on ions emitted from the strips that in turn, kill the algae.  It’s not a full-proof method as algae can feed off humidity, but can certainly help.

Additionally, apply a stain-blocking solution to your roof to prevent stains from forming.  You can find these products at your local hardware store or online.  The best of these products can allow for up to three years of a stain-free roof.

Stains may seem like your roof is at its end, but in actuality, it’s far from it.  Removing stains isn’t the easiest process, as it involves crafting a special algae-killing formula and climbing up there for a day’s work, but ultimately, you’re extending the longevity of your roof.  Considering all that your roof does for you as a homeowner—and how expensive replacing one is—cleaning your roof stains doesn’t seem that bad in the end.

Get a New Roof

There comes a time when cleaning a roof is not enough and the only viable option is to get a replacement. At Feldco Roofing, we have the outstanding installation done by factory trained professionals who are licensed to work on a roof.

Our brand new asphalt shingles are made with triple layer protection and adhesive power to protect your home from wind, rain and snow. Speak to a product specialist and get a free quote online today.

Recent Posts

roofing felt

What is Roofing Felt?

Roofing felt is that extra layer of protection that will keep your home insulated from outside weather elements. Learn all about roofing felt right here.

Read More
roof stain removal

How to Remove Roof Stains

Those stains on your roof leave an ugly mark. Consider these roof stain removal methods to get rid of them once and for all.

Read More
roof safety

All About Roof Safety

The most dangerous project is working on a roof. Consider these roof safety tips and checklists so you can be prepared to work on your roof.

Read More
roofing terms and components

Understanding Roofing Terms

From roof frame to design, it’s easier to make a decision on your roof replacement once you understand these roofing terms.

Read More
©2019 Feldco Roofing. All Rights Reserved. | View Promotional Details | View Our Privacy Policy Roofing Companies As seen on Roofer-Locator.com

Over 400,000 Homeowners Trust Feldco. Replace Your Roof Now.

Get Started I'm not ready yet.