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Roof Stain Removal: How to Get Rid of An Ugly Roof Stain

Roof Stain Removal Tips to Get Rid of Ugly Stains | All Climate Roofing

A beautiful house is nothing without a beautiful roof. But oftentimes, rooftops can become dingy, stained, and dirty. When this happens, it’s important to know what options you have when it comes to roof stain removal. The fact that this happens to your rooftop is not surprising, since roofs take the heaviest beating of any part of a house. The roof is the only thing standing between the contents of the home and the harsh elements of the outdoors.

When your rooftop develops an ugly stain or two (or more) it might be intimidating, as a roof is not necessarily an easy area to clean. However, roof stain removal is a relatively simple process if approached carefully and thoughtfully, and with safety and prevention in mind.


What Causes Roof Stains?

Roof stains can vary, but most of the time they are seen as dark black streaks running down the north side of a rooftop. These can take a beautiful black, asphalt-shingled roof and make it look dingy, old, and in need of replacement.

The real culprit, though, is blue-green algae that grows on asphalt shingles, leaving its mark in the form of an unsightly stain on rooftops. This is a major problem, especially, in areas that are humid. The algae travel through spores in the air and often affects several houses in a subdivision at a time.

It feeds on the limestone that exists in black asphalt shingles, and is usually apparent most noticeably on the north side of a roof—this is because the north side of a roof usually receives the least amount of sunlight, and also remains damp the longest because it takes longer to dry out from rain or other moisture.

Because algae not only threatens the aesthetics of your home, but also the structural integrity, it’s important to utilize roof stain removal techniques to get rid of the stains.

How to Get Rid of Roof Stains | All Climate Roofing


How to Get Rid of An Ugly Roof Stain

Once a homeowner learns what that unsightly stain is on his or her rooftop, they’ll likely want to know roof stain removal tips to get rid of it. Doing it yourself can save you money, and also give you more options on how exactly you want to clean your roof.

Using chemicals is the best option for roof stain removal if you’re not wanting to replace your roof right away. These vary in strength and composition, so it is worth considering what exactly you’re comfortable with using on your home—whether it is a bleach or a chlorine mixture.

Stain Removal Techniques

Cleaning unsightly stains off a roof is a simple process, as long as homeowners consider these options before doing so:

  • Gather materials necessary for safely cleaning a roof. You may want to use a harness to safely attach yourself to the roof and avoid falling; you’ll also need some sort of liquid sprayer. Professionals recommend not using a pressure washer as this could damage the shingles themselves. You’ll also need a garden hose and the solution you’ll use to treat the roof. These materials can be easily obtained at a hardware store.
  • You can use bleach or chlorine. Bleach is typically more harmful to plants, trees, and other shrubbery, so that’s a consideration if your home is surrounded by greenery. You’ll want to mix either substance with 50% water to dilute it a bit before using it on the roof.
  • Lye is also another option, and is less harmful to plants.


Stain Removal Process

Regardless of which roof stain removal technique that you choose, the process of cleaning your roof is the same:

  1. Choose a day that is cool, minimally humid, with no wind (you don’t want the solution to float over to your neighbor’s home in a breeze). Make sure you clean out your gutters and cover any plants, cars, or furniture to protect from the solution.
  2. Use a gentle sprayer to gradually spray the solution over the roof, starting at the bottom and working your way up.
  3. Let the solution sit undisturbed on the stains for about twenty minutes.
  4. Use a garden hose or gentle sprayer with clean water to rinse the solution off evenly.

This is not a permanent fix, but it can certainly help restore a clean and newer look to your roof for a significant period of time.

Cleaning Roof | All Climate Roofing


Preventative Measures

Of course, the best way to prevent unsightly stains on a roof is to get right to the source and install shingles that are resistant to algae. These shingles often have copper or zinc included in them to get a jump start on preventing the growth of this unsightly stain on the shingles, thereby avoiding any need to wash the roof with any chemicals.

Another option is to treat the shingles with a stain blocking solution. This often comes in a spray that can be applied to shingles after a thorough cleaning. This will not entirely eliminate any algae that may grow in the future, but it may help your thorough washing last for at least a year or two longer.

You also may want to consider applying zinc or copper strips throughout the roof. Zinc and copper are toxic to the type of algae that causes roof stains. When it rains, metal molecules from these two substances will wash down onto the roof, making it impossible for algae to grow anywhere near these metal strips. This will kill any algae before it has the chance to form a substantial presence on the shingles.



Stains on a rooftop can dramatically decrease the curb appeal of your home, so roof stains are something worth paying attention to each year. Roof stain removal is not a difficult process; on the contrary, they can be addressed with minimal time and investment.

The most important things to keep in mind are roof top safety (you may want to use a harness while cleaning your roof) and choosing substances that will work well for your home. Bleach, chlorine, or lye will provide a clean result, but you’ll need to be sure to take steps to protect plants and other property that may come into contact with the cleaning solution as you rinse your roof.

Ultimately, taking preventative measures such as using algae-resistant roofing or installing zinc or copper strips on your roof will be your best defense against algae; so, this is definitely something to consider next time you’re planning to replace your roof.