The Best Roof Cleaners for Mold, Mildew, and More

Bring your home’s roof back to its original glory by removing dark streaks, moss, and other roof-hitchhiking debris. These cleaners will help.

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Best Roof Cleaner Options

Photo: amazon.com

While most homeowners spend the majority of their time maintaining the ground-level features of their homes, the roof is often an afterthought. It’s not until dirty, dark streaks and patches of moss show up that they realize their neglect is affecting their roof.

If that describes you, fear not; you can save your roof. All you need to do is block off some time, arm yourself with the best roof cleaner, and get to work. In conjunction with a little spraying and scrubbing, these special formulas will have your roof looking fresh and renewed in no time. They cut through the dirt, grime, and sludge, revealing your roof’s true colors.

  1. BEST OVERALL: Wet and Forget Moss, Mold and Mildew Stain Remover
  2. BEST BANG FOR THE BUCK: Mold Armor E-Z House Wash 64 fl. oz.
  3. BEST BLEACH: MOLD ARMOR CLEANER 1 GAL
  4. BEST CHEMICAL: Spray & Forget Revolutionary Roof Cleaner Concentrate
  5. BEST ECO-FRIENDLY: Simple Green, SMP13006, Industrial Cleaner/Degreaser
  6. BEST PRESSURE: Oxy Solve Total Outdoor Pressure Washer Cleaner
  7. BEST FOR MOLD REMOVAL: Rust-Oleum Jomax 308764 Spray Once
  8. BEST FOR EXTERIOR MILDEW: Star Brite Mold & Mildew Stain Remover
Best Roof Cleaner

Photo: istockphoto.com

Types of Roof Cleaners

Don’t rush out and set up the ladder quite yet. You first need to educate yourself on the different types of roof cleaners available. They all work a little differently, and some are much harsher on the environment than others. It’s important to do a little research before you choose the best roof cleaner for your needs.

Bleach-Based

For particularly stubborn stains and discolorations, beach-based cleaners might be the way to go. They’re so strong, in fact, that you don’t even need to scrub or rinse the roof down for them to work. Simply apply them to the roof and let them dry. The bleach will eat through the dirt and grime all on its own.

Here’s the thing about bleach-based chemicals, though: They’re extremely harsh. They can bother you if you breathe in their vapors, and your overspray (or runoff when it rains) can wreak havoc on your plants. These cleaners are so strong that you should try to keep your windows closed for a few days to avoid the fumes and odors.

Chemical-Based

Bleach isn’t the only chemical manufacturers use to restore your roof to its former glory. Some formulas feature ammonia, copper sulfate, and trisodium phosphate, all of which can do a great job of removing the stains, molds, and mosses that grow on roofs.

These formulas can be harsh on your plants as well, though usually to a lesser degree than bleach-based cleaners. They rarely require the user to scrub or apply a second application, and in most cases, there’s no need to keep your windows closed after application. They usually come in concentrates, so you’ll probably want to mix them with water unless you have a really stubborn stain.

Eco-Friendly 

If you’re looking for a safer, less environmentally detrimental approach to cleaning your roof, check out an eco-friendly cleaner. These formulas break up the dirt, algae, and mold on your roof without the inherent dangers of chemical and bleach compounds.

Eco-friendly cleaners are safe for your kids, plants, and the wildlife that might roam through your property. While it’s entirely possible to have some type of allergic reaction to these products, they’re generally safe.

Eco-friendly cleaners tend to use oxygen to break down dirt and roof-loving molds and algae, so they work best with a bit of agitation. Since you’ll probably have to scrub most of your stains and discolorations away, having a long-handled brush on hand will be incredibly helpful.

Pressure Cleaner

If you want to blast your roof clean, you can always set up a pressure washer and get to work. The pump inside your pressure washer boosts the amount of pressure with which the water comes out of the nozzle, knocking dirt and film clear off your shingles.

But pressure washers can also blast your shingles off, so be careful when you’re spraying your roof.

To help increase your pressure washer’s effectiveness, there are lots of products available that you can mix into the water. If you don’t use a chemical, realize that water alone might not kill any residual moss and algae.

What to Consider When Buying the Best Roof Cleaner

Now that you have a bit more background on the different types of roof cleaners, there are more factors to consider. This section will outline the most important considerations to keep in mind while you’re shopping for the best roof cleaner for your home. It covers aspects like the different types of roofing materials, how much coverage you’ll get, and how easy the products are to use.

Roof Material

The first thing you need to consider is the materials that make up your roof. Keep in mind that you need to consider all the materials to ensure you’re using the right product.

Less durable materials like vinyl and rubber membranes found on flat roofs or RVs are particularly susceptible to damage from harsh chemicals. These heavy-duty cleaners can wear the roofing components down faster than if you used an eco-friendly option.

Tougher materials, like asphalt, metal, or slate roofs, can take much stronger chemicals. You’ll be able to use bleach or chemical-based cleaners without worrying about what they’ll do to your roof’s finish.

Chemical Composition

The best roof cleaners break down into two options: eco-friendly and chemical. Eco-friendly options don’t contain harmful chemicals, so they’re safe to use on roofs above gardens and plants. The composition of chemical-based products, on the other hand, isn’t always so environmentally conscious.

Chemical-based cleaners often use chemicals like ammonia, copper sulfate, and trisodium phosphate. They can be harsh, but they’re extremely effective at removing the stains as well as the molds, algae, and mosses that cause them. Simply diluting them to the manufacturer’s recommended mixture does reduce some of the risk, so read the directions carefully.

Coverage

Not all roof cleaners can cover the same amount of square footage, so it’s important to understand how much roof a bottle or jug can handle. To do this, you have to know the size of your roof first: Simply multiply each section of your roof’s width by its height. Tally each of those sections. The number you get after you add up all the different planes is your square footage.

Some of the best roof cleaners come in concentrated formulas that you can dilute for maximum coverage. While their bottles might be small, they can often cover thousands of square feet of roof if you dilute them correctly.

User-Friendliness

Cleaning your roof isn’t all that entertaining or fun, so it should be made as painless as possible. Finding a user-friendly product can make all the difference.

A chemical that you can spray on your roof and leave to do its work is by far the easiest way to clean your roof. Other chemicals might require you to scrub the surface, which can be a challenge for high roofs.

Also, consider the application. Spray bottles can be easy to use, but they can make covering a large area difficult, so they’re ideal for smaller roofs. Concentrate bottles that attach to the end of your hose make applying the chemical to larger roofs extremely easy, but you might not be able to reach high peaks from the ground. Whatever you choose, be sure to select a product that you can apply easily for your particular roof.

Effectiveness

Ultimately, how well the product works at removing stains, molds, algae, and discolorations is one of the most important factors to keep in mind. The more effective the product, the fewer coats you’ll have to apply, and the less often you’ll have to apply it.

Less effective products don’t always kill the root cause of the discoloration, even if the stain disappears. If that root is still present, there’s a good chance that whatever caused the stain will come back, and you’ll have to apply your product more often to keep up with it.

Harsh chemicals are by far the most effective and often take just one application. Eco-friendly products might take follow-up applications or more frequent cleanings.

Our Top Picks

All your research is about to pay off, as you’re now ready to shop for the best roof cleaner. The products listed below are some of the best roof cleaners that you can buy for removing ugly stains, algae, and dirt. You’ll find budget-friendly options, products with environmentally safe formulas, and heavy-duty formulas for tough stains. Compare them all to ensure you choose the best product for your needs.

Best Overall

Best Roof Cleaner Options: Wet and Forget 10587 1 Gallon Moss
Photo: amazon.com

The quicker you can clean your roof and move on to enjoying your free time, the better. Try this one-step process that will remove roof buildup, reactivating and washing contaminants from the surface each time it rains. Its bleach-free, non-caustic, non-acidic, chemical-based formula means you can use it on your roof, as well as almost any other outdoor surface.

After you spray your roof, you’ll only need to reapply if you see new growth or stains reappearing. This concentrate comes in 1-gallon bottles that you can dilute to make up to 6 gallons of cleaner. Depending on the strength you mix, and how porous your roof material is, you can cover anywhere between 750 and 2,250 square feet with one bottle.

Best Bang For the Buck

Best Roof Cleaner Options: Mold Armor E-Z House Wash 64 fl. oz. Jug
Photo: amazon.com

If you’re looking for a heavy-duty cleaner at a value-minded price, with a straightforward application process, it’s hard to beat this two-pack of 64-fluid ounce jugs. This product comes as two half-gallon bottles of cleaner, each with a hose attachment for extremely easy application.

The hose attachment will reach second-floor roofs without issue, and it starts killing mold and mildew within 10 minutes of application. There’s no follow-up scrubbing necessary either; simply apply, allow it to work for 10 minutes, and rinse it off to reveal a clean surface.

Best Bleach

Best Roof Cleaner Options: MOLD ARMOR CLEANER 1 GAL
Photo: amazon.com

This bleach-based formula is worth checking out if you’re on the hunt for a heavy-duty cleaner that will provide near-instant results. This one-gallon concentrate can cover up to 2,000 square feet if diluted with a three-to-one water-to-chemical ratio. Simply apply it with a tank sprayer, a roller, or a sponge. It starts killing mildew and mold, and removing the stains involved, within 10 minutes.

Though the formula has a bleach base, you can use it on multiple outdoor surfaces, including roofing, siding, vinyl, and aluminum, but you should avoid using it on rubber. If you have a particularly tough stain, you can use the concentrate at full strength to help remove it quickly. In most cases, there’s no need to reapply or scrub.

Best Chemical

Best Roof Cleaner Options: Spray & Forget Revolutionary Roof Cleaner Concentrate
Photo: amazon.com

This one-step cleaner is specifically formulated for your roof. This 1-gallon jug of concentrate mixes with water to create up to 10 gallons of cleaner, offering a maximum coverage of 2,000 square feet.

The cleaner continues to clean your roof after application, eliminating the need to scrub or reapply. The ammonia-based formula reactivates each time it rains, providing follow-up cleanings for up to 24 months at a time. It’s safe for use on asphalt, wood, slate, clay, and tile shingles, though you should avoid rubber or vinyl.

Best Eco-Friendly

Best Roof Cleaner Options: Simple Green, SMP13006, Industrial Cleaner
Photo: amazon.com

When it comes to an eco-friendly roof cleaner, consider going with the original in the environmentally-conscious business. This is a non-toxic alternative to chemical-heavy products. While it’s nontoxic and biodegradable, it’s powerful enough to cut through oil and grease, so the dirt and grime on your roof shouldn’t be an issue.

This 5-gallon bottle is a concentrate, so you’ll be able to mix it with water or use it at full-strength to cut through tougher stains. You can apply it with a roller, sponger, or sprayer, but its eco-friendly formula means you can use it in a pressure washer without worrying about overspray.

Best Pressure

Best Roof Cleaner Options: Oxy Solve Total Outdoor Pressure Washer Cleaner
Photo: amazon.com

Pressure washing with harsh chemicals can cause a lot of unintended damage, as it’s hard to control your overspray. This solution is peroxide-based, so overspray won’t destroy your plant life or other surfaces. It lifts dirt, grime, and stains as well as mold, mildew, and algae, so it works well for the substances hanging out on your roof.

If you stretch out this concentrate to its most diluted but usable ratio, the 1-gallon jug can make 21 gallons of cleaner. If you run the concentrate straight through your pressure washer, you’ll be able to cover up to 6,400 square feet.

Best For Mold Removal

Best Roof Cleaner Options: Rust-Oleum Jomax 308764 Spray Once
Photo: amazon.com

A heavy-duty cleaner can remove stubborn molds and the stains they leave behind on your roof. This bleach-free formula uses quaternary ammonium salts and ethoxylated alcohols to kill mold while still being safe to use around your plants.

This 1-gallon jug of concentrate yields 5 mixed gallons, providing up to 1,500 square feet of roof-cleaning coverage. Simply apply it to your roof surface and let it dry. It works with natural weather conditions to clean mold and prevent regrowth, requiring very little effort on your part.

Best For Exterior Mildew

Best Roof Cleaner Options: Star Brite Mold & Mildew Stain Remover
Photo: amazon.com

If mildew calls your roof home, you need a product specially designed to kill it and remove its stains. This stain remover uses sodium hypochlorite and sodium hydroxide to break down these challenging films and is safe for use on a variety of materials, including rubber roofing and vinyl siding.

You can apply this concentrate at full strength or dilute it for lighter stains. The application requires spraying the roof surface and letting it break down the stain. Once the stain disappears, rinse the roof thoroughly. If the stain remains after the roof dries, another application of Star Brite should remove the rest of the mildew.

FAQs About Roof Cleaners

If you still have some questions about choosing or using the best roof cleaner, you wouldn’t be alone. It’s a complicated subject, and it can be tough to understand at first blush. This section contains some of the most frequently asked questions, so check to see if there’s an answer to your question here.

Q. How often does the roof need to be cleaned?

Many of the best roof cleaners recommend cleaning your roof every 12 to 24 months to ensure your roof stays clean and free from growth. But anytime you notice discoloration, moss, mold, or mildew, it’s a good idea to give your roof a spray.

Q. Can awnings be cleaned with roof cleaners?

It depends on the cleaner. Many of the heaviest duty cleaners will damage vinyl or fabric awnings, while some biodegradable or lighter-duty cleaners will work quite well.

Q. Can a single roof cleaner be used with and without dilution?

Most roof cleaners are available in concentrated forms, and you can mix them to whatever strength you’d like. If you’re planning to use yours at full strength, it’s a good idea to test it on a smaller space first.

Q. How can plants be protected when using a roof cleaner?

There are a few steps you can take to minimize your roof cleaner’s impact on your plants.

  1. Cover your plants in tarps or plastic sheeting.
  2. Use only as much chemical as you need to.
  3. Ensure your gutters aren’t clogged so any chemical-laden rainwater can flow away from the eaves.
  4. Water your plants heavily before, during, and after using your cleaner. Diluting the concentration of chemicals is the best way to lessen the risk of damage.

Q. Is special equipment required to clean my roof?

Basic safety items like safety glasses, a respirator, gloves, and long sleeves are certainly important. You can also equip yourself with a long-handled brush or roller, or a garden sprayer, to make applying your roof cleaner a little more straightforward.