6 Methods for Cleaning Stains off Your Roof

Scott Dylan Westerlund
Reviewed by Ami Feller
Updated January 31, 2022
Cottage home with a peaked, shingle roof
buzbuzzer/iStock/Getty Images Plus via Getty Images

Follow these six tips to get stains off your roof safely

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A dirty roof can lead to serious damage, possibly void your roof’s warranty, and lower your home’s value. That’s why it’s essential you maintain your roof by cleaning it or hiring a pro. Follow these easy cleaning tips to remove roof stains, mildew, mold, and algae, to keep your roof looking polished.

1. Chemical-Free, Low-Pressure Roof Cleaning Method

Worried about the chemicals used to clean stains off your roof? Don’t be! Many roof cleaning companies offer chemical-free roof cleaning. Be sure to ask for this method specifically when hiring a roof cleaner in your area.

A chemical-free roof-cleaning should be free of the following:

  • Chlorine bleach

  • Phosphates

  • Vegetation-killing chemicals

  • Waterway-polluting chemicals

Another plus is that this method uses a low-pressure rinse finish to clean stains off your roof instead of high-pressure scrubbing and brushing, which could ruin your roof.

Other perks of this roof-cleaning method include:

  • Instant results

  • Won't damage shingles

  • Won't damage surrounding landscaping

Be prepared to pay between $0.20 to $0.60 per square foot for this ultra-safe, eco-friendly roof-cleaning option compared to cleaning with chlorine bleach.

Make sure your contractor guarantees that algae, lichens, and moss will be 100% gone before they leave. Ask about signing up for an annual "roof stain" prevention program.

2. Chlorine Bleach Roof Cleaning Method

Have tough roof stains that you haven’t been able to remove in the past? Many professional roof cleaners offer a stain-removing option that consists of sodium hypochlorite (chlorine bleach) and sodium hydroxide mixed with other chemicals like trisodium phosphate (TSP). 

The chlorine bleach roof-cleaning method works like this:

  • Spray your roof with the formula

  • Apply formula a second time after drying

  • Lingering stains, moss, and lichens disappear gradually

Keep in mind that it can take months for lingering roof stains and growth to sluff off. While rain makes the process quicker, you'll need to inspect your roof to monitor your progress with this method.

Lower cost is the perk of choosing the bleach method. A bleach-based roof cleaning typically costs between $0.15 and $0.30 per square foot. The big downside is that the results aren't instant like they are with a low-pressure spray wash. 

Here's a look at some other things to be mindful of when choosing a bleach roof-cleaning method:

  • Possible strong odor

  • Exposure could harm people or pets

  • Bleach can hurt landscaping

  • Potential waterway leakage

If you're avoiding a bleach roof-cleaning, ask your contractor about bleach usage ahead of time. Contractors that use runoff recovery systems, cover plants, or wet plants before, during, or after the job, probably use bleach.

The bottom line is that deciding to use bleach comes down to your home's location and local environment.

3. High-Pressure Power-Washing Method

This roof-cleaning option "blasts" stains with high-pressure water, but it’s not right for every roof. “You should never, ever use a power washer on a shingle roof, but it can be used on metal and tile roofs,” says Ami Feller, Angi Expert Review Board member and owner of Roofer Chicks in New Braunfels, TX. The main concern is that high pressure can damage shingles. It also doesn't get rid of the root systems of things growing on your roof. Algae often returns.

4. Upgrade to Algae-Proof Shingles

If it feels like you can't keep up with what's needed to maintain your roof to get rid of algae black streaks, consider upgrading to algae-resistant shingles, which cost about 10% to 20% more than non-treated roofing materials. 

Designed for climates that are susceptible to algae growth, these shingles feature copper granules mixed with standard roofing materials.

5. Get a Separate Estimate for Moss

If you have what looks like a moss infestation, you may need a local roof moss removal expert with a separate bag of tools. 

Moss removal for your roof typically entails:

  • A special de-mossing spray

  • Low-pressure spraying to loosen moss

  • Getting on the roof to manually remove remaining moss

6. DIY Method for Roof Stains

If your roof angle is not too steep and you feel comfortable working up there, you can try to handle roof stain removal yourself. However, it’s always best to hire a roof-cleaning pro to ensure safety. If you decide to clean stains off your roof yourself, be sure to use safety equipment. 

To DIY roof stain removal, you’ll need the following items:

  • Full-body safety harness

  • Hand sprayer

  • Cleaning solution

  • Gloves and goggles

  • Long garden hose

Whatever method you choose to remove roof stains, keep in mind that roofing is dangerous work with a high accident rate. Before you DIY, get a quote from a local roof cleaning contractor. You will probably find that hiring a pro is easier and safer than doing it yourself.

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