How to Clean Roof Shingles Properly

My friend was complaining about his roof shingles the other day and how they looked dirty. He was frustrated because they were only a few years old and in good shape. He wondered if he could clean them somehow and bring the “new” look back. But he wasn’t sure how to clean roof shingles.

The best way to clean roof shingles is to use a garden hose with a vinegar mixture. Use a sprayer to spray vinegar solution mixed with dish soap. Be sure to coat the entire roof. Protect your landscaping and divert downspouts to avoid collateral damage. Let sit and gently blow a few days later. Repeat if necessary, then rinse once the roof is clean.

In this article, we’ll go over everything you need to know about cleaning your roof, including a step-by-step outline of how to clean your shingles, alternative options for cleaning, and methods to avoid when it comes time to clean your asphalt roof shingles.

How to Clean Roof Shingles

Can You Clean an Asphalt Shingle Roof?

You can clean an asphalt shingle roof, and you should if you notice any type of damage occurring on it. There are numerous products available to clean asphalt roofing – the aisle that sells shingles at your local home reno store will also probably sell cleaning products.

Cleaning of asphalt shingles is primarily done via chemical means. Using brunt force to scrub or scrape shingles is not a good idea and will only exacerbate the wear on the shingle itself, shortening its lifespan more. There are several recommended cleaners, but using a bleach mixture is usually best.

Should You Clean a Shingle Roof?

If your asphalt shingles don’t look damaged, and the roof looks about the same as when it was installed, then it doesn’t need to be cleaned. A little fading should be expected but does not necessarily indicate a need for cleaning.

If you do notice damage, such as black streaks or white lichen splotches, then it is time to consider a clean. If you don’t clean the shingles, the problem will not solve itself. Leaving dirt, lichen and other roof damage left to sit will result in several issues if not dealt with, such as:

  • Water damage
  • Premature aging of shingles
  • Increased likelihood of blowing away
  • Aesthetically ugly and decreases home value
  • Algae stains

Do My Shingles Need Cleaning?

If your roof has black streaks, white-looking “spots” called lichen, or moss growing on it, then it needs to be cleaned. Failure to do so can cause the top asphalt layer to degrade prematurely. Moss growth will cause shingles to curl upwards, creating a greater chance of wind and water damage.

If your roof has any of this type of damage, exposing the roof to the sun by removing foliage will not solve the problem. Increased daylight will indeed mitigate the growth of moss and algae, but once it has grown, it will not simply disappear. It must be removed chemically.

Black Streaks on Roof Shingles

One of the most common stains on an asphalt shingle roof are the black “streaks” that seem to cascade down the face of asphalt roofs. While these streaks may resemble mold or mildew, they are a specific type of blue-green algae. This type of algae travels by air and can be transferred to your roof from a neighbors roof.

This type of algae loves hot, humid environments. Most commonly found on shingles in the Southeast, it will grow anywhere that experiences hot, humid weather at any time of year. This type of algae will coat shingles and degrade them, trapping moisture on top of the shingle. You can defeat this type of algae with a simple bleach wash, which we’ll describe below.

Lichen

Similar to the black streaks, lichen will hold moisture on your roof, causing premature degradation. It looks like white spots and can grow into larger patches covering the entire roof.

Lichen is dangerous due to its ability to hold water. It traps water against the shingle. Then, if the temperature dips below freezing, the water freezes against the shingle. This can cause the shingle to crack or allow water up underneath the shingle. Left unchecked, lichen can cause water beneath your shingles and eventually in your attic.

Moss

Everyone knows what moss looks like – the green, soft, sponge-like growth that you find on a moist rock in the forest. Moss loves moisture, and it is also quite wet to the touch. As you can imagine, having this growth living on your roof is an invitation for roof problems.

Moss likes shaded moist environments. It commonly takes hold of shingles near gutters, especially gutters that haven’t been cleaned in a while. Once rooted, it will spread. When it grows, it finds its way beneath shingles, trapping water. It will cause shingles to crack, move, and wear down quickly. When it gets cold, water will freeze, causing shingles to fail.

Can You Power Wash Asphalt Shingles?

No. You should never power wash a roof. A garden hose sprayer is the highest pressure a roof shingle should experience – no higher than 70 psi. Since pressure washers commonly spray up to and beyond 3000 psi, they should be avoided. Shingle manufacturers even ask that shingles not be walked on, much less pressure washed.

Using a pressure washer to clean your asphalt shingles can void their warranty and speed up the decay of your shingles. After pressure washing, you’ll likely notice tons of roof “granules” in your gutters because you’ve blasted your shingles too much. Avoid.

What Is the Best Roof Shingle Cleaner?

Vinegar is the best shingle roof cleaner for a few reasons. First, it is cheap and easy to find. Second, you can mix it with dish soap to increase effectiveness. Use a higher concentration of vinegar for more severe damage or less for a quick wash. Vinegar is not harmful to paint or nearby landscaping, but bleach and store-bought “roof cleaners” are harmful.

Bleach

A bleach mixture to clean your asphalt shingles will not harm your roof and clean off most types of roof damage. Use liquid chlorine bleach that you use in your laundry, and mix a 50:50 solution with water. Apply with a garden hose or sprayer and leave to sit for 20 minutes, then rinse. While it may take several applications, this treatment will not damage shingles.

Spray And Forget Roof Cleaner

Spray & Forget Revolutionary Roof Cleaner Concentrate – Exterior Mold Stain Remover - 1 GallonYou will also be able to find many iterations of spray and forget roof shingle cleaner. These cleaners have no bleach and don’t require rinsing. Once applied, you leave it. The issue with these cleaners is that they can take up to a year to remove stains and are also more expensive than bleach.

If you want to avoid bleach at all costs, these are environmentally friendlier options. However, the results may not be as effective as bleach. But due to ease of application, consider these products if your roof damage is still relatively mild.

Vinegar

Vinegar will not hurt roof shingles and is the best way to clean asphalt shingles. Vinegar bough at the store will have different concentrations of acetic acid. 5% is adequate for most roof damage, although you can go as high as 25% for very stained roofs. If using a higher concentration, be sure not to let it sit for longer than an hour or so before you blow and rinse.

Mix vinegar with dish soap. This will keep the vinegar from simply sliding off the roof, as it will be more viscous. Once applied, let it sit for several days. When you begin to notice the damage starting to wear off, use a leaf blower to remove any stubborn moss or lichen. Repeat the process if necessary. Once the damage is removed, rinse the shingles thoroughly.

How to Clean Roof Shingles

Cleaning roof shingles

When it comes to cleaning asphalt roof shingles, there is a right way and a wrong way. We’ll go over how to clean your shingles with vinegar step-by-step.

Cover Landscaping

While vinegar is a non-toxic solution meant to protect nearby surfaces as much as possible, it is possible that your nearby shrubs or garden will not like being sprayed with vinegar. You should cover any plants that could experience spray from the roof.

Also, when you rinse your roof, it will all be diverted into your downspouts. The area around the outlet for those spouts will experience a significant amount of vinegar. Again, if you have any plants or grass you’d like to protect from the vinegar, then divert your downspouts away.

Get a Sprayer and Mix Solution

A garden sprayer with a pump-action handle works well to apply the vinegar solution. A tall ladder will allow you to spray the entirety of the roof from the ladder without walking on the roof. If you need to get on the roof, you should use the appropriate fall arrest safety procedures and walk carefully.

To mix the bleach solution, simply dump your vinegar into the garden sprayer with about an ounce of dish soap.

Start Spraying

Start spraying, working your way from top to bottom. Ensure the entire roof is coated, even the non-damaged parts. An even cleaning will ensure a uniform look once finished. You will likely need to re-fill the garden sprayer a few times.

Wait

Watch your roof. You may need to re-apply the solution if you don’t notice the damage fading. But be patient, you may need to wait several days to notice any difference. If you still don’t, repeat the spray process until you do notice a change.

Blow Roof (If Necessary)

Use a leaf blower to gently dislodge any remaining debris or roof damage. This is important if you have moss on your roof. The vinegar will kill the moss but not dislodge it. You will need to remove it manually. Using a blower is the best way to remove the moss without hurting your roof shingles.

Do not use a brush or a pressure washer; these will only worsen your roof damage.

Rinse Shingles

After you’ve sprayed your roof and blown it, removing all remaining roof debris, you can thoroughly rinse your roof. This step is critical as you don’t want the vinegar solution to stay on your roof permanently, as it can damage your roof over time. Acetic acid, the active ingredient in vinegar, will degrade asphalt eventually.

How to Clean Roof Shingles From the Ground

If you are concerned about voiding the warranty on your roof shingles due to walking on them, then you can clean your shingles from the ground. In this instance, using a garden sprayer attachment with your hose is ideal. Put liquid bleach in the sprayer and apply from the ground. Apply bleach from top to bottom, as you don’t want to spray up and under the shingles.

It is important to note that leaving the bleach on the roof to sit too long will damage the roof. Ensure that you rinse the roof after 15 or 20 minutes. Repeat if necessary until all the damage is gone.

Best Time to Clean an Asphalt Shingles Roof

The best time to clean a shingle roof is when there is no rain in the forecast for several days and when temperatures will not drop below freezing. Freezing will freeze water to your roof’s surface, negating the effects of the cleaner.

Asphalt Shingle Roof Cleaning: What Not to Do

Cleaning a roof is a simple process, but there are easy ways to seriously damage your roof. Therefore, it is prudent to avoid the following when cleaning your roof:

  • Never use a pressure washer.
  • Spray roof from top to bottom. Spraying from bottom to top will force water up and under your shingles.
  • Do not clean in the winter, as you risk having excessive amounts of water freeze on your shingles. Freezing water is expanding water, which means water could travel up and under your shingles.
  • Don’t let bleach or vinegar stay on your roof indefinitely. Vinegar or bleach left to sit can permanently disfigure your roof shingles or cause them to degrade prematurely.

Conclusion

If you do opt to walk on your roof, ensure you use proper safety precautions. Also, if you opt to use a store-bought chemical on your roof, read the label carefully to avoid damaging your shingles further.

Regular maintenance is the key to maintaining an attractive, functional roof. Cleaning every one or two years with vinegar will keep your asphalt shingles looking like new and ensure your roof is doing its job – keeping your home dry!

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