How To Remove Algae Stains From Your Roof

Roofs ONE



The stains on your roof mean something depending on the color they are. Recognizing which color matches which problem helps with how to solve it. Please don't apply the same solution to all different colors of stains on your roof.

Algae on roofs

The different colors of roof stains are: black or brown stains are caused by black algae. The black algae feed off of the calcium carbonate or powdered limestone that is in the asphalt shingles. Black algae growth used to only occur around warm and humid locations, but has spread north because the asphalt shingle manufacturers use more and more limestone as a filler material in asphalt shingles.

Limestone is cheaper than other materials and helps with asphalt shingle durability, but the calcium carbonate in the limestone multiplies the algae growth. If you have algae-resistant shingles, then they have zinc or copper granules mixed in. When it rains, it activates the algae resistant properties in the copper and zinc.

More algae on roofs

The green algae gets on the roof from the near-by tree branches. Keep trees trimmed away from your roof as they can cause the biggest risk of damage to your roof during storms.

To clean your roof, begin by mixing powdered oxygen bleach with water. Oxygen bleach is safe for your asphalt shingles because it doesn't discolor them.

Oxygen bleach

You'll need a pump sprayer. Don't use high pressure on your roof because high pressure will create granule loss on your shingles. The granules are the first layer of defense and an important structure of your roof.

Keep spraying for about 10 to 15 minutes on each area of your roof. The oxygen bleach attacks the roof algae and will remove the stains. Get a scrub brush and lightly scrub the asphalt shingles. Don't press too hard on the brush because you want to keep the granules intact.

Pump Sprayer

Once the algae on your asphalt shingles is gone, use plain water to hose your roof and remove the oxygen bleach. You might need multiple applications of this algae cleaning roof system before your roof is rid of all of the algae completely.

I would suggest to avoid the hottest part of the days to clean your roof. Excess heat will cause the oxygen bleach to evaporate. Early mornings or late evenings are the best time to clean your roof.

Cleaning your roof yourself is dangerous business. If you insist on DIY, then please be careful with your ladder placement. Your gutters are vulnerable to scratching (from the ladder) or breaking. One thing is for sure, don't climb a ladder without the Lock Jaw. Buy two (one for each side). The Lock Jaw holds the ladder in place so the ladder doesn't move side-to-side.

Lock Jaw for Ladders

The Lock Jaw is an expensive gadget, but well worth it if you care about your safety. We ordered ours from Amazon, but you can buy them in so many more places.

Buy 2 (one for each side).

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I have black stains on my roof. How can I get rid of them? My neighbors have them, too; now that I think about it

Hi Aristi, thank you for your question. Use oxygen bleach to clean your roof and please read the article we wrote because it explain with great detail how to do it correctly. We even gave tips on ladder placement. Better yet, let us do it. Contact us for exact pricing. ( Our roof cleaning service starts at $200 and goes up from there. Thank you

It's my understanding buying a class 4 shingle will lower my insurance premium, but will it lower my coverage?

Hi Bailey, thank you for the excellent question! The safe answer is "please check your coverage detailed in your policy". For the more thorough and deeper way to answer your question, I asked many colleagues and only one had a unique answer. Robert from Oklahoma City said one of his clients that bought class 4 shingles did receive a lower premium, but he lost the hail coverage. I was shocked to learn about this real world example about how this specific insurance company handled this upgrade. It could strictly be a case of correlation and not causation, but it's still interesting. Thank you for taking the time to ask your question.

One of your employees left a postcard on my door and I figured you could answer my question - What questions should i ask roofing companies before i hire them?

Hi Chad! thank you for your question. Several very important questions you need answered before hiring a roofing company are: - what is the square footage of my roof? - what waste % are you calculating for the complexity of my roof? - what brand/type of shingles are you offering me? - how much are you paying for the shingles from your supplier? - show me your certificate of insurance - show me your certificate of worker's comp insurance - show me where you have added me as an additional insured on your insurance policy - do you have a 3 day cancellation fee? if so, waive it. - how much will deck repairs be per sheet of plywood when decking is exposed and visible? - show me the list of materials necessary to install to keep the asphalt shingle warranty valid - what are the additional steps you are taking to protect my home from debris and nails being left behind? - provide me a full list of materials that are being installed on my roof. - what is warranty for labor? for how long? This list of questions is a great place to start. Most roofing companies don't want you to ask them because they are underinsured, overcharge for materials, cut corners by reusing your old roof parts, etc... I hope this helps!

A company is telling me I can get my roof for free from the insurance and they would cover the deductible if I hire them. Is this true? (I'm in Texas)

Please don't do that. The insurance deductible is a contractual agreement you have with your insurance company. In Texas, Texas Law House Bill 2102: It is illegal for contractors or roofers to offer to waive a deductible or promise a rebate for all or part of a deductible. Under the new law effective September 1, 2019; violators could get up to a $2,000 fine and up to six months in jail. If a contractor offers to waive a deductible, report it to the Texas Attorney General’s Consumer Protection Hotline at 800-621-0508. Do not commit insurance fraud by accepting unethical and illegal practices. Thank you for your question

This article will certainly help me make an informed decision.

Hi KD, glad we could help. We'll have a new feature on the website where you'll be able to get a Date of Loss for your insurance roof claim. Coming soon, FREE!

How long should it take for a company to give an estimate?

Hi Holly, responsiveness is a great way of showing a customer we care. We can do an informal estimate within a few hours and a formal estimate within 24 hours.

The last roofer gave me a two line estimate so I asked for more information. Haven't heard anything yet.

Hi Melinda, a detailed estimates should have detailed line items of the type of products including brand, quantity, color (if possible), with price. If you would like contact us and we can help you with a detailed quote. Thank you.

Great information. What city are you referring when you give the $350 to $450 average?

Hi Sally8100, thank you for your comment. This article is referring to Texas and Oklahoma City.


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How will I know how many layers of flat roof my house has before I commit to re-doing the roof? I don't want the roofers to discover a second or third layer and then the job exceeds budget

Hi Kasey, thank you for your excellent question. Pay the roofing company to perform the test on a small area of your flat roof before you start the project. Have the contingency in place that the price paid for the test includes the repair in the event you don't proceed with your new flat roof.




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