Now that the roofing companies have witnessed the error of their ways, they have taken action! Most quality shingles that are being produced these days are algae resistant (AR). The key word you need to take notice of here is “resistant”. They are not algae proof and they may never be, if they could do it then they would. The common length of algae resistance is said (by the manufacturer) to be 10 years although the shingle that they are selling is supposed to be a 30 year shingle. The math is easy to do, and the customer is the one that is left with at least 20 years of algae issues! I have even witnessed many roofs that are only a few years old (algae resistant shingles) and are already showing those dark streaks. Mother Nature is putting up quite the fight, and there is only one thing that you can do about it. That one thing is to either clean your own roof or hire a roof cleaning professional. Roof cleaning is very important and if it is not done and done right, you will literally shave years off your roof’s life span, and pay for a new roof needlessly.

Roof Algae and the roof cleaning it necessitates is going to be existent for a long time to come. As long as it is, we will be here to provide you with the most up-to-date methods and techniques for battling algae!

1. Pressure Washers and Power Washers produce far too much pressure for any type of roofing system. Some of these units produce 3000 PSI or more! This is enough pressure to not only remove granules from your shingles but also to cut your shingles in half. The average garden hose puts about 40-80 PSI which is all that you need to properly and effectively clean your roof. 3000 PSI is overkill and an unacceptable cleaning method for your roofing system whether it is an asphalt roof, tile roof, cedar roof or even a metal roof. You may say to yourself “I think that the wooden and metal roofs can take the pressure”. The fact is that you may hire the most talented pressure washer in the world and he may make your roof look amazing with his high pressure methods. Although, a Pressure Washer will not kill the algae, it will only blow it all over the place, such as on your siding, car and your neighbor’s home. It will even push the algae deeper in the pores of your roofing system, which for obvious reasons is a “no go”!
2. Pressure Washing accessories still produce far too much pressure! Another tool out there is a “Pitch Witch” and is a “No Go”. It is a device that is on wheels and travels up and down your roof. It has three nozzles so instead of 3000 PSI it puts out about 1000 PSI, which is still way too much pressure. On top of that it is not killing any of the algae, so you can be sure that your algae will grow back very quickly. This is sometimes called a “gitter” along with many other names, so you must be sure to ask for a Soft Wash Roof Cleaning method! The picture below is of the infamous “Pitch Witch”

What this all boils down to is remembering one thing, to only allow the pressure of a garden hose on your roof!

First and foremost, you’ll need a trailer to haul your gear.  We’ve seen several examples where a roof cleaner successfully jammed all of his equipment into the bed of a pickup, but life will be a lot easier if you can afford a trailer.  Affixed to the trailer (or truck) should be a ladder rack and a few extension ladders.  A moonlighter rack will usually suffice if you can’t afford a full-size.

You should have at least one large poly tank strapped down to the trailer.  If you’re just starting out then a 100 or 125-gallon tank should do the trick.  These can be found at Tractor Supply, but if you want to save a few dollars then consider purchasing online. You’ll run through an average of 60 gallons of chemical solution per job, so a tank of this size should be able to get you through two jobs before a refill.

Next, you’ll need to purchase a pump to transfer fluid from the tank up to the roof surface.  We recommend the Delavan PowerFLO 5800 Series.  It can push up to 5.3 gpm at 60 psi. This little beauty will need to be powered by a deep cycle marine battery, which, like the tank, can also be found at Tractor Supply.  The pump itself will most likely need to be purchased from an online retailer.  Ideally, you would have two pumps in case one gives out in the middle of a job.

Now, as for the transfer of the roof cleaning chemicals, you need to find two 100′ pieces of clear, poly-braided tubing.  The ideal diameter would be 5/8″ for maximum flow.  Run a five foot piece from the tank to the pump, and the rest of the line out of the other side.  This will give you plenty of line for those hard-to-reach roof sections.  Better to have too much length than too little.  Connect the two pieces with a chemical-resistant fitting.  If you can afford a hosereel then great, but it’s not absolutely necessary in the early stages.

At the end of the hose should be a poly gun assembly.  Our assembly of choice has a trigger gun, a 12″ poly lance, a 45 degree elbow, and a 1/4″ coupler to handle an assortment of tips.  Find a setup that you’re most comfortable with, but just make sure that all the materials consist of poly plastic or stainless steel.  A simple plastic gun from Home Depot will not do – the solution will eat through that stuff in no time!

Of course there are lots of other miscellaneous items that you will need to get the job done.  You’ll need a few water hoses for rinsing, a couple buckets for storage and dilution, and a large tarp in case plants need to be covered.  A ladder stand-off would also be a smart addition if you can swing it.

Last, but not least, you need to invest in safety equipment.  Let me repeat that.  YOU NEED TO INVEST IN SAFETY EQUIPMENT.  Roof cleaning is one of the most dangerous jobs in the world, and if you’re not prepared for the inherent risks then you are just asking for trouble.  Please take the time to read our post that is dedicated to roof cleaning safety products.

Those are the basics for setting up a roof cleaning rig, but as time goes on you will define your own style and methods that may require specialized tools and gear to make the jobs easier.  At the end of the day it’s about finding a system that works for you and is safe for everyone involved.

Myth #1:  Black roof stains are caused by tar, acid, dirt, or jet fuel. Roof stains are caused by a hardy type of blue-green algae called Gloeocapsa Magma.  All it takes is for one algae spore to land on your shingles and take hold and then it’s off to the races.  The algae will continue to multiply and spread, its growth fed by the limestone filler in the shingles and moisture.

Myth #2:  Algae on roof shingles is really a signal that it’s time for a new roof. Simply the presence of algae stains does not necessarily equate with needing a new roof.  In many cases all a roof needs is a good professional cleaning to restore its original look and health.  You might notice that roofers don’t like roof cleaners very much, and this is because we keep them honest.  If a roofer tells you that you need a whole new roof just because of some algae staining tell him to take a walk and look up your local non-pressure roof cleaning company instead.  You’ll save a huge amount of money.

Myth #3:  Roof algae removal will have no real impact on a home’s curb appeal. Most people are shocked when they see how much better their home looks after a roof cleaning.  I think this is because most homeowners have gotten so used to seeing the stains on their roof that they’ve completely forgotten how good it once looked.  I’ve lost count of how many times I’ve cleaned the roof of a house that had been on the market for months with virtually no activity and within days of the cleaning it finally started getting serious offers.  I’ve said it before and I’ll say it again that no matter how beautiful your landscaping, no matter how clean your windows, no matter how precise the painted trim, if your roof is covered in filthy algae stains then it will still ruin your curb appeal, if not in your eyes then in the eyes of your family, friends, neighbors, and potential buyers.

Myth #4:  Roof algae is only a cosmetic issue so it can be ignored for now. If not cleaned off and kept at bay roof algae has the ability to shave years off the life of your shingles.  It’s important to remember that roof algae is a living organism that needs food to continue to grow.  Guess what the favorite food of roof algae is?  That’s right – your shingles!  Shingle makers now use limestone filler in the manufacturing process which the algae just loves to chew on.  This will result in premature loss of shingle granules and general deterioration.  Shingle granules are vital to the health of your roof and home because they work to deflect UV rays and heat away from your roof surface.  If they are gone or covered with algae then you will have a hotter attic and higher AC bills.  You’ll also have to replace the roof a lot sooner, and with the average new roof these days topping $10,000 it’s just a no-brainer to keep your shingles clean and functional for a fraction of the cost.

Myth #5:  The best way to go about removing roof algae is with high pressure. I’ve beaten this one to death on this site but it bears repeating that, next to positioning your home in the path of a tornado, power washing your roof to remove algae stains is the worst thing you could possibly do to it.  Just because your concrete, deck, and brick siding were pressure cleaned doesn’t mean you should do it to your shingles.  Don’t you have any idea how flimsy and fragile your shingles are?  Don’t you realize how many thousand or tens of thousands of shingle granules will pop right off with the use of a power washing wand?  It just always blows my mind that people think this is a good idea.  Yes, blasting your roof with 2000 PSI will remove some of the stains, but if it removes some of your actual roof in the process then what the heck is the point?  If you bought a roof algae remover and somewhere in the instructions it says that you should walk up on your roof with a power washing wand in hand and unleash hell on your shingles then it’s safe to say that you purchased the wrong product.

Myth #6:  Chemical roof cleaning will damage shingles, gutters, and landscaping. If you’re using the right chemicals with the proper procedures and rinsing techniques then you have nothing to fear.  I’ve cleaned hundreds of roofs with non-pressure chemical methods and have never once seen a situation where we caused damage to someone’s home.  I also only clean roofs with a helper present who’s sole responsibility is to rinse the heck out of the grass, bushes, and perimeter landscaping so that there’s absolutely no chance of plant damage.  We usually do such a good job of rinsing that homeowners notice that their landscaping actually looks especially healthy and vibrant in the days following the cleaning.  ARMA (the Asphalt Roofing Manufacturers Association) and GAF (North America’s largest shingle maker) both recommend that shingles be cleaned with non-pressure, chemical methods, and any home inspector worth his salt would also concur.

Myth #7:  It’s only necessary to clean the sections of the roof that have visible stains. Just because you can’t see algae stains on certain parts of the roof doesn’t mean that it’s not already there and beginning to develop.  Keep in mind that in its early stages roof algae is completely invisible to the naked eye.  It’s not until the more advanced stages that it actually turns black and becomes visible.  So if you can see algae on even one section of your roof that means that it’s probably already taking hold on your entire roof.  I always try to explain this to my customers but occasionally I still get people who don’t believe it and demand that I only do a spot-clean to remove visible stains.  I reluctantly oblige their demands but am never surprised when I drive by a year later to see the untreated areas now completely covered in black algae!  Then they usually call me back with the standard, “You were right.  Can you please come back and clean the whole roof as you originally recommended?”

Myth #8:  Ambient temperature has no effect on the effectiveness of a roof algae cleaner. If you’re using the correct chemical mixture then it will be most effective when the temperature is above 50 degrees.  Below 50 and the power of the solution drops off rapidly.  If you absolutely must have the roof cleaned on a day when it’s right around 50 or a little bit lower just keep in mind that the chemicals will need to sit for a little bit longer on the roof to be effective.  So instead of giving it five minutes to kill the algae give it 15.  Then reapply if necessary.  On the flip side, if it’s an extremely hot day you may find that your chemical is
evaporating before it even has a chance to kill the algae.  In this situation you can simply soak the roof with water to cool it down before applying the chemicals.

Myth #9:  Roof cleaning is an easy DIY project that any homeowner can do in an afternoon. There’s nothing easy or quick about roof cleaning.  In fact, if you approach it with a cavalier attitude you run a good chance of injuring yourself.  If you want to have any chance of cleaning your roof safely and effectively then you need to set out a clear plan of attack, have safety procedures in place, and, above all, take your time.  Rushing through a roof cleaning only leads to trouble.  Unless you’re one of these guys that absolutely has to do every home improvement job on his own I would highly recommend that you just find a qualified, non-pressure roof cleaning company in your area.  Either you can hire somebody who has the equipment and experience to clean your roof in a few hours or you can spend an entire weekend doing it yourself and risking your life.  Your choice.

Myth #10:  Roof cleaning companies tend to overprice their work and take advantage of consumers. I guess I’m always a little disappointed when I tell someone that it will cost $300-$500 to clean their roof and they give me attitude and insinuate that I’m somehow ripping them off.  I think people hear that word “cleaning” and they think it should be cheap like carpet cleaning or house cleaning.  Think about it.  Does a carpet cleaner spend three hours at your house sweating his butt off and getting sunburned?  No.  Does a carpet cleaner run the possibility of paralysis or death by simply doing his job?  No.  Does a carpet cleaner spend $100 on chemicals for every single job?  No.  Can a carpet cleaner offer you a guarantee that the treated surface will stay clean for years to come?  No.  There’s so much more that goes into a professional roof cleaning than for any other kind of residential cleaning service that it’s really not even fair to lump them into the same category.  As a matter of fact, I actually think that most roof cleaning companies come in too low with their prices when you consider all the variables involved.  I also challenge you to name me one other home improvement service that can instantly transform a home’s curb appeal in a single afternoon for under $500.  Can’t be done.  And when you consider that it not only makes your home more beautiful but also extends the life of your expensive roof by a matter of years I think that having a roof cleaned is one of the smartest and most cost-effective things that a homeowner could possibly do to protect their biggest investment.

So now that I’ve cleared the air and educated you about the myths that surround the roof cleaning industry I hope you’ll take these words of advice to heart because they represent the straightest talk about this topic that you’re going to find.  I’m not here to serve up a load of BS just because I’m trying to sell a product.  I’m telling you like it is because there are too many lies flying around.  Either you can buy into one of the myths and be disappointed with the results or you can clean your shingles the right way and be satisfied with your new-looking, beautiful home that is free of roof algae.

Just to be thorough, there are other types of organic growth that can form on a roof other than roof algae (or mold).  There’s also the possibility of lichen or moss growth.  Lichen is usually a whitish color, but it can also have tones of green, yellow, and brown.  It often forms in patches of individual circles, each averaging about the size of a dime.  It’s also noticeably raised from the surface, unlike the black algae stains.

Roof moss, on the other hand, almost always has a green color and if left untreated for several years will become so thick as to be noticeable from the ground.  I’ve seen some situations where it’s been ignored for so long that it literally looks like a roof is covered with green carpet.  Honestly I don’t know what people are thinking when they allow this to happen to their home especially when you can remove roof moss fairly easily most of the time.

So how does one go about treating a roof with lichen and/or moss?  Well, in most cases it should be handled in the same manner as the black algae roof stains (or “roof mold“), which has already been described in length on this site.  In a nutshell, a bleach or chlorine-based solution applied with non-pressure methods will kill lichen and moderate moss growth almost instantly.  It should turn a whitish color within minutes, which tells you that it’s dead.  Unlike black algae stains which come off immediately with the rinse phase of the cleaning, dead lichen and moss will require a few heavy rains to finish rinsing off the roof.  It could take awhile but rest assured that lichen and most moss situations, once dead, will eventually dislodge and rinse off the roof thanks to mother nature.

If you are the impatient type and want the lichen and moss removed immediately, you’ll have to use a pressure washer, but as you should know by now I highly discourage the use of high pressure on a roof.  In those rare cases where the moss is extremely thick and out of control (this is more common in the northwest) your only choice might be to use a pressure washer, but even in these extreme scenarios you should dial down the pressure and use extreme caution.

In summation, black roof “mold” stains (algae) should come off immediately if using the proper methods.  Roof mold removal doesn’t have to be rocket science, people. White or green lichen and roof moss removal on the other hand, can be achieved by the same chemical solution but will need a few heavy rains to finish rinsing away.  If this all just sounds like too much of a hassle and you’d rather keep your feet safely on the ground (good idea) then do take a look at our directory of non-pressure roof cleaning services.  There’s more than likely a company in your area that knows how to remove your roof algae in a professional and safe manner.

I can pretty much guarantee that if you try to clean your roof stains with aggressive scrubbing or agitation, you’re going to lose a lot of shingle granules in the process.  With enough force these will pop right off of asphalt shingles, which is why I also do not recommend roof cleaning with a power washer.  Granules do more than just add the color to your shingles.  They are vital to your roof’s health because they reflect sunlight, thus keeping your attic cooler and your AC bills lower.  If you think your attic is warm now just climb up into one that is covered by a roof that is missing a lot of granules or is covered in black algae stains – you’ll probably notice the difference in temperature.  In general, the quicker your roof loses granules the quicker it will lose its integrity, and the quicker you’ll need to get a new roof.  So hopefully you can see how important this so-called “shingle grit” actually is.

The other reason you shouldn’t be scrubbing or pressure washing your roof stains is that in most cases it’s simply not necessary.  I go into this in a lot more detail throughout this site, but the bottom line is that if your contractor is using the correct chemicals then no surface agitation should be required.  You simply spray on the chemical with the help of a non-pressure pump, allow several minutes for it to kill the algae, and then rinse gently with a garden hose.  The only rare instance where a power washer might be useful is with very thick, green moss, but if all you have are black algae roof stains then you should have no need for scrubbing or power washing.  Make the mistake of cleaning your roof with high-pressure or aggressive agitation and you will probably only shorten its lifespan.  Use the right roof stain remover without pressure and you will extend your roof’s lifespan.

Roof stain removal doesn’t have to be complicated, but it is so important that you do it the correct way or hire someone who knows how to do it properly.  It’s very possible that you’ve had some so-called “expert” try to convince you that chemical roof cleaning is “bad” and will destroy your roof, gutters, and plants but it just isn’t true.  I’ve performed so many roof cleanings with chemicals alone that I could practically do it in my sleep, and I’ve never once had a situation where we caused damage to a home.  All we’ve ever done is ADD years to a roof’s life, not subtract them.  I can’t say the same for someone who relies on pressure or scrubbing, however.  Either you can take my advice or toss it aside, but don’t blame me when you decide to hit your shingle stains with a power washer and notice afterward that there are literally piles of shingle granules sitting in your gutter and on the ground.

• First and foremost, you would be wise to find a roof cleaning service that uses non-pressure methods for roof stain removal.  If you’ve been digesting the other reading material on this site you should know by now that high-pressure roof cleaning is generally not a great idea.  The only rare exception could be in situations where there is very thick green moss like a carpet on your roof, and even in this extreme situation the pressure should be used carefully and responsibly.  Educated roof cleaners know that in the vast majority of cases, black roof stains can be completely and safely removed with the gentle application of a bleach or chlorine-based solution followed by a non-pressure rinse.  If you come across a contractor that wants to clean your roof with a high-pressure wand, run in the other direction as fast as possible.
• Find a roof cleaning service that operates in teams of two on every job.  Theoretically, a roof cleaning could be done with one person, but the ideal scenario would be to have two roof cleaners on site for your job, one to apply the chemical and do the rinsing at the roof level, and the other to remain on the ground for perimeter rinsing and just as a “safety valve” in case the roof-man needs assistance.
• Roof cleaners that have been in the game for any length of time know that your whole roof should be cleaned, not just the areas where black stains are visible to the naked eye.  If you can see stains in any one area, that’s usually an indication that algae is already taking hold over your entire roof and will just require a little more time to become completely visible everywhere.  Best to clean the whole thing and start with a clean slate, so to speak.
• Ask to make sure that the contractor has liability insurance.  This one’s a no-brainer for any home improvement job, of course.  It not only protects you but it helps to weed out the handyman types who probably don’t understand the proper methods for roof cleaning to begin with.
• Though this last one isn’t a necessity, you might check to see if the roof cleaner is BBB accredited.  If so, that’s usually a good sign that they have been around for awhile and are truly knowledgeable about roof stain removal.  If they aren’t a member of the BBB then ask for a few references that can vouch for them.  It’s also a good signal if they have their own before and after pictures to show off, either on a website or in a portfolio.

So there you have it.  Follow this list and you should be very happy with the results.  Ignore it at your own risk.  By the way, we have an ever-growing directory of professional roof cleaning services on this site for your convenience.

However, it’s important to understand that even though the sun helps to slow the growth of algae on southern-facing surfaces, it does not stop it.  If you have stains beginning to develop on the northern-facing surfaces of your roof, it means that it’s just a matter of time before the entire roof is covered with algae stains.  You might not yet see black stains on the southern-facing surfaces, but that doesn’t mean that algae hasn’t already taken root and begun to multiply in these areas.

That’s why it’s a good idea to have the whole roof surface cleaned, even though it may appear that stains are confined to one side of the roof.  If you can see it somewhere on the roof, that means it’s everywhere on the roof.  You can demand that your roof cleaning contractor only cleans the area where you can actually see black stains, but don’t be surprised when, 12 months later, that area is still clean but the rest of the roof is suddenly covered in now visible black algae.

1. Get some Cougar Paws – amazing traction.  The grip on these shoes is so good you’ll feel like spiderman (or a cougar, I suppose).  In fact it is so slip-resistant that it can almost give you a false sense of security.  Wearing good shoes does not mean you can turn your brain off.
2. Wear jeans or long pants.  No matter what chemicals, products, or procedures you’re using some of the stuff is bound to get on you, and better it land on denim than skin.  Of course whatever does get on your skin should be rinsed off immediately.
3. Wear latex gloves.  Cheap dish gloves from the grocery store will work fine.  Again this will help in keeping chem off your skin.
4. Wear goggles.  If most of this stuff is bad for your skin just imagine what it can do to your eyes.  If something does splash in your eyes flush them immediately!
5. Wear a respirator.  You DO NOT want to get the fumes from this stuff in your lungs.  Trust me.  Make this a priority.  Getting dizzy from exposure 45 feet off the ground is playing with fire, not to mention the potential long-term effects of repeated close-range exposure.
6. Use a fiberglass ladder if possible to minimize the possibility of electrocution from bumping a power line.
7. You’d be wise to invest in a roof harness system if you’re uncomfortable or unfamiliar with heights, ladders, or roofs in general.  Heck, everyone would be wise to use one.

Sounds like a lot, right?  Why not do yourself a favor and just hire a professional roof cleaning service like our friends at Safe Roof Cleaning, who already have the equipment and know-how to do it right.  Considering all the chemicals and gear you’d have to buy to do it yourself it would probably be cheaper to hire roof cleaners anyway, so why wouldn’t you?  Even if you think that it might save you a few pennies to do it yourself, is it worth it when the potential risks include paralysis or death?  I want to say this one more time to make it perfectly clear:  chemicals or water on a roof will render it EXTREMELY SLIPPERY (think ice), so you better be prepared if you’re a hard core DIY guy.

Instead they’ve developed these powdered or condensed products that they can manufacture cheaply, ship light for next to nothing, and let you deal with doing all the work (like mixing, renting a power washer, etc.).  They go to great lengths to bash bleach/chlorine based solutions because it’s not something that they can profitably sell!  They’ll tell you how “green” their product is and how “bad” bleach is but if you do your research (the fact that you’re here at this site is a good start) you’ll discover that bleach-based roof cleaning is the superior method from both a safety and effectiveness standpoint if you know what you’re doing.  I’ve cleaned hundreds of roofs with bleach (and ZERO pressure, by the way) and an experienced rinse man, and we’ve never once seen roof, gutter, or house damage as a result.

On the other hand, I can tell you there’s a chance that if you try to use one of those fad products on your roof in conjunction with a pressure washing wand that you’ll lose significant numbers of granules from your shingles.  I’ve seen it first hand where other roof cleaners have taken high pressure to a roof and there are literally hundreds if not thousands of shingle granules on the ground circling the entire perimeter of the house.  This is not good!  They might even tell you that they’ll use an extension piece to disperse the pressure through multiple nozzles and though this is a step in the right direction it’s still too much psi for my comfort level.  Other purveyors of these kinds of products will tell you to spray it on a few times over the course of a few weeks without the aid of a pressure washer and you’ll see some results three months to a year down the road.  Well, I guess if you’re willing to wait that long then be my guest.

As for me, I’ll stick with non-pressure and bleach, thank you very much.  I suggest you do the same, or at least hire a professional non-pressure roof cleaning service to do it for you safely and effectively.