3 Roof-Cleaning Methods for Ugly Stains

Leave a Comment - 24



Subject: roof cleaning

Everyone ,its not rocket science .Diluted chlorine used properly is the best and most economical way of cleaning ALL roofs Do NOT and I will repeat DO NOT PRESSURE WASH ANY ROOF.I don't care what the pressure is Roofs are not designed for that kind of abuse.The very fact a person has to walk back and forth over a roof to follow the surface cleaner should be you first sign of a problem The %s of damage being done goes up incrementally .I usually ask the lightest guy in my crew or myself to do the roofs.Anyone over 180lbs may do damage especially on older roofs.The best way to do the job 1 cover all plants for any over spray low pressure application.2 make sure the contractor uses al reasonably long application wand [.Reduces foot wear on roof] 3Make first application and wait 10 mins.[this will give a guide to how much more may be needed..4 do final application .While all this work is being done a crew member should be rinsing all the over spray and over flow on the building and over the cover over the plants.Rince of plantt covers fold them towardd building and rise once more.This way is designed for the best results and minimizes damage to the roof and building and plants .Check please and I will see you in2-3 years Being in S FL you cant guarantee a time frame .It all depends on local weather and how much spore is in the air in local conditions The priceing is either by square feet or in most caes roof conditionor how long since roof was last treated . I call my Co Common sense PW That's all it requires.


Subject: Non-Pressure Washing Methods?

Hello, does anyone know if there are any methods for removing moss and cleaning a roof WITHOUT using a pressure washer? Our roof is composition material, and I am so fearful of damaging the roof, causing water to leak. Any help would be appreciated. Thank you.

Overspray Solutions Roof Cleaning Services

Subject: Roof Cleaning

I just love all the claims with the proprietary chemical claims out there, unlike many here we have been in business for only 8 years. Yet before we started this services we purchased and attended lots and lots of training seminars, further we researched using information provided in the MSDS sheets. After spending roughly about 25,000 USD we concluded that Sodium hydrochloride truly is the most cost permissive and effective product when used properly, all these so called Eco-friendly product are potentially similarly dangerous if improperly used. The truth is in the MSDS, to date I have seen no noticeable advantage to these products.

Outdoor ProWash - George

Subject: Bleach is best!

We have cleaned a bunch of roofs over the years and have been back to many for repeat service after 3-5+ years. We found no damage and have had no damages to shingles from bleach or anything else. In many cases the roofs were 20+ years old at the first cleaning. There are many factors that contribute to the return of the algae. Any process that does not contain bleach will require a lot of rinsing. Perhaps some bleach can be harmful, but we only use industrial food-grade bleach that is then diluted to below store bought concentrations. This causes the bleach to have much more effectiveness and less of the harmful salt byproduct. It is literally salt you could eat, but is not good for plants so it needs to be rinsed off. Rinse or no rinse is a debate too. We have a lot of rain here in Nashville so we don't have to rinse, but it's no big deal to rinse and we would if anyone wanted us to. Now, my friends in California who don't get much rain all tell me they rinse. We do produce instant results in spite of what others may say. Roof cleaning does very much require workers to be responsible. Roof shampoo is a captive franchise and these services can only use that specific method. They attack bleach simply because it is not an option to them and they have never tried it. Professional roof cleaners do this every day and don't stay in business very long if they are killing plants or damaging shingles. I am sure the RS people do fine too, but would you rather have someone walking on your shingles or showering them with something you probably drink. To address the comment about pets. The salt left over from bleach could dry out your pets paws, but how would it get from the roof to the pet? Salting your sidewalks in the wintertime requires some caution as well. Bleach would be on your roof and washed down the spouts into your yard along with gobs of water. Roof cleaning process that uses bleach is safe for your pet if done responsibly. Pressure washing would be a big no no! Never let anyone rinse your roof unless they arc their spray so the water falls onto the roof or it is too much pressure. Another thing, about the corrosive nature of bleach, that does not apply to roof cleaning because it only exposed for a short time so I have never had shingles to get corroded. I would trust Doug Rucker and Ed Thompson on my roof any day. Thanks guys!


Subject: 5 Year Roof Cleaning Warranty!

If you properly kill the bacterial growth on the shingles you can offer a "FIVE YEAR" warranty for your services.

If you do not kill the bacterial growth and just spread it around and then you will need to offer a "YEARLY" maintenance plan because you just made a bigger mess and it will come back ASAP all over the roof.

Gary Boyd

Subject: roof cleaning

having read the articles pertaining to roof cleaning I find that most have no clue what they are talking about. I have over the past 25 years been cleaning roofs and have experimented with just about every product available from chlorine to sodium hydroxide to copper sulfate. The secret to roof cleaning is the proper mixture of chemicals. No matter what method used. Folks do not realize that one gallon of chlorine (not bleach) will kill bacteria in 10,000 gallons of water. I won't reveal my mix ratio but it certainly does not have to be flooded. And proper rinsing is without a doubt of utmost importance. Roof shampoo, roof-a- cide, spray and forget, jomax.some require adding chlorine others are just high concentrates of sodium hydroxide. The use of a HVLP system works best and will NOT cause harm to plants pets or humans. Choose a professional. One is is not ashamed to tell what is being used. I currently have over 4300 active accounts. This algae is caused by an airborne spore and along with heat and moisture forms algae. No matter what method used, without preventative maintenance it will return.


Subject: All roof cleaners are full of baloney

Most roof cleaning solutions will eliminate existing growth yet leave untouched their microscopic spores tucked down around the granules. After a year or less those spores will grow to generate more stains which is why many promote an annual treatment. The soft-wash crowd use basically straight Clorox bleach with some soaps tossed in. They spray it on but don't rinse since the stout bleach mix does remove all the stains' color so looks clean. They also claim that their 'special soap mix' will keep the stains from returning for several years. They think it's due to the residue soap film but actually it due to straight bleach's (5%) ability to kill spores.
Bleach solutions degrade back into salt water within 15 minutes when exposed to the air and sunlight. Bleach also degrades rapidly when applied to organic matter so is no big deal any dribbles onto the ground. Their overspray will create chemical burns on plant leaves but won't kill them.
The eco-green-friendly nonsense is nothing but oxygen bleach made in a strong solution. It works pretty good except you have to keep applying more when it starts evaporating so most folks apply it twice before rinsing. It won't kill the spores so the stains will redevelop within a year.
I've been cleaning and treating roofs for 35 years. I use what ARMA recommends with something else added to make it more effective. I never rinse for liability reasons, to reduce the cost of the service plus the rain does a good job. My anti-growth treatment will allow stain removal by rainfall over time plus kills off the spores so the roof stays stain-free for several years. It costs much less than the ARMA bleach treatment so most folks opt for it.
BTW the black crud that discolors flat concrete walks and drives is the same junk creating stains on the roof so might as well get those surfaces cleaned at the same time.


Subject: Roof Cleaning Options

After reading several publications and actually calling three manufactures that make various roof cleaning solutions I've come to a realization that it comes down to cost. According to each manufacture, EACH ONE mentioned their competitors method (Bleach and No-Bleach) was actually SAFE, when used correctly. Also, EACH ONE mentioned their own methods COULD harm roof AND plants when used incorrectly. With this said, I chose the LOW bleach solution method with no pressure rinse. The cost was very reasonable, the results look great and it came with a longer warranty and no requirement for an annual contract. My rental properties now have greater curb appeal and look nice. Three other things I didn't like about the "no-bleach" option was the higher cost, need for an annual contract and someone having to walk on my roof to rinse the nasty growth off.. That's my experience and my feedback-. I feel I made the right choice.


Subject: Roof Cleaning from a roofing contractor

I agree 100% with this gentleman. Bleach causes no harm to the roof as long as it is diluted at least 2 gal water per gallon of bleach and spray on and off with a low pressure hose. I have been in roofing in Houston, Texas for 15 years and also worked for one of the premiere pressure washing companies before I got into roofing. I have also opened my own line of roof cleaning. There are products that can actually coat the roofing shingles, tiles, wood, brick, and siding. I'm an independent insurance adjuster for 15 national insurance companies and have never seen an issue with this and as of now no major shingle manufacture has any issue with this. GAF, Certainteed, and TAMKO.
Hoped this helped all the misinformation.


Subject: Follow ARMA guidelines to maintain your shingle warranty

Roofs washed professionally according to ARMA guidelines using sodium hypochlorite (bleach) with an experienced operator will have absolutely none of the issues in the article come up. No dead plants, no damage to the property in any form and your shingle warranty will stay intact along with the granules on your shingles. Sodium hypochlorite goes right back into the world as salt.

Bleach does NOT evaporate into "chlorine gas". That's basic chemistry.

Using scare tactics to convince a consumer to use a method that will void their shingle warranty is unethical.

Charles Bergman

Subject: In Charlotte County Florida Roofs Become Very Algae Blackened

I have cleaned roofs without using damaging pressure washing machines for many years.
Here in SW Florida, roof algae flourishes and infests roofs to their ultimate destruction.
The only thing that ruins a roof faster, is pressure washing it or worse, using a surface cleaning machine, such as is used by the roof cleaning Shampoo company! These are actually called "Flat Surface Cleaners" They are meant for driveways and all flat cement. Their jets are set at an exact distance from a flat surface and work wonderfully! Roofs are not all flat! Imagine powerful pressure jets, hitting the tops of barrel tiles slam bang! Then barely scratching the barrel tiles low spots and crannies! No, this so called Shampoo is just pressure washing with the most powerful tool available to use with a pressure washer and simply the fastest way to clean roofs.
I fully agree with Matt. Use ARMA guidelines. It's just like the manual that comes with your car or other items.
It tells you how to maintain and clean them without voiding your warranty.
Gaf, Pabco, Owens Corning and other roofing manufacturers all say to clean without pressure and all say to do so with sodium hypochlorite bleach. NONE suggest the use of these new non bleach alternative "Homeowner Special" cleaners.
I have seen some awful looking roofs, after homeowners and so called professionals have sprayed some of these spray and forget, wet and forget and the list goes on forever, gimmick products. I think it is far wiser to clean your roof according yo manufacturer instructions and according to their ARMA roofing manufacturers association! You can watch Youtube videos of cleaning roofs with a surface cleaner and watch me cleaning with the ARMA soft wash method. Mine is on Youtube under "BERGMAN ROOF CLEANING"


Subject: Roof Cleaning


FACT: Both bleach and Tri Sodium Phosphate will corrode metal even in weak concentrations, and HIGH concentrations of Chlorine Bleach will accelerate damage, espaecially if the roof is not rinsed properly. Most companies that use the BLEACH method also use high concentrations of phospahtes as well which have been banned by 16 states. They promote algae growth in water systems and choke off drainage systems with thick algae build up causing a multitude of problems.

FACT: Chlorine Bleach releases toxic Chlorine Gas as is evaporates

FACT: Bleach splashed on plants and small trees will kill them PERMANENTLY.

FACT: ARMA states in their own bulletin that the use of Chlorine Bleach will merely "lighten" the appearance of algae stains, NOT remove them. The proprietary ECO-FRIENDLY chemicals used in the ROOF SHAMPOO method cause the entire root base to be removed. That is how it is easily rinsed from the roof using a low pressure, high volume rinse to thoroughly remove the vegetation root and all. To address the comments made above concerning the machine that is used by ROOF SHAMPOO contracors. It is a 13 hp pressure machine, but the equipment is dialed down to very low pressure. It is merely used to generate the HIGH VOLUME of water required to thouroughly rinse the shingle and does not use damaging high pressure. The vegetation that grows on asphalt shingles does not have a protective "cuticle", or "skin" like other vegetation does. That is why the proprietary solution used by ROOF SHAMPOO contractors removes the vegetation from your roof, but does not harm any other plants around the property. To address the "Annual Maintenance" arguement posted above, it is to guarantee that the vegetation doesn't return, and is a fraction of the cost of the original cleaning. It is NOT necessary to match the results of the bleaching method, but merely a guarantee that with annual maintenance the vegetation will NEVER return. The cost is about the same or less as having your roof BLEACHED every 3 to 5 years. Bottom line is, the ROOF SHAMPOO method is the safest, most effective way to clean and maintain your shingle. Companies that use bleach will point to the recommendation from ARMA to use bleach to lighten roof stains, but the ARMA bulletin was written a year before ROOF SHAMPOO was developed and is frankly out dated material. My personal company has had thousands of satisfied customers and I hear dozens of complaints annually from customers that had either used a BLEACHING company in the past that destroyed their landscaping, or know of someone who had and that's why they called us.


Subject: roof cleaning

It is safe to use chlorine on roofs of all types.A responsible contractor with experience will know the right amount to apply There are no guarantees on how long the application will work,but in the long run Chlorine and a proper rinse with all vegetation covered for obvious reasons is the best and most economic solution to cleaning roofs driveways side walks etc Having cleaned over 3000 roofs plus many other surfaces I have never had one complaint or call back for any damage by my cleaning sytems.I do use surface cleaners for what they were designed If a customer asks me to use a surface cleaner on ANY roof be it 3 tab shingle or Barell roof tile I WONT DO IT .The problems are obvious as you need to do a lot of walking back and forth over the roof .Barrel roofs will brake chip and crack..Its also wise to use the lightest man in your crew to walk the roof for obvious reasons I call my C Common Sense.Thats what t is needed not a sales job.Lets face it its not rocket science but a real good way to make a very good living and the reaction is instant and very rewarding at the end of the day..

Charles Bergman

Subject: Roof Shampoo Simply Uses A Flat Surface Cleaning Machine!

All your pictures and videos show you using flat surface cleaners on roofs. You could spray baby shampoo on and blast the roof with your big surface cleaners and they would appear clean! Of course, only bleach, such as the manufacturers of roofing specify, will kill off the living algae spores. I have been in the pressure washing business here in SW Florida since 1989, I'm 67 years old and know a gimmick when I see one! What you are doing is still just a form of pressure washing roofing and will undoubtedly blow a good % of granules off of shingled roofs! Tile will not be uniformly cleaned, because surface cleaners are set at an exact distance for a surface. I congratulate you on being quite successful. Shampoo sounds so gentle and homeowners can be fooled by well written sales pitches and yours is GREAT!
However, the ARMA and many roofing manufacturers disagree with you and none suggest you be used on their websites.
They don't want to replace roofs prematurely due to your taking years off of a roofs life with your method.
YOU SHOULD HAVE NOT SAID "FACT" YOU SHOULD LIST THESE AS "SCARE TACTICS" NONE OF WHICH ARE FACTUAL. The ARMA method I use, is applied with a 12 volt 45 - 60 psi pump and never gets under roofing as you suggest.
FACT: Both bleach and Tri Sodium Phosphate will corrode metal even in weak concentrations, and HIGH concentrations of Chlorine Bleach will accelerate damage, espaecially if the roof is not rinsed properly. Most companies that use the BLEACH method also use high concentrations of phospahtes as well which have been banned by 16 states. They promote algae growth in water systems and choke off drainage systems with thick algae build up causing a multitude of problems.

FACT: Chlorine Bleach releases toxic Chlorine Gas as is evaporates

FACT: Bleach splashed on plants and small trees will kill them PERMANENTLY.

ANOTHER FACT: ARMA states in their own bulletin "Caution!

High pressure washing systems are likely to damage asphalt roofing and should not be used on asphalt roofing for removing algae or for any other purpose." Your surface cleaners require hundreds to thousands pf pounds of pressure to function. I know, I own 2 of the! Watch one in operation in my Youtube video. Look up on Youtube "BERGMAN DRIVEWAY CLEANING"


Subject: Not sure I agree with this article.

The roof manufacturers website suggests using a bleach solution to kill the moss and algae. Eco-friendly sounds great, but it won't fully kill the algae and moss. That's why Sandy Prisak, the owner of Exterior Surface-Brite, Inc., says you'll need an annual maintenance with their eco-friendly method. The bleach method is less expensive, works instantly, and no pressure washing like roof Shampoo. Some companies using bleach offer up to a 5 Year Warranty. Sandy and Roof Shampoo will beat you over the head with their "low-pressure" system, but the bottom line is that gadget is hooked to a gas power high pressure washer. How can you kill mold and algae with an eco-friendly product. Just doesn't make sense. Roof Shampoo method is like mowing the lawn. Comes back thicker and fuller, hence the need for their annual maintenance plan. Sounds like a money grab.


Subject: Roof Cleaning w/Bleach

I worked for a company that uses high concentration of bleach to clean roofs. The facts are, It is very hazardous to breath or come in contact with, Residue left behind is dangerous especially if you have pets or children that play in the yard, even if the ground is rinsed, it is still in the dirt and because the roof is not rinsed, the bleach will continue to drip from the gutters long after the worker leave. And one of the biggest issues is that it will rust out your gutters within a year or two depending on the concentration used. This article is very true, as least as far as the bleach is concerned, no roofer will ever tell you he is using bleach on your roof, they will call it a "sodium based product" or sodium hypochloride (which is bleach in technical terms). Beware! The company I worked for is on Angie's List!

Ed Thompson

Subject: Why should you need an annual treatment plan?

Every one knows bleach works the best. Some companies who use bleach offer a 5 year warranty. But Roof Shampoo tries to milk you for an annual plan because eco-friendly soaps and power washing does not solve the infection. It's mold, algae and moss. If you don't fully kill and sterilize the shingles it will grow right back. If you want to be eco-friendly, leave it alone. Don't disturb it. Let it grow unmolested.

There are many articles from the roof manufacturer pertaining to moss and algae stains. None of them suggest using eco-friendly soaps or any form of power washing. They all suggest using a mild bleach solution. Roofs are expensive. Go with the manufacturers recommendations. Bleach is good. Effective sanitizer. Go visit your local water treatment facility and see how much bleach is added to our drinking water.

Doug Rucker

Subject: Roof Cleaning

You forgot to mention that using the so called Eco Friendly cleaning product does not nothing to kill the algae. Using the bleach based solution does. And there for prevents the algae from returning for a longer period of time than your pressure washing method. The solution you use, if not mixed and diluted properly, can cause plant damage and other property damage. Same goes with using Bleach. A professional roof cleaner that uses the beach method will know how to mix properly, as well spray properly to prevent any roof damage. Your pools have bleach in them, your drinking water has bleach in them, you wash clothes with bleach, and many other everyday products and uses for bleach. WHEN USED PROPERLY. Bleach is one of the most eco friendly products you can find. It starts as salt, and ends as salt. There is a reason the Asphalt Shingle Manufactures only recommend using Sodium Hypochlorite (which is the active ingredient in bleach/chlorine) and no pressure washer. Because it is what is best for the roof. Using any other method or product can possibly void the warranty of the roof.


Subject: Buyer - Do your own research (always a good tip)

First, customers, please do your research...contact your shingle manufacturer and ARMA and see what they have to say.

Next, I have 3 questions for this vendor, and are some of the questions customers should ask people that are going to be cleaning your roof.

1) Question: What chemical does the ARMA and asphalt shingle manufacturers recommend using on their shingles to kill and remove the dark stains (the plant also known as algae, and other plants such as lichen and moss) so you do not void their warranty or damage the shingles? You may get different answers, but I was told to use a bleach based cleaning solution. No matter how you twist it and disguise it or steer people away with what I consider to be scare tactics, the answer is still the same, a bleach based cleaning solution. Customers, call and check for yourselves. They also cautioned against using a pressure washer as it could damage your roof and even void your manufacturers warranty.
2) Question: If your eco-friendly cleaning solution won't harm the plants around the customers house, how is it going to kill the plants on the customers roof? (Algae, lichen, moss etc...these are also plants).
3) Question: Does your cleaning process include the use of a pressure washer in ANY way, shape or form? You condemn the use of high pressure on a roof yourself so I would guess no, yet the last I heard you were using a 'sprinkle disc' as you call it, which looks suspiciously like a pressure washer surface cleaner, and were connecting this sprinkle disc to a 13 horsepower Karcher pressure washer. I've had a 5 or 6 HP pressure washer for nearly a decade that easily puts out 2700 PSI of water pressure (which is far too much pressure for a roof), so I personally wonder why a company condemning high pressure would require a 13 HP pressure washer as a part of their roof cleaning process?

View Comments - 24 Hide Comments

Post New Comment

Offers <
Popular <
Answers <


I second the original question (still unanswered). Speaking as someone who logged in today to try to find an attorney, I see this category as one that's exactly what I have my Angie's List membership for:

1. It's important that I find a good one
2. I'm not an expert enough to know myself who is a good one
3. The industry is full of advertisements and misinformation
4. I wish I knew what experiences other people have had

I don't care about lawns--I planted mine in clover and don't have to mow it. When I do need to mow I use a rotary Fiskars mower, which is great--or a scythe. That's right--a scythe (the European type, which is smaller, and it's very good exercise). Gas-powered mowers, chemical fertilizers and weed killers--all nasty stuff that gets into everyone's air, soil, and water. I'm sure my neighbor doesn't like my wildflowers, semi-wild pockets of fruit bushes, and unmown areas and yes, dandelions (I have 10 acres) but that's too bad. It's better habitat for wildlife, especially the pollinators on which our food supply depends. I think this obsession with the Great American Lawn is a waste of time and resources. Plant some food instead.

I'm not sure Angie et. al. want you to have a complete answer to this question. By re-subscribing at the Indiana State Fair in 2012, I think I paid $20.00 per year for a multi- year subscription. Maybe even less. At the other extreme--and I hope my memory isn't faulty about this--I think the price, for my area, for ONE year was an outrageous $70.00. And they debited me automatically without warning. I had to opt out of that automatic charge. I like Angie's List, but if some of the companies they monitor behaved the way they do in this respect, they'd be on some sort of Pages of Unhappiness. I'll be interested to see if this comment gets published or censored out of existence.

That's very difficult to answer without seeing the house. As one poster said, the prep is the most important part. On newer homes that don't have a lot of peeling paint, the prep can be very minimal even as low as a couple or a few hundred dollars for the prep labor.

On a 100 year old home with 12 coats of peeling paint on it, then the prep costs can be very high and can easily exceed 50% of the job's labor cost.

A 2100 sq ft two story home could easily cost $1000 just for the labor to prep for the paint job. That number could climb too. Throw in lots of caullking  or window glazing, and you could be talking a couple or a few hundred dollars more for labor.

Painting that home with one coat of paint and a different color on the trim could run roughly $1000 or more just for labor. Add a second coat  and that could cost close to another $1000 for labor.

For paint, you may need 20 gallons of paint. You can pay from $30-$70 for a gallon of good quality exterior paint. The manufacturer of the paint should be specified in any painting contract. Otherwise, the contractor could bid at a Sherwin-Williams $60 per gallon paint and then paint the house with $35 Valspar and pocket the difference. $25 dollars per gallon times 20 gallons? That's a pretty penny too.

That was the long answer to your question. The short answer is $2000 to $4000 and up, depending upon the amount of prep, the number of coats, the amount of trim, and the paint used.