Roof Cleaning Chemicals and Products Guide

Roof Cleaning Safety Products For The DIY Enthusiast.

You all should know by now that I discourage DIY roof cleaning because of the hazards involved, but I know that some people will attempt to do it anyway.  So I wanted to throw together just a short list of safety products for roof cleaning that many of the pros use (yes it can get expensive to buy all this stuff but roofs with slippery chemicals on them are a recipe for disaster if precautions aren't taken (don't say I didn't warn you)).

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 that already has 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.

Roof Cleaning Products - My Two Cents

People are always asking my opinion of different fad roof cleaning products that they saw in the store or on the internet or wherever, and I always try to patiently explain that there is a safer, more effective way.  Trust me that if there was a way to profitably package and sell a bleach-based roof cleaning solution to the public I believe these companies would do it because they should know it's the safest and most effective method, but there isn't so they don't. 

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. 

Cold Weather Chemical Roof Cleaning Is A No-Go

In a previous post I outlined, in detail, the most effective roof cleaning chemicals and how they should be applied.  I neglected to mention, however, that these chemicals begin to drastically lose cleaning power once the air temperature drops below 50 degrees.  Therefore, winter roof cleaning is nearly impossible in most of the Midwest and Northeast.  Of course, those of you lucky enough to live down south will have more opportunities to clean your roof in the winter, but fresh sodium hypochlorite could be hard to come by.  Your best bet is simply to hold off until Spring or Summer if you can wait, not only to maximize the potency of the chemicals, but also to assure that you're doing it safely.  It should go without saying that attempting to navigate a roof or ladder when there is ice or snow is extremely dangerous.

The Best Roof Cleaning Chemicals

In my last post I detailed why I feel that certain roof cleaning chemicals are a superior alternative to roof power washing.  There are many roof cleaning products and solutions on the market these days, all claiming to be superior, and all claiming that their's is the safest and most effective, but it's important to keep in mind that these are companies that are just trying to make a buck and will say just about anything to sell their product.

In my considerable experience, there's only one way to clean a roof the right way, and that's with a sodium hypochlorite-based solution.  Sodium hypochlorite is the active ingredient in bleach and chlorine, and when applied to a roof at the right ratios is quite simply the safest, most effective way to clean a roof.  It is the recommended method for cleaning roofs by ARMA (the Asphalt Roofing Manufacturers Association), and their technical bulletin on the topic can be viewed here (pdf file). 

ARMA recommends a mixture of bleach, water, and TSP (which can be found in paint stores), but be careful with the TSP on painted surfaces as it can remove the gloss in high dosages.  I have found that the TSP is helpful but not necessary, as the bleach is the primary cleaning agent.  In addition, every roof cleaning professional that uses this method has his or her own "secret" additives that they add to this mix to give it just the right cleaning potency for their climate, but the common denominator is a final liquid solution that is about 3-4% sodium hypochlorite.  So if your common household bleach is around 6%, you would need to have equal parts bleach and water to get you down to 3%. 

This is by far the safest and most effective way to clean a roof, but the catch is that an average one-story ranch house is going to require anywhere from 30 to 60 gallons of total mix.  That means you'd need about 15-30 gallons of typical 6% household bleach.  Typically, the pros will have the whole mix in a large poly tank on their truck or trailer, and will use a battery-powered pump to deliver the solution through a long polybraided hose up to the roof surface.  They'll usually have a bleach resistant tip on the end of the hose that evenly disperses a soft spray over the roof surface.  They'll leave the solution on the surface to let it do its thing for several minutes before rinsing the surface with water from the garden hose.  So no power washers or scrubbing should be required (the only exception could be for thick moss accumulations).  If you're doing this yourself, you'd also want to keep the whole perimeter of the home rinsed down very well during the application (preferably by a second person) as sodium hypochlorite can have a negative effect on landscaping if not properly diluted.  Be especially mindful of areas where downspouts empty into grass or other greenery.   Occasionally you might have to go over a few spots a second time, but the results should be instant!  Rinse the roof and perimeter very well, let dry, and enjoy your new-looking roof.

You can do this yourself, of course, but you'd be looking at having to purchase hundreds of dollars worth of equipment and chemicals, so why not just hire a professional that specializes in no-pressure roof cleaning?  Try to find one that utilizes the roof cleaning chemicals that I just outlined.

If you do decide to go for it yourself, BE CAREFUL.  The hazards include, but are not limited to: falling off ladders, slipping on the roof surface (which is made very slick when solution is applied), getting bleach spray in your eyes or lungs (wear eye protection and a mask), leaning a ladder against a power line, etc.  This work is not for the faint of heart.  Harnesses and support systems might be a good idea.

You can expect this type of treatment to keep the roof clean anywhere from two to six years before stains start to return, with an average of three to four years.  I've yet to come across any so-called "sealers" that actually work.  Your best bet is just to have the roof re-cleaned by a professional when the algae streaks have returned.  The zinc strips that some try to market don't work that well in my opinion.  They may be somewhat effective for the 2-3 feet of roof surface directly below the strip, but what about the rest of the roof?  The zinc is also a very expensive material.  Just have a pro clean your roof every couple years and save yourself the hassle.  If you need guidance on how to find a good contractor then read this post about roof cleaners.

Roof Cleaning Chemicals Are A Good Alternative To Power Washing

Power washing a roof is usually not a very good idea.  High pressure cleaning will often result in the loss of shingle granules, which are crucial to the health and effectiveness of your roof.  Aggressive power washing can even result in water intrusion below the shingles, and places like skylight edges are especially susceptible.  Power washing will usually remove most of the algae, but is it worth it if it removes part of your shingles in the process?

There are some roof cleaning chemicals on the market now that require the use of medium-level pressure.  This method involves the use of a power washer, but instead of a high-powered wand at the tip, it has a device which helps to disperse the water pressure through three separate nozzles.  While this method is better than using high pressure, you should be aware that each nozzle is probably still delivering somewhere between 800 and 1300 psi of water (you garden hose psi is under 100).  It is quite possible that this method will still result in the loss of some surface granules, and thus could contribute to compromising the integrity of your roof over time.  Why would you want to lose any shingle granules if you don't have to?

My advice?  Skip the fancy roof cleaning products that require pressure, if possible.  Your best bet for safe, effective roof cleaning is to utilize chemicals that will kill the algae on your roof without the need for any pressure whatsoever.  This method simply involves spraying on the chemical solution, allowing it several minutes to work, and then rinsing off the dead algae with water from your garden hose.  Think it's not possible?  Think again!  Our next post will detail exactly how this is accomplished.