How To Clean a Dirty Roof
Most homeowners are familiar with the dirty algae that grows quickly on house siding. Beginning with black dots, developing to green algae, it doesn't take long for the sides of a home to become so dirty and unsightly that the discerning homeowner will seek out a professional power washing service to remove the filth. But meanwhile, there's a blight growing on many Georgia roofs, that the typical homeowner is unaware of how to remedy. That ugly blight, is a bacteria called gloeocapsa magma. It grows quickly by feeding on the limestone granules of asphalt shingle roofs, basking in the warmth of the Georgia sun - and as it grows and spreads, it creates ugly black streaks that can eventually leave an entire roof solid black.
Many homeowners interpret the blackened shingles as a sign that the whole roof needs to be replaced. Well, roof replacement is a very expensive project. It's something you really only want to do once, if ever, during the lifespan of a house. Some theorize that maybe the black streaks is the asphalt losing it's "stick" and beginning to slide down the roof like some kind of sludge. Others think it's some kind of weird sun-damage. But at any rate, not wanting to spend thousands of dollars on a roof replacement, it's common to put off the project for many years, meaning the algae growth on the roof gets worse and worse, ruining all curb-appeal in the meantime.
And so, many homeowners are very surprised to learn that there's actually a very logical solution to the problem growing on the roof, and that solution is roof cleaning.
So how does roof cleaning actually work? What are some factors to consider when choosing a contractor to clean your roof? Can it be done as a DIY project? We'll discuss all these questions below:
How Does Roof Cleaning Actually Work?
The fundamentals of roof cleaning are fairly basic: Since the stains on the roof are organic in nature, some kind of cleaning agent needs to be applied to them. Speaking broadly, the cleaning agent needs to include an algaecide - or, an ingredient that can kill algae. It needs to be applied a low-pressure, because while high-pressure will certainly blast away all of the algae, it'll take most of the shingle-grit along with it too. And that's obviously a good way to reduce the lifespan of your roof - not prolong it.
So it seems like a simple matter: find a good, strong algaecide and spray it all over the roof at low-pressure. Easy. Done. Well.... not so fast. Since we're effectively spraying a "plant-killer" all over the roof, great care must be taken to avoid killing the plants in the yard. You know, the plants you actually care about. So over-spray needs to be controlled and mitigated, as does runoff from the roof, either through the gutters and downspouts, or off of the unprotected lip of the roof. Some plants may need to be covered with tarps - but in such a way that they won't cook while they are covered. Other plants may need to be continually wet-down with water, to dilute any over-spray and render it impotent. Downspouts might need to be diverted and/or bagged, so that any runoff can be collected and disposed of correctly. All of this means that roof cleaning is often a 2-man job, although a skilled contractor can still carry out a cleaning while running solo, if he knows exactly what he or she is doing.
Once the algaecide has been sprayed onto the roof, it should slowly kill all of the organic matter up there, and within about 20 minutes the roof should begin to look a lot more like it did when it was brand new. It's pretty dramatic to watch. Once the cleaning agent has completely done it's job, and all the black stains are gone, the contractor has a choice to make: to rinse or not to rinse. There are pros and cons to both, which we won't go into detail with here, but often his or her choice will be a mixture of both, depending on many different factors.
How To Choose a Roof Cleaning Contractor
Given the aforementioned details about how roof cleaning actually works, it becomes clear that the following questions should be asked of any contractor you indend to hire for roof cleaning:
- Will you use high-pressure? (If they'll use anything more than the kind of pressure you'd expect from a hard rain, move on to the next candidate.)
- Is your cleaning agent A.R.M.A approved? (The Asphalt Roof Manufacturers Association recommends only one cleaning agent for roof cleaning: sodium hypochlorite, aka, bleach. Homeowners natually get a little nervous about the use of bleach on their roof, but sodium hypochlorite is the only chemical which is both safe for asphalt roofs, and potent enough to get the job done. Alternative cleaning agents are either too weak to do a proper job, or harmful to the shingles themselves.)
- How will you protect my landscaping? (Since bleach must be used to clean a roof, great care must be taken with the surrounding landscaping. Unpredictable variables like wind, operator error, etc, must be accounted for by the cleaning company, to ensure your beautiful rose-bushes aren't accidentally killed along with the roof-algae.
- Are you insured for roof cleaning? (If a contractor is not specifically insured for roof cleaning, then buyer beware. Much more can go wrong with roof cleaning than with simple pressure washing of a driveway for example. It's possible for a contractor to clean a thousand driveways without any kind of insurance coverage, and possibly never need it. Concrete is a pretty tough substance, after all! But that is not the case with roof cleaning. Even the most expert roof cleaning technician can make a mistake, and at that time, they better have excellent insurance!)
Can Roof Cleaning Be Done As a DIY Project?
The above explanation of the roof cleaning process is a very simple, general overview. The reality is that each job presents a number of other variables, some of which can significantly impact the way a job is carried out. Only top-level power washing contractors will even endeavor to offer roof cleaning - and even then, it can take years to really become proficient at it. Given that fact, a homeowner should be very wary of attempting this kind of work by themselves. We haven't even discussed the personal safety aspects of being high above the ground, spraying a potent algaecide through the air and onto a roof. Here at Cyclone Roof Cleaning & Pressure Washing, we do occasionally meet customers who like to do their own driveway power washing, for example. Some like to do their own window cleaning. Or even gutter cleaning. We respect the kind of hard-working ethic that shows on the part of the homeowner. But when it comes to roof cleaning, it is a task that we will always recommend seeking a professional to carry out.
If you're looking for someone to take care of your dirty roof, we invite you to request an estimate to have your needs taken care of. You can be sure that our years of experience, our professional process and equipment, and our bulletproof insurance will help you get this job taken care of safely, effectively, and without you having to lift more than a finger.
Written by: Chris Kinny
October 14th, 2018
Cyclone Roof Cleaning & Pressure Washing