1:  Q:  What are those black streak streaks on my roof?

A:  The streaks are caused by a microorganism called Gloeocapsa Magma (we refer to it as “GM”).   It’s an algae that thrives in warm, humid climates.  It usually appears on the north side of a roof first, for much the same reason moss grows on the north side of a tree – it likes the shaded area where the sun does not burn off the moisture early in the day.  You will notice it starting in a number of places.  Moisture will spread it out and up the roof, causing the black streaks to form (it usually begins at the eaves and works its way up to the peak).  Eventually the streaks blend together, and in a case of severe infestation the whole roof will turn black.  Most often, other organisms will be present: lichens, mildew, mold, and especially damaging for cedar roofs, a couple varieties of fungus.  Before applying a cleaning solution we evaluate precisely what is present on the roof, and adjust the mixture to safely and thoroughly remove all of these.

2.  Q:  How does GM get on my roof?

A:  It’s airborne.  If you have it, your neighbor will have it shortly.  If your neighbor has it now, it’s only a matter of time before you will see it on your roof.

3.  Q:  I don’t remember seeing this stuff as a kid.  Why is it so noticeable now?

A:  It’s probably a combination of things.  Changes in temperature and moisture permit GM algae to thrive today in areas where it did not before (like armadillos, which ten years ago were unknown in Missouri, but today are nearly as common as they are in Texas).  Increased density of residential housing over the past couple decades has improved conditions favorable to GM growth, and that the proximity of residential roofs facilitates airborne transfer of it from one roof to another.  It’s been proposed that changes in roofing material composition may be partially responsible, and roofing manufacturers have invested in engineering solutions to the problem.  For whatever reasons, it is accurate to point out that it is getting more widespread and more noticeable.

4.  Q:  Do shingle manufacturers recommend immediate removal of GM algae?

A:  Absolutely.  As is stated in this bulletin from the Asphalt Roofing Manufacturer’s Association: http://www.asphaltroofing.org/pdf/tb_217.pdf.  The advice of the ARMA is to not procrastinate, but clean the roof as soon as stains appear.  That’s easier said than done.  Just thinking about this chore is enough to make you want to sit down.  Sifting through the volumes of available “how to” articles and trying to settle on one of the myriad methods advocated by the various proponents of different techniques is a mind-boggling exercise.  This is, simply put, not an easy task for even the handiest of do it yourselfers.

Consider the advice in the attached “Do It Yourself” article, which for a variety of reasons cautions against procrastination in cleaning a stained roof:  http://www.doityourself.com/stry/roof-stain-prevention-advice.  (If you decide to do this yourself on a composition shingle roof, please do not follow the advice to use a stiff bristled brush.  Never do anything that would dislodge the limestone granules on the surface of your shingles.)

5.  Q:  I’ve heard some say that it is really just a matter of aesthetics and I should not be concerned about my roofing material failing prematurely because of infestation.

A:   The harm from fungus, moss, algae and the like on cedar roofs is well documented and universally accepted.  In the case of composition shingles there is near universal agreement that roofing materials are degraded by the presence of infestations, although disagreement exists on how that occurs (some say it is the direct result of the organism and/or its waste dissolving the limestone granules, and others point to indirect effects like higher water retention due to the discoloration).  Either way, it is clear these infestations are more than cosmetic, and do affect roof material longevity.

The proof is in the pudding.  The Certainteed Roofing warranty, which specifically addresses this point on pp. 3-4, is limited for algae and void if (as is almost always the case) other forms of infestation are present, like mold, fungus and lichen).

6.  Q:  I’ve heard some say that it is really just a matter of aesthetics and I should not be concerned about any ill effects to health from an infested roof. 

A:  The infestation can be a health hazard.  A relationship between airborne green algae spores and allergic reaction has been demonstrated.

Recently, a homeowner we know of was served with a written notice that his insurance would be terminated by the carrier if he did not have his roof cleaned.  The carrier (a well-known and established company) considered the moss, mildew, algae and fungal infestation to be a health hazard to occupants and neighbors that posed an unreasonable liability.  For more information on insurance ramifications view: http://www.articlesbase.com/insurance-articles/how-to-prevent-cancellation-of-homeowners-insurance-and-costly-roof-repair-in-tampa-4577512.html

7.  Q:  I’m having my driveway cleaned, should I have the pressure wash people also do the roof?

A:  Pressure washing is possibly the worst thing you could do to your roof.  It will literally blast the limestone granules from the surface of the shingles.  Depending on how high the pressure, it can strip off paint, crack vinyl siding, drive moisture into areas it should not be, and etch holes through wood surfaces.
Spraying your roof with as little as 800PSI will damage your shingles and reduce the life of your roof.  We use no more than 80 lb psi to apply our solution, and in most cases our technique results in no more pressure than a mild rainfall.

8.  Q:  I only have stains on one side of the roof, and even on that side they cover only a part of the surface.  Will you clean just the stains, and not the whole roof?

A:  Of course we will do anything the customer asks, but we’ll offer our advice first.  In this instance, barring any unforeseen circumstances to the contrary, we would probably respond that a significant part of the service fee represents travel, set up and post service clean up.  That means the difference between a partial and a complete roof cleaning is minimal to start with.  Also, if one side of your roof is infested, so is the rest of it.  You just don’t see it yet; GM grows at different rates depending on a host of variables such as exposure to morning sun.  If we do a partial job, we will probably have to come back in a much shorter time to finish what should have been done to begin with.

9.  Q:  How long does the treatment last?

A:  That’s tough to say with precision.  There are so many variables, many of which are dependent on weather and the amount of sunlight the roof gets.  We’ll let you know as a part of the inspection if we see anything that might reduce what we expect to be the average time between treatments, which is between five and eight years.

10.  Q:  Do you offer a guarantee?

A:  If stains reappear within five years we will return and clean the areas where the stains are showing up (this is short of a full roof treatment except in the highly unlikely instance of total re-infestation).

 11. Q:  Hmmm, I was just thinking I could do this myself.  Why shouldn’t I save the cost of a professional job and do it on Saturday morning…

A:  It is not as simple as it looks.  Without the right application equipment and expertise, the layman can spend a lot of time, money and effort, and achieve an unsatisfactory result.  We’ve already made the investment in researching the optimum solution components and concentrations for various types of infestation.  We know how much to apply and how to keep it from damaging surrounding vegetation or stripping paint off gutter and fascia.  We have the proper equipment and we’ve prepared ourselves by developing professional roof inspector and roof cleaner credentials and undergoing the requisite safety training.  Consider what you would have to spend to do the job yourself (this touches only on the most basic requirements):

  • A ladder of sufficient height,
  • A spray apparatus of some kind (and be assured that a hand-pump tank type sprayer is going to take a lot of time and effort, and will result in a spotty result)
  • Solution runoff diversion/recovery equipment to protect your landscaping
  • Risk:  It can be dangerous without the proper equipment and training.
  • Time:  Research equipment and techniques.  It’s important to have the right equipment.  Potentially even more important is to use best practices consistent with the characteristics of the structure.  Liquid improperly directed onto soffit, for example, could travel inward to stain your walls or cause moisture damage behind siding and masonry.
  • Time:  Research cleaning solutions and decide on one.  If you’ve used any of the on-the-shelf preparations for cleaning roofs and gutters, you are aware that even if they contain the proper chemicals they are dilute enough not to present any danger if improperly used.  Consequently, they don’t do much.  We, on the other hand, prepare a solution from concentrates, mixed in the proper proportions for each individual situation, to achieve the maximum effect without damaging the structure.
  • Time: locate a price worthy source of the chemicals you’ve decided to use.
  • Time:  Probably more than just one weekend… 

12.  Q:  Do you offer pressure washing services?

A:  No.

13.  Q:  Is the soft wash method effective on vinyl siding or other surfaces that are infested with growth?

A:  Yes.   “Show Me Clean Roofs” cleaning services include

  • Roof Cleaning (Including soffit and fascia)
  • Gutter Cleaning – we offer complete gutter/soffit cleaning service.  We’ll remove all debris and clean the inside of the gutter of blockages that could affect proper flow.  We’ll chemically clean the exterior of the gutter of those “tiger stripe” stains.
  • Siding, patio and pool decks – the same process as is used on the roof is effective for patios and decks – we can include these in our proposal for your property, if you like.