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Roof Washing

More and more, homeowners and property managers are realizing the aesthetic and economic benefits of simply cleaning their roofs.

Roof Washing or Roof Cleaning in Massachusetts


Unsightly black streaking on roofs is caused primarily by a wind-borne roof algae (known as Gloeocapsa Magma) and can be safely removed with minimal impact on the roof shingles. Removal of mold, mildew, moss, and accumulating lichen can not only improve the appearance of the roof, but also improves the effectiveness of the roof by allowing the shingles to properly reflect heat and moisture.


Cedar shingle roofs are designed, with proper maintenance, to last between 30 and 40 years! However, accumulating mildew or moss and long-term exposure to the elements can cause premature failure. Cleaning cedar shingle roofs provides a dramatic improvement in appearance.

The need for roof cleaning

The need for cleaning has grown exponentially over the last 15-20 years.

Your roof is obviously the most important feature of the structure of your home.  It keeps you safe, dry and warm!

The asphalt shingles that make up your roof are made up of multiple layers of material, including layers of asphalt, and an aggregate; pebbles or small granules on the outermost layer.  The body of each individual roof shingle, over the last 20-25 years typically has included limestone.  Limestone was added during this time frame, since asphalt, the primary material in the shingle, is made from oil, and the price of oil, was skyrocketing.  The roofing manufacturers were looking for a way to keep the quality of the roofing product high, without having to double or triple the price! So, they came up with the use of limestone, as filler, in the body of the shingle.  It is clear that this formula helped roofing manufacturers, and many homeowners.  It enabled them to replace their old, failing roofs with new roofs at a fraction of the cost of what it would have been without this change in the manufacturing process.

All was well and fine to start.  And then, after a few years after installation of the new roof many, many homeowners began to see the dark streaking occur.  It became pretty obvious to someone who “just” installed the roof, or bought a newly constructed house, that something unusual was going on.  The roof installation companies became the first call.  After some study, it was found, that a naturally occurring, tiny microorganism or algae, called Gloeocaspsa Magma was thriving on the limestone!!

Typically, the colonies of this algae start forming on the north facing, or heavily shady elevations of roofs.  Humidity and dampness help give the algae a great environment to grow.  Left alone, this algae is not a health danger to humans.  And, minor amounts of these accumulations of algae are NOT a danger to the roof.  However, over time, this algae presents a major problem for the roof.

For starters, it’s very ugly.

Secondly, it affects the effectiveness of the roof.  Over time, as the colonies develop, they keep the moisture on the roof just a little bit longer that it would be there normally after a night of dew, or a rain storm.  With the added moisture, it is inviting other organisms to grow.  Specifically, here in the Northeast anyway, moss can take hold.  The moss presents a major issue to the roof.  Since the moss is a much more voluminous growth, it holds onto rain and moisture.  As it grows, it gets thicker and holds more moisture.  A vicious cycle.  And this accumulated material stays damp for a long time!  This dampness does not allow the roof to ever dry out.  The roof will decompose or rot out right under it.

Lastly, the algae invites different species of fungi to join the growth party.  And, very interestingly biologically, fungus and algae together can form various forms of another growth called lichen. (pronounced liken).  These generally roundish growths can always be seen on the north side of many tree trunks, rocks near streams, and growing on many other shaded surfaces.  Lichen are extremely harmful on roofs, since they have very destructive root systems.  These roots will grow into, and under the asphalt shingles and definitely cause damage!

Oh my, what a problem!  It is time to call a professional roof cleaning company.

The process of cleaning the roof must not have an effect on the quality or integrity of the roof surfaces.  At INSTA-BRITE we will treat the roof surfaces that need cleaning with the utmost care.

  • Browse our before-and-after photos of INSTA-BRITE roof projects!

  • INSTA-BRITE has done work for me a number of times. Their prices are reasonable and their workers are very courteous. I highly recommend them.

    – John M., Scituate, MA
  • Thank you for a fantastic job! We will highly recommend you!

    – John & Lauren S., Abington, MA
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