Save Your Roof
For some of us, the black streaks or
stains we see on asphalt shingles is
something relatively new. The black
streaks are Gloeocapsa Magma. This cyanobacteria is an algae
that gets its strength to survive through
photosynthesis and the limestone filler
found in the composition of shingles.
In the past, shingles were constructed
using felt and asphalt. Now that shingle
composition has changed to mostly
fiberglass and limestone, the GM blue-green
algae thrives, using the limestone
as its source of food. It is black when
found on the north- and east-facing
sides of the roof because it has the ability
to form a black outer coating, protecting
it from UV rays. When there is no light
or low light, GM has a blue-green color.
Its other self-protective feature is that it
enjoys the cooler, shady areas of the roof
where moisture is usually present.
There is very little information on
the damage GM will cause to roofing
materials. Some states classify it as only
an aesthetic problem, while others
maintain that it causes significant
damage. We have seen shingles carrying
GM on the north side of roofs begin to
curl, but on the south side to remain
flat. One thing is certain, however: GM
is on all sides of the roof, carried by the
wind, birds and trees. On the south and
western sides, the sun’s heat and lack of
cool moisture keeps it in check. Both The
American Roof Manufactures Association
(ARMA) and Canadian Asphalt Shingle
Manufacturers Association (CASMA)
state that GM is a problem that can be
rectified with low-pressure cleaning.
Roofs with GM will attract other life forms
that do cause damage on all sides of the
roof. These infestations are also present
on other types of roof surfaces like slate,
metal and tile, and can be removed with
the same cleaning process.
Lichen is a photosynthetic fungus that has roots
which wrap around the granules, feeding
on the nutrients of the GM and the filler
in the shingles. Once on the roof, lichen
is not easily removed. It takes a safe,
biodegradable, low-pressure chemical
treatment to completely eradicate this
fungus. A low-pressure system (under
100psi – about the same pressure as a
garden hose) is the only method approved
by ARMA and CASMA to remove these
organisms. Scrubbing or power-washing
the lichen will only do more damage.
Another organism growing on your roof
is moss, which is a plant – not a fungus
or algae. Moss shortens the lifespan of
your roof because it lifts the shingles,
retains moisture and in cold climates can
freeze, causing damage to the shingle
and granules. A no-pressure treatment
can add 5 to 10 years to the lifespan of
your roof.
When you’re trying to decide whether
to clean your roof yourself or to have a
professional perform the cleaning, please
keep a few things in mind. Roof-cleaning
is not a DIY project. Some homeowners
might want to tackle this project but
without proper training and equipment,
the result could be a disaster. Roofcleaning
is a dangerous occupation. With
the use of surfactants which allow the
cleaning agents (biocides) to penetrate
the algae down to the shingles, the roof
surface becomes very slippery. Without
proper fall-prevention and protective
equipment, bad things can happen.
ARMA, CASMA and the asphalt roof
manufacturers state that shingles
should not be cleaned using a highpressure
washing system. Cleaning with
a pressure washer will strip the shingles
of their protective granules, leaving your
home unprotected against the harsh
elements of Mother Nature. Professional
roof cleaners have special equipment
and will clean the roof in the manner
recommended by roof manufacturers:
a low-pressure chemical treatment. A
roof-cleaning will remove black streaks,
moss, lichens and/or other discoloration
for a fraction of the cost of replacement.
Algae, moss and/or rust-covered siding,
fencing, decking, brick, brick pavers, and
cement should also be cleaned this way.
My fiance and I saw a need to not only
keep asphalt shingles out of the landfills
but to save homeowners money. That’s
why we founded Renew Roof & Exterior
Cleaning, LLC. Since your roof is one
of the most expensive structures of
your home to replace, having your roof
professionally cleaned at a fraction of
the cost of replacement makes sound
financial sense. Please visit www. and see how much
money you can save.
before… … and after.
603-477-5562 •
Charlestown, New Hampshire
We are fully insured.

Dirty roof? Why spend $5000-$20,000 replacing your roof before it's time is up? A typical asphalt roof should last from 20-35 years. I have seen lots of roofs 8-10-15 years old that are covered with GM (Gloeocapsa Magma-Black streaks) Moss, Lichen and or Rust stains that are being replaced needlessly costing home owners thousands of dollars.
We use the industry's only cleaning method approved by the ARMA (American Roofing Manufacturers Association) which are the asphalt shingle manufacturers of North America.
Non pressure cleaning leaves your roof & exterior surface Damage Free!!


With your roof being one of the most expensive structures of your home, it makes sense to maintain it as best as you can. Hiring a professional roof cleaning contractor will save you thousands of dollars on premature roof replacements.
We also clean and revitalize Slate roofs, Metal roofs, siding, decks, patios, cement, fencing.



​   Roof Cleaning & exterior cleaning

    serving    New Hampshire & Vermont