Deep down Cleaning

Slime Busters

So you might say "Why would I want to clean my roof? That's the way a roof is supposed to look...right?. Why "waste" the money?" Well, there a couple of reasons why it is important to clean a slate roof. The first reason is that it simply looks fresh and bright but the most important reason is Winter Weather in New England. Almost without exception, slate problems occur where snow, moss or algae has lain on the slate surface for prolonged periods. In cases where trees are not hanging over a roof, the surface is problem free (trees create a fertile environment beneath them that fosters moss, algae and lichen growth which holds moisture and snow in place). In winter as the daytime sun melts some of the snow, the water falls into the slate through fissures and cracks and absorbs into the slate. At night it freezes and expands, widening the cracks and pores, providing larger cavities for the next days melting water. The cycle continues with tremendous expansion and contraction of the slate around the cracks. A once strong and solid surface has become broken and flakey. This situation will requires expensive repair or replacement. The best way to eliminate or reduce this problem is to eliminate the algae, moss and fungus.

Important Note: Proper surface cleaning involves either physical scrubbing or some level of pressure to remove the plaque and fertile substrate. There are several enterprises out there marketing products that they claim do not require rinsing. "Spray and Forget" and other "No Rinse Roof Treatments" are good starts but do not remove the foundation which will only invite regrowth in a very short time, sometimes in only a few months. We all know that mouthwash alone doesn't make for healthy oral hygiene, and that brushing and flossing are necessary. It's no different with roofs, siding, decks, or any other surface. There is lots of documentation on this. Common sense also works.

While not illustrated here, lichen  will completely digest the silica grit, exposing bare asphalt. This will not be  visible on a darker surface. It is important  the silica granules remain on an  asphalt shingle roof so that they can  do the job of reflecting the sun's rays.  Use of proper cleansers and a low  pressure rinse will ensure that your  silica granules remain intact.
 There was enough lichen and moss on this 25 year old roof in Northern New Jersey to support a habitat for tree frogs. Once cleaned, this roof looks nearly new even after all these years. This is mostly due to two factors. One; the lack of strong sun at the location of this particular home and two; these shingles were handsplit tapered shakes. Nothing really can compare to these. They will absorb a lot of abuse. Nonetheless, there were some rotting edges.
If we all lived on Nantucket, the 
airborne sea salt would cure and 
preserve the cedar shingles for 
us, which would prevent 
wet rot.
If you want your investment to 
stand up to our New England 
environment, then it's time to 
consider a maintenance plan.
Our technique is gentle on roofs 
and not at all harmful to plants 
or people.  

Roof Preservation

Shingle Shield!
The maintenance free roof protector. Protect the appearance of that new,
or just cleaned roof with Shingle Shield
Roof Protector zinc strips. These strips are engineered to provide long term protection from fungus, moss, and
algae. Simply install one row at or near the roof ridge line to protect the entire roof.
Shingle Shield zinc strips react
with rain water to release powerful,
non-toxic, fungistatic compounds of
zinc oxide. For best results, thoroughly clean and disinfect the roof prior to installing
the zinc strips. 20+ years is
is the expected period of protection.

for more info call us or go to or


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Dharma - Clean Response 
Surface Cleaning
and Restorations
368 Village St.
Millis, MA  02054
(508) 376-4635
(800) 749-3133

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This page last edited on: May 09, 2007