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Joined: 21 Jun 2008
Posts: 3
Location: Jacksonville FL
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This is an article about why you should not use sodium hydroxide to clean asphalt shingle roofs. I've cut and pasted it from my website.
Why you should not use sodium hydroxide
based chemicals to clean roofs
Roof cleaning is a trade that requires special equipment and knowledge to insure that it is being cleaned safely, and that you are getting the results that you want, and deserve. It is important that only non pressure roof cleaning methods be used on asphalt shingles.
Did you know that most of the roof cleaning chemicals that are sold at the bigger box stores, and certain ones sold at other local suppliers contain sodium hydroxide? If you are unfamiliar with what sodium hydroxide is it is a very strong caustic chemical that is widely used as a degreaser in many industries. The reason this is such a problem when used for cleaning roofs, is that asphalt roofs are a petroleum based product and logic says using a degreaser on something held together with grease is probably not a good idea. It can, and probably will, degrade the asphalt holding the shingles together.
Here are a few other disadvantages that make sodium hydroxide based chemicals a bad choice for asphalt shingle roof cleaning:
Too much pressure – Once these chemicals have been applied, they will require at least 400-500 psi of pressure to insure enough agitation to the roofs surface to successfully remove the top layer of algae which can also loosen and remove the granules that are embedded in the asphalt. Roofs that are properly cleaned, using the right cleaning mixtures, should not require any agitation, or pressure, for the algae to be removed successfully.
Sodium hydroxide does not kill the algae that is growing on the roof – Rather it simply works as a surfactant to loosen and remove the top layer of visible algae, while traces of living algae and the algae spores remain intact and ready to re infest the roof top. That's why after cleaning with these chemicals, even though the roof may appear clean, you will usually see visible re-growth within as little as 3-6 months. When a roof is cleaned correctly, even with the conditions we experience here in Jacksonville, Florida, it can stay free of any visible algae for as long as 2-4 years.
Risk to painted surfaces – because of the strength of mixtures needed for a sodium hydroxide based chemical to be affective at removing the top layer of algae on a asphalt shingle roof, it can put painted surfaces such as painted exterior sidings, painted roof vents, stained fences in close proximity to the house, etc at risk of being damaged by way of stripping. In fact, sodium hydroxide is a common main ingredient in many chemicals designed for stripping wood finishes such as stains and sealers.
As you can see there are many disadvantages to using these kinds of chemicals for cleaning asphalt shingle roofs. They are manufactured simply because they are cheap to produce, and stable on a shelf for long enough to sell for big profits. Also, because these products are fairly safe to use around landscaping, these sodium hydroxide based products are an easy marketing tool for an inexperienced contractor or do-it-yourselfer. The fact is, roof cleaning isn't easy, and shouldn't be attempted by homeowners or anyone else that doesn't have the proper knowledge, experience, and equipment to make sure it gets done the right way, and the safe way.
Author, Lance Powell
Clay County Pressure Cleaning, Inc |
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Lance Powell
Clay County Pressure Cleaning, Inc
Pressure Washing Jacksonville Florida
Roof Cleaning Jacksonville Florida |
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