Friday, May 7, 2010

Black Staining on the Roof (Answer)

Hey Tony,

The black staining is caused by the growth of algae and fungus spores that land on your roof. Trees do not have to be nearby for these air-born menaces to set up camp on your roof. All they need to grow is the nutrients from both the dirt on your roof and the limestone granules on the shingles. Heat and moisture on your roof will help them turn your whole roof black.

Roof shingles come in a wide variety of quality as indicated by the prices. The higher quality shingles have treatment to prevent algae and fungus growth. This treatment involves adding varying amounts of copper and zinc granules, and petroleum distillates on the shingles. Cleaning and controlling algae and fungus growth can add to the life of your roof.

If you choose to clean the roof yourself, be careful of products that are just bleach or chlorine. This type of product can leave your roof streaked and can also dry out the singles and cause premature cracking and a shorter shingle life. Some of these products also will kill grass and shrubbery. Read product labels carefully and follow the application directions. Most of all, be careful working on the roof, because you can cause damage to yourself and the roof.

Another alternative is to call a qualified roof cleaning company. You still need to ask if the products they use will cause streaking or grass and shrub damage. Roof cleaning companies can also provide preventative maintenance services that can prevent future algae and fungus growth.


Thanks for your question.

Please send questions to Please put "Hey Al" in the subject box.

No comments: