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Moss Prevention in Portland Oregon

I am a licensed moss killer (no joke) and moss preventer. My License number is AG-L1002064CPO. Many businesses operate illegally without a license. Verify my license at Oregon Dept of Agriculture (put 1002064 in license search field.)

It is more economical to prevent moss than to let it grow and then remove it.

If you have neighbors with moss on their roofs, the moss spores will travel to your roof. This makes it more likely for your roof to grow moss sooner or speed up its rate of growth. If your neighbors prevent moss on their roof, their moss prevention efforts will help you.

Since moss needs moisture, it makes sense to keep your roof clean of debris that slows the rate water runs off your roof. Keeping the roof's flatter areas and valleys blown clear of leaves and needles will help your roof dry out more quickly after rain or dew. For roof maintenance, it is better to blow the roof clear of debris with an air blower than to sweep your roof. Sweeping the roof will dislodge more granules than forced air.

To prevent moss growth on composite/ 3 tab/ fiberglass shingle roofs, I recommend zinc sulphate. It is non staining, residual and very effective. It stays on the roof until the rains wash it away. As long as enough zinc is on the roof, moss cannot get started. Zinc on the roof also stops and kills mildew. This helps prevent roof staining. Click on the link to the left "request a quote" to get a quote on moss prevention for you and or your neighbor's roof.

Since trees drop needles or leaves on roofs, it makes sense to keep branches cut back from the roof. Keeping at least three feet between roofs and branches allows your roof to "breathe" better and dry out sooner. Also overgrowing branches may shade the roof and slow evaporative loss of water.

Bleach water is effective at killing moss growth on tile roofs. You cannot use zinc sulphate as moss preventative on concrete tile roofs. You can use bleach to kill moss on tiles roofs. It can often be applied from every 1-4 years to prevent visible growth.

The temporary salty look of zinc sulphate on a dark dried roof .
Photo by Brad Lewis

Dark colored roofs will have a salty appearance that goes away in a few days or during the first rain after it has been sprayed with zinc. This appearance is normal and temporary.

Some people try zinc strips. I don't recommend them because of their lack of effectiveness, expense and appearance. Read more about zinc strips.