Why do roofs turn green

Topic: Why do roofs turn green?

Algae and Mossy Roofs

Algae on a roof. It happens after a wet winter. You know the green or brownish stuff growing on your roof. It can look real horrible and in some cases create big problems with your roof if not taken care of.

Why do roofs turn green?

I have found in Sacramento, California, that moss, algae and lichen have more of a chance to growing on the north side of a roof. We live in the northern hemisphere on earth and because of this, our steeper roofs don’t see enough of the sun to dry out. These areas of the roof stay damp and wet which helps in the spreading of that ugly green stuff. Algae is a plant and loves damp shaded areas like roofs that are shaded by a large tree or is covered with debris.

Clean your roof

Algae can grow on any type of roof, so a regular roof maintenance program ia advised. Using a licensed roofing contractor to clean off the algae and do any repairs that may be needed would be a good idea. I like the seeing this done right before Dec. This means the leaves have all fallen and your roof will be all cleaned of debris and ready for the winter.

How to stop algae and discoloration on my roof

For new construction, GAF StainGuard® labeled shingles are warranted against algae discoloration for 10 years. Make sure the shingles have the StainGuard® logo. For more information visit the GAF website.

Copper Ridge to control algae.This will help with a new roof but if you have a roof that is not ready for replacement having zinc strips installed can reduce the growth of algae infested areas. The roof installed zinc strips, have a reaction when mixed with rain water. The zinc precipitates a mixture of fluid that organic materials do not like and thus helps stop those green roofs. Ask a licensed roofing contractor for advice and installation. The photo to the left is a heavy shake roof I contracted to do few years back. The customer had problems with moss and algae and requested copper on all the ridge to control the algae. A return back to this roof is proof for me that it works and I have used this same system on more than just this house.

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