Roof Alage

Old 04-23-06, 08:41 PM
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Angry Roof Alage

I have a north facing house with a light grey roof, and after 8 years, the alage growing on it is very noticeable and ugly! Is there any way of cleaning it without doing damage to the roof shingles? Bleach was suggested, but that might stain the roof also, scrubbing is out due to killing the life of the roof, plus due to the pitch of the lawn and the height of the house, only a professional would be able to get up on the roof. If any one has a tip for cleaning the alage off, I'd greatly appreciate it.
Old 04-23-06, 09:45 PM
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Roof Alage

Roof stain causes vary with the location.

A bleach and water (1/3 bleach or so) can be effective and it is not necessary to physically brush the roof.

Brushing will remove any dead algae and improve the appearance, but he the bleach will kill active algae and the dead algae will very slowly weather off.

If you can get the the edge of the roof with a good strong sprayer you should be able to reach the ridge unless you have a steep pitch and a sloping surround.

It is not a perfect solution, but it works if you are not a mountain climber. An ideal situation would be to install a zinc strip along the ridge.

Old 04-23-06, 10:45 PM
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This is from an earlier post.
Hope it helps a little.
As mentioned earlier, pressure washing will knock the granules off the shingle which will expose the asphalt underneath. The granules serve only one function (other than make your roof colorful)....they protect the asphalt, which is the shingle's waterproofing, from the sun's UV rays. Without granules, the exposed asphalt would deteriorate much faster and drastically shorten the life of the shingle.

Mold/algae/fungus is very common along the gulf coast and other humid areas.

The most popular theory is this:
Mold typically grows on the north and west sides first because the sun rises in the southeast most of the time (since we live in the northern hemisphere). Therefore, the north and west sides of a roof tend to hold more moisture since the morning dew burns off slower.

You can use a very low pressure wash with a bleach solution to wash off the mold/algae.
The most common "home remedy" is 1/3 water, 1/3 bleach, and 1/3 TriSodium Phosphate (TSP). The more bleach, the better, however, your plants on the ground do not like beware of the runoff.

Basically, you could spray your solution on the area, let it sit for 15 minutes or so, then wash it off. Darker areas may need to be sprayed more than once.
Old 04-24-06, 04:17 PM
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Thanks for the tips, I may be able to score a lunch-time with my bucket-truck so as to be able to reach the roof. Thanks again!!

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