Spring cleaning: How bad does your roof look?

By Tom Phelan - ReminderNews
Featured Article - posted Thu., May. 2, 2013
- Contributed Photo

Now that we are getting more bright, sunny days, take a good look at your roof. Don’t just look at one side. Check it out from all four points of the compass. Sure, you should look for damage from winter winds and weather. Hopefully you have no repairs to do. But that’s not what I want you to notice.

Look particularly at the north-facing side of a pitched roof. If any side looks like a picture of a cottage from soggy old England, you are going to want to do something about it. In fact, even if you see discoloration and patches of gray or green here and there, this is a good time to schedule some maintenance.

Roof-cleaning seems to be a burgeoning business, I have noticed. If you are averse to climbing on ladders, particularly as high as the peak of your roof, call one of those companies to give you a quote. However, if you think this is something you can tackle, there are some things that you should know.

The first bit of advice I would pass along has nothing to do with the roof, and everything to do with being smart. This is not something you should do by yourself. Partner with a good, fit person to help you move things, and be your back-up should you get into difficulty.

What you may see on your roof is probably one of three things. The rainwater falling on your shingles for years brings pollutants, which usually show up as dark black streaks at first. The whole side of the roof might get pretty dark or black. This isn’t the worst condition, but over time, you should think about getting it off the roof materials.

The gray and green patches are algae or moss. Algae can be black-ish, as well. Unlike the pollutants, these are living things. They attach to the roof material tenaciously, and grow. When it rains, they hold the water longer than does the rest of the roof. They grow outward and, in the case of moss, will grow thick as well. They hold more water. Water, if you haven’t heard, is the enemy of all building materials. It will eventually lead to deterioration or rot over time.

Removing these freeloading roof occupants is not difficult. If moss is one of the problems, use a gentle brush to shake it free. Be sure not to be too rough on the shingles. You only want to loosen the moss. You can wash it off the roof with a garden hose. Point it down the slope of the roof, never up.

The next step will be to apply oxygen bleach to one section of the roof at a time. Oxygen bleach is available in powder form. You mix it with water, and apply it using a garden sprayer. Power-washing is not recommended on shingles. As the bleach dissolves, oxygen molecules are released. It is this release of oxygen that breaks down the living material in the algae, as well as the roots of the moss clinging to the shingles. The solution will foam up as it is working. Do not let the surface dry. Keep spraying it, if necessary. Work in small sections, and allow about 20 minutes before lightly scrubbing the residue from the shingles. Reapplication may be required for stubborn situations.

Oxygen bleach is the preferred agent, not chlorine bleach, because it is benign to the building materials as well as the plant life around your home.

Work from a dry section of roof. The moss and algae, particularly when wet, are very slippery. Sitting down on the roof helps to stabilize you, as it lowers your center of gravity. Use a securely fastened safety line as well.

The preventative action against this condition is to install strips of copper or zinc. When inserted under the shingles near the top of the roof, they release their metallic ions, discouraging the presence of these pollutants, moss, algae and lichens.

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