Why Clean Algae Off of My Composition Roof?  How?

Cleaning algae off of a composition roof is not as crucial as cleaning moss off of a composition roof but it is important. Algae usually manifests itself by causing a dark discoloring of your roof. On a white roof the results are of course much more noticeable than they would be on say a black roof. Cleaning off this algae can return your roof to its natural color which makes a very noticeable and a very desirable change in appearance. The aesthetic benefits are of value but are not the most important factor to consider. Though algae is not as immediately damaging as moss it can take its toll on your roof. Primarily the problem is that it will hold water and water of course breaks things down, things like your roof. Algae can also encourage moss and other damaging biological growth, such as lichen*, to grow by creating a moist environment and by providing other nutrients.

Cleaning algae off of your roof is not as stressful to your roof as is cleaning moss off of a composition roof. Most of the cleaning power comes from the use of a chemical solution, not high pressure. In this picture the right side has been sprayed with a chlorine solution and has not even been rinsed. Already the algae discoloration has nearly been removed. Unfortunately the moss does not come off with out the added use of pressure but as you can see the algae can be cleaned with not much more than a rinsing.

 See technical bulletin from the Asphalt Roofing Manufacturers Association

Practical Pressure uses this same recommended method for cleaning algae discoloration off of composition roofs.

In view of the potential dangers such as slipping and falling from dangerous heights and the potential to damage your roof via pressure washing we recommend that you do hire a professional to care for this maintenance. Practical Pressure has experience not only in pressure washing but has also spent years in the professional roofing trade. We can assure you that with our experience in pressure washing as well as with roofs that your composition roof is in good hands with Practical Pressure.

Of course preventative maintenance is always best so please look over the material under the question "How Often Should I Have My Composition Roof Pressure Washed?"

*Lichen seems to do the fastest damage to a composition roof but fortunately it does grow in a very constricted area. Lichen is actually fungus and algae working together to survive. With this partnership it is very successful at growing in harsh conditions and is often growing on roofs where there no other plant growth. MSN Encarta states that "Lichens release acids that break down inhospitable rock, permitting soil-trapping mosses and grasses to grab hold." Obviously then Lichen can be a very destructive plant life. The point here is that if Lichen can actually break down the surface of the rocks that it grows on imagine what it can do to your roof! Keeping up a routine of the same preventive maintenance used to keep moss and algae from growing on your roof can also keep Lichen from becoming a problem.