Black stains on roof shingles are very common, especially in shaded areas. While roof stains can be any number of things from tree sap to chimney soot, most roof stains are caused by algae and fungus growth. These types of stains normally form on the north and west sides of the home. Although they are not pretty to look at, algae and fungus will not harm your roof or eat through the shingles.
If you're tired of looking at unsightly roof stains, there are several things you can to do remove and prevent them.
Clean It with Bleach
Fortunately, roof stains aren't difficult to clean. However, you must take care not to damage your roof while doing so. To clean stains, spray lightly with a mixture of bleach and water. You should mix approximately one part bleach per three parts water. Allow the mixture to remain on the stain for up to 15 minutes before rinsing your roof thoroughly. While rinsing your roof, take care to use light water pressure. If the pressure is too fierce, you may damage your shingles. If you don't want to use bleach, there are several chemical roof-cleaning agents that you can purchase, and many of them are safer for the environment than bleach.
Install Copper Strips
If you don't want to have to clean your roof all the time, you can install copper or zinc strips at strategic points of your roof, such as the ridge. When it rains, water passes over these strips and picks up algae-fighting ions. The ions are then washed over the surface of the roof where they fight off algae growth. Strips are a great option when your roof is still in great condition.
Get an Algae-Proof Roof
If it's time for a new roof, you may want to think about installing algae-resistant shingles. These shingles have copper granules in them so the effect is similar to that of copper strips. If you live in an area where algae growth is common, such as the central and eastern portions of the United States, your roofer will likely use these shingles without being asked. However, it's always a good idea to confirm that you're getting the product you desire.
Roof stains aren't difficult to clean, but it's less work to prevent them. In addition to installing copper strips and algae-resistant shingles, you can spray your roof with a sealant to prevent algae growth between cleanings. For assistance, talk to a roofer like Starkweather & Sons Roofing & Siding.