When it comes to preventing algae there are in fact several things homeowners and roofers can do.
How did my roof get algae.
The most common class of roof algae is gloeocapsa magma a bacterium that eats water and expels oxygen.
Why do shingles get algae.
Gloeocapsa has the ability to form a protective darkly pigmented outer coating that shields the algae from damaging uv rays.
Roof algae prevention tips.
That way whenever it rains some of the metal molecules will wash down the roof and kill any algae trying to regain a foothold on your shingles.
Roof algae generally have a black green hue.
All of these options have been tested and show clear signs of decreasing and eventually preventing algae growth.
Although algae can be found on all types of roofing it tends to be most common on asphalt shingles.
Common algae that form on roof surfaces including asphalt shingles and roll roofing include the algae shown above and gleocapsa magma a species that generally appears black on the roof surface but under some lighting conditions even on the roof gleocapsa magma can appear as a blue green color as might other algae genera species.
The roof algae is doesn t harm the shingles but looks bad.
This is what makes those unattractive black streaks on your roof.
To remove roof algae a solution of oxygen bleach can be applied to the roof shingles and then rinsed off.
You may think you have roof algae when really you have moss mildew or mold.
A copper strip at the top of the roof can prevent future roof algae.
To keep the algae from coming back insert 6 inch wide strips of zinc or copper under the row of shingling closest to the roof peak leaving an inch or two of the lower edge exposed to the weather.