Thousands of roof on homes and other buildings suffer from black streaks. The roof algae is doesn't harm the shingles, but looks bad. To remove roof algae a solution of oxygen bleach can be applied to the roof shingles and then rinsed off. A copper strip at the top of the roof can prevent future roof algae.
Cupolas and weathervanes can add a touch of class to a structure's roof. However, the cupola design must be properly sized for your structure. Here are some other tips when building a cupola for structural support and standing up to Mother Nature.