One of our customers sent us an article claiming that if you install a 12-inch wide roll of very thin copper on top of the cap shingles that run across the ridge of the roof, that each time it rains some of the copper ions wash down onto the shingles. The copper bonds to the asphalt and to cut to the chase, ensures the roof will last longer. Oh, and you need to use solid copper nails. Has anybody had any experience with this? Or is it just b.s.
We use zinc strips at the last row of shingles. It prevents the algea growth you see on most roofs. Look around your pipe collars if they are metal. The algea will not grow below the galvinzed or aluminum pipe collar.
We've been using Pabco shingles out here. 10% of their granules are coated in copper, giving them a lifetime warranty against algae. I believe a lot of other shingle manufacturers use zinc, and give 5-10 year algae warranties. May be worth looking into, it seems copper is the better metal. But either way check out Atlas and Pabco as anti-algae shingles. You won't even need to use a strip.
Algae is not going to reduce the life of the roof. It is a strictly cosmetic issue. That said copper or zinc will help with the situation but often does an imperfect job. Also zinc can be toxic:
Zinc can be a danger to unborn and newborn children. When their mothers have absorbed large concentrations of zinc the children may be exposed to it through blood or milk of their mothers.
Read more: https://www.lenntech.com/periodic/elements/zn.htm#ixzz5LSa3co00