There’s much talk about algae resistant shingles. Some manufacturers make big claims that their shingles are better than others because theirs offer better resistance than others.
Buyer beware. First, algae will naturally cause streaking on all shingles. The question is whether you can see it or not. Darker colored shingles will naturally hide more algae. What’s the trade off? If you choose a darker shingle, apply simple logic — darker colors absorb more heat. Heat is the enemy of an asphalt shingle and it can break down much faster than a lighter colored shingle.
The work around for darker shingles is ventilating them very well, but most of the salesmen who are selling this as a major benefit don’t understand the rudimentary elements of ventilation. Rather than adding more ventilation, to accommodate these darker shingles that hide algae, it makes more sense to put a shingle on that won’t heat up as much in the first place.
Most of todays shingles will resist algae for 10-15 years anyway. By adding copper sulfate, which algae doesn’t like, manufacturers can delay problems associated with streaking. If you look at most roofs that have lead flashings around their soil pipes, you will see that there is no algae below that pipe flashing. Lead, copper and even zinc will always help you retard algae growth.
But most of all consider the colors available with these algae resistant shingles. They come in various shades of algae. There’s not one light color in their pallet. It’s a bit like promising that the rusty car you have isn’t truly rusty because you had it painted the color of rust. Sure, you won’t notice it as much, but you’ve now lost the ability to have a shingle that could have saved you energy in the long run.
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