Q&A: Copper Corrosion on Cedar Roofs

A.The soluble tannins in cedar can cause corrosion of copper flashing, and the textbooks discourage using copper with cedar. However, I have seen dozens of roofs with a combination of cedar shingles and copper flashings where the flashing has lasted as long as the cedar shingles. In most cases, flow lines or patterns had been etched into the copper, but I have never found one that has corroded through.