Galvanized metal roofing systems are coated with a thin layer of zinc to protect them from rust or corrosion. However, over time, natural wear and tear, as well as installation errors, can damage the zinc coating and leave your metal roof vulnerable to corrosion.
Galvanic Corrosion and Dissimilar Metals
Galvanic corrosion occurs when two dissimilar metals come into contact with each other while being doused in water. How can you tell if two alloys or metals are dissimilar? The farther two metals are from each other on the Electrochemical Series chart, the more dissimilar they are. Should these two alloys come into contact with each other, the metal located higher up in the chart will begin to corrode. (The other metal will as well, although the rate of corrosion will be much slower).
Avoid Installing Lead and Copper Roofing Components
What are the metals that home and building owners should avoid? Lead and copper can corrode the zinc coating on galvanized metal roofing. Aluminum and stainless steel, which are located next to each other on the chart, are safer to use.
Keep an Eye Out for Trace Amounts of Copper and Lead
Keep in mind that even tiny amounts of copper and lead are enough to start the process of corrosion. As such, you should avoid using treated lumber, which contains trace amounts of copper or marking aluminum panels with a pencil. You shouldn’t worry about these kinds of installation errors though – a qualified roofing contractor would know which roofing components to avoid.
One more thing: trace amounts of copper and lead could come from other sources aside from roofing components. For instance, since AC units’ evaporator coils are made from copper, AC condensation run-off can contain trace amounts as well. As such, to prevent galvanic corrosion, it’s best to have an experienced and reputable contractor conduct a comprehensive roof inspection.
Punum Roofing of Houston, Inc. is the highest rated roofer in the local area, boasting of a highly qualified team with 20 years of combined roofing experience. To request a free estimate, call us at (713) 466-4447, or fill out our form here.