Metal Roofing Science: Two Galvanic Metals Just Aren’t Meant To Be

By Author: Max Boughner
Total Articles: 6
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When you put two different metals together, it’s like putting two mortal enemies in the middle of a gladiator arena. It’s a fight to the death as to which of the two will corrode the most first under normal conditions. This is the dynamic in metal roofing since it’s not only your roof that’s made out of different metals.

In light of this, turn your attention to the galvanic scale, a simple chart that measures metals that are anodic (strong corrosion) and cathodic (weak corrosion). It took two Italians and one British to fully uncover the mystery behind the galvanic effect between two metals. Roofers take note of metals that don’t go well together to avoid vital parts of the metal roof from corroding very easily. Rust is one common form of galvanic corrosion.

Philip Marshall, a professor at Roger Williams University in Rhode Island, explains three factors for galvanic corrosion to happen. The process can only take place if: (1) two different metals are present; (2) a conductive path between the two is present; and (3) a way for metal ions to move from the anodic metal to the cathodic metal is present. ...
... To put it simply, here’s an example.

Anodic zinc and cathodic gold are placed together like magnets, right next to each other. There are already two conductive paths between the two metals: one along the metal substance and the other in the air. The anodes (positive ions) in zinc will transfer to the cathodic gold, causing the zinc to corrode and losing its integrity.

To prevent galvanic corrosion, roofers Concord has to offer keep dissimilar metals away from each other by using non-conductive materials. Sealants and tapes work best since these things are poor conductors, as well as poor absorbents. In some cases, roofers refrain from using two metals that are far apart from the galvanic scale. Marshall said that risk of galvanic corrosion is higher the farther two metals are in the scale.

Aside from conduction, seawater is an excellent electrolyte that can promote corrosion. Given the fact that Concord is within the Bay Area, the combined forces of salt and water can provide a conductive path for the transfer of ions. Roof repairs Concord residents do involve protecting the metals with non-absorbent materials like paint.

For more information about galvanic corrosion, you can check out Marshall’s comprehensive guide online at PhilipMarshall.net. For more details on how it can affect your metal roof, visit the online roofing help guide at RoofHelp.com. At these situations, you’ll be glad to call a Concord roofing contractor for the job.