One of the most important considerations when building sheet metal roofing is galvanic corrosion. In this blog, Roofmasters Roofing and Sheet Metal Company, Inc shares a look at what galvanic corrosion is and how it can be prevented.
What is Galvanic Corrosion?
A metal roof is made of various components that can be made by different manufacturers: sheet metal, fasteners, and flashing among them. A contractor must know the metals these components are made of, because the wrong combination can lead to galvanic corrosion.
Galvanic corrosion is an electrochemical process where one metal would corrode when it is in contact with another metal, in the presence of an electrolyte. Water is a type of electrolyte, but is enough as a catalyst to start galvanic corrosion. In areas close to saltwater, the effect can be more pronounced.
Roofing contractors who offer metal roofing must know which metals go with the main roofing material. One of the most common examples of galvanic corrosion is using lead and copper with sheet metal roofs. Most standing seam roofing is made of galvanized steel, which reacts with lead and copper. An inexperienced roofer, therefore, might use copper flashing or lead exhaust pipes and cause galvanic corrosion.
Another common example is installers who use pencils for marking aluminum roofing. Graphite, the primary material used in making pencil “lead,” is extremely corrosive to aluminum. A knowledgeable roofer will use a fine felt-tip pen or grease pencil.
Preventing Galvanic Corrosion
The best way to prevent galvanic corrosion is to hire a contractor who knows better than to combine metals that shouldn’t go together; imagine if someone used galvanized steel flashing on a copper roof. It also helps that the contractor is aware of other factors that may also lead to galvanic reactions. Exposed wires or a roof-mounted HVAC unit’s coils have copper, which may leach into rainwater and react with the roof. Anti-algae solutions may either contain copper or zinc. While these products are intended for use on asphalt shingle roofs, they may react with the flashing.
Roofmasters Roofing and Sheet Metal Company, Inc is your leading provider of sheet metal fabrication and other roofing services. Give us a call at (785) 727-7575 or fill out our contact form. We serve customers in Hays and Colby, KS.