The installation of a new metal roof can be a great investment to your home or business — but you should be aware of what materials to use throughout the process. If you’re not sure about the types that are compatible, you could end up with corrosion.
Galvanic corrosion can occur when steel and aluminum are in contact with each other. The least “noble” of the two metals — usually aluminum — will end up corroding. This is the anode surface. The other metal becomes the cathode and will be protected against corrosion. In addition, it’s not a good idea to have a large cathode surface in contact with a smaller anode surface.
You should also avoid using zinc screws in aluminum. Over time, the screws will cause corrosion in the metal. Why does this happen? The contacting metals create a bimetallic couple due to their different affinities for electrons. This leads to a current that flows between the two metals.
Then there is the issue of pressure-treated lumber in conjunction with metal roofing. The chemicals inside the lumber can be very corrosive when they come in contact with the metal. Although the coating on the back side of the metal will protect it somewhat, it won’t last forever. For this reason, it’s a good idea to use non-treated lumber or to include an underlayment between the lathe and the metal. In addition, be sure to ventilate the air chamber as well as the attic.
If you’d like to know more about the dangers of combining improper roofing materials, 1st Coast Metal Roofing Supply is here to answer any questions you may have. Contact us today!
