DISSIMILAR METALS / METAL ROOFING


An important area for metal roofers to know is regarding dissimilar metals. Not all metals get along. Did you know that if you allow contact of two dissimilar metals or have a runoff from one dissimilar metal to the other it will cause corrosion (rust)? Time and time again we’ve inspected fairly new roofs to find this very preventable issue.

We use BlueScope Steel for all our new roof sheets and custom flashing so we’ve added their technical bulletin attachment below. Call us if you have any questions, we’re more than happy to provide free advise.


Avoid incompatible metals

Due to a phenomenon known as galvanic corrosion, some commonly used metals can cause accelerated corrosion when used with ZINCALUME® steel or COLORBOND® steel. Copper and lead are two such metals. Copper pipes and lead flashing should not come in direct contact with either ZINCALUME® steel or COLORBOND® steel. If building design is such that water will flow from lead flashing onto ZINCALUME® steel or COLORBOND® steel then it should be painted. Water from copper pipes should not be directed onto COLORBOND® steel or ZINCALUME® steel. Stainless steel fixings and fixings containing copper should also not be used with ZINCALUME® steel or COLORBOND® steel. BlueScope Steel