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Gerard Roof

Tech Tuesday: Dissimilar Metals

Make sure you know about the effect of dissimilar metals and how to avoid corrosion on your Gerard roof!

Contact between or run-off from lead and /or copper onto Galvalume® will result in an accelerated corrosion of the Galvalume coating in the area of contact. The rate of corrosion increases with the severity of the environment and can result in premature failure. Although Gerard’s coating and acrylic primer will isolate the contact initially, the extended lifespan of the roof may be affected.


  1. Copper roofs, flashing and rain gutters or eaves trough may direct water onto a Gerard roof

  2. Copper lightning protection systems

  3. Lead skylight or pipe flashings

  4. Pressure treated lumber


  1. Redirect rain water run-off to a point below or beyond the Gerard roof system

  2. Install lightning cables below the roof panels through a space in the strapping with no contact of the Gerard panels

  3. Use other long life flashing material other than incompatible materials such as Galvalume,

    galvanized, stainless steel, etc.


Contact Gerard’s Technical Department at 1-800-237-6637 for additional information.


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