Yes – these materials should be isolated. In the presence of water they will develop galvanic cells that will result in damage to the protective metallic coating by a process called “bi-metallic corrosion”. Isolation is simple: lead flashing can be isolated from the frame using an underlay of plastic membrane, while copper pipes can be isolated from the frame by the incorporation of nylon grommets, or by face-fixing to the studs using plastic clips. Both of these systems also resist water hammer noise.

For a more detailed explanation, refer to BlueScope Steel Corrosion Technical Bulletin CTB-12.