A technical guide to separating aluminium from incompatible metals, managing runoff paths, and detailing fixings, membranes and interfaces to reduce contact-corrosion risk.
Contact corrosion can occur when aluminium is electrically connected to a more noble metal in the presence of moisture. Roof and facade details should therefore be reviewed as complete assemblies, including panels, clips, fixings, flashings, outlets and any nearby metalwork rather than considering the PREFA covering in isolation.
Direct contact with potentially incompatible metals should be avoided by selecting suitable components or introducing a durable separating layer appropriate to the detail. Particular care is needed at penetrations, parapets, eaves, valleys and support interfaces, where trapped moisture can keep dissimilar materials connected for longer periods.
Rainwater routes matter as well as direct contact. Runoff from copper or other metals can carry dissolved ions onto aluminium surfaces, so drainage layouts, upper-level flashings and adjacent facade elements should be coordinated to prevent contaminated water washing across the aluminium covering.
Fixings, clips, membranes, sealants and treated timber must be checked for compatibility with the selected PREFA system and exposure conditions. Final material choices and separation details should follow current manufacturer guidance and the project designer’s specification, with site substitutions referred back for review rather than assumed to be equivalent.
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