Use of dissimilar metals in building facades

June 29, 2009
Publication: Construction Specifier p 94-105
Author(s): Ceruti, Jeffry J.

Abstract: Designers have long been aware of the need to separate dissimilar metals. This requirement frequently appears in project specifications for sheet metal and other trades, but industry references for galvanic corrosion are inadequate for today's use of architectural sheet metal in façades and roofs. This makes it difficult to assess the real risk of combining different metals.|Architectural design of façades has become more complex, and buildings now commonly include multiple materials that may be incompatible over the long term. Even relatively standard rainscreen wall systems, such as aluminum panels supported by galvanized steel framing, can create durability issues. Runoff or dripping from roof and gutters over the façade, or projected ledges covered with metal, may also create potential for galvanic corrosion and staining.