Although not originally intended as an aesthetic finish, many architects turn to batch hot-dip galvanized Architecturally Exposed Structural Steel (AESS) to create artistic, durable, and sustainable showcase elements with a modern, industrial aesthetic. However, there are some misconceptions about the appearance of after-fabrication batch hot-dip galvanized (HDG) steel that can lead to misaligned expectations between the architect, steel fabricator, and galvanizer. Some architects expect the shiny, smooth, or spangled finish of galvanized sheet metal common in ductwork or corrugated panels; however, most fabricators and galvanizers know after-fabrication batch HDG steel elements rarely yield this type of appearance.

Unlike painted or powder coated steel, stainless steel, concrete, or metal plating, the initial appearances of hot-dip galvanized steel is not consistent. Furthermore, the galvanizing process can produce uneven surface conditions (i.e. runs, inclusions, roughness, excess zinc) normally acceptable by ASTM specifications for steel products outside the architectural world, but unacceptable for showcase or feature elements without additional smoothing and filing after galvanizing. Despite these challenges, it is possible to achieve high-quality coatings when the necessary aesthetic requirements are clearly and directly communicated.

The intent of this publication is to explain how to use the AESS category systems developed by the American Institute of Steel Construction (AISC) and the Canadian Institute of Steel Construction (CISC) to facilitate such communication, minimize the cost premium for achieving galvanized AESS, and examine best practices to maximize hot-dip galvanizing appearance.

Created in 2021, this publication provides best design practices to maximize Hot-Dip Galvanizing appearance for AESS projects. The guide is 16 pages and contains a table matrix guide and high-resolution sample photos are also available. DOWNLOAD ONLY