Wire Arc Additive Manufacturing for Widespread Architectural Application: A Review Informed by Large-Scale Prototypes

This paper reviews the potential of Wire Arc Additive Manufacturing (WAAM) for architecture. It uniquely addresses its feasibility by evaluating existing large-scale, real-world prototypes developed to date and compiling critical gaps identified in the literature. Although previous review papers concerning WAAM for architecture exist, they focus on the technical aspects of the technology, such as the mechanical properties, defects, and process parameters. No existing review analyzes which architectural applications are being implemented nor the scale and degree prototyping accomplished for each application. WAAM, a form of metal additive manufacturing using an electric arc to melt and deposit wire, offers unique advantages for the construction industry. It allows for high deposition rates, structural integrity, and cost-efficiency using steel. However, challenges such as producing large-scale components and limited design freedom and lower resolution compared to other additive manufacturing processes remain. This review first contextualizes WAAM within the broader landscape of additive manufacturing technologies for construction and examines its proposed architectural applications, such as steel connections, columns, trusses, and bridge elements. This study emphasizes the need for real-world experimentation through large-scale prototypes to assess the practicality and scalability of WAAM in architecture. The results of this study reveal that 36 architectural projects using WAAM exist in the literature, whose application range from structural (such as beams, columns, and nodes) to nonstructural components (such as facades and ornamental elements). Based on these, a classification for WAAM in architecture is proposed: (1) stand-alone WAAM structures, (2) printed connector pieces to join standard steel parts, and (3) reinforcement for conventional steel elements using WAAM. The size of typical functional prototypes to date averages 200 x 200 x 200 mm, with exceptional cases such as the diagrid column of 2000 mm height and the MX3D Bridge, which spans over 12 m. A detailed analysis of seven projects documents the scale and development of the prototypes, functional lab configuration, and process parameters. Through this review, the current technical feasibility of WAAM in architecture is established.