KPF Designs a Precast Terra Cotta Assembly at ACAW 2019

As featured in the May issue of The Architect’s Newspaper, Boston Valley’s TerraPreCast® line embeds terra cotta as a finishing material into precast concrete units. This product provides a durable barrier wall system that can meet energy codes, support blast resistance, and provide disaster relief. The strength and durability of precast concrete construction combines with the wide variety of profile and finish options offered by terra cotta, creating an unlimited range of design possibilities.

Boston Valley projects that have utilized TerraPreCast® include the Pike & Rose development in North Bethesda, MD (left) and 1200 17th Street in Washington, DC (right).

For the 2019 ACAWorkshop, Kohn Pedersen Fox (KPF) developed a precast terra cotta spandrel, in cooperation with façade engineer Walter P. Moore and ceramic artist Anne Currier. The team aimed to investigate the relationship between geometry and glaze — how profile, texture, and color amplify form. KPF created a “kit of parts” that could be arranged into different abstract compositions, using terra cotta panels of various profiles to highlight the variance in glaze pooling that results from distribution over edges and curves:

“More tightly-spaced curves created deeper shadows and collectively appeared like a harder, darker line, while looser curves attenuated a gradient of light, creating much softer lines of relief.”
– Team Kohn Pedersen Fox, “Amplified Form,” Bioclimatic Ceramic Assemblies IV

A close-up view of KPF’s assembly shows the complex layering of texture and glaze.

Adding a level of textural interest to their prototype, KPF also wrote custom software to develop 3D-printed rollers that could be applied to the terra cotta, after its extrusion by Boston Valley and before being cut into panels. These subtly dimpled and hatched portions of the surface collected glaze for a unique finish.

Extruded terra cotta panels are textured using KPF’s custom 3D-printed rollers.

KPF decided against using clip-and-track installation due to the number of separate pieces in their design. Instead, the team set the panels in a thin layer of GFRC, including a dovetail profile that creates additional surface area for the terra cotta and concrete to adhere. This solution is similar to Boston Valley’s TerraPreCast® system, with adjustments made for curtain wall construction.

During presentation week at ACAW 2019, the KPF team cut and assembled the terra cotta pieces into their final composition, doing two concrete pours — a large one for the full spandrel and a small one as proof of concept.