The Function of Form in Terra Cotta Manufacturing
A recent article on Louis Sullivan and the use of terra cotta in developing what was once considered a new style of architecture led us to explore his maxim, “form ever follows function.” This design principle is often applied to minimize decoration in modern architecture, to focus on the function of a structure — but is this the correct approach?
Sullivan suggested that beauty is found in the rationally designed form — that the exterior of a building should reflect its interior purpose. The tall skyscrapers designed by Sullivan arose to address functional considerations of his time rather than use historic architectural forms. However, Sullivan still chose to follow the tradition of ornamentation, adorning his towers with intricate elements inspired by nature to add visual interest. These also served to accentuate structural and functional features of his designs, uniting both form and function in harmony.
Interpretations of “form follows function” vary — should today’s architecture favor clean, minimalist design, or is there still space for decoration to be incorporated? When building with terra cotta, we don’t have to choose. Terra cotta’s inherent properties allow it to be shaped into a wide range of shapes and adapt to styles from classical to contemporary. By managing profile type, forming method, and aesthetic appearance, a terra cotta façade can be made to embody any rational design.
The Purpose of Profile
With Boston Valley’s expertise in manufacturing terra cotta, we understand the limitations of the material — lengths, profile depths, wall thicknesses, etc. — for architectural applications. We can assist clients through the initial stages of a project to rationalize their design and determine which forming method will be most appropriate for creating the terra cotta profile or product type, as each offers a unique function that is enhanced by its shape.
Clay used to produce architectural terra cotta is malleable and can take virtually any form, to best suit design intent as well as specified construction and attachment methods. RAM-press or hand-pressed units maximize a dense mass suitable for compressive masonry structures, while lightweight continuous panels hung for rainscreen and sunscreen cladding are easily extruded and cut to length. Custom roof tile can be produced in a range of unique shapes and sizes, from thin shingles to barrel profiles or tapered tiles for curved roof application. Thin veneer panels can be produced for Guastavino vaulting systems or unitized with precast concrete to offer a blast-resistant façade system with a wide range of profile and finish options.
Clockwise from top left: (1) TerraClad® extruded panel; (2) Terra cotta roof tile on the Federal Trade Commission building; (3) Guastavino tile vaulted ceiling of the Queensboro Bridgemarket; (4) TerraPreCast® veneer piece made for 1200 17th Street.
Manufacturing Form
Extrusion, RAM press, hand-press, and slip-cast forming methods are all available when manufacturing terra cotta, taking into consideration the need on a given project for continuity of mass production, design fidelity, and efficiency of installation. Boston Valley employs these four methods alone or in tandem based on the forms required by the proposed design.
Extrusion is the quickest and most efficient method for producing terra cotta building units, particularly for large quantities of panels with the same profile. RAM press has similar benefits but is best for producing many non-linear components of repeating patterns.
Left: Extrusion of a terra cotta unit using a die to achieve a specific profile. Right: RAM-press helps to create many masonry units with repeating forms.
For ornamental forms that have fine detail or undercuts, slip-casting in a mold produces a fully formed masonry unit that is lightweight but retains accurate detail. Hand-press is the traditional method of manufacturing terra cotta, and the most laborious — skilled sculptors must work with a mold by hand, so it is best suited for unique, small-run pieces. These highly detailed units, once hand-pressed or slip-cast, will be refined by Boston Valley finishers after forming.
Left: Hand press was used to create highly sculptural pieces for 150 Nassau Street. Right: These ornamental masonry units on 7 Gouverneur Slip East were slip cast, allowing placement at the building’s peak without creating heavy weight.
Designing for Installation
The advantage of using TerraClad® panels for a building’s façade is that terra cotta units can be made to work with a range of different attachment systems. This gives us the flexibility to modify panel profiles with custom notching or slots to fit a client’s custom system if needed, affording greatest ease of installation possible when considering the design.
From left: (1) TerraClad® panels are designed with shiplapped joints to efficiently hide clip attachments; (2) Hidden joints in action on 120 Stockton’s façade in San Francisco; (3) A sample of TerraPreCast® highlights the dovetail profile between the terra cotta veneer and concrete block; (4) Terra cotta louvers are connected with vertical spline shafts to create a sunshade at the University of Texas at Dallas.
Our horizontal TerraClad® panels feature shiplapped joints that cleverly hide the clip attachment to the track system. We can also accommodate vertically hung systems by clipping to the panel core instead. Rainscreen panels help shield the structural wall from precipitation, also allowing for air flow and ventilation. Sunshade systems can be constructed in combination with rainscreen or as standalone feature; long terra cotta baguettes connect with typical or custom attachment options as needed.
For precast façades, the back of a 30mm terra cotta panel is extruded with a dovetail profile — the triangular notch locks in to the concrete, bonding the materials into a single unit. Interlocking tiles are used to install roofing, while structural vaulting, such as in Guastavino tile systems, gains strength from layers of thin tiles set with Portland cement in a herringbone pattern. RAM pressed, hand-pressed or slip-cast hollow units can be designed to accommodate anchoring for masonry façade systems.
It’s clear that manufacturing with the product’s intended use in mind influences what form it takes, and even how it’s made. However, the principle can apply to any building material, not just terra cotta. The next part of this blog series will assess how terra cotta’s fundamental aesthetic qualities are undoubtedly of benefit in architectural applications — and how Boston Valley harnesses that potential to achieve a wide variety of designs for our clients.
