In his late nineteenth century textbook on the subject, S. Edward Warren defines stereotomy as “the application of Descriptive Geometry which, comprehensively defined, tends to the cutting or shaping of forms, whether material or immaterial, so as to suit certain conditions” (Warren 1875). This definition of stereotomy is remarkable for its emphasis on geometry over issues of stability and material specificity. Various types of stone would have been the only materials available for permanent stereotomic construction in the 19th century, yet Warren downplays the importance of compressive materiality and structural behavior, focusing instead on geometric knowhow and the deployment of techniques to shape forms, both material and immaterial.
Over 140 years later, Warren’s definition of stereotomy is prescient and relevant. Tools that allow descriptive geometry to be applied to both immaterial—i.e., “virtual”—forms through 3D modeling and material forms through digital fabrication are now widely available. Not merely an extension of the geometric techniques of the past, contemporary digital tools have ushered in a new paradigm in which everything digital is variable and tunable to specific architectural needs or desires (Carpo 2011). Despite this paradigm shift, there is a noticeable tendency for contemporary projects exploring the subject of stereotomy to do so with materials and structural logics duplicating those of historic structures, even as these projects cultivate the latest in digital tools. These projects often suggest that digital stereotomy and contemporary masonry in general should still be primarily defined by heavy materials and compression-only configurations. For example, the developers of an innovative parametric brick placement tool state in their paper on the topic that the “main feature of masonry construction is its [compressive] structural behavior” (Rajabzadeh and Sassone 2016). The high profile “Armadillo Vault” structure built from large limestone blocks for the “Beyond Bending” exhibition at the 2016 Venice Biennale also unequivocally “advocates for the logic of compression-only forms” (Block et al. 2016). Similarly, the recent MIT Collier Memorial project designed by the Boston firm Höweler + Yoon Architecture is made from granite, weighs 190 tons and is described as a “compression-only, balanced, rigid body system” (Höweler and Yoon 2016).
Yet, as Warren’s definition suggests (by prioritizing “the cutting or shaping of forms” over structural behavior), stereotomy does not need to be narrowly defined as constructions employing heavy elements working in strictly funicular arrangements. Contemporary fabrication technologies—like large CNC routers, hot-wire foam cutters and robot arms outfitted with a variety of attachments—allow many different types of forms to be shaped from an increasingly wide variety of materials, creating the possibility for masonry with hybrid behavior. The work featured in this paper joins a growing collection of projects that employ alternative materials, particularly lightweight foam and GFRP, to achieve lightweight constructions with structural performance that employs both tension and compression. The Periscope Foam Tower by Matter Design Studio is a significant project in this category. The mast-like structure employs large-but-lightweight, stacked foam elements pulled into compression by multiple perimeter tension cables (Naboni and Paoletti 2015) (see also http://www.matterdesignstudio.com/#/periscope/).
Likewise, the RDM Vault—a collaboration between Matthias Rippmann, Silvan Oesterle and Jelle Feringa—is another hybrid structure built from discrete, lightweight EPS foam elements shaped by robotic hot-wire cutting (Feringa and Søndergaard 2014) (see also: http://www.rok-office.com/projects/dragon-skin-vault-1017/). In this project, the elements are ultimately fused together into a monocoque shell structure through the application of a gypsum/acrylic composite material combined with glass fiber reinforcement. Despite the RDM Vault’s funicular form, the low weight of the EPS elements are insufficient to keep the structure stable if significant external forces are applied; moreover, the structure does not use restraining abutments. To make the structure more robust, it was fused into a shell that could accommodate tensile forces.
Although the RDM vault is not viable as a compression-only structure, the volumetric, large and close-fitting nature of its elements make the design thoroughly stereotomic. Importantly, each of the project’s 53 individual components is sculpted by a contoured cutting path to produce a visually striking surface. Once assembled, each element reads as a cascading shingle that overhangs the part below. This visually flowing design could not have been easily achieved by other methods; it requires individual parts with carefully cut surfaces to produce the shingling effect. In this case, stereotomy—the consequential cutting and shaping of discrete elements to be joined in a construction—is what gives the project its architectural character, not simply its ultimate structural strength. Both before and after it is fused with composites, the RDM vault stands as an innovative deployment of descriptive geometry, employing parts that might be characterized as exceptionally expressive.
The development of exceptionally expressive stereotomic parts is also an ambition of the research presented in this paper. Although it is not a consolidated term in the literature discussing stereotomy, the idea of an exceptionally expressive part—whether the part is called an element, component, trait or voussoir—is employed here to refer to stereotomic parts that have designs shaped by concerns that (may include yet) go beyond the requirements of efficient construction, the flow of forces and non-slipping pieces. While it is tempting to use the more known term “ornament,” ornamented masonry is strongly associated with carved relief. In contrast, the looser idea of an exceptionally expressive part can encompass both carved relief, parts with special shapes and the complex patterns of joints—the tessellations—that result from tiling special shapes.
Exceptionally expressive parts produce qualities and constructional consequences that are vital to stereotomy. Parts that produce noteworthy qualities are not particular to lightweight plastic stereotomic constructions like the RDM vault and the research discussed in this paper. Historic structures also employ parts that could be identified as exceptionally expressive. Recognizing that significant differences exist between historical and contemporary precedents, there are two cases worth mentioning. These examples suggest that exceptionally expressive parts—masonry elements with unique shapes that produce visually stimulating tessellations or elements that have graphic qualities produced by carved relief—are intrinsically important to the practice of stereotomy.