Craftsmanship: For the Love of Limestone
Limestone is found all over the world: as soft, yellow stone in southern England, creamy buff stone in southern France, a variety of interesting colors found in the Burgundy region, as well as numerous types in Portugal and Asia. It has been used as a building material for thousands of years: from the pyramids of ancient Egypt, to the medieval cathedrals of Europe, to a myriad of governmental buildings throughout the United States. Many examples can be found here in Washington, D.C., most notably Federal Triangle and the National Cathedral. Limestone is a sedimentary stone (unlike granite or marble), meaning its formation began millions of years ago as sedimentary deposits at the bottom of ancient sea beds. In fact, some stones contain fully formed, visible fossilized sea shells, plant forms, and other creatures of the sea.
Our firm is most familiar with the stones available in what has come to be known as the limestone belt of the US. This region extends from southern Indiana through Kentucky, Tennessee, and all the way down to central Texas. We have worked with several of these stones on dozens of projects for over 30 years. The variety we know best is the warm, gray limestone from Indiana. It has the longest tradition of use on government and institutional buildings in this country. By virtue of its continued use for hundreds of years, it has become intertwined with the themes of permanence, timelessness, and tradition. While buff/gray in color, there are subtle variations in color, tone, and veining from one stone to the next, giving buildings a sense of warmth, liveliness, and character not found with other construction materials.
The limestone industry is broken into three major components. Quarries are responsible for extracting the material in large blocks that are then marketed and shipped to nearby fabricators, which cut the material in their purpose-built factories. Ultimately, specialized subcontractors, known as erectors, install the material on buildings. Each entity has a specific area of expertise and each is necessary for the job. [Trivia alert: Breaking Away, set in southern Indiana and produced in 1979, is a fun movie that offers a unique view into the world of limestone.]
Designing with limestone as an exterior cladding material presents a unique set of challenges and opportunities. The primary challenge is understanding the different tools and methods used to fabricate, or rather to cut and carve the stone. As one can imagine, the material itself as well as the resources required to shape it and install, it are not inexpensive. Successful jobs, therefore, require knowledge and sensitivity in finding ways to use the material resourcefully to get the most impact from project budgets.
Limestone is not an off-the-shelf material like standard units of lumber, brick, or steel; each and every piece is custom-carved for a specific job. Each job therefore, becomes a jigsaw puzzle of stone pieces, each of which is destined for a specific spot on a building. We sometimes think of this much like fabricating millwork: material can be sawn, either across or with the grain, it can be planed, and it can be cut with specially profiled knives into a variety of decorative shapes, much like moldings are in wood. The difference, of course, is in the heaviness and robustness of the tools used; most knives are encrusted with industrial grade diamonds and water is frequently used to mitigate the high amounts of friction generated.
There is also a long tradition of hand carving limestone. Even in the current age of computer guided laser and water jet cutting, hand carving is still the preferred method of realizing intricate designs in limestone. While this once happened exclusively with mallet and chisel, pneumatic bush hammers are now the primary tool for hand carving. The high level of training and the thorough understanding of working in three dimensions (to envision something from an architect’s two dimensional drawings) that carvers must have to successfully ply their craft are no less necessary now than they were generations ago and a lengthy apprenticeship is still an integral part of the path to becoming a fully qualified stone carver.
Since each job is custom, there is an opportunity to create a unique set of shapes; a distinctive vocabulary of parts that will make a building special and that will give it added relevance to its particular time and place. Ultimately, the added relevance provided by custom carved limestone gives an architect the opportunity to create something singular that will be fully embraced by the community it will serve.
A good example of this is the carved column capital for one of our current projects, the Gaillard Center, under construction in Charleston, South Carolina. We had the chance to work once again with Bybee Stone Company, a limestone fabricator based in Ellettsville, Indiana. They are well known in the industry for their fine hand carved detail work. We have previously work with Bybee on Schermerhorn Symphony Center in Nashville, Tennessee, The Palladium in Carmel, Indiana and The Smith Center in Las Vegas, Nevada.
Of particular interest on the Gaillard project are the hand carved column capitals. Capitals are usually the most overt expressions on a building and, therefore, a great opportunity to incorporate symbols and iconography meaningful to a place, time, and culture. For Gaillard, we took this as an opportunity to incorporate the crescent and palmetto palm tree from South Carolina’s flag, the jasmine (state flower), and woven motifs recalling both palmetto bark as well as the sweet grass baskets prevalent in the Gullah culture of the Lowcountry. The Gaillard’s capitals are classically inspired, drawing from both the beaked Ionic and Corinthian orders. This kind of eclecticism and marriage of different elements is nothing new: we find it in column capitals comprised of sea creatures and fish in places like Venice and, closer to home, the ears of corn in the columns of the US Capitol building here in Washington. This kind of ornament is not only fun and interesting, but it is the opportunity to memorialize the symbols and icons we hold dear, literally etching them in stone for generations to come.
This article was authored by DMSAS Associate Steve Knight. Steve received his MArch from North Carolina State University in 1997 and joined the firm that same year.