Strolling through the countryside — more in the U.K. than in America — your eyes may be drawn to the visual appeal of the undulating garden walls snaking along the landscape. "What a waste of brick," you may think, assuming a straight wall would be more cost-effective. But, au contraire. Those wavy borders — called crinkle crankle walls, oddly enough — offer more than a visual aesthetic. They're quite practical and protective, as well.
"Everybody thinks about masonry as just square pieces of clay, and the fact that you can actually make them into walls that are very elegant, sinusoidal or curved, it just puts a different perspective on what masonry can be," says Brian E. Trimble, PE, LEED, AP, director of industry development and technical services for the International Masonry Institute.
Trimble knows a thing or two about crinkle crankle walls because he's done a bit of research on the topic, having written a technical paper on the subject nearly a decade ago for the Canadian Masonry Symposium. "Of course, here in the U.S., they are usually referred to as serpentine walls," he points out. It's easy to see why. They're shaped like a snake's S-shaped slither. (The term "crinkle crankle" comes from the Old English term for "zig-zag.")
The walls' unique shape makes them stand apart, both aesthetically and in practicality. The pattern of concave and convex waves, known as a sinusoidal pattern, serves a number of important purposes. During the Middle Ages, it was discovered that undulating walls helped fruit trees grow better in cooler climates. The curves created pockets that protected the trees from the wind while also trapping heat from the sun and radiating it back into the trees, essentially creating a longer growing season, Trimble says.
Another benefit was cost. While the footprint of a wavy wall is much greater than a straight one, taking up more landscape, its design helps reinforce it better than a straight wall of the same material. In other words, serpentine walls can be made one wythe (a single brick layer) thick, while straight walls generally require two wythes. Thus, fewer materials are needed to construct a serpentine wall versus a straight one.
"Straight cantilever walls require reinforcing of a thicker wall with pilasters or piers located along its length to resist lateral loads," Trimble wrote. Conversely, "serpentine walls can be infinitely long without a pier if the geometry is proper."
And yes, the geometry has to be correct for it to work. In 1958, the Structural Clay Products Institute, now the Brick Industry Association, published a technical note on formulae for a serpentine wall's geometric properties. The equations are based on radians and not degrees.
If you want to learn more, check out this explanation from John D. Cook, a consultant in applied mathematics, statistics and technical computing, who has studied and written about crinkle crankle walls.
The Crinkle Crankle Backstory
The design of crinkle crankle walls was likely first conceived through a process of "trial and error," Trimble says, with different ideations adding curves for more stability and interest.
While the origin of the walls is not entirely known, the design has been used in many cultures for centuries — and, as it turns out, even millennia. In September 2020, upon the discovery of the "lost golden city of Luxor" in Egypt, archeologists found a distinctive "zig-zag" mudbrick wall as much as 9 feet (2.74 meters) high in some places snaking through the 3,400-year-old royal city built by Amenhotep III.
The walls were also used in the Middle Ages, making an appearance during the Renaissance in the 14th century, for the very specific purpose of protecting fruit trees, Trimble says.
Dutch engineers brought the concept to the U.K. in the 1600s. Obviously well-versed in building on coastal plains, engineers from the Netherlands were hired to transform a marshy region of East Anglia, England, known as The Fens, into farmland. They created a drainage and irrigation system for the area and then surrounded it with a relatively thin, wavy brick walls they called slangenmuur, which translates in English to "snake wall." It was like nothing the English had seen before.
Around the same time, this style caught the attention of Francisco Borromini, an Italian architect and leading figure in the emergence of Roman Baroque. He used a version of serpentine wall when he designed the church of San Carlo alle Quattro Fontane in Rome.
Thomas Jefferson Brought Crinkle Crankle Walls to the U.S.
By the 1800s, the concept caught on like wildfire in the U.K., particularly in Suffolk, which now touts more than 100 crinkle crankle walls. Thomas Jefferson is credited for bringing the style to the U.S. when he added the design to the architecture of the University of Virginia (UVA) in Charlottesville, which he founded in 1819.
The walls at UVA flank both sides of the landmark rotunda and run the length of the lawn, where 10 pavilions, each with its own garden, are separated by serpentine walls. They stand 6 to 7 feet (1.8 to 2.1 meters) high and have weathered time relatively well save for a major renovation of the campus in 1953, which resulted in many of the walls being rebuilt, as Trimble wrote in his technical paper.
Jefferson likely discovered the concept of crinkle crankle walls during his extensive travels to Europe and through his studies of classical architecture, especially that of Italian architect Andrea Palladio, Trimble wrote. Though Jefferson is often erroneously credited for inventing the serpentine wall concept, he may have been one of the first to "put down on paper" the cost savings of undulating walls, Trimble says.
Now That's Interesting
While the number of crinkle crankle walls in the U.S. pales in comparison to the U.K., the U.S. does boast one of the largest ones. A 1-mile-long (1.8 kilometer) serpentine wall approximately 7 feet (2.1 meters) tall and just 4 inches (100 millimeters) thick surrounds a portion of the Ford Motor Company's Dearborn Development Center in Michigan.
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