Passionate About Purple Heart
When architect Ted Touloukian selected South American purpleheart wood for construction of the pergolas and pavilion at Center City Park in Greensboro, North Carolina, he was initially drawn to it as a low-cost alternative to ipé. But once he saw the lovely amethyst-colored hardwood, he was awed by its vibrant violet hue.
When it is first milled, purpleheart is intensely, passionately purple. Light lines of sap, which dry up within about ten days after milling, delineate its grain lines. The purple wood turns to purplish brown and then to medium reddish brown a few weeks after installation. It eventually fades to gray with exposure to sun and weather, but the grain lines remain pronounced giving purpleheart a distinct textured expression.
According to The Wood Database, purpleheart (Peltogyne spp.) is a heavy, stable wood that offers good decay resistance. It is very resistant to dry wood termites, but purpleheart has little resistance to marine borers, making it more suitable for non-marine projects, such as pergolas.
In 2004-05, when the Greensboro Center City Park project was under development, purpleheart cost significantly less than ipé, Touloukian recalls. “It was economical in the short term; and over the long term, because the structures are not painted or seal coated, it will require very little maintenance,” he said. “Not having to re-paint or re-treat the wood every three or four years adds up to big cost savings over the lifespan of a structure,” Touloukian added.
Another feature that attracted Touloukian to the purpleheart lumber was that it came in very long lengths. “We were able to obtain 16-foot and even 18-foot planks, which were very useful for this application,” he noted. Touloukian used the longer planks to envelop structural steel beams giving them the appearance of solid wood beams and used more moderate lengths for the structural applications. “That extreme length is pretty rare,” Touloukian explained.
Center City Park, with its seven louvered pergolas and vaulted pavilion, occupies an urban block in downtown Greensboro. The park also boasts a fountain, sculptural elements and interpretive graphics on the paving and plaza areas. The pavilion itself contains storage areas, support facilities for vendors and special events, and plumbing and mechanical equipment for the park operations. Its 18- to 23-foot cantilevered roof shelters space for community gatherings, outdoor performances and special events.
The roof is detailed with a folded purpleheart wall and soffit made from tongue and groove panels assembled in an alternating pattern. Continuous steel support beams are wrapped with pressure-treated blocking and finished with ripped purpleheart wood that splays out gradually.
The space between the beam enclosures tapers at the roof’s edge to create a ribbed effect evocative of a woven fabric and analogous to the porous louvered pergolas nearby. Silicon bronze plaques knitted into the purpleheart wall recognize the donors whose philanthropy underwrote construction of the park.
The pergolas provide shade and sheltered seating in the park. They are oriented to create a gateway from the street and to overlook the park’s lawn and outdoor performance area. The pergolas are constructed of two different types of shop-fabricated box rafters assembled from 2’ by 12’ wood planks ripped to profiles that create a fluttering edge.
All of the park’s features were designed to reflect the rich history and varied culture of Greensboro, and specifically its heritage of weaving and textile production. The structures are intricately detailed to reflect the shuttle and weaving looms of the textile mills that once made Greensboro the heart of the southern textile industry. In the early 20th century Greensboro was home to many large mills, such as Crone Mills and Burlington Industries, and was celebrated for its denim and flannel fabric and its sturdy jeans, overalls and work clothes.
Structures throughout the park emphasize the city’s proud industrial tradition. In the pavilion, for example, the tongue and groove panels of standard and custom sizes alternate to form a warp and woof pattern. “Even the gradual changes in color and texture of the purpleheart wood contribute to the textured material design aspect,” notes Touloukian. “It’s sort of like a pair of faded denims that gain more character as they age.”