Bending Decking for Decorative Inlays
The ability to heat-form synthetic boards on site paves the way to designs that can set a deck apart.
Synopsis: Although synthetic decking is becoming more and more popular, one of its advantages over wood has not been exploited much: its ability to be heated and shaped into curves. Author Kim Katwijk, a deck installer in Washington state, spent several years trying various methods of heat-forming synthetic decking. None of them worked to his satisfaction until he tried a system from Heatcon. Now he uses this system on both cellular-PVC and composite decking. In this article, he describes the steps he took in order to include a Celtic-knot design in a deck made from PVC: marking the frame, blocking the curves, building the bending jigs, heating and shaping the boards, and prepping the decking for the inlay. In a sidebar, he describes the Heatcon kit that makes this process possible, and he provides a chart that indicates the heat-forming ability of various brands of synthetic decking.
It wasn’t long after I started building decks full-time in 1996 that I got the opportunity to create a curve. I had designed a beautiful curved deck in cambara for a client who wanted the railing cap to follow the shape of the deck. The logical solution for most deck builders would have been to laminate thin strips of cambara into a curved rail on a bending form, but I wanted to try something completely different: Heat-form composite decking to the desired curve.
Composites are made from a mixture of wood fiber and plastic. Because these plastics are not thermally stable, it’s possible to heat and bend the decking.
A literal learning curve
My first attempts at board-bending were with Trex. My apparatus involved a 20-ft. by 20-in.-dia. Sonotube laid on the flat with #3 rebar shoved through the sides to suspend the decking. Two kerosene space heaters forced heated air into…