Composite decking is increasingly becoming the go-to for public boardwalks. City planners are being pressured by environmental lobbyists, and many are giving in. However, there are some serious problems with composite decking products, particularly for boardwalks. Find out why tropical decking such as Ipe or Cumuaru would be a far better choice.
Reason 1: Inferior Hardness
Composite decking simply doesn’t hold a candle to tropical lumber like Ipe or Cumaru. How much harder are those species? We’re talking 10 times as hard or harder! The moderate hardness of composite decking might be okay for a deck on a private home, but with thousands of feet pounding on a public boardwalk every day, hardness really counts!
Reason 2: Heat Retention
We all know that plastic is infamous for heat retention and easily becomes hot to the touch when exposed to direct sunlight. Well, not everyone realizes that composite decking is essentially made from plastic. While some manufacturers blend plastic with wood flour, others use pure polyethylene — the same plastic used for disposable water bottles — for the outer layer.
In a shaded yard, that might not be a big deal, but for a boardwalk exposed to sunlight all day long, it is. A related reason you don’t want to trust this big of a project to plastic: as it heats up, it lets off gas byproducts, causing it to weaken and break down over time. Since plastic retains heat long after exposure to sunlight, the plastic will continue to break down long after the sun actually sets.
Reason 3: Oily Surface
We’ve already discussed the fact that composite decking is essentially made from plastic. As such, it’s oil based. And a boardwalk by the ocean is going to get wet. We all know that oil and water don’t mix, so when water hits the surface of composite decking, it creates a slippery surface. Adding faux wood grain may provide a little extra texture to help with the issue at first, but as the plastic breaks down, it can actually weep oil; no amount of added texture will make up for that. Add in sunblock, surf wax, and all kinds of boardwalk-friendly food, and you definitely have a recipe for disaster. Again, this becomes a liability issue for the city. And that’s no picnic.
Reason 4: Unpredictable Movement
Wood movement isn’t something we can stop; what we can do, though, is predict it and allow for it. With composite decking, which is essentially made from plastic, there will be movement accompanying the heating (expansion) and cooling (contraction) of the decking boards. Since composite decking is also made of wood, its wood flour core also moves. But since that core lacks the grain structure of solid wood to direct that movement, it expands along each “board.” As it does so, the outer shell also expands. But when the core contracts, the plastic remains stretched. The resulting space between the core and the shell leads to uneven warping, with the exposed ends swelling even more than other areas. Across a wide boardwalk, this situation results in swelling not only at the ends of the structure, but also at several points in between.
Continue with Part 2.
Read the Series
• Composite Decking or Tropical Decking: Which Is Best for Boardwalks? Part 1
• Composite Decking or Tropical Decking: Which Is Best for Boardwalks? Part 2
• Composite Decking or Tropical Decking: Which Is Best for Boardwalks? Part 3
J. Gibson McIlvain Company
Since 1798, when Hugh McIlvain established a lumber business near Philadelphia, the McIlvain family has been immersed in the premium import and domestic lumber industry. With its headquarters located just outside of Baltimore, the J. Gibson McIlvain Company (www.mcilvain.com) is one of the largest U.S. importers of exotic woods.
As an active supporter of sustainable lumber practices, the J. Gibson McIlvain Company has provided fine lumber for notable projects throughout the world, including the White House, Capitol building, Supreme Court, and the Smithsonian museums.
For more information on J. Gibson McIlvain’s lumber products and services, call Monday-Friday toll free (800) 638-9100 to speak with one of their representatives.