Composite decking debate Solid vs. Hollow

was designed using a hidden fastener system for a clean look when finished, a unique TimberTech feature at the time that is taken for granted today."

A LL composite decking is not crell,ated alike. Most noticeably, some manufacturers produce solid boards, while others craft hollow or "voided" profiles. Visually, solid profile decking better simulates the shape of real wood, while hollow profile decking often has an engineered look. But are there deeper differences?

The main advantages of hollow profiles are lighter weight, lower raw material consumption, and consequently lower material costs. (Although final production costs aren't necessarily lower since voided decking is often considerably slower to produce.) Several manufacturers contend that their voided boards are up to 30Eo lighter than competitors' solid profiles.

In addition, with less mass than solid boards, composite decking will have fewer expansion and contraction properties. But they may also experience "differential thermal expansion," in which one side of the board expands more than the other. The upper surface of the board is exposed to heat from sunlight during the day, while the lower, shaded surface remains cooler. Differential swelling and contracting of top surface relative to the bottom surface reportedly can result in cracking.

Hollow profiles also may be less impact resistant and more susceptible to yard or jobsite damage. Solid boards generally have better fastener holding power.

Bill Ross, v.p. of sales & marketing for Fiber Composites, says solid decking's greater mass permits it to hold more additives needed to protect the plastic molecules in each board.

"Solid profiles are more readily accepted by deck builders and building professionals because it's a more traditional profile," Ross says. "Solid boards also are easier to work with; they require a minimal learning curve. Solid profiles do not need special end treatments, plugs, picture framing, etc., to hide the hollow cavities."

Whether solid or voided makes for a stronger board is up for debate. GAF/Elk maintains that speciallyengineered arched voids in its CrossTimbers decking result not only in a board thatis 3OVo lighter, but also stronger and stiffer than many solid boards. Instead of polyethylene, they use polypropylene to achieve a greater strength-to-weight ratio, eliminating bounce or sag, so boards feel more solid under foot.

Contractors should just be sure that, from a strength perspective, they check to see how the decking is rated, to ensure correct spacing ofjoists.

TimberTech offers both a traditional solid 5/4 profile and a hollow profile-Floorizon-which it developed over 10 years ago to replace then-popular 2x6 decking. "It requires less framing and in many cases could be used on a deck with 24" on center joist spacing due to its l-1l2" height," said Tom Day, senior product manager. "It

Although the 5/4-style has since become the standard of today's decking industry, the hollow profile remains popular with certain customers, said Day, "because it is costeffective in installation and still gives a 6" wide profile look to a deck. It also spans 24" on center due to its design versus the 16'-20' of a typical TimberTech 5/4 plank."

Since both solid and hollow profiles can do the job, one wonders why solid is so much more prevalent in North America. while hollow boards dominate Europe and Asia. The experts at BuildDirect think it comes down to nothing more than "perception. Wood decks are solid, and the first composite deck boards on the market were all solid. This seems to have created an image in the minds of many consumers that that is what composite decking is."