Most decking sold in the U.S. today is wood, with synthetic decking making up a little less than 30% of the total residential market. But pros install a lot more synthetic decking than the average weekend warrior; our surveys show that PDB readers install wood-plastic composite (WPC), PVC, and other types of non-wood decking products on nearly 60% of their projects.

A few years ago, capped WPC decking was just a blip on the radar; now these products command more than 70% of the synthetic market, according to Principia’s 2015 Decking and Railing Report. The market research and consulting firm says that this growth has come primarily at the expense of uncapped WPC decking, which saw its share of this market drop from 41% in 2012 to just 15% last year, with a further decline to a mere 8% share projected in 2017. (By the way, PVC sales are falling too, but not as fast as those of uncapped composites.) These figures confirm what we had observed at the most recent DeckExpo, where uncapped WPC decking had virtually disappeared from the show floor.

In general, the market for composite decking is growing at a faster rate than the market for other types of decking, according to Principia’s Lou Rossi, with most of the growth occurring at the top of the price scale. “The general trend is toward higher value, better performance, longer life, better aesthetics,” Rossi says. He says that the middle of the decking materials market is not growing, which has resulted in an increasingly polarized market—with treated lumber at one end and the more-expensive composite decking at the other.

Capped composites are also taking market share from PVC decking, a shift Rossi attributes to improvements in composite technology in general and capstock in particular. The latest capped composites match PVC in looks and performance but cost less. For example, dark capped composite decking is less expensive to manufacture than dark PVC decking because expensive UV inhibitors are required only in the capstock; with PVC decking, they must be added to the entire board.

Because of these trends, there are some in the deck industry who believe that sales of uncapped WPC decking will continue to decline, and that the category will eventually disappear altogether in a few years. On the other hand, we’ve heard from several contractors who say that the current generation of uncapped WPC decking offers great value for cost-conscious homeowners, now that manufacturers have eliminated the problems associated with early versions of the product.

Coat the Fibers, Not the Board

Capstock decking was developed as a solution to the well-known problems with first-generation deck boards. Those early products—relatively porous blends of plastic resins and sawdust—stained easily and tended to fade in the sun. In addition, there were many homeowner complaints about mildew problems, which led to several class-action and direct-action lawsuits against some of the major decking manufacturers.

As manufacturers refined their capstock technology, they began eliminating their uncapped lines. Trex, for instance, dropped its last uncapped product in 2014, four years after introducing its high-performance Transcend capped decking. At this point only a few uncapped WPC players are left, among them AERT (MoistureShield and ChoiceDek), Tamko (Evergrain), Midwest Manufacturing (UltraDeck), TimberTech (TwinFinish, ReliaBoard, and DockSider), and probably a few others. Each of those companies also has a capped decking product.

The manufacturers of these products say that because they’re made using a different process than the one used for that early decking, they don’t need a cap. “Instead of putting a raincoat over our decking, we make it differently,” Randy Gottlieb, AERT’s president, says. For one thing, he says, each individual fiber is coated with plastic. This is done by blending the wood fibers, pigment, plastics, and colors together for an hour or more in the mixer before sending it all to the extruder. Cooling the extruded boards slowly also makes them more stable.

Despite insisting that their products don’t need a cap, all of these companies also offer lines of capped decking, saying that it’s necessary because some buyers won’t consider any other type. “In certain places, like the Northeast, early composites performed so badly that people won’t even look at uncapped,” explains Brent Gwatney, MoistureShield’s vice president of sales and marketing.

In fact, MoistureShield’s capped WPC decking—called MoistureShield Pro—is essentially its uncapped Vantage product line with a protective layer that the company claims is for enhanced slip and scratch resistance rather than moisture protection.

Proven Track Record

Uncapped products still account for a substantial portion of sales for both AERT and Tamko. According to MoistureShield marketing assistant Faye Rook, demand for the company’s uncapped decking is even growing in certain regions like the Mountain West, where she says that many homeowners prefer its more rustic look.

Contractors who continue to install uncapped WPC decking point to its proven performance. One of these is Monica Quinby, owner of Kingston, Tenn., Dock It, which builds upscale docks and marinas on local lakes and rivers. She has used MoistureShield’s uncapped decking for more than 20 years with no mildew problems, despite the damp waterfront environment. She also credits the product with quite good resistance to staining and fading.

Another contractor who’s sold on uncapped decking is Kim Katwijk, from Olympia, Wash., who says that 40% of his decks are finished with Tamko’s Evergrain. Price is, of course, a big motivator: According to Katwijk, Evergrain costs $2.30 per lineal foot compared with roughly $3.20 for capped and around $3.65 for PVC in his area, making it a great value for customers who are on a tight budget.

Uncapped composite boards are available in square-edged versions and in grooved versions for use with hidden fasteners, though Katwijk argues that the latter are not worth the cost for most uncapped-decking customers. “The extra price for hidden fasteners won’t fly with budget-conscious people,” he says. “Instead, I use color-matched screws from Screw Products and skip-screw so there are fewer screws on the deck. No one notices them.”

Katwijk also rejects the oft-cited argument that the ability to rip an uncapped composite board offers a big advantage, saying that if you have to rip boards, it’s usually because you didn’t lay out your deck correctly. “You should be using 100% full deck boards all the time,” he says. “Ripped boards scream ‘amateur.’”

Aesthetics and Maintenance

Of course, uncapped WPC decking wouldn’t be such a great value if the boards didn’t perform over time. Katwijk says he’s installed Evergrain for years, and hasn’t experienced any of the problems that other uncapped composites have had. “The uncapped products that have survived are the ones that were problem-free even when other uncapped products were failing,” he says.

He agrees that uncapped decking is slightly more prone to fading than capped products (though not nearly as prone as first-generation products), but points out that it hasn’t been an issue with his customers. “A deck is like a new car. Once the newness wears off, people don’t notice.”

When it comes to stains, while these products are nowhere near as susceptible as first-generation decking, they’re also not immune. “If you drop a hamburger on capped decking, you can leave it there for a week without a grease stain, but you have to get it off uncapped quickly,” Katwijk says. He notes that grease stains can be removed from uncapped composites with dishwashing liquid, though you have to rinse it off quickly; otherwise, the dried surfactants will attract dirt. What if it’s a really visible stain? “If a red popsicle sits on the deck, it will leave a stain. But in six months, it will fade to the point where you won’t even notice it.”

Both Quinby and Katwijk advise customers that if they want to keep their uncapped composite decking looking good over the long haul, they’ll need to clean it at least once a year. Katwijk recommends a bicarbonate laundry detergent like OxiClean (1/4 cup per gallon of very hot water). Some of Quinby’s customers opt for her company’s maintenance contract: an annual cleaning with a product called Wet and Forget to prevent mold and mildew growth.

Neither deck builder considers maintenance a big deal—after all, capped decking should also get an annual scrubbing. The point is that they’re confident enough in these products’ long-term performance to make them a standard offering—Quinby and Katwijk both offer capped and uncapped decking, while Katwijk also gives customers the choice of PVC decking.

Both also say that while uncapped’s lower price is an attraction, in the end, aesthetics is what’s most important to customers, with the final choice usually hinging on the colors each product offers. “I tell them the pluses and minuses of each type of decking,” says Katwijk. “Ultimately, however, color is usually the deciding factor.”

Charles Wardell is a freelance writer based in Tisbury, Mass.