Wood is the undisputed king of all decking materials, but the crown is under attack. The widespread acceptance and availability of manufactured “plastic” lumber has continued to gain ground amongst do-it-yourselfers and professional deck builders alike.
Which material is best for your new deck or deck-remodeling project will depend on several factors including decking color, available board sizes, maintenance requirements, and, of course, price. Here’s a detailed look at the main differences—and similarities—between wood decking and plastic lumber.
Natural wood decking products can be roughly divided into three categories: pressure-treated lumber, redwood and cedar, and tropical hardwoods. You’ll find most types of wood decking at your local lumberyard or home center, although availability may vary depending on where you live. And a growing number decking options, tropical hardwoods in particular, are only available online.
Pressure-treated lumber—This ubiquitous green-tinted wood has been the best-selling decking material for several decades—and still is today. Each year, approximately 75 percent of all new decks are covered with pressure-treated (PT) decking. And the understructure frame—posts, ledgers, beams, joists—of virtually every deck is constructed with PT lumber.
Most PT decking is cut from southern yellow pine, and then chemically treated to resist decay, fungus and wood-boring bugs. For over 70 years treated lumber was infused with chromated copper arsenate (CCA), a suspected carcinogen. However, CCA hasn’t been used in residential lumber since December 2003. Today, most PT lumber is treated with less-toxic chemicals, such as alkaline copper quaternary (ACQ), copper azole, or carbon-based, non-metallic preservatives.
PT decking is the most affordable and widely available decking material. The most common size of treated decking is 5/4 x 6-in. planks (about 80 cents per linear foot), but 2x6s (70 cents per linear foot) and 2x4s (50 cents per linear foot) can also be used for decking.
The main disadvantage of PT decking is that because it’s cut from pine, it’s not very dimensionally stable; it has a tendency to swell, crack, split and warp. And when wet, it’s surprisingly heavy. PT decking requires a fair amount of routine maintenance, too, including an annual power washing, and application of stain or clear wood preservative every two or three years.
Redwood and Western red cedar—These two western softwood species are valued for their rich crimson color and natural beauty, and for the fact that they are not pumped full of chemicals. Redwood and cedar contain tannins and oils that make them naturally resistant to rot, decay and voracious insects. These two decking products are also very lightweight and extremely easy to cut and fasten with nails or screws. And they’re very stable and much more resistant to warping and splitting than PT lumber. The most common sizes of redwood and cedar decking are 2x6s and 2x4s.
Unlike PT lumber, redwood and cedar come is a wide variety of grades, ranging from the most expensive and clearest, to the least expensive and most knotty. The California Redwood Association suggests using Construction Common or Deck Common redwood for decking. For a clearer—and more expensive—grade, choose B-grade redwood or Construction Heart redwood.
The Western Red Cedar Lumber Association recommends four grades of cedar for use as decking: Architect Clear, Custom Clear, Architect Knotty, and Custom Knotty. Again, the clearer the grade, the more it costs.
Redwood typically costs slightly more than cedar, but both species are three to five times more expensive than pressure-treated lumber.
It’s difficult to give accurate pricing information on tropical hardwoods since there are so many species available from so many different sources, including local hardwood suppliers and online lumber dealers. And complicating the issue is that some species are known by different names. For example, ipe (‘ee-pay) is also called Ironwood or Brazilian walnut. Generally speaking, however, tropical hardwoods are the most expensive real-wood decking option, costing slightly more than redwood and cedar.
No wood decking is 100 percent maintenance-free, but tropical hardwoods come close. Prices fluctuate widely across the country; cheaper out west, more expensive in the east.
Even though redwood and cedar are naturally resistant to the weather, it’s recommended that you lightly scrub or power wash the surface annually, and apply a stain or penetrating clear finish every three to four years. If you wish to maintain the wood’s natural color and texture, you must apply a semi-transparent stain.
If you don’t apply stain, both redwood and cedar will eventually weather to a light silvery-gray color. It’s fine to let the wood weather naturally, however, it’s still advisable to apply a clear wood preservative every few years to block out excess moisture.
Tropical hardwoods—The newest entries into the real-wood decking market come from Africa, South America, Malaysia, the Philippines, and other exotic locales. And most have very exotic-sounding names, such as Massaranduba, jatoba, meranti batu, camara, abaco, red tauari, tigerwood, and ipe.
Tropical hardwoods share several common characteristics: they’re all very dense, extremely hard, heavy, durable and naturally resistant to rot and insects. In fact, they’re so dense, it’s impossible to drive a nail or screw without first boring a pilot hole, which is why most tropical decking is installed with hidden fasteners that clip or screw into the edge of the boards. Decking sizes commonly available include ¾- and 1-inch-thick boards, which come 3½ and 5½ inches wide.
Most need little more than an occasional scrubbing and perhaps a coat of clear wood preservative. They’re so dense they don’t accept stains very well, but if you choose to apply a stain, be sure it’s a penetrating stain that’s specifically formulated for tropical hardwood decking. Standard decking stain won’t be completely absorbed, and it’ll leave behind a sticky film. Note, too, that it’s often recommended that you wait two or three months before applying a finish to tropical hardwood. This extra time allows natural oils to leach out of the hardwood, so the decking will better accept the finish.
If you choose not to stain tropical decking, it’ll eventually weather to a light silver color. Finally only buy tropical hardwood that has been certified by the Forest Stewardship Council. This is your assurance that the wood was grown and harvested in a legal, sustainable manner—and not chopped out of a rainforest.
Man-made plastic lumber represents the fastest-growing decking material sold today. There are more than two dozen companies now manufacturing plastic lumber, which can be divided into two categories: composite decking and PVC (polyvinyl chloride) plastic decking.
Composite decking—Composite decking, such as Trex, TimberTech, Fiberon, and Veranda, is a hybrid product that’s composed primarily of wood fibers and recycled plastic. The result is an extremely weather- and stain-resistant deck board that won’t splinter, warp, rot or split. It’s also very dense and heavy.
What makes composite decking—and plastic decking, too, for that matter—attractive to many homeowners is that it requires very little maintenance. It never needs to be sanded, scraped, refinished or stained. An occasional scrubbing with warm, soapy water will remove most dirt and grime. Use diluted bleach to kill mold and mildew, which can grow in damp, dark areas of the deck.
Standard composite decking comes in limited colors—brown, gray, tan—though many manufacturers are now offering darker colors that resembled stained hardwood. Most colors fade over time, especially when exposed to direct sunlight. However, there are fade-resistant composites, which cost a bit more, but retain their color much longer.
Composite decking comes in lengths up to 16 feet and in many of the same sizes as PT decking, including 5/4 x 6 inch. Most products also have realistic-looking wood-grain patterns molded into their surfaces. Prices vary widely because there are so many different companies manufacturing composite decking, but expect to pay between $2 and $4 per linear foot for most standard-grade 5/4 x 6-inch composites.
Capped-composite decking is similar to standard composite decking, except that each board is encapsulated—or “capped”—in a thin layer of plastic. The result is a deck with a smoother surface that’s much easier to clean. Capped-composites cost about $1 more per linear foot than standard composite decking.
Plastic decking—Unlike composite decking, plastic decking, such as Azek and Evolve, is made from 100 percent plastic (recycled and/or virgin); it contains no wood fibers or fillers. It’s highly stain-resistant, doesn’t require finishing, and won’t ever crack, warp or splinter. And, plastic decking comes in many more sizes than other decking options, in some cases up to 12 inches wide and 20 feet long.
On average, plastic decking costs about the same as composites, but prices vary widely because there are some many different types and sizes of plastic decking. And unlike any other decking option, plastic decking is designed as part of an overall system, and therefore, it must be installed with strict adherence to manufacturer’s instructions. This often requires purchasing special fasteners, fascia boards and trim pieces.
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