Durable decking

No home is complete without a deck. But before you build, you'll have to decide exactly what should be underfoot. It's not an easy task. Dozens of companies make synthetic decking. Wood products range from Siberian larch to Brazilian Ipe to more traditional California redwood and western red cedar. The most popular type of decking is still pressure treated with a chemical preservative. It's made from southern pine in the eastern U.S. and several types of hemlocks and firs in the West.

Deck builder John Mortimer has worked with many materials during his five years of running Sweetwater Deck, Inc. in Sweetwater, Tennessee.

He says the two most widely used types are pressure-treated lumber, which still has three-fourths of the market, and synthetics, especially composites made of finely ground wood or plant wastes and recycled plastics. Composite sales are growing by double digits each year.

Initial cost vs. lower maintenance

A professionally made deck of treated lumber will cost 70% as much as one of newer composites, says Mortimer, who is also president of the North American Deck and Railing Association.

But treated decking may need sealing and stains annually. "I tell people if they pay a contractor to take care of their deck, they will pay for a composite in about five years," he says.

Here's how Mortimer and others rate decking.

Pressure-treated lumber. It no longer has arsenic. With the right stains, "you can make a pressure-treated deck look like a cedar deck," says deck builder Sean Brady of Des Moines, Iowa. A downside is newer treatment chemicals are corrosive. They can weaken fasteners that aren't stainless steel or hot-dipped galvanized, a danger if the wrong fasteners tie an upper-story deck to a house.

Not all lumber absorbs chemicals equally. Southern pine soaks it up. Western hem-fir types have to be incised to get good penetration, says Don Bender of the Wood Materials and Engineering Laboratory at Washington State University. Tom Jacques of Hickory Dickory Decks in Hamilton, Ontario, prefers cedar to treated. Pressure-treated wood there has "way more cracking, way more slivers, and inconsistency, " he says. Some treated wood, such as spruce, takes in chemicals poorly.

Synthetics. "They will be way cheaper in the long run," says Jacques. But, adds Mortimer, "It isn't maintenance-free. You have to take care of it. You can't let leaves rot on it. Bird droppings will pit most brands." If a product has high amounts of cellulose or wood flour, spilled wine or ketchup could stain it. Most companies recommend twice-yearly cleaning, in some cases with power washers.

Some plastics will fade slightly. Vinyl products fade least but are also softer. Trex, the industry leader, is made from recycled polyethylene and wood fibers. Others, such as CorrectDeck, are made from harder recycled polypropylene. Products made from all plastic need even less maintenance but may also look less like wood. Aluminum, which looks even less natural, is completely watertight.

Natural woods. These materials need more care, but the right woods are very durable. Ipe from South America is so dense it won't float and so hard you can't drive a nail through it. Redwood and cedar are softer, and a nick is easier to sand and restain than plastics. If you buy redwood or cedar, the most durable will be the darker heartwood, not the sapwood from the outer layers of a tree. "Most decks get replaced not because decking goes bad but because the under structure goes bad," says Charlie Jourdain of the California Redwood Association. "A well-built deck ought to last 25 years."