Innovative solutions for creating healthy, efficient, eco-friendly homes

Natural Decks

Despite it's reputation, untreated wood decking can last a lifetime all on its own. Choosing the right species and grade of wood, and installing it properly, are the key steps to a long-lived, natural alternative to either pressure-treated wood decking or the composite wood options being popularized today. Although costly, real wood decking may also be the best choice for determined "green€


So what type of real wood is right for your deck? "As usual, there is no easy answer,€

says Steve Chappell, founder of the venerable Fox Maple School of Traditional Building, which focuses exclusively on green construction methods. "But in general, I would say start local and find the most rot-resistant wood at a local lumber yard. That's usually the most sustainable approach.€

Based in Brownfield, Maine, Chappell notes that local cedar can be a good decking material for homeowners in the Northeast, provided the lumber is selected carefully and installed with longevity in mind. In fact, there are some ironclad rules to follow when selecting and installing any decking lumber, whether ordinary domestics like western red cedar and cypress or fancy imports like ipé and meranti.

The Heart of the Matter

Before focusing on any single wood species for decking, it's critically important that homeowners understand something about rot-resistant lumber. Foremost is the issue of heartwood versus sapwood. Simply stated, sapwood rots when heartwood doesn't - even in the most rot-resistant species.

In most species, sapwood is noticeably lighter in color than heartwood and tends to be located at the edge, or on the "down side,€

of an individual decking plank. Regardless of its location, sapwood will rot years before the heartwood portion of the plank shows any deterioration at all. When ordering any untreated decking lumber, always specify "no sapwood.€

It's also important to order untreated decking lumber with a minimum of knots and sap pockets. The knots and sap pockets themselves are usually rot resistant, but the wood immediately around them often will get punky within a few years of exposure to rain and sun.

Knots and sap pockets also tend to make a decking plank warp or split because they can create uneven shrinkage and swelling within the plank. So it's also best to specify a high quality of decking lumber, requiring either "select€

or "clear€

grade planks. Note that "clear€

planks are sometimes called "firsts.€

Most decking lumber comes kiln dried, making it stable and easy to install, with little worry about excessive shrinkage, warping, splitting or cupping. But when venturing into the world of local rot-resistant lumber, kiln-dried decking planks are sometimes unavailable and "air-dried€

lumber is substituted. Air-dried lumber is fine, provided it's been properly air-dried a minimum of one year, with longer periods of air-drying time being better than less. Any lumber air-dried less than a year comes with a strong likelihood of warping, cupping and splitting after installation.

The Home Team Lineup

In any case, prices for domestic deck planking are between 30 and 70 percent more expensive than comparable pressure-treated planks. But nearly all species are less expensive than composite deck planking, which is usually a mix of wood fibers and recycled plastics. Composite planking runs between 90 and 120 percent more expensive than pressure-treated wood. Overall, though, deck-planking materials tend to be slightly less than half the cost of a professionally installed deck. The rest of the cost is in hired labor. Domestic wood decking species include the following:

€. Western red cedar. Among the most common and readily accessible deck lumber options, western red cedar is well known for its ability to resist decay for decades. But perhaps even more importantly, it is the most stable of all the domestic decking lumbers. It neither shrinks nor swells appreciatively as the weather cycles through dry and wet periods. This means a lower likelihood of splitting, of fasteners backing out or of big gaps opening up between planks.

Grown throughout the Pacific Northwest from California to Alaska, western red cedar is generally considered a sustainably harvested lumber, although a few smaller environmental groups may argue that point. It regenerates reasonably quickly in its native habitat, although it is not considered a fast-growing tree. It is usually only 30 to 40 percent more costly than a pressure-treated alternative.

€. Redwood. A bit more difficult to obtain than western red cedar, redwood is just as rot resistant as its West Coast brethren, with only slightly more tendency to shrink and swell seasonally. Redwood also darkens more when exposed to the sun. While western red cedar turns a medium gray in the sun, redwood changes to a more charcoal-gray color. Both woods take preservative and coloring stains equally well.

With the smaller supply area of redwood comes a heftier price tag for the lumber. Expect to pay 20 to 30 percent more than western red cedar. Also expect more objections from environmentalists who claim, with some justification, that the slower-growing redwood is being depleted in many West Coast forests. Since it grows in a much smaller area of the available Pacific forest region, redwood is sometimes difficult to obtain. There are, however, many redwood forests that are completely protected from any cutting for the lumber industry.

€. Other cedars. Some lesser-known cedars that are frequently available outside their growing area include Alaskan cedar, Port Orford cedar and Northern/Atlantic white cedar. Each one is naturally rot resistant but also has some distinctive features you must be aware of before specifying the wood for your deck.

For instance, Alaskan cedar (sometimes called yellow cedar) has a distinct raw potatoes or turnip-like smell that will be evident whenever it rains during the first year or so after installation. While the odor may be offensive to some, it does go away on its own or can be masked by virtually any finish. As its name indicates, Alaskan is found on the Pacific Coast from Alaska to Oregon.

Like Alaskan cedar, Port Orford cedar is a harder wood than western red cedar or redwood. But unlike Alaskan, its natural growing area is smaller, stretching from Oregon southward into California. A small problem with Port Orford cedar is the lack of a color difference between its sapwood and heartwood. Because they are almost the same color, the less rot-resistant sapwood sometimes ends up being used in a deck.

Although both Alaskan and Port Orford are shipped to East Coast markets, they are by no means as plentiful as Northern and Atlantic white cedar, which grow from the Carolinas northward into New Brunswick, Canada. Northern and Atlantic are botanically two different species but their lumber looks and acts so similarly that they are often sold together. Oddly, they are rarely shipped in great quantities west of the Mississippi. Their rot resistance is not as highly rated as western red cedar, but when installed properly, they can last decades, turning a light gray color when left untreated.

€. Localized options. Baldcypress is a fine wood for decking but it is rarely marketed outside its native Dixie habitat. Known by numerous other names (southern cypress, yellow cypress, Gulf cypress and others), it is best when sawn from old-growth trees. Shrinkage and swelling is greater than most cedars too.

Some hardwoods that make good decking lumber include osage orange in the Midwest, black locust in the Mid-Atlantic states, white oak from southern New York State to the Carolinas, and sassafras from the Virginias southward.

The Import Option

Imported wood can be more problematic for devoted green deck builders. Controls on how individual species are harvested are in place worldwide, but these controls are frequently circumvented by aggressive sawyers, unscrupulous exporters and the like.

Complicating matters are the numerous agencies that certify foreign lumber or logs for export. Led by the Forest Stewardship Council (FSC), there are at least half a dozen additional non-governmental agencies trying to curb illegal logging, not to mention government agencies that are supposed to help with export and import controls. And some environmental groups oppose the import of any lumber from tropical rain forests.

With that said, it's difficult to make blanket statements on what a local lumber company means when it advertises imported decking planks as being "certified.€

For devoted greenbuilders, it's best to find out which agency has done the certifying, look up the agency on the Internet and check to make sure the species being advertised is indeed covered by the certifying agency.

Commonly used imports run from 60 to 200 percent more expensive than local pressure-treated lumber. Wood species commonly imported for deck planking include the following:

€. Ipé. Pronounced ee-pay, this Brazilian hardwood solidified its reputation as a decking material when it was used recently to re-plank Atlantic City's famous oceanfront boardwalk. Hard, heavy, strong and more rot-resistant than the vast majority of common domestic decking woods, ipé has been designated by several non-governmental agencies as harvested in a sustainable manner. Indeed, there are ipé tree farms springing up in some tropical countries.

With all of its attributes, however, comes a heavy price tag. Ipé is frequently 90 to 130 percent more expensive than pressure-treated decking. It is also difficult to install; contractors generally charge extra for the additional labor time needed to deal with it. Newly installed, it has a noticeable earthy odor to it, which some find objectionable. But the smell disappears within a year. It is sometimes sold under the name "ironwood€

or "pau lope.€

€. Meranti. Also known as "luan€

or "Philippine mahogany,€

meranti is lightweight, strong and straight-grained, and generally knot-free. Significantly less expensive than ipé, meranti is also less durable - although if red meranti is specified, it will give decades of good service in ordinary conditions. A product of Southeast Asia and the East Indies, meranti is farmed as well as logged. It's been a marketable lumber for a lot longer than relative newcomer ipé, so it's easier to be confident that certified red meranti lumber actually is legitimate. Prices run between 70 and 100 percent more expensive than pressure-treated domestic lumber.

€. Teak, mahogany and other woods. The list of other highly rot-resistant imported woods is extensive, particularly if cost is no serious consideration. Teak is sometimes used and much of that harvest comes from tree farms, although there are still some "renegade€

countries that cut teak down in the forest willy-nilly. African mahogany tends to be harvested in a sustainable manner and often comes with legitimate certification. Spanish cedar is also farmed and can be obtained with reliable green certification, as well as a more reasonable price tag than many other imports. Afromosia, santa maria, iroko and cambara are some other imports that occasionally find their way into the deck lumber market.

A Proper Finish

Improper installation of even the most rot-resistant lumber can significantly shorten the life expectancy of a deck. Here are some general rules of thumb to keep in mind during the building process.

€. Keep all deck timbers from contact with either the ground or the cement foundation pillars.

€. Make sure there's an air space where the deck comes in contact with the house, as well as air spaces under any large clay plant pots.

€. Use nonferrous fastenings throughout.

€. Design the entire deck so there's a very slight slope away from the house, to ensure proper runoff of precipitation.

Finally, finishing a deck can lengthen its life. But if you don't plan to maintain the finish annually in southern climates, and at least every other year elsewhere, don't finish the deck at all. It will quickly end up looking like a multicolored mess. When finishing, use a penetrating, colored stain for long-lived results. Paints and oils usually don't last a summer. And the goal with any wood deck is to ensure, with proper installation and finishing, that it looks good and lasts for years to come.

Ken Textor wrote about energy-efficient sunrooms in the March/April 2006 issue of Smart HomeOwner. He's based in Arrowsic, Maine.