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All Hands on Deck

New wood treatments, plastic lumber seek share of insect- and rot-resistant timber market

August 9, 2004 | A version of this story appeared in Volume 82, Issue 32

Plastic/composite lumber (left) and wood pressure-treated with chemicals other than chromated copper arsenate (right) are choices for outdoor projects.
Plastic/composite lumber (left) and wood pressure-treated with chemicals other than chromated copper arsenate (right) are choices for outdoor projects.

When U.S. homeowners think of building a deck for their summertime enjoyment, most of them likely think of pressure-treated wood. Such wood, predominantly made by infusing southern pine under high pressure with chromated copper arsenate (CCA), has been the mainstay of outdoor builders because of its weather and insect resistance. But now they have more choices to consider, including composites of plastics and wood.

It might have taken marketers much longer to gain share of mind for alternative decking and railing materials but for a dispute a little more than two years ago between environmental groups and the major pressure-treatment chemical makers.

The Healthy Building Network and the Environmental Working Group argued that wood infused with CCA and used to make playground equipment exposed children to unsafe levels of arsenic, which fends off rot and termite damage but is a carcinogen. CCA producers voluntarily agreed to withdraw Environmental Protection Agency registration for their product in residential uses, though they say CCA-treated wood poses little hazard.

Beginning on Jan. 1 of this year, a ban went into effect on CCA treatment of lumber intended for play structures, decks, landscaping timbers, patios, and walkways. Now that CCA-treated wood is no longer available for use where people could come into contact with it, consumers have several new options.

Pressure-treated wood is still available; it's just treated with compounds other than CCA. Two of the three major CCA formulators--Osmose and Rockwood Specialties subsidiary Chemical Specialties--supply ammoniacal copper quaternary (ACQ) compounds, which have been on the market since 1996. The third, Arch Chemicals, supplies copper azole (CA), which has been around since 1992. The two treatment alternatives add about 20% to the cost of treated southern pine--the species of wood most often used in the U.S.--compared with CCA-treated pine.

Other wood alternatives include naturally rot- and insect-resistant redwood, cedar, and mahogany--all of which can be two to three times as expensive as pressure-treated pine. And there are the new, also more expensive, challengers: extruded all plastic and wood/plastic composites. Like ACQ- and CA-treated wood, they have been around for only about a decade. But because pressure-treated wood has received so much scrutiny, consumers are considering such alternatives.

THE SIZE of the U.S. market at the producer level for decking and railing, but not including structural lumber, was about $4 billion in 2003, says Jim Morton, a senior partner with the consulting firm Principia Partners. He estimates that pressure-treated woods account for 60%, or $2.4 billion, of that market. Extruded wood/plastic composites already have a 15% share. By 2010, Morton expects wood/plastic composites to garner nearly 30% of an even larger market.

Morton sees sales opportunities for makers of both recycled and virgin plastics. Producers of additives incorporated into composites such as lubricants, ultraviolet light stabilizers, pigments, and biocides will have opportunities, too. Two years ago, when the consulting firm studied the market for such additives, it predicted demand would grow from $57 million in 2001 to $120 million by 2006. Principia is planning a conference in October on how plastics suppliers, additive makers, and composite producers can realize the full potential of this burgeoning market.

While wood treatment chemical formulators recognize that consumers have alternatives to pressure-treated lumber, they say low cost and good performance will keep treated-wood products competitive with plastics and composites. Huck DeVenzio, a spokesman for Arch Treatment Technologies, acknowledges that pressure-treated wood is likely to lose some ground. "Pressure-treating companies are in some cases distributing composite lumber or making composite decking themselves," he says.

The shift from CCA to the alternatives has gone smoothly for consumers who pick up lumber at their local lumberyard or home improvement store, but it has been awkward for the pressure treaters and professional installers, DeVenzio says. For the pressure treaters, the new chemicals are pricier. CA also requires more moldicide, and it arrives in a less concentrated form than CCA. This means treaters have had to expand storage space for chemicals. They also have had to upgrade their treating equipment because the new chemistry is more corrosive than CCA, he says.

Corrosion was also a sticking point with professional installers. Early tests showed that metal in contact with the new chemicals corrodes faster than with CCA, DeVenzio says. While specifications called for galvanized fasteners to be used with CCA lumber, the newer wood treatment requires heavier galvanized hardware or stainless steel.

Higher costs made for some unhappy wood treaters and professional installers, DeVenzio admits. However, "We are still the lowest priced alternative," he says.

David Fowlie, vice president of sales for Chemical Specialties, also acknowledges that the ACQ treatment his firm developed--and which won a Presidential Green Chemistry Challenge Award in 2002--is more expensive than CCA. But he says the 10 to 20% impact is negligible considering the frequently large swings in the price of lumber and plywood.

Fowlie, whose firm licenses ACQ technology to Osmose, says he thinks that ACQ will be around for a long time despite the challenge from wood/plastic composites. Mold is not a problem for ACQ-treated wood since the quaternary ammonium compounds are good mold inhibitors and do well with the same level of mold-inhibiting isothiazolin that is incorporated into CCA-treated lumber.

Fowlie and DeVenzio both say that another wood preservation technique, pressure treatment with borates, should be reserved for interior use only to prevent infestations from termites and similar wood-destroying pests. Arch, Osmose, and Chemical Specialties all provide borate products to pressure treaters. Though borates have a good environmental profile, executives from these firms say borates readily leach from wood exposed to the weather.

However, a start-up firm called Wood Treatment Products claims to have found a way to fix disodium octoborate tetrahydrate in wood. When the wood is pressure-treated twice--first with the borate solution and then with a silicate binder--Jack Rombough, the firm's general manager, claims the borate-based treatment will endure outdoors. The firm is working on building code acceptance for its product and says two wood treaters are using its chemistry for lumber that is not subject to code restrictions.

The jury is still out on whether this borate will provide yet a third pressure treatment option for the decking market. But the future clearly lies with plastic lumber and wood/plastic composites.


GROWTH in this category is due in part to efforts, supported by the American Plastics Council (APC), to gain building code acceptance for the new material. Prabhat Krishnaswamy, vice president of Engineering Mechanics Corp., says APC sponsored his work to help write the International Code Council (ICC) standards for plastic and composite decking and railing adopted by most local building code enforcement agencies.

Engineers are also working with ICC to develop codes that would allow use of plastics and composites for joists, posts, beams, and girders. Such products are already found in commercial demonstration projects, and codes allowing these uses could be published later this year, allowing wide adoption of structural plastic lumber, Krishnaswamy says.

Plastic and composite lumber, however, are not likely to see growth in structural applications as rapid as they've experienced in decking. Given prices today, most composite producers agree that composite decks are affordable only with a pressure-treated understructure.

"A pressure-treated understructure and a Trex deck and railing make a good marriage," says Maureen Murray, spokeswoman for Trex, the largest maker of wood/plastic composites, with 2003 sales of $191 million. The firm, spun out of Mobil in 1996 and now a public company, combines waste wood from furniture manufacturing with polyethylene mostly captured from recycled grocery bags to make extruded decking and railing materials.

Consumers are willing to pay extra for composites, Murray points out, because they do not splinter like wood and require less maintenance. But the firm has its critics. The Superior Court of New Jersey certified a nationwide class-action lawsuit against Trex at the end of May. The suit alleges that Trex products rot, splinter, and degrade. It seeks reimbursement for deck customers to fund repairs and replacement. Trex says the claims are unfounded.

U.S. Plastic Lumber also has had its problems. The firm, which makes all-plastic and composite lumber and has about $30 million in annual sales, voluntarily filed for bankruptcy reorganization at the end of July because of a weak balance sheet. While the firm would not comment, sources say that a wood drier explosion and warranty claims on disintegrating decking accounted in part for the financial crunch.

Although composite lumber has experienced some growing pains, Principia's Morton is bullish on its continued growth prospects. Big construction materials makers, including CertainTeed, Louisiana-Pacific, and Alcoa Home Exteriors, are taking an interest in the market, he says.

Thanks to the involvement of these firms and the growth of the composite lumber category, the industry is set to enter a new phase of growth. Pressure-treated lumber will be around, Morton says, but mainly for structural supports. He predicts that composite producers "won't just be mixing waste streams. They will be taking more of a science-based approach" in the future as specialty chemical firms and plastics producers take a greater interest in the growing category.


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