Pressure treated wood grows in acceptance, use

ByHrry Anton Regional Representative WWPA Field Senices Dept. Marletta, Ga.

nessuRE-TREATED wood

6a5 grown rapidly in acc@tance and use during the past five years, and now is being used structurallY and non-structurally in fences, decks, farm buildings, marine structures and in the residential wood foundation.

Wood is man's most versatile Product, but because it is a natural product it is subject to decay and insect attack. These natural enemies can greatly affect the seivice life and strength of wood products. Chemical preservatives are one way to make wood resistant to fungusgrowth and insect attack.

Fungi need four generalconditions to live and cause decay: (1) ProPer temperature, generallY between 50 and 90 degrees; (2) moisture content in excess of ?.0s/o; (3) air, particularly oxygen, and (4) a food source, such as wood fiber. Pressure treatment of wood fiber eliminates it as a food source.

The most common types of Pressure chemical treatments sold today by retailers are known as the "waterborne salts." They are most preferred because they leave the treated surface relatively clean, paintable, and odor free, and can be used both inside and out.

There are a number of different water-borne preservatives available to the treater, but the one most commonly used is CCA, chromated coPper arsenate. The copper base gives the wood a green color and makes it easy to recognize from untreated wood. CCA treated lumber is known by different trade names. The KoPpers Company uses the term "OutdoorWood" and "Wolmanizing" to describe its CCA treated lumber. The Osmose CompanY uses the names "All-Weather Wood," "AllSeasons Wood," or "Osmose K-33," to describe its CCA treated lumber. Other companies use names such as "Green Salt" and "Langwood." Whatever the trade name, the lumber is treated with CCA salt compound.

Different lwels of Protection are provided by pressure-treated wood. The American Wood Preservers Bureau (AWPB) writes standards for presure treating for various species of wood with different types of chemicals and treating processes, including the water-borne CCA Pressure treatment. AWPB also provides a quality control program which checks to make sure that treated lumber is properly treated. Standards whichretailers should be aware of are LP-2 for above ground use, such as fences and deck boards; or LP-22 for glound contact for such as fence posts, or for immersion such as dock pilings; and the FDN Standard for use in the wood foundation. These three standards are differentiated by the amount of chemical preservatives retained in the wood. The LP-22 standard requires more chemicals, .40 pounds per cubic foot of wood, and the FDN Standard requires even more chemicals, .60 Per cubic foot.

In addition to the chemical retention requirements, AWPB or other

Sfory at a Glance

Pressure trcatedwood continues to galn acceptance. dllferent trsatlng standards lor dlfferenl uses. retaller should know best specles lol customer.

quality control agencies must check for additional treating requirements, including the depth of chemicd p€netration, the moisture cont€nt of thewood at thetimeof treatmcnt(25 moisture content, 25 MC, or less)' the p€rcentage of heartwood and sapwood (heartwood is very difficult to treat), and the spccies of wood being treated. Due to natural characteristics, some species treat bett€r than others.

C€A waterborne salt treatmcots work best on species which are mostly sapwood. Ponderosa pine, Southcrn yellow pine and, around the Great lakes, red Norway) Pine are used almost exclusively for CCA treatment. These three species do not re' quire "incising" to ace1f, the pmper amount of chemicals fortreatment, so they grve a nicer aPPearance after treatment. All other species require the cutting of tiny holes in the surface of the wood, incising, for ProPer treatment lertels.

Treated lumber is identified bY a "quality mark" much the same as lumber is identifi ed by a grade stamp. A qudity mark identifies the treater, the quality control agency, standards used for treating, the type of chemicals used, and in what Year it was treated. The quality marks assure the dealer, the user, and other interested parties, such as building inspectors' that this is properly treated for its intended use.

Because the CCA chenicals are carried into the wood by water, all treated lumber should bc redried to is original moisture content level. Lumber that is "kiln dried after treatment" (KDAT) will maintain stability and have a dry, paintable surface. All dry, treated lumber

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UESTION: when a local building official questions a builder's use of a Western wood product supplied by your yard, or you have a question about proper usage of a specific grade of Western lumber, where do you turn for help?

Answer: The Western Wood Products Association Field Services staff. With managers in every region of the country, w€ are ready, willing and able to provide the technical expertise you need on any Western wood product.

But we're more than just a group of troubleshooters. Our primary goal is solving problems before they happen. We do this through education, providing dealers and their employees, builders, architects and engineers, and local building officials with the technical information and know-how needed to sell and use Western wood products effectively.

Using the time and talents of onlyI I men, the WWPA field services staff tries to reach every city and town in the entire country. It's an ambitious program. We distribute product information, answer questions, and, just as importantly, learn and listen. Part of our job is to gather market information for the manufacturers we represent to help them meet market demands.

Each WWPA field services manager has strengths and experience in the field of architecture, building or lumber manufacturing. But just as importantly, each knows how to effectively present that information and deal with people. Good communication is the key to our success.

With a limited staff, we've had to come up with some innovative ways to achieve these goals. And that's just what we've done. In the last four years we have developed a successful program with a two-pronged approach.

First, we've targeted our calls, focusing on people we call "influentials" in each segment of the industry. These are the people who can get things rolling, starting a chain reaction.

Secondly, we have created a series of highly acclaimed professional seminars for building supply retailers. In the typical seminar, retailers and their staff spend an intensive seven hours learning about lumber manufacturing, grades, species, specifications, storage and usage, span tables, rights under reinspections, and so on. The