According to the American Wood Preservers Institute (AWPI), the North American building industry uses approximately 3.8 billion board feet of preservative treated lumber per year. Wood treatment refers to protecting wood from damage caused by insects, moisture and decay, and fungi. In wood-framed walls, treated wood is used as the base plate in contact with a concrete slab. Treated wood is also used in outdoor applications where the wood will be exposed to harsh conditions. These applications include decks, walkways, and direct ground contact. At present, there is not an environmentally sound method for disposal of treated wood. Every effort should be made to minimize the use of treated wood by using alternate materials or designing alternative details.

There are three primary methods of pressure treating wood: creosote, pentachlorophenol, and inorganic arsenical. The pressure-treating process is done by commercial facilities and made available to users in the final wood product. Copper napthenate, zinc napthenate, and tributyltin oxide are other wood treatment options that can be site applied. All of these treatment processes involve dangerous chemicals and all require adherence to safety precautions approved by EPA (see Guidelines).

EPA regulations govern the manufacture of pressure-treated materials and require extensive environmental safety precautions. Wood treatment does offer a method to extend the usable life of our wood resources, but treated wood should be handled carefully to protect against inhaling or ingesting its dust. It should not be burned, and should be considered toxic waste when disposing sawdust and scraps.

Chromated copper arsenate (CCA) has been the most popular wood treatment product available up until very recently. However, the presence of chromium, a heavy metal, and arsenic, which poses human health threats, has hastened the exploration of less harmful wood treatment alternatives. In early 2002, the EPA announced a phase-out of CCA treated wood products for residential and playground applications to be completed by December 31, 2003 (Other applications will still be permitted, such as marine pilings, utility poles and highway uses).

Several different alternatives to CCA treated wood currently exist.

ACQ

ACQ is a wood treatment containing alkaline copper and quaternary ammonium compounds. It does not contain arsenic or chromium. "Preserve" is a brand name for wood products treated with ACQ. Copper is the principal active ingredient, providing protection against termites and fungal decay.

Copper, boron, and azole treatments

CBA-A and CA-B are two different treatments that are formulated from copper, boron, and azole. As with ACQ, copper is the principal active ingredient, protecting against termites and fungal decay. Protection against copper-tolerant fungi is provided by an organic azole also used in fungicides applied to fruits, peanuts, and other crops. A third ingredient is boron acid, which is found in eyewash, vitamins, and antiseptics. In damp conditions, boron acid diffuses through wood and offers supplemental protection. This preservative is not a restricted use pesticide and does not meet the definition of hazardous waste. "Wolmanized Natural Select" is a brand name for wood products treated in this technique.

Testing has indicated that the above two treatment methods are more corrosive to metal fasteners and connectors than CCA treated wood previously was. Use of ACQ, CBA-A or CA-B might require the use of stainless steel connectors and fasteners or at least those with thicker galvanized coatings to withstand this higher corrosivity. Contact the treated wood chemical supplier for more specific information on this developing area of research.

Borate pressure-treated wood

Borate pressure-treated wood uses an EPA registered borate wood preservative for protection against termites, carpenter ants, and fungal decay. This type of wood can be used in aboveground, weather-protected structural framing in residential and commercial applications. However, full-scale commercial introduction of borates in the U.S. awaits resolution of the leaching problem of borates. Since borates are water soluble, water dilutes them and leaves the wood unprotected from decay after a period of time. In a location unexposed to water, borates are effective in preserving wood, and site-applied borate products are available.

Avoiding wood treatment

1. Use building methods that reduce moisture access to and/or build-up on wood products.

One method is to build a high enough foundation (at least 8-12 inches, frame grade) to reduce the chances of water-retaining soil building up against it. This is something that needs to be checked by the homeowner from time to time. Another method is to use a sturdy sheet of polyethylene plastic under the concrete slab to reduce moisture wicking up from the ground and through the concrete.

For pier foundations, be sure to remove water-absorbing forms that can retain water or attract termites. In addition, it is good practice to place a non-absorptive material between the concrete pier and wooden beams such as a plastic or metal anchor or plate. Proper building design and installation of building materials have the largest effect on opportunities for moisture to affect wooden building materials. Comprehensive understanding and maintenance of the thermal envelope of the home, including the HVAC and ventilation systems, also has a great effect on the control of the inevitable movement of moisture within the building.

2. Use building methods that hinder the attraction of termites to wood within the home.

The use of termite shields and barriers as well as other integrated pest management (IPM) practices described in the "Integrated Pest Management" section of this Sourcebook will be of great service in reducing the chances of a termite attack.

3. Use alternative materials to wood where possible and appropriate.

For wood frame buildings, building material alternatives such as lumber made of recycled plastic or wood/plastic composites are good options for moisture-prone areas such as sill plates, doorframes and thresholds, porches and outdoor decks, and stairs.

Fiber/cement or fiber/plastic materials for siding, roofing, soffits, and fascias are also good low-maintenance alternatives to wood because they do not rot or attract termites. Alternatives to wood framing such as steel, concrete, structural insulated panels, earth, and straw are also methods that eliminate most of the termite and some of the moisture problems associated with wood frame construction. Refer to other sections of this Sourcebook for information on these systems.

4. Use naturally pest resistant woods, such as Black Locust for fenceposts, or high resinous cedar.

Precautions

The U.S. Environmental Protection Agency requires that this information be available to persons using Inorganic Arsenical Pressure-Treated Wood (CCA), Pentachlorophenol Pressure-Treated Wood, and Creosote Pressure-Treated Wood.

Generic precautions for all types of treated wood

• Do not use treated wood under circumstances where the preservative may come in contact with food or animal feed, like food containers.
• Do not use treated wood for cutting-boards or countertops.
• Only treated wood that is visibly clean and free of surface residue should be used for patios, decks and walkways.
• Do not use treated wood for construction of those portions of beehives that may come into contact with honey.
• Treated wood should not be used where it may come into direct or indirect contact with public drinking water, except for uses involving incidental contact such as docks and bridges.
• Dispose of treated wood by ordinary trash collection or burial. It should not be burned in open fires or in stoves, fireplaces, or residential boilers because toxic chemicals may be produced as part of the smoke or ashes. Treated wood from commercial or industrial use (e.g., construction sites) may be burned only in commercial or industrial incinerators or boilers in accordance with state and federal regulations.
• Avoid frequent or prolonged inhalation of sawdust from treated wood. When sawing and machining treated wood, wear a dust mask, goggles, and protective clothing. Whenever possible, these operations should be performed outdoors to avoid indoor accumulations of airborne sawdust from treated wood.
• When power sawing and machining, wear goggles to protect eyes from flying particles.
• Wash exposed areas thoroughly after working with the wood and before eating, drinking and touching the eyes, nose or mouth.
• If preservatives or sawdust accumulate on clothes, launder before reuse. Wash work clothes separately from other household clothing.

Additional Precautions for Inorganic Arsenical Pressure-Treated Wood (CCA)

Wood pressure-treated with waterborne arsenical preservatives may be used inside residences as long as all sawdust and construction debris are cleaned up and disposed of after construction. Because of its leaching possibilities, use this wood in gardens and on roofs with rainwater catchment systems with caution.

Additional Precautions for Pentachlorophenol Pressure-Treated Wood

• Logs treated with pentachlorophenol should not be used for log homes or exposed in any way in a home's interior.
• Wood treated with pentachlorophenol should not be used where it will be in frequent or prolonged contact with bare skin (for example, chairs and other outdoor furniture), unless an effective sealer has been applied.
• Pentachlorophenol-treated wood should not be used in residential, industrial, or commercial interiors except for laminated beams or for building components which are in ground contact and are subject to decay or insect infestation, and where two coats of an appropriate sealer are applied. Sealers may be applied at the installation site.
• Wood treated with pentachlorophenol may be used in the interiors of farm buildings which are in ground contact and are subject to decay or insect infestation and where two coats of an appropriate sealer are applied, except where there may be direct contact with domestic animals or livestock which may bite or lick the wood. Sealers may be applied at the installation site.
• Do not use pentachlorophenol-treated wood for farrowing or brooding facilities.
• Do not use pentachlorophenol-treated wood where it may come into direct or indirect contact with drinking water for domestic animals or livestock, except for uses involving incidental contact such as docks and bridges.
• Urethane, shellac, latex, epoxy, enamel, and varnish are acceptable sealers for penta-chlorophenol-treated wood.

Additional Precautions for Creosote Pressure-Treated Wood

• Wood treated with creosote should not be used where it will be in frequent or prolonged contact with bare skin (for example, chairs and other outdoor furniture), unless an effective sealer has been applied.
• Creosote-treated wood should not be used in residential interiors. Creosote-treated wood may be used in interiors of industrial building components that are in ground contact and are subject to decay or insect infestation. For such uses, two coats of an appropriate sealer must be applied. Sealers may be applied at the installation site.
• Creosote-treated wood may be used in interiors of farm buildings for building components which are in ground contact and are subject to decay or insect infestation, and if two coats of an effective sealer are applied, except where there may be direct contact with domestic animals or livestock which may crib (bite) or lick the wood. Sealers may be applied at the installation site.
• Do not use creosote-treated wood for farrowing or brooding facilities.
• Do not use creosote-treated wood where it may come into direct or indirect contact with drinking water for domestic animals or livestock, except for uses involving incidental contact such as docks and bridges.
• Avoid frequent or prolonged skin contact with creosote-treated wood. When handling the treated wood, wear long-sleeved shirts and long pants and use gloves impervious to the chemicals (for example, gloves that are vinyl-coated).
• Coal tar pitch and coal tar pitch emulsion are effective sealers for creosote-treated wood block flooring. Urethane, epoxy and shellac are acceptable sealers for all creosote-treated wood.

Borate Site-Applied Products

Impel Rods

• Available in various sizes in a "glass" rod.
• Holes are drilled in the wood and the rods are inserted according to manufacturers' calculations that consider the size of the wood and the amount of boric acid needed to protect the wood.
• The rods contain boric acid that is absorbed by the wood when the moisture content of the wood exceeds 25 percent. The boric acid penetrates heartwood and sapwood, stopping decay.
• When the wood is dry the boric acid is inactive.
• In logs of 8-inch diameter, one rod per linear foot is needed (rod size is 3/4" x 3").

Auro Borax Wood Impregnation No. 111

• Effective against fungus; preventive against insects; suitable for brush application, spray application, or dipping.
• Must be diluted according to method of application, type of wood, and wood moisture content.
• Is corrosive in solution.

Tim-Bor

• Available in a powder form.
• Can be applied to wet lumber (over 20 percent moisture).
• Can be dipped or sprayed.

Bora-Care

• Available in a liquid form.
• Includes a glycol solution that helps diffusion.
• Can be dipped or sprayed.

ACQ (ammoniacal/alkaline copper quatenary)

• Used the same as CCA preserved material.
• Currently available in Texas but is 15% more costly than CCA.

CCA

• Available as Type A, B, and C. Type C is recommended as superior in resisting leaching.
• CCA preserved wood does not properly fix in wood in cold weather. If buying CCA treated wood in the winter (and the wood was treated in the winter), use extra care in handling and applying since leaching of the CCA is possible, posing an environmental and health risk. When buying CCA treated wood in warm weather (above 70 degrees), the chemicals should be fixed in the wood in 3-4 days.
• Protect CCA wood from UV degradation with a sealer.

Other chemical treatments

ACA (ammoniacal copper arsenate)
ACZA (ammoniacal copper zinc arsenate)
ACC (acid copper chromate)
CBA (copper boron azole)
SBX (sodium borates)
CS (copper citrate)
DOT (disodium octaborate tetrathydrate or "borates")
CZC (chromated zinc chloride)

These lesser-known water borne preservatives are used in hard-to-penetrate woods. Use the same safety precautions as outlined above.

Decay Resistant Domestic Woods

Along with cedar and redwood, the following woods are considered resistant or very resistant to decay: bald cypress (old growth), catalpa, black cherry, chestnut, Arizona cypress, junipers, black locust, mesquite, red mulberry, burr oak, chestnut oak, gambrel oak, Oregon white oak, post oak, white oak, osage orange, sassafras, black walnut, and Pacific yew.

Borate Pressure-Treated Lumber

• Any wood--engineered, sheathing, dimensional--can be treated by this method.
• Eliminates need for termite treatments and maintenance calls.
• Penetrates heartwood (CCA does not)
• Non-toxic for handling, cutting and disposal.
• Does not need to be site-treated on cut ends (CCA does)
• Cannot be used in contact with ground or water.

Southern Forest Experiment Station
Forest Sciences Lab
P. O. Box 906
Starkville, MS 39760
(601) 324-1611

Texas Forest Service
Forest Products Lab
P. O. Box 310, Hwy. 59 South
Lufkin, TX 75901
(409) 639-8180

Texas Forest Service
Texas A&M University
100 Research Parkway
College Station, TX 77843-2136
(409) 845-8575

Pressure treated materials are commonly available at all building material outlets

ACQ products
Austin Wholesale Decking Supply
10900 N Lamar Blvd.
Austin, TX 78753
(512) 834-1200
www.austinwholesaledecking.com
Preserve and Preserve Plus

North Texas Flameproof
2653 Warfield Ave.
Fort Worth, TX 76106
(972) 529-6200
Preserve and Preserve Plus

Borate products

Arch Wood Protection, Inc.
1955 Lake Park Dr., Ste. 250
Smyrna, GA 30080
(866) 789-4567
www.naturalselect.com
www.wolmanizedwood.com
"WolmanizedÆ Natural Select TM" copper azole treated lumber

Aztec Pest Service
3100 Fontana
Austin, TX 78704
(512) 443-0123

Tim-Bor
Chemical Specialties Inc. (CSI)
200 East Woodlawn Rd., Ste. 250
Charlotte, NC 28217
(800) 421-8661
(704) 522-0825
www.treatedwood.com
Impel Rods (Borate), "ACQ Preserve" and "Preserve Plus"(has built-in water repellant) treated lumber

Common Sense Pest Management
920 East 11th St.
Austin, TX 78702
(512) 476-5577

Eco-Wise
110 W. Elizabeth
Austin, TX 78704
(512) 326-4474
www.ecowise.com
Auro products

Environment Sensitive Pest Control
726 Oakwood Loop
San Marcos, TX 78666
(512) 754-7774
www.kennpest.com
Tim-Bor

Nisus Corp.
Cherokee Place
215 Dunavant Dr.
Rockford, TN 73853
(800) 264-0870
www.nisuscorp.com
Bora-Careô

Osmose, Inc.
Wood Preserving Division
1016 Everee Inn Rd.
Griffin, GA 30224
(800) 241-0240
Fax: (770) 229-5225
www.osmose.com
"NatureWood" ACQ treated lumber, "Advance Guard" borate pressure-treated wood

Term-Trol
8908 Georgian Dr.
Austin, TX 78753
(512) 836-3309
Tim-Bor

American Forest and Paper Association
1111 19th Ave. NW, Ste. 800
Washington, DC 20036
(202) 463-2700
www.afandpa.org

American Wood Preservers Association
P. O. Box 5690
Granbury, TX 76049-0690
(817) 326-6300
www.awpa.com

American Wood Preservers Institute
2750 Prosperity Ave., Ste. 550
Fairfax, VA 22031-4312
800-356-AWPI
(703) 204-0500
www.preservedwood.com
www.awpi.org

Bio Integral Resource Center
P.O. Box 7414
Berkeley, CA 94707
(510) 524-2567
www.igc.apc.org
Non-profit education organization produces publications, newsletters, and handbooks

Southern Forest Products Association (Southern Pine Council)
Treated and Residential Markets Manager
P. O. Box 641700
Kenner, LA 70064-1700
(504) 443-4464
www.sfpa.org
www.southernpine.com