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Explore the options for preserved wood for home projects in the PreserveTech overview on preservatives from Western Wood Preservers Institute. This 2-page sheet details the waterborne preservatives that are used in products for decks and other outdoor structures.

Preservatives Used Today

Preserved Wood Deck

Users today have a variety of preserved wood products to choose from that offer the durability and performance needed for any application. The preservatives available today contain components that are approved by the EPA and provide an effective way to preserve the natural benefits of wood.

The requirements for penetration and retention of preservatives in the wood are set by national consensus standards administered by the American Wood Protection Association (AWPA). Treating companies in the West use preservatives that have been approved by the AWPA.

There are two types of preservatives available: waterborne and oil-type. Waterborne preservatives are commonly available in the retail marketplace. Oil-type preservatives are most often used in commercial/industrial applications.

Waterborne Preservatives

Found in preserved wood products used in residential and some commercial applications, waterborne preservatives are typically promoted and sold under the brand names of the preservatives rather than the acronyms of the chemicals in each formulation. Click below to review the formulation, preservative brands, common species available, code compliance for preserving, use options and typical locations for purchasing.

ACQ, or Alkaline Copper Quaternary, is a soluble copper-based preservative that provides long-term protection against fungal decay and termite attack. The main preservative in ACQ is copper, which has been used for centuries in controlling fungi. The amount of copper in a 2x6 board, 12 feet in length that has been pressure treated with ACQ for ground contact contains the equivalent of 24 copper pennies.

Quaternary biocides such as DDAC, are similar to chemicals used in kitchen disinfectant cleaners and to prevent algae in swimming pools.

Brands:  Preserve® ACQ, NatureWood®
Species:  Douglas Fir, Hem-Fir, Southern Yellow Pine
Use: Above ground, ground contact, fresh water contact, salt water splash
Availability: Home centers, lumber yards, distributors
Safety Sheets: Preserve ACQ®, NatureWood®

Ammoniacal Copper Zinc Arsenate , or ACZA, is commonly known by its brand name Chemonite. ACZA-treated wood has been used in commercial and industrial applications since the 1930s.

ACZA preserved wood is often used in aquatic environments, docks, piers and applications where it will be exposed to water. It is also used in treating utility poles, railroad ties, foundation pilings, structural timbers and permanent wood foundations.

Brands:  Chemonite®
Species:  Douglas Fir, Hem-Fir, Southern Yellow Pine
Use: Above ground, ground contact, fresh water contact, salt water splash
Availability: Specialty lumber yards, distributors
Safety Sheets: Chemonite®

Copper Azole-treated wood is often sold under the trade name Wolmanized Outdoor Wood. Copper is main preservative, accounting for 96% of the active ingredients. A 2x6 board, 12 feet in length, treated with Copper Azole to ground contact contains the equivalent of 13 copper pennies.

Azoles serve as a co-biocide to protect against decay fungi and termites.

Brands:  Wolmanized® Outdoor® Wood, Preserve® CA, NatureWood® CA
Species:  Douglas Fir, Hem-Fir, Southern Yellow Pine
Use: Above ground, ground contact, fresh water contact, salt water splash
Availability: Home centers, lumber yards, distributors
Safety Sheets: Wolmanized® Outdoor Wood, Preserve® CA, NatureWood® CA

CCA treated lumber was voluntarily removed from residential construction by the preserved wood industry in 2003.

CCA is not available in lumber dimensions except by special order allowed by the EPA for use in permanent wood foundations. CCA is also allowed for shakes & shingles, along with commercial applications such as aquatic, highway, utility and others where it is used in larger dimensions and in plywood. For a list of approved uses for CCA products, visit the EPA website.

Brands:  SupaTimber®, Koppers CCA, Wolmanized® CCA
Species:  Douglas Fir, Hem-Fir, Southern Yellow Pine
Use: Non-residential construction: Above ground, ground contact, fresh/salt water immersion. Residential construction: plywood, shakes and shingles, permanent wood foundations
Availability: Specialty lumber yards, distributors
Safety Sheets: SupaTimber®, Koppers CCA, Wolmanized® CCA

PTI is a carbon-based preservative that is used exclusively in above ground applications, such as deck boards and railings.

PTI consists mainly of Azole biocides, which are considered safe and are similar to those used in other household products. The preservative has earned a Good Housekeeping Seal and is certified as a termite-resistant material in the National Green Building Standard.

Brands:  Wolmanized® EraWood®, Nexwood®
Species:  Douglas Fir, Hem-Fir, Southern Yellow Pine
Use: Above ground only
Availability: Home centers, lumber yards, distributors
Safety Sheets: Wolmanized® EraWood®

Sold under the trade name Ecolife, this carbon-based wood preservative is used exclusively for above ground applications, from exterior deck boards to outdoor furniture.

While protecting against termites and fungi, the preservative also acts as a stabilizer for the wood, helping maintain dimensional stability.

Brands:  Ecolife® 
Species:  Douglas Fir, Hem-Fir, Southern Yellow Pine
Use: Above ground only
Availability: Home centers, lumber yards, distributors
Safety Sheets: Ecolife®

SBX is an inorganic boron used to prevent termites and fungal decay. It may also be referred to as DOT.

Sodium borate is water soluble and is only used in interior applications, such as sill plates or where it is continually protected from water. It shares similar ingredients that may be found in consumer products such as eye drops.

Brands:  AdvanceGuard®, HiBor®, SilBor®, TimberSaver®, TimBor® TimberSaver®
Species:  Douglas Fir, Hem-Fir, Southern Yellow Pine
Use: Interior applications; “where its application is continually protected from liquid water.”
Availability: Home centers, lumber yards, distributors
Safety Sheets: AdvanceGuard®, HiBor®, SilBor®, TimberSaver®, TimBor®

Oil-Type Preservatives

As the name notes, oil-type preservatives are formulated from petroleum products. They are suited for demanding exposures where the maximum protection is needed. Click below for more information on these important preservatives.

Copper Naphthenate is an industrial strength, oil-type wood preservative with proven performance and a superior environmental profile. It has clean handling characteristics with virtually no dripping or bleeding.

Copper Naphthenate is commonly used to field treat cuts and holes in preserved wood made during construction. It is classified as a general use preservative by EPA, is considered acceptable for consumer use and can be purchased at building supply centers.

The preservative meets AWPA standards for the pressure treatment of utility poles, railroad crossties, bridge timbers, fence products and laminated wood beams. It is also standardized by AREMA for railroad crossties and bridge timbers and by AASHTO for highway components.

Utilities and others use Copper Naphthenate as a remedial treatment for wood poles and bridge timbers. The preservative may also be used in conjunction with DOT borate treatments for railroad crossties.

Brands: QNAP®
Species:  Douglas Fir, Hem-Fir, Western Red Cedar, Southern Yellow Pine
Use: Above ground, ground contact, fresh water contact, field treatment
Availability: Home centers, lumber yards, distributors
Safety Sheets: QNAP®

Creosote has been successfully used as a preservative for well over a century. Its most prominent and recognized application is in the production of wooden railroad ties. However, it is also used extensively in marine pilings and wooden utility poles.

Through the years, creosote-treated wood has been among the most economical and highest performing preserved wood products, as well as offering a lower total environmental impact.

Brands: Not typically branded
Species:  Douglas Fir, Hem-Fir, Western Red Cedar, Southern Yellow Pine
Use: Above ground, ground contact, fresh water contact, salt water splash
Availability: Order direct from manufacturers

Pentachlorophenol, commonly referred to as Penta, is an industrial strength preservative that is primarily used in the treatment of wooden utility poles. The light honey brown color of wood treated with Penta adds to its aesthetic appeal.

Penta is very effective in resisting fungal decay and wood poles treated with Penta have been known to last  70 years or more. Penta has historically been dissolved in diesel oil for pressure treating wood. More recently biodiesel has been used as a carrier for Penta. This has virtually eliminated the offensive solvent petroleum smell of a freshly treated pole. Biodiesel is also a more sustainable alternative to petroleum-derived diesel fuel since it is produced from renewable sources such as corn and soybeans.

Penta is one of the few industrial strength preservatives where wood treated with it can be burned in biomass-fed power generating facilities, thus adding to its promotion as a sustainable alternative for the preservation of wood poles.

Brands: Not typically branded
Species:  Douglas Fir, Hem-Fir, Western Red Cedar, Southern Yellow Pine
Use: Above ground, ground contact, fresh water contact, salt water splash
Availability: Order direct from manufacturers

IPBC is a biocide used as a preservative for wood, as well as in some cosmetics and in HVAC ducts to control mold and fungi. It has been in use since 1975 and can be found in over-the-counter stains and water repellents.

Brands: Not typically branded
Species:  Douglas Fir, Hem-Fir, Western Red Cedar, Southern Yellow Pine
Use: Above ground, ground contact, fresh water contact, salt water splash
Availability: Order direct from manufacturers