ACQ Treated Wood from Great Southern Wood

Wood products treated with ACQ (Alkaline Copper Quaternary) preservatives are available to retailers, consumers, builders and architects for outdoor building projects that require protection against rot, fungal decay and termite attack. ACQ treated products have been commercially used since 1991 throughout Europe, Asia, and the United States. and can be used for many backyard and commercial projects such as decks, fences and landscaping.

They are:

● Durable and designed for outdoor construction.

● Lifetime Residential and Agricultural Limited Warranty against structural damage caused by fungal decay and termites. Click here for specific warranty provisions.

● Limited 15 Year Warranty on Fence Boards. Click here for specific warranty provisions.

● Use for structural lumber, sill plates, outdoor furniture, patios, decks, garden edging, and landscaping structures

● Building code compliant

● Copper-based preservative with a co-biocide

● ACQ preservatives meet AWPA standards.

ACQ Weathering Information

Freshly treated ACQ products begin with a dark, greenish color and will over time turn to a light tan/brown color upon exposure to sunlight. As with most outdoor wood products, they will eventually fade to gray over time.

Characteristics of the ACQ Preservative

Based on the well-established effectiveness of copper combined with an organic quaternary compound applied to wood by pressure treatment, the alkaline copper quaternary preservative system from Osmose, Inc. provides long-term protection of wood exposed in exterior applications. Copper and quaternary compounds are effective fungicides and termiticides. Together they provide protection from a broad spectrum of fungi and termites. The active ingredients in products treated with ACQ preservatives, copper oxide and quaternary compounds, are dissolved in an alkaline carrier. Depending on the desired product application, wood species, and exposure hazard, the ACQ preservative system may be formulated with a number of specialty additives such as water repellents to enhance product performance.

Characteristics of ACQ Preserved Wood Products

Properly treated and processed products with ACQ preservatives are similar to traditional pressure treated wood products - both are pressure treated, long lasting, durable, clean to the touch and have no objectionable odor. More than a decade of field test performance and commercial use worldwide establishes the proven effectiveness of ACQ and the preservative technology for protecting against termites and fungal decay. Products treated with ACQ preservatives offer termite and fungal decay protection similar to that of traditional treated wood. Ground contact testing of treated stakes confirm that while untreated Southern Yellow Pine stakes fail in less than 5 years, stakes preserved with ACQ preservatives perform similarly to traditionally treated stakes.

Products treated with ACQ preservatives are available in many softwood species. Approved uses include: Above Ground 5/4" Decking & Specialties, Above Ground General Use, and Ground Contact. ACQ treated products are building code compliant.

Warranty Information

A Lifetime Residential and Agricultural Limited Warranty is offered on products with ACQ preservatives for material used in residential and agricultural applications, plus a limited 15 year warranty is offered on fence boards treated with ACQ preservatives. Click here for specific warranty provisions.







Fastener Information

Wood products treated with ACQ preservatives are designed for long-term performance in outdoor applications and, therefore, require high quality, corrosion-resistant nails, screws, and hardware. Use hot-dip galvanized (conforming to ASTM Standards: ASTM A153 for hot-dip fasteners and ASTM A653, Coating Designation G-185 for hot-dip connectors and sheet products), type 304 or 316 stainless steel, or other fasteners and hardware as recommended by the hardware manufacturer. Direct contact of products treated with ACQ preservatives with aluminum fasteners is not recommended. See “Important Information” below.

Regulatory Requirements

The preservative technology used in treated wood products with ACQ preservatives is registered by EPA as a non-restricted use pesticide and does not require Proposition 65 labeling in California. ACQ treated products, as described in National Evaluation Report - NER# 628, are building code compliant.

  • Use corrosion-resistant fasteners. Wood products treated with ACQ preservatives are designed for long-term performance in outdoor applications and, therefore, require high quality, corrosion-resistant nails, screws, and hardware.  Fasteners (and other metal products) for use with wood products treated with ACQ preservatives include:

    - Hot-Dip Galvanized*

    Fastener, hardware and other metal products manufacturers have suggested the minimum hot-dip galvanized requirements for use with treated wood should conform to the following ASTM Standards: ASTM A153 (for hot-dip fastener products) and ASTM A653 (Coating Designation G-185 for hot-dip connector and sheet products).

    - Stainless Steel

    Stainless steel fasteners and connectors are required for Permanent Wood Foundations below grade and are recommended for use with treated wood in other severe exterior applications such as swimming pools, salt water exposure, etc. - Type 304 and 316 are the recommended grades to use.

    - Other fasteners, hardware and other metal products as recommended by the manufacturer

    There may be additional products (other than stainless steel or hot-dip galvanized), which are suitable for use with ACQ treated wood. Please consult with the individual fastener or hardware manufacturer for recommendations for use of their products with ACQ treated wood.

    - Aluminum should not be used in direct contact with wood products treated with ACQ preservatives

    Spacer materials or other physical barriers are recommended to prevent direct contact of wood treated with ACQ and aluminum building products. When using products treated with ACQ in close proximity to aluminum, such as aluminum siding, flashing, furniture, and door and window frames, a 1/4" minimum spacing must be allowed for between the treated wood and the aluminum products. Another option is to use a polyethylene barrier, with a minimum thickness of 10 mils, between the ACQ treated wood and the aluminum product to prevent direct contact of the wood and the aluminum. Certain adhesives add extra holding power. Apply adhesives in accordance with manufacturer's directions.

    * Electroplated galvanized fastener and metal products are typically not accepted by the building codes for use in exterior applications, regardless of the type of wood used.

    Click here for a printer friendly version of our Fastener Information Sheet

  • When appearance permits, attach boards bark side up.

    As a general rule, attach boards bark side up (annual rings arc upward) to reduce cupping; however, the best face should be placed up when a defect of the wood is apparent. Fasten thin boards to thicker boards to maintain structural integrity.

  • Drill pilot holes.

    Drill pilot holes especially when nailing or screwing near the edge or end of a board. Pilot holes will help minimize splitting.

  • Use an endcoat preservative.

    Brush-on endcoat wood preservative is recommended on all saw cuts and in drill holes during construction of wood projects. Also apply on areas where moisture can collect. Always follow manufacturer's recommendations. 

    The moisture content of pressure treated wood products can vary. If the moisture content of the treated wood is high, deck boards should be butted together because spaces will occur between the boards as they lose moisture content in service. If the wood has been kiln dried after treatment or otherwise has low moisture content, a 1/8” spacing is recommended.

    Mold growth can and does occur on the surface of many products, including untreated and treated wood, during prolonged surface exposure to excessive moisture conditions. To remove mold from the treated wood surface, wood should be allowed to dry. Typically, mild soap and water can be used to remove remaining surface mold. For more information visit www.epa.gov.

    The ACQ preservatives penetrate deeply into and will remain in the wood for a long period of time. Some preservative may migrate from the treated wood into soil/water or may dislodge from the treated wood surface upon contact with skin. Wash exposed skin areas thoroughly.






    IMPORTANT INFORMATION

    ● Consult the end tag to determine which preservative or preservative system was used in the treatment of that particular product.

    Warning-Certain metal products (including fasteners, hardware and flashing) may corrode when in direct contact with wood products treated with ACQ preservatives. To prevent premature corrosion and failure, consult the end tag to determine which preservative or preservative treatment was used and follow the metal products manufacturers’ recommendations (including Fastener Information Sheets, if any) as they relate to the specific preservative or preservative system indicated on the end tag.

    ● Warning-Do not use wood treated with ACQ (Alkaline Copper Quaternary) in direct contact with aluminum.

    ● Use fasteners and other hardware which are in compliance with building codes for the intended use.

    ● Do not burn preserved wood.

    ● Wear a dust mask and goggles when cutting or sanding wood.

    ● Wear gloves when working with wood.

    ● Some preservative may migrate from the treated wood into soil/water or may dislodge from the treated wood surface upon contact with skin. Wash exposed skin areas thoroughly.

    ● All sawdust and construction debris should be cleaned up and disposed of after construction.

    ● Wash work clothes separately from other household clothing before reuse.

    ● Preserved wood should not be used where it may come into direct or indirect contact with drinking water, except for uses involving incidental contact such as fresh water docks and bridges.

    ● Do not use preserved wood under circumstances where the preservative may become a component of food, animal feed or beehives.

    ● Do not use preserved wood as mulch.

    ● Only preserved wood that is visibly clean and free of surface residue should be used.

    ● If the wood is to be used in an interior application and becomes wet during construction, it should be allowed to dry before being covered or enclosed.

    ● If you desire to apply a paint, stain, clear water repellant or other finish to your preservative treated wood, we recommend following the manufacturer's instructions and label of the finishing product.  Before you start, we recommend you apply the finishing product to a small exposed test area before finishing the entire project to insure it provides the intended result before proceeding.

    ● Projects should be designed and installed in accordance with federal, state and local building codes and ordinances governing the construction in your area, and in accordance with the National Design Specifications (NDS) and the Wood Handbook.

    ● Mold growth can and does occur on the surface of many products, including untreated and treated wood, during prolonged surface exposure to excessive moisture conditions. To remove mold from the treated wood surface, wood should be allowed to dry. Typically, mild soap and water can be used to remove remaining surface mold. For more information visit www.epa.gov.

    ● Disposal Recommendations: Preserved wood may be disposed of in landfills or burned in commercial or industrial incinerators or boilers in accordance with federal, state and local regulations.



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