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Frequently Asked Questions
The NatureWood® wood preservative is a waterborne preservative system developed to provide long-term protection of wood exposed in exterior applications. The NatureWood® chemical treatment is based on the well-established effectiveness of copper combined with a co-biocide and is applied to wood by pressure treatment.
The NatureWood® lumber preservative system meets all major model building code requirements. NatureWood® is an American Wood Protection Association (AWPA) standardized wood preservative.
NatureWood® treated lumber and other wood products are available for: Above Ground, Ground Contact and Fresh Water Contact. NatureWood® products are NOT currently approved for saltwater immersion applications.
The NatureWood® wood preservative can produce wood products treated to these End Use Categories:
- ABOVE GROUND Interior Dry (UC1)
- ABOVE GROUND Interior Damp (UC2)
- ABOVE GROUND Protected (UC3A)
- ABOVE GROUND Exposed (UC3B)
- GROUND CONTACT General Use (UC4A)
- GROUND CONTACT Heavy Duty (UC4B)
Retention levels refer to the amount of preservative retained in the wood following the treatment process. Retention levels can be different based on the wood preservative system used to pressure treat the wood product and its intended end use (ground contact, above ground contact, etc.). It is important to purchase treated wood products for the intended exposure condition. Typically, wood products are treated for “above ground use” and “ground contact/freshwater immersion use.” The treated wood end tag should state the recommended end use for the treated wood product.
Pressure treated wood products help protect wood from rot, fungal decay and termite attack. However, moisture, sun, and outdoor conditions may cause the wood project to show signs of weathering. Natural weathering such as raised grain, splitting, checking, twisting, warping, shrinkage, or swelling occurs in wood treated or untreated. To help reduce the effects of natural weathering, the use of a clear water repellent coating or a semi-transparent water repellent coating product is recommended.
Yes. If you desire to apply paint, stain, water repellent, or other finish to your preservative treated wood, follow the manufacturer’s instructions and label of the finishing product. Before you start, apply the finishing product to a small exposed test area before completing the entire project to ensure it provides the intended result before proceeding.
Check the manufacturer’s instructions regarding period of application. The amount of exposure to sunlight and other weather conditions may affect how often a protective finish should be applied.
Depending on the look you want to achieve you can use a clear water repellent coating or a semi-transparent water repellent coating product. If you desire to apply a paint, stain, clear water repellent, 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 completing the entire project to ensure it provides the intended result before proceeding.
Wood deck cleaning products are available. These products may be referred to as cleaners, brighteners, or restorers. Always follow the manufacturer’s recommendations.
Yes, follow the pressure washer manufacturer’s recommendations and guidelines. Wood can be damaged if these instructions are not followed.
Fasteners (and other metal products) for use with NatureWood® preserved wood products include:
- Hot-Dip Galvanized* (The minimum standard) Fastener, hardware, and metal product 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 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 or any metal product as recommended by their manufacturer. There may be additional products (other than stainless steel or G-185 Hot-Dip galvanized) which are suitable for use with NatureWood® treated wood. Please consult with the individual fastener, hardware, or metal product manufacturer for recommendations on the use of their products with NatureWood® treated wood.
- Aluminum should not be used in direct contact with NatureWood® treated wood. Spacer materials or other physical barriers are recommended to prevent direct contact of NatureWood® treated wood and aluminum products.
View NatureWood® Fastener and Hardware Information page for further details.
NatureWood® pressure treated wood posts produced for “Ground Contact Use” can be placed in the ground with or without the use of concrete. When placing a pressure treated wood post in the ground, the freshly cut end should not be placed in, or on the ground. Orient the posts so that the original factory-treated ends are in contact with the ground.
We do not recommend this use for treated wood, however if NatureWood® treated wood products are used for this application, it is suggested that all of the treated wood products be treated for “Ground Contact” end use.
NatureWood® treated wood products may be used to construct raised bed gardens. For this application, use NatureWood® treated wood products that are treated for “Ground Contact.”
Very small amounts of copper and the co-biocide (quaternary or azole) will migrate out of NatureWood® treated wood over time. If it is desirable to minimize the migration of copper and the co-biocide into the soil of a raised bed garden, we recommend that a suitable thin plastic material be used as a barrier between the NatureWood® treated wood and the raised bed garden soil.
The use of a plastic barrier will also help keep the raised bed garden soil within the bed area. For proper drainage, the plastic material should not be used underneath the raised bed garden soil.
NatureWood® pressure treated wood products can be used for outdoor picnic tables. We recommend that the picnic table be covered to prevent food from contacting the wood surface. It is not recommended that any treated wood product be used as a countertop. Do not put food directly in contact with treated wood.
Do not use preserved wood under circumstances where the preservative may become a component of food, animal feed, or beehives.
Yes, NatureWood® pressure treated wood may be used for animal fencing. However, it's always a good idea to monitor your animals to ensure they aren't excessively chewing on the wood.
Mold occurring on pressure treated wood products is typically not an indication of fungal decay attack. 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
Koppers Performance Chemicals wood preservative products do not contain formaldehyde. However, glues used to produce plywood, glue laminates, and other engineered wood products may contain formaldehyde. Contact the engineered wood producer for information regarding the use of formaldehyde in their products.
Yes, NatureWood® and MicroPro® treated wood products can be used together; however, use fasteners compatible with NatureWood® where they may come in direct or indirect contact with the NatureWood® treated wood.
