Finding an effective wood preservative for ground contact requires evaluating durability, safety, and code compliance. The following products are well-suited for below-ground installations, pressure-treated lumber, and other high-moisture environments. This guide highlights each option’s key benefits, use cases, and application considerations to help you choose the right preservative for exterior projects, including decks, docks, and supports that sit near water or soil.
Overview of Selected Products
| Product | Brand | Primary Use |
|---|---|---|
| Rust-Oleum 1904A Wolman CopperCoat Green Wood Preservative | Rust-Oleum | Below-ground, ground contact, exterior wood protection |
| Tenino Copper Naphthenate 17% Double Strength | Tenino | End-cut and ground-contact protection with high copper content |
| Valhalla Wood Preservatives 5-Gallon Pouch | VALHALLA WOOD PRESERVATIVES | Lifetime, non-toxic wood treatment for large projects |
| Scott’s Liquid Gold Wood Cleaner Preservative | Scott’s Liquid Gold | Wood cleaning and conditioning for natural wood surfaces |
Rust-Oleum Wolman CopperCoat Green Wood Preservative
Features: EPA-registered, insecticidal exterior wood preservative that protects against termites and other wood-boring insects while preventing rot and decay. It is transparent with a natural green color, suitable for below-ground, ground contact, fresh water contact, or above-ground installations. This product is designed specifically for exterior untreated or pressure-treated wood in challenging environments, making it a versatile option for ground-contact projects.
Tenino Copper Naphthenate 17% Double Strength
Features: Ready-to-use copper naphthenate 17% (2% copper as metal) with AWPA M4 standard compliance. Required by building codes for end-cuts of all pressure-treated lumber in many jurisdictions. Low VOC (<350 g/L) and domestically sourced from recycled copper and reclaimed by-products. It is designed to meet typical substructure requirements where ground contact is present, offering robust protection against fungal decay and insects while aligning with code expectations.
Valhalla Wood Preservatives 5-Gallon Eco Friendly
Features: Lifetime wood treatment that is non-toxic and suitable for marinas, houses, and decking. Natural substances penetrate wood fibers, permanently modifying wood structure for durable protection in contact with moisture and soil. This option emphasizes long-term safety and environmental considerations for larger projects or spaces requiring frequent maintenance.
Scott’s Wood Cleaner Preservative
Features: Organic solvent-based wood care with an almond scent that hydrates and deep-nourishes wood while cleaning. It is suitable for natural or unfinished wood used in furniture, cabinets, trim, and doors. Not recommended for laminates or veneers due to non-porous surfaces. The product darkens wood slightly during initial application as it absorbs, followed by a natural finish as it cures.
Buying Guide
Key purchase considerations for ground-contact wood preservatives include environmental impact, VOC levels, code compliance, insecticidal efficacy, and long-term durability. Here are multiple perspectives to help you decide:
- Code and regulatory compliance: Copper-based preservatives like Tenino’s copper naphthenate are often required for end-cuts and ground-contact lumber per AWPA and local building codes. Check your jurisdiction for approval and specification requirements.
- Environmental and safety factors: Non-toxic and low-VOC options, such as Valhalla’s eco-friendly treatment, reduce health and environmental risks for homes with children or pets. Consider spill resistance and ease of cleanup on job sites near water.
- Durability under moisture: For below-ground or high-moisture exposure, choose preservatives with proven rot and insect resistance. Copper-based formulations create an effective barrier against fungal decay and wood-destroying insects.
- Ease of application: Products vary from ready-to-use liquids to concentrated forms requiring dilution. Some offerings provide end-to-end protection and simpler application for DIY projects, while others target professional installers.
- Aesthetic considerations: Some copper-based coatings impart a green tint. If appearance matters for visible exterior elements, select a transparent or semi-transparent finish that aligns with design goals.
- Environmental footprint: Lifetime or long-term treatments reduce reapplication frequency but may involve heavier chemical loads. Balance long-term durability with sustainability goals and local regulations.
- Project scale: For large decks or marina structures, consider volume options (like Valhalla’s 5-gallon packaging) to minimize refills and ensure consistent coverage across extensive areas.
When selecting a wood preservative for ground contact, align the product features with your project’s exposure level, local code requirements, and environmental considerations. Always follow label directions for surface prep, application method, curing time, and safety precautions to ensure optimal performance and compliance.