- Copper is used in several wood treatments, including chromated copper arsenate (CCA), copper azole (CA) and micronized copper. Because of concerns about the arsenic in CCA-treated wood, it is no longer available commercially but is limited to industrial uses such as highway guardrails and marine exposures, according to the website StrongTie.com.
In damp or wet environments, stainless steel or hot-dipped galvanized hardware is recommended for use with copper-treated wood. Galvanized fasteners should meet American Society for Testing and Materials (ASTM) code A153, and connectors should conform to ASTM A653. Check product labeling for references to the ASTM codes.
In wetter environments, areas such as swimming pools, ponds or locations within five miles of an ocean, stainless steel hardware is recommended. Look for type 304 or 316 stainless steel.
Aluminum is not recommended for contact with CCA- or CA-treated lumber. Aluminum hardware, however, can be used with micronized copper-treated materials for interior or above-ground exterior applications.
Hardware galvanized using an electroplating process usually has a thinner coat of zinc than hardware that was hot-dipped. For this reason, it is not recommended for use with lumber treated with copper-based preservatives.
According to StrongTie.com, stainless steel and galvanized metal hardware pieces should not come into contact with each other. The dissimilar metals can cause corrosion of the zinc coating of the galvanized hardware. - Inorganic boron (SBX) also is used as a wood preservative. According to the SPC, the use of SBX wood is limited to above-ground, interior applications. The SPC's website information states that SBX-treated wood poses no more corrosion to hardware than untreated lumber. SPC advises choosing hardware suitable for the level of environmental exposure it will receive.
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