ACQ FASTENER INFORMATION

  Fasteners (and other metal products) for use with ACQ pressure-treated wood 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. 

OUR RECOMMENDATION: We recommend using stainless steel in either grade 18-8/304 or 316 for your project if you are going to be using ACQ lumber. The primary reasons is that it’s a complete alloy, not a coating that can be chipped or impregnated, is also resistant to the marine environment and will provide superior corrosion protection. SPECIFICALLY FOR USE IN A HIGH CORROSION, COASTAL OR MARINE ENVIRONMENT OR APPLICATION. 

• Hot-Dip Galvanized*
Fastener and hardware manufacturers have suggested higher levels of protection should be used with ACQ and Copper Azole treated wood compared to CCA treated wood. 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). 

OUR RECOMMENDATION: We recommend using Hot Dip Galvanized for your project if you are going to be using ACQ lumber.  Most of the Hot Dip Galvanized that is being used in these applications is a special process of double and even triple dipping the material. Although it holds up in some coastal applications, we are still seeing some corrosion early in the life of the fastener or hardware. It is up to the individual plans and customer to determine if they want this material in their project.
 

  • Dry Use Applications
When ACQ pressure-treated wood is used for interior applications with continuous dry conditions, where the wood in service will remain below 19% equilibrium moisture content, the performance of fasteners, hardware and other metal products in contact with the treated wood should be similar to that experienced with untreated wood.

• Aluminum should not be used in direct contact with ACQ (Alkaline Copper Quaternary) pressure-treated wood
Spacer materials or other physical barriers are recommended to prevent direct contact of ACQ pressure-treated wood and aluminum products.

These fastener recommendations are comparable to fastener recommendations from other wood preservative manufacturers of ACQ and Copper Azole.

*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.
 
The 2006 International Residential Code Fastener Statement (section R319.3) issued by the ICC (International Code Council), verifies the above fastener recommendations for use with ACQ pressure-treated wood:

“Fasteners for pressure-preservative treated wood shall be of hot-dip zinc-coated galvanized steel, stainless steel, silicon bronze or copper. The coating weights for zinc-coated fasteners shall be in accordance with ASTM A 153. Exceptions: One-half inch (12.7mm) diameter or larger steel bolts. Fasteners other than nails and timber rivets shall be permitted to be of mechanically deposited zinc-coated steel with coating weights in accordance with ASTM B 695, Class 55, minimum.”