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Hot dipped nails and CCA lumber?

 

Using hot dipped galvanized nails to fasten CCA (Copper, Chromates, Arsenic) treated lumber. This carpentry is only expected to be exposed to moisture once a year. Could this be a situation for accelerated corrosion?

Jim Baker
- Nanaimo, BC, Canada

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I see no basic incompatibility to worry about, but what kind of corrosion resistance are you expecting? If your need is for functional corrosion resistance you should be in good shape. But if you want the galvanization to not discolor, not form white rust, and not form red rust, I think you may be disappointed. In brief, galvanization is not usually a decorative finish.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
 

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Condensing moisture from the diurnal cycle will mean moisture if the equipment is in the outdoors. Corrosion theory is complicated, so I can't predict if the ions of metal in the wood will make the nailhead more or less cathodic.

I installed HD galvanized nails in CCA treated planks for steps (horizontal), in Beach Haven, NJ (Six miles at Sea, etc.). After six years, approximately 1/2 the nails have red rust where the zinc used to be, some have the steel exposed around the outer perimeter of the nail head, and some are still fully covered with clean zinc.

This variation is probably related to the thickness of the HD coating, which is so much more variable than plated work.

  
Tom Pullizzi
Falls Township, Pennsylvania