After replying to a thread this morning about treated lumber I decided to share some additional information regarding fasteners/ hangers and copper based preservatives. I know this information has been making the pro circles for a while now, but a lot of homeowners and diyer’s seem to be unaware of it.
It has been reported now quite extensively that copper treated wood is corrosive to galvanized fasteners and hardware. This includes the double galvanized (zmax for Simpson) variety. This also includes coated screws/ nails, as the coating can become compromised during installation. Corrosion has been documented to begin as early as three weeks after installation though is somewhat dependent on how “wet” the wood is with preservative.
It has also been documented that stainless steel is more resistant to corrosion. Though more expensive this is a better choice for framing activities involving copper preservatives. Type 304 is recommended for inland use (maybe required in geographical ranges close to coastal areas check with your building department if your within 30-90 miles of brackish water or ocean coasts) and type 316 (0-30 miles) is mandated for coastal areas.
If you choose to use galvanized materials you should inspect the structure often for signs of corrosion. If you find any such signs you should obviously replace the fasteners and hardware in question. Failure to do so can lead to structural failure.