What's the difference between G90, G185 and hot-dipped galvanized steel? USP Structural Connectors, a Mitek brand, has produced a video and technical bulletin that sorts out the various types of anti-corrosive treatments used for fasteners and framing connectors. For the most part, the information applies to all metal connectors, regardless of brand. Some examples: 

  • There are three classes of corrosion-resistant treatments available for fasteners and steel connectors: 1) zinc-coated, 2) zinc-polymer hybrids, and 3) stainless steel. For zinc-coated products, the thickness of the zinc determines the level of protection. For hybrids, an extra barrier is applied over the layer of zinc, offering protection near the level of stainless, but at less cost. [More detail: Click "Read more" below.]
  • Always match the fastener metal or anti-corrosive treatment with the metal or anti-corrosive treatment of the connector.  Stainless connectors call for stainless fasteners, period. You never want to have dissimilar metals in contact
  • If you are using an impact driver, note that the repeating banging of the screw head as it turns can nick the anti-corrosion treatment, introducing an access point to the steel. This is typically not an alarming occurrence, as th nick occurs on the head surface and not the bearing surface.   

Read more >