Hands down the best and most permanent fastener to use in treated lumber is stainless steel. However, availability and expense of stainless steel have forced consumers to seek other safe and cost effective options. Hot dip galvanized steel fasteners and mechanical connectors have always been, and still are, recommended for use in treated wood construction. Electroplate galvanized steel or aluminum have never been recommended for contact with treated lumber. As a minimum, nails and screws for ACQ or CA treated wood must be hot-dipped galvanized in accordance with ASTM A153.