Why does my package of Porter-Cable galvanized finishing nails say not to use them outside?
First of all, they are not hot-dipped galvanized, they are electroplated. That’s why they are not rated for exterior use. Second, galvanized screws or nails react with the acids in cedar or redwood, and will turn black. This will cause streaking. The best thing to secure your deck boards is stainless deck screws. For 5/4″ boards, you will want to use 2-1/2″ screws. They are expensive, but worth it. Finish nails will never hold deck boards down. Once the sun hits them, they will pull out. I’d definitely recommend the screws.
