I have a redwood deck. We are replacing the old lattice siding with 1x8 redwood lumber. Should I just use the coated deck screws I have been using on the deck boards or something else? Is a 3 inch screw okay, or should I got with something bigger? At first I thought this was a simple question, but I looked online and see lots of opinions. I also have a nail gun with galvanized nails, but that has some drawbacks and this isn't a huge project (I have the time). Also, should I do two screws per 4x4 post, or just one?

Any advice would be appreciated.