In the book I have it suggests caulking joints between the 2x's if doubling then up for a beam. Should I? I live in Florida so melting and freezing snow isn't an issue, but we do get lots of warm rain. Should I bother, cause I'm not sure I will see much benefit?

Hello, I have an existing deck that is only a year old that we would like to put a privacy wall up/wind block on the west side of the patio. I was thinking it would be about 6 feet tall or so and possibly made of cedar are my initial thoughts. The current deck is about 12x12’ and about 32 inches off the ground or so and I would only have this on west side. I live in ND and I is really windy in our area. Do I need to dig and pour footings for this or can I attach it to the existing structure and lag bolt it to the existing structure? Being 12 feet, how many posts 6 feet in the air do I need to have? Any tips in building one of these? Thanks