When I do the framing on my addition, I think I would like to seal the 2x4 contacting the slab at the bottom of the wall. What is the best way to way to seal this (ie, caulk)?

 

Good idea to caulk the seams at the corners and along the bottom of your base plate. For code in my area it's required if there's any sort of gap between the framing, (i.e. barked out or warped studs), other than that it's not required, but we do it anyway to ensure you have a closed interior envelope. We use regular silicone caulk.

Hope this answers your ??