What would be best to use as a sealer between the sill plate and a concrete base? This would be to prevent air leaks and stop the bugs getting thru! My local Lumber Yard guy says use ready-made black tar which does not disintegrate over time and is cheap. He says standard caulk will deteriorate over time with bugs/bacteria eating it.
I've heard different things from different parts of the country. I will tell you what I have been accustomed to using over the years, and what others use, in my region; The standard material is "sill foam", or "sill seal". Examples: