I'm goin' back to my boatin' days which met their conclusion in the early '90s, but the hot product for sealing marine seams to stop water permeation was made with polyurethane. 3M was the innovator, but now there are other manufacturers of polyurethane caulk. I won't use anything else in any landlubber projects that require caulk. It is an awesome, impenetrable bond that adheres to most surfaces with a vengeance (including concrete) and remains flexible and paintable. Latex and silicone are a part of my past.
