Yes you dont need caulk on them but I can tell you from experience with our old trailer that its a good idea to cover them with some kind of caulk. The reason being if you ever have to take that cover off and the screws were left uncovered they will be rusted and almost completely deteriorated making them impossible to remove. When we got out new trailer that was one of the first things I did. Water will sit in those little depressions and make it ten times worse too.