Sealing Roof Vent

[BirdMan]

Dan, I would use silicone when ever possible.  Especially if you have to remove it later for some reason.  Silicone is very flexible yet adhears very well until you want to remove it.  I also believe all 100% silicone products are UV proof which may be a concern where you go camping or if you store it outside.  Then it comes off really easily on most surfaces.  The only downside I know of to 100% silicone is it is not usually paintable, though it usually clear when it dries.