We bought our Airstream in the summer; we live in a rather dry and mild climate, so because we hadn't had any rain, we weren't sure if there were any leaks or not. But, when we washed the trailer for the first time we found there was water on both the floor and table at the rear end. It appeared to be coming from the Fantastic Fan, but we weren't exactly sure.
After a little homework, we decided that we wanted to try Eternabond Tape. To us the pros were that it was easy to use, appears to have an extremely long life, is virtually leakproof, and best of all, does not require the removal of the existing caulk. This stuff is sticky! That's good and bad. The only con we saw was if we ever have to remove it, it will admittedly be very difficult.
We have a 2008 25 ft Safari. We ordered a 20 foot roll of 4 inch white and a 50 foot roll of 2 inch gray Eternabond Tape. (See direct Amazon links below.) Our plan was to use the white around the Fantastic Fans and Skylight and the gray the length of the gutters and around the smaller rounded vents. It probably would have been enough if we had better "tape management skills," but there was a bit of overkill in some areas so we ended up being a little short and ordered an additional roll of gray. We are actually happy to have some with us in case of emergency.
It was easy to use; we thoroughly cleaned the areas where we were applying it. We first cleaned the areas with a rag and a general household cleaner. We followed that by thoroughly cleaning with denatured alcohol. We made sure the area was completely dry before applying the tape. Eternabond does sell their own cleaner and primer as well. We went up on the roof with the tape, scissors and a seam roller. Because it is so sticky, you get one chance to lay it down; so, once you peel the clear plastic backing that exposes the sticky part of the tape, you have to be prepared to apply it immediately to your roof. It's most effective to peel only a small amount of the plastic at a time or it can roll back on itself and you just can't separate the pieces at that point. The tape is simply cut with scissors. The final step is to apply pressure to all of the tape with a seam roller which activates the bonding process. We did not remove any caulking or sealant before applying Eternabond.
Only time will tell how well it will hold up. But, we went camping this weekend and it poured for about 12 hours and there was absolutely no sign of a leak. So, we're off to a great start! If anything changes, we'll be sure to update this post.