So this is weird, but I know the answer, I'm just not sure that I've asked the correct question!
The answer is "Autobody Seam Sealer, available at O'Rielly's and other fine retailers.?"
Well, Alex, I'm going to have to go with "What do I use to stop the water from coming in between roof panels?"
I've removed all of my ceiling panels, exposing the inside of the ribs. Every other rib has 75 holes on the inside/bottom from where the rivets were.
I've got a few rust spots that I'm currently treating and patching in the floor and the where the chair rail meets the floor.
However, I have noticed that after it rains or the snow melts there is a slight amount of moisture where the ribs meet the floor. I have also noticed that when there is a little bit of moisture inside the rib, which I can feel through the opened rivet holes.
These are the same ribs which have the seams between two roof panels riveted to the top (outside) of the rib. My thought is that the water is either coming in at the seam between the two roof panels, or maybe even around the outside rivets.
Now I have realized that I want to prevent anymore water from coming into my bus before I finish treating and patching rust holes in the floor.
Is this where people are saying that I should use Autobody Seam Sealer? The product I have found at ORielly's is in a caulk tube at about $10 per tube, I think. Do I just follow the instructions and use it to seal up the seams on the roof?
Do I need to seal around all of the rivets?
If it matters, once the temperature warms up (maybe over spring break), I am going to paint the roof with white BusKote.
(Pictures to follow later today)