Unless you are very lucky, all airstreams leak somewhere, sometime. So
will your house if the roof is old.
Before fixing anything, you should get 4 tubes of Vulkem and attack
every single seam on the trailer, and every place there is a hole cut in
the skin. The awings are notorious, the flexing losens the rivets and
bolts. You might think you could find the leak and just fix that. Sadly,
the cause of the leak is probably miles from the wet spot. And anyway,
if you have one or two, you will have four next year. Nobody tells you
about this part. It's true for other RV's as well.
check the archives for other people's techniques for calking.
I'll repeat mine if you want, but it's very messy.
Daisy ( about to be drowned in slush )