I put in a sound deadner material. There are
all kinds out there. I got one from J. C. catalog because of price. Its a dense foam piece that has a selfsticking glue on one side.
The glue didn't hold that well and I still had to buy some contact cement and reglue it, but I'm still happy with it. I don't believe that
original material you found was ever there for
moisture. You can go to the search function
and try different words to see what there is
on this topic. I know its been discussed before. Cecil...........