[Richard]

Ben,

Sorry about the deluge. My comments are based on what I have observed. They may or may not apply to your coach.

I have seen three major sources of water ingress in the slide rooms. First is the seam between the outer skin and the perimeter of the slide room. Because the skin is about 1/8 proud of the perimeter, it forms a little dam, and if there is the slightest crack, water will come in. Lots of water will come in. I know you said it was just sealed, but I would inspect it carefully.

Second is that the top of the slide room bows down in the middle. Bows down so far that the seal does not actually seal when the room is deployed. This phemenon seems to be worse as the ceiling treatment becomes more elaborate. On the fancier treatments, aka later model coaches, all of the substrate is plywood and it is too heavy for the structure trying to hold it up. This problem is sort of tricky because you have to remove the valence to actually see the slide seal. Water runs under the seal, towards the valence, and then changes direction and runs into the ceiling of the slideout.

The third, and I don't think this applies to what you described. For those of us with flanged windows, they have to be resealed from time to time or water seeps between the flange and the coach skin.

I don't have any experience with that product, and I don't recognize it's composition looking and Safety Data Sheet. I generally use one of the urethane air cure sealants.

I don't know about small amount. I used a generous amount. Enough to form a nicely radiused filet between the skin and the roof. I also ran that filet down both the verticals.