What do I use for bare spots on roof and walls?

My lower roof piece has a lot of bare metal where the vinyl seal of the top roof piece rides on the lower roof piece. This may be indicative of a bigger problem, but what do I use to cover/seal the bare metal? I am trying to attach a photo.

I have a similar problem on one or two spots on my exterior walls and assume I can use the same material to seal the walls.

I've read lots of posts but could not find an answer to this question.

Dennis Hickethier
Gettysburg, PA