Repairing leaks on a barn roof
Sorry to leave you hanging like that, meant to get back to you sooner, I got caught up in a work thing.
So like I said, cleaning that caulk off would be very difficult, and silicone caulk will not bond properly with other kinds of sealant.
As far as a recommendation for a good silicone sealant, I would probably go with Dow Corning 795 Silicone Building Sealant. I've used it a lot for roofing applications and it performs very well.
Hope this helps and good luck with your roof!
(But feel free to follow up with any more questions.)
Thank you again, Jack. No problem with the delay. There have been some issues for me here also.
I feel like the elastomeric caulk was a mistake, but it occurred to me that at the very least, it would protect the neoprene washers under the nails and screws, and extend their life. In some sense, it's double protection against leaks, so I am not worried too much about short-term problems (i.e., less than ten years). I am going to keep an eye on them for as long as I am able.
One of the things I discovered was that, in my laziness, I had assumed that nails that had been driven through the raised ridges would be less of a leakage problem, so I held off covering those. I learned that was a bad idea after a heavy rain last week, and saw some leakage -- not much, but some. So I covered those nails (and replaced some with new screws/washers), and after a big gulley-washer passed through here Saturday night was pleased to see complete dryness in the barn the next morning. There are still few nails left on those ridges to be covered, and then I think I'll be done!
This will come as welcome news to my wife, who has been wringing her hands about my safety on that roof.
I doubt I will need to trouble you with this again, but I really do appreciate your help and your patience!