I recently started building a shop in a large 27 year old pole barn that is sitting on my property. One of the most urgent repairs I need to do is fix the hundreds of slow leaks in the metal roof. It appears that most of the leaks are just where the steel sheets have been nailed down. Likely the slow movement in the building structures and the thermal expansion in the metal roof has over years loosened many of the nails.
I have never really worked with a metal roof so I am pondering some very basic things about how to do this right. At this point I have not yet even climbed to the top of the roof, as until yesterday I did not have a safety harness setup to keep my old bones from falling. Anyway, here are some of my very initial questions:
1. I was told by a local pole barn salesman that the cheapest solution I would have is simply to replace all the nails with grommeted screws. Any opinions on this? Are the screws any more likely to withstand against the movement without slowly loosening?
2. How long screwas are required? Same lenght as the nails or will a bit shorter (50 - 75% of the nail lengt) do?
3. Is it likely that I will have to replace all the nails to stop the leaks, or just the nails that are visibly elevated from the surface of the roof? The entire roof is about 7500 sq ft with about zillion nails.
4. What is the best way to remove the old nails without damaging the steel sheets?
5. Other than trying not to fall off, what else should I know before starting the job?
This for now anyway. I will probably have a few more questions later if I try to climb onto the roof to inspect closer. Would appreciate any experienced and knowledgeable comments.