I have an old tin roof - the thin embossed type that is like long shingles - not the standing seam type. I want to put down 30 lb felt and install regular fiberglass shinges over top. I think that all the nail holes thru the tin will provide some air and condensation relief for anything under the tin. I could put extra holes in the tin as well if need be. Really don’t want strip the tin off. I am in Northern Virgina - and the roof is very steep - 10:12. There is about a 3 feet separation between the roof and ceiling - with cross attic ventelation.
Does anybody have any experience or knowledge about this - pls let me know -