Repair of an old leaky corregated metal roof

Guest User
I have a 4-stall boat storage building with a 'lean-to" type roof (slanted about 1/12, no ridge) about 28'deep X 40' wide. The corregated metal is rusty and leaking. I have spoken to contractors regarding repairing the roof in this wet, humid climate. Some say they will lay new galvanized corregated metal over the existing rusty metal. Others say to overlay the rusty metal will result in a very short life for the new metal due to the rust from the old metal migrating onto the new metal. The old metal was nailed so there are no protrusions as would be the case with screw heads. Obviously, to remove the old metal would be much more costly. What are the facts and what would be the expected life of both scenarios?
Ken Buchinger
NCI Building Systems, Inc.
I am assuming from your comment about the existing roof being attached with nails that the structure is wood. Do you know if the wood is treated? If it is, the metal should not be allowed to come into contact with the wood. This can be accomplished by applying stips of a peel and stick membrane to the wood before the roof panels are installed. You should also use stainless steel or specially coated screws to attach the metal. Either way, I would remove the existing corrugated metal and start fresh.
Guest User
You need to remove the old metal. Anything else is a waste of time and money. You could prolly get by if new nailers were installed over the old ones.
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