I recently had to replace a piece of vinyl siding and found the nails to be rusty. The house was built 2 years ago, the vinyl siding is installed over housewrap and the wall sheathing is 7/16" OSB. The nails are 1 1/2" galvanized roofing nails purchased from a Do-It center. The head of the nails and the first 1/4" or so are fine, the portion that is in the sheathing and the part that protudes thru the sheathing into the wall stud cavity are rusty. The interior has 6" of fiberglass insulation with kraft faced vapor barrier. Has anyone else had this happen and what are what do you think the causes are.
Could be a few issues. The nails were electroplated so the coating is thin. This along with too much moisture in the wall could be the issue.
As an aside, the nails(all the nails) should be in the studs not just the siding.
What kind of vapor barrier do you have? And was it installed correctly?
The only way you'd know was if you were there during construction or had removed a good section of wall during a renovation.