Haven't experience that, but guessing it may be simple condensation. The
nail conducts the cold from the base of the shingles, and if you have a
warmish, humid attic, it will condense, just like on the inside of a single
glazed window on a cold day. Perhaps your attic needs more ventilation to
lower the humidity.

"Gntry" wrote in message
news:HQwzf.2167$pq5.1585@trndny02...
I live in western NY and the weather here for the last week or so has been
around low 30"s, I was in the attic the other day and the nails coming
through the roof are dripping water....I have a full ridge vent, full
soffit on the west side of the house(and they aren't blocked by any
insulation), and gable vents. It is definately cold in the attic and there
is about R25 on floor w/ barrier down towards living space, the roof was
replaced about 10 yrs ago....what is causing this and should I be
concerned?