My house just had a complete roof tearoff and application of 50 year
architectural asphalt shingles over 30 lb. felt and 1/2" CDX plywood.
The roofers finished last Friday, and I see some exposed nails and they
presumably replaced some shingles, therefore. Going up there now I see
more exposed nails. Some I can see standing over them, maybe half of the
nail head (1.25" galvanized roofing nails). Many more, I can see from
the side, if I look up the slope of the roof. I figure those are less
exposed than the ones you can see from above, but some moisture is going
to reach those nails too. How exposed does a roofing nail in this
circumstance have to be before it presents a problem? Thanks for the
information.

Dan