If the nails are to high, like in the tar strip, that means that the nail is probably not going through the shingle on the lower coarse. If the shingle doesn't have the nail in the back if it, what could happen? Could a group of shingles somehow float, especially if the sheathing expands/contracts? Another question: When water wicks back up through the shingle, is this called capillary effect? Thank for all your help. Frank