I work down the Cape a lot and the Waska shingles are soaking wet when you buy
them so it doesnt matter how dry you keep them after you buy them. The proper
nailing is 1 1/2 inch above where next course will fall. Anything over 4 inches
wide takes a nail 3/4 inch from each side and two spaced about 2 inches apart
in the middle. The only way to prevent the curling to to either seal the
shingles on all four sides before installation or lay them out to dry
thoroughly before putting them up and leave at least a 1/8 gap between 4 inch
shingles and up to 1/4 inch on wider ones. Once the water soaks in they will
swell and buckle from side to side too. I have had shingles curl from bottom my
self but if you watch them they go back when it rains! It's nature not much you
can do about it. Remove the real bad ones and live with the rest or start over
with prestained on four sided shingles.
Hope this helps