This sounds more like a framing problems than a drywalling problem or a
problem with shrinkage. Properly built corners inside or outside - as in
whether they'd be taped (inside) or beaded (outside), or internal (walls
interal to the house) or external (an outside wall) should not crack as
you've defined, whether made of 2x4 or 2x6.


"donald girod" wrote in message
...
Over the seven years we have been in the house, all of the exterior
vertical corners in my house have opened up about 1/16" or more in the
middle part of the corner (starting about 18" up from the floor and
extending to about 18" short of the ceiling). The framing is 2x6, of
course. Because of the layout of the house, there are three such corners
in the house; there are two corners in the attached garage, which is 2x4
construction, and these corners have not cracked to any significant
degree. None of the interior partition corners, nor corners where
partitions meet the exterior walls, have opened up. Two possibilities
occur to me: the nature of an exterior corner post assembly is different
from other corners, and 2x6 lumber moves 60% farther under moisture
changes than does 2x4 lumber.

So, what is likely going on with these corners, and what might I have done
with the drywall to prevent this? By now, probably not much can be done
to fix it, since the corners open and close with the seasons to some
extent (it will be less noticeable when summer humidity and heat return).
I am going to clean out and fill the three corners with flexible white
caulk, but I expect there will still be some cracking, at least of the
paint layer.