The vertical coves where two outside walls meet open up every winter
and close every summer, apparently in response to temperature change
in the framing lumber (2x6 studs, which move a lot more than 2x4); I
say temperature because the motion shows up long before the humidity
in the house starts to drop. Doubtless if I had been more attentive
to letting one wall float in the corner this would have been
minimized, and using paper tape instead of mesh would probably have
been better too. But the corners are pretty well screwed down and
have mesh tape.
Is there a fix for this? We are talking a crack which goes from more
or less 0 to 1/8" or more, and then back to 0. I almost think that
even if my drywall was floating this would be a lot of motion to cope
with. I would think some kind of paintable stretchy tape could be
used to cover the crack and move with it, but I don't know if stuff
like that exists.