A.Myron Ferguson, a drywall contractor in Galway, N.Y., responds: Framing, drywall, joint tape, and compound expand and contract at different rates. Under normal conditions, these differences don't amount to much, but when you factor in all those heating and cooling cycles and the heat from the wood stove, the joint failure you've observed is not that surprising. Under sustained temperatures of more than 125°F, drywall, compound, and tape gradually deteriorate, while tape can crack, pop loose, or peel when panels shift significantly due to structural movement.
Remember that problems can also arise during installation. For example, under very dry conditions (which can be caused by direct sunlight as well as by the heat from a fireplace or wood stove), freshly taped joints can dry out too fast and the tape can come loose. If too much compound is left behind the tape, or if the compound is thinned down...
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