Previous homeowners vented clothes dryer into enclosed garage for approximately 2o years. All joint tape has fallen off the ceiling drywall. The wall joints are in a poor condition, but do not exhibit the problem to the extent that the ceiling drywall does.
Replacement tape and drywall compound adheres to old ceiling drywall for approximately one week, then begins to separate at the feather edge, ultimately dropping off the ceiling in another two weeks.
The drywall condition when the home was purchased had a dull brownish color. When I was away from home for 4 months, the drywall apparently dried out to some extent, changing color to more near the original white. The problem was less severe, but still a major problem.
I suspect that "clothing softener chemicals" were added to the wash and vaporized onto the garage ceiling by the dryer every week for those twenty years.
The question is how do I retape the existing drywall for a permanent solution short of tearing out the drywall and reinstalling new drywall? (Yes, the dryer is now vented to the outside wall.)