sheet rock paper rippling
I painted over a painted wall. Two months later there is an area where the paper on the sheetrock is rippling with air bubbles. It looks like long verticle air bubbles. This is an exterior wall. The sheetrock was laid only 2 years ago. It was tapped and prepped correctly and then primed then painted. No problems until now.
It started about 1 foot from the ceiling went down 5 inches, and overnight it has now gone up the wall to the cieling. There is wallpaper border where the rippling has stopped in the middle of the wall. Does anyone know what causes this? Could it be setteling? If there was water damage, wouldn't the sheetrock be soft or the paint stained?