How can I reapair a wall and ceiling in the bath that shows waterstains following the stack? My husband thinks it's due to cold air that causes condensation on the stack due to lack of insulation in an old 1911 house. House has blown in insulation and an add on bathroom not over the original foundation. I don't think the ceiling is insulated. Its only a very small space from ceiling to roof There is a good bathroom fan installed and the air is moving out well. The ceiling has a teltale yellow stain which I fixed last year and sealed with Binz. The wall paint on the walls bubbles up in a couple of spots as big as softballs. Could there have been a wood stove pipe in that wall which backs up to the kitchen? These stains are on an interior wall which would have been an exterior wall in the kitchen originally. The walls and ceiling are plaster, not sheetrock. Suggestions?
Is the stack going up and out the roof? if so, the roof flashing may be the problem.
If your house has a bathroom on the second floor, the pipe (cast iron ? ) may be leaking.
Is the bathroom fan vented into the attic? If so, moisture from bathroom will be the culprit. it should be vented out side.
The wall and ceiling must be opened to ascertain the source of the moisture and to remove any mold that has occurred.