I recently noticed a stain on the living room ceiling of my second floor condo unit. Above this ceiling is the master bedroom. I had a contractor come by who informed me it was likely condensation from the AC leaking onto the ceiling. He said he would need to take down that entire out-set portion of the ceiling, replace all of the insulation along it, and then replace the drywall. Does this make sense? Why wouldn’t he just fix it at the location of the stain/right around it? Does it make sense for him to be pulling the whole thing down? Is he just trying to gouge me?
The insulation the contractor is referring to, is the insulation on the heat pump refrigerant lines. *
This is not the fiberglass or rockwool insulation that homes have to keep out the outside cold/hot. That would not normally exist between interior spaces, anyway.
It's a tubular pipe insulation that goes around the pipes. It works best if it is a vapor barrier also, to limit the circulation of humid air near those pipes (can't condense if it can't physically get there).
It sounds like in the original installation, the insulation was an after-thought or neglected, or, has deteriorated.
But certainly if condensation is enough to actually leave water marks in your ceiling, it is quite serious indeed! Perhaps they can also address how humid air is getting into that ceiling space.
* Air conditioners are a type of heat pump which has the reversing valve deleted, so it cannot heat.