Noticed a wall in the kitchen was peeling and cracking. Thought it was the roof leaking but after the roof was replaced the damage was still continuing to get worse. Started to remove damage from the wall and noticed a pipe plastered inside the wall. I am hoping this was just condensation from the pipe that caused the damage. The pipe appears to be cast iron and I was told that it's unlikely that is leaking, but maybe at the elbow. I turned in the heat and check the pipe for leaks with no leaks found. There is green residue in the pipe though. The heat in that particular ,room is poor as well. The pipe was basically covered inside the plaster inside the wall. Is this common in older homes?