I recently gutted my Bathroom. This Bathroom was old from the 1930s. I removed all the plaster and took out those wood strips or slats? not sure what they are called. I am going to put wonder board around the tub and drywall on the rest of the bathroom. This bathroom is on the thrid floor facing a windy driveway. Picture a wall directly in front of a bathtub, this is an exterior brick wall behind it is a driveway. It gets ice cold in the winter. A co-worker from my office told me I should not put any pink insulation behind a tile wall around the tube. He said the moister behind the wall will make the pink insulation damp. Is this true? I was thinking of using that hard white foam the one they use to pack applainces. It comes in sheets from Home Depot. I understand it is good for moister. However this does not look like it smothers and traps the cold air. Also I have alittle more than an inch thickness to work with. Please give me any suggestions you can. I would greatly appreciate it.
P.S. Should I extend the wall out in front of the tub to make thicker for insulation? I could move the new tub out more.