I plan on doing a full gut/rebuild on our bathroom this spring, and one of the things I plan on is his/hers shower heads. Problem is, one of these will need to be on the exterior wall of the house to accomplish this. Since I'm ripping the entire bathroom out, I planned on insulating all of the walls with kraft-face insulation for noise reduction, then putting the plumbing on top of it. Floor to ceiling tile will be installed on all the walls. The shower will be a tub with tile surround, not fiberglass.
Would insulation be sufficient to keep the pipes located on the exterior wall from freezing in winter? I'm located in the Midwest, Saint Louis specifically.