We're converting an old bathroom addition in our house to be a utility/laundry room. The bathroom wasn't properly vented or sealed, so we are completely gutting the room to deal with mold and mouse damage.
We've already removed the old shower plumbing, which was behind a false wall, as well as the false and underlying interior walls as well. We've run new pvc supply and waste lines up through the crawl space and into the floor, where the washing machine will be located. The pipes are about 8 inches away from the sheathing of the exterior wall:
How can I protect this from freezing? We're in Bloomington, Indiana, which has gotten as cold as -12F (-25C) in the dead of winter. The wall itself is fairly exposed, as it is a corner room sitting on top of a half-exposed crawl space.
My initial thought was that, since this is effectively a double-thick wall, we could just use two layers of fiberglass and then throw our drywall on top of that. Alternatively, we could use some combination of foam, fiberglass, and pipe insulation. Would that be good enough, or should I create a more rigid barrier? If mice get into the wall again, they could damage any softer insulation that we use. Do I need to go through the trouble of building an entire false wall, or could I just build a little protective box around the pipes? Should I install an active heating element as a backup, like a pipe-heating cable system?