Necroposting, sorry, but this was exactly my question too. It's about 10 degrees here today and I'm thinking about exactly this issue. I'm putting a 60" tub and shower into the end of a room where the studs of the walls are exactly 60.25" apart, so it's a tight squeeze. It's a short room, too, so what I've done is put the doorway off center at one end of the room. As you walk in, the small vanity is on your right in the corner--turn right 90 degrees and you're facing the sink and mirror. Right in front of you is the toilet, backed up to the left wall. Beyond that is the tub. It should actually flow pretty well, but everything is close. I've been modeling it with boxes and rolls of insulation standing in for the fixtures, and it's not uncomfortable to get around. But the right end of the tub will have easy access, while the left side of the tub will be only about six inches away from the toilet tank. So my wife wants a right-hand tub, reasoning that we want the controls and faucet on the right side, where we can step in at the "front" of the tub and where she can reach the controls when she's kneeling next to the tub to bathe the baby.
I'm fine with that, but that would be the only place in the house where water lines are going to run through an outside wall. The roofline outside ends near the 2nd floor, so all the pipes above floor level will be in an outside wall. The wall on the left would be an interior wall . . . .
So what's the best way to insulate that outer wall? It can get well below zero Fahrenheit here in the winter. The house is ancient and drafty, but I've taken these walls down to bare studs and sealed every gap, crack and nail with expanding foam. There won't be any air moving between the studs where the pipes are located.
So, questions:
1. It sounds like I want the pipes right up against the backerboard, but won't the control valves determine the depth of the pipes in the wall?
2. What is the best insulation between the pipes and the outer wall sheathing? Spun fiberglass (the pink stuff?) or should I be filling the remaining space with more of the expanding foam? It's a very small space, so I'm not concerned about cost.
Thanks!