Plumbing In Cold Walls:
I live and work in the Northeast, metro Boston area. When remodeling or building construction we take measures to design and install all plumbing lines inside interior walls and avoid the exterior wall due to the reality of them freezing.
I don’t care how well you wrap a pipe and surround it in insulation , on the coldest day in January or February they will freeze.
Do As I Say and Not As I Do:
The job site is where theory usually stops and reality begins. There are occasions when the only alternative is to install a shower head in an interior wall. Maybe this is due to design, location or aesthetics that the customer will not budge on. So after exhausting all alternatives to avoid placing a shower head in a cold wall what should you do?
Installing a Shower Head In A Cold Exterior Wall:
We recently built a walk in shower against and exterior wall. This shower had one interior wall and a half wall. The half wall and entrance to the shower was slotted to receive glass. the interior wall faced the opening so we did not want the shower head on that wall as it would be spraying the door with water which we all know will lead to water on the bathroom floor.
The only alternative left was to install the shower head in a cold exterior wall.
In my opinion you should NOT install plumbing in an exterior wall, however there are two reasonable options that will solve your problem:
Build a Second Wall:
In this situation I would insulate the exterior wall with high density insulation then cover it with 2″ of rigid polystyrene insulation with the seams tapes and all edges sealed. See how to do this here.
A second wall would then be build in front of this wall and the plumbing installed inside it. The plumbing pipes should be wrapped in pipe insulation and all seams taped.
Shower head Only:
Install The shower head in the cold wall and pitch the shower feed to drain out of the shower head. This means that your “charges” water lines and shower valve are installed in an interior wall and the shower pipe leading to the shower head is pitched to drain all water out of the shower head. [photo: red pex water line is pitched toward shower head]
This pipe once turned off at the valve can not have water in it at all or it will freeze.
RELATED POST:
Keep Your Pipes From Freezing