Piping in exterior basement walls – GreenBuildingAdvisor

For our basement reno we would prefer to keep our washer/dryer along the exterior wall where the previous owners positioned them, and add shower controls/head along the same side. We’re insulating on the interior, and the new assembly where piping is present will be 8″ concrete foundation wall – continuous 2″ XPS (R10) – 2×6 wood stud wall 16″ OC filled with Rockwool (R22) – 1/2″ drywall. Supply piping would be run roughly in the middle of the rockwool. Concerned about the risk of frozen pipes, I inquired with the city. They advised me:

The City’s requirement for waterlines in exterior walls is that they are located on the warm side of the insulation. So, concrete wall à insulation à waterlines à vapor barrier à drywall.

My question for the community is: How would you interpret the “warm side of the insulation” in our proposed assembly? Would you expect the XPS and ~2inches of Rockwool to be enough to prevent freezing? Should we consider going with thicker foam to be safe[r]? Or, is it obvious that we should avoid the exterior wall altogether? I wish it were easy to do so but we’re quite limited on square footage and layout options.

Climate zone 7A (Calgary AB).

Thanks,

E.