Chris in Mississauga wants to put a pedestal sink on an outside wall but is worried about the pipes freezing.
You are right to worry, Chris. When we put sinks on the outside walls, we need to run the plumbing pipes on the warm side of all that insulation, which means inside the sink cabinet. A pedestal sink does not have a cabinet, and the old "S" traps that would go down through the floor are no longer allowed because with that long vertical drop they tended to lose their water through the siphon action, breaking the seal against sewer gasses. There is nothing in the code against putting a pedestal sink against an outside wall -- it is just that in Canada you will have to leave the pipes exposed on the inside of the bathroom wall to keep them from freezing. That same sink on an inside wall poses no problem as you can run all the pipes back and into the hollow wall with no freezing problems.