Quote Originally Posted by keith3267 View Post
You can use 2x4's for the wet wall of the sink and tub. If this is an exterior wall, I would bias the supply pipes to the interior and get plenty of insulation between them and the outside wall, otherwise you will have a freeze problem. If you are using an enclosed cabinet as a vanity, you should use louvered doors so that some warm room air can get in there or have a gap at the back.

Glad to see that you are going with vent (fume) lines. The issue that I have with the mechanical ones is that they become a maintenance item. They have to be replaced every 10 or 20 years or so. The vent lines are not a future maintenance item. Rubber deteriorates over time.
Keith,

Thanks again for the info. I think there is only one wall that I will have to frame using 2x6's. I definitely don't want pipes freezing.

Thanks again...