insulation does many things, keep heat in, keep heat out, keep sound out, keep sound in. depending on where you live can determine what it does for you. I insulate all the walls of my bathroom, interior and exterior for all those reasons.
With regard to moisture, vapour barrier in SO Cal. shouldn't be critical as you don't do a lot of heating although with a bathroom you will have a room with a lot of warm moisture so a good vapour barrier would be important. the idea is to keep the moisture from diffusing thru to the interior of the wall. this can accomplished with a plastic membrane (on the warm side) or with a good vapour barrier type paint. all penetrations in the wall such as switches, light fixtures, etc. should be sealed for best results.
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Bart Blainey, B.E.R.
Consultant/Journeyman Carpenter
Building Envelope Specialist
Master Renovator
provip@prodeck.org
http://www.prodeck.orgBarton Blainey (provip) specifically assumes no legal liability or responsibility for the accuracy, completeness or usefulness of any information or process disclosed. The above further expressly advises that any use of or reliance upon the information and or opinion disclosed is at your risk .
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