Vapor Barrier Required At Shower?

[fj80]

A building inspector is telling my contractor that he needs to install a vapor barrier behind the cement board at a shower enclosure. This is a single family house. It's not on an exterior wall. Is there any portion of the IRC or other code that requires this? I can't think of one.

 

[mark handler]

NO code requirement BUT there is a requirement that you do need moisture and water protection, 2012 IRC 702.7 install tile backer per manufactures instructions

Not all Cement/Tile backer is moisture resistant,

If you install the vapor barrier behind the cement board where does it terminate? You do not want to trap the moisture between the VB and Backer or in the wall.

Some tile backer Manufactures address vapor barriers in installation instructions.

 

[conarb]

I built in a jurisdiction recently that required a lath inspection at the time of the shower pan inspection, I had never seen this before and I called the field inspector asking him what was required for the lath inspection? He said he wanted to see that the membrane had no holes and was properly tied to the shower pan, then he asked me what I was using, I told him I was installing sheetrock, Vycor, and expanded metal lath and he said that was fine. When I've remodeled homes that I built 30 years earlier the biggest failure I've had is shower leaks, the worst spot was around the shower valves since no manufacturer makes a flange on shower valves to tie the waterproof membrane to, the worst are those 5" and 6" round valves that Moen pioneered. There is nothing in a house more important that waterproof showers, especially on two story homes. I've gone in to install a modern kitchen and ended up having to do the bathrooms too.