Quick help Texas - unfaced insulation on tub/shower exterior wall?

[Jhtx]

I know this has been discussed a million times and I have been researching for a week but keep finding conflicting or very old (15-20 years back) internet threads on this topic. I'm in the middle of renovating my mom's bathroom - original to her 1958 built home in Dallas. The long side of the tub is right on an exterior wall.

I just finished ripping everything out and spending a few days fixing subfloor and joist rot. I need to get the tub installed here in the next day or so. There was NO insulation on the exterior wall which explains why the shower is always brutally cold in the winter. Beyond the wall studs on the brick exterior side, there seems to be some drywall type material with black backing that says "complying with sheathing C-79-50 ASTM specifications" all over it. The tub was installed right on the cedar subfloor with solid 1" gaps between planks which also didn't help the temps.

My understanding is you don't want a plastic vapor barrier behind the cement board if you're doing a waterproofing method on the tub side of the cement board. My understanding is that it's one or the other.

I'm hoping somebody can confirm my plan is fine for climate and vapor/moisture requirements. Here's my plan:

Put UNFACED insulation into the walls
Install Durock around tub
Redgard over Durock
Tile

Is this copacetic? I did already buy the Durock and Redgard so not really interested in a Kerdi or other waterproofing method debate. I will also be installing an exhaust fan.

Thanks everybody! I joined here just to ask this because my research kept bringing me to posts here.

 

[Breplum]

We always want to see a waterproof barrier behind the Durock but, I am a plumber not a tile guy. Haven't exp. with Redgard per se.
Tar paper or similar behind the Durock is what I always see.

 

[Sponsor]

 

[Reach4]

If you use XPS foam boards, the place for the vapor barrier becomes not critical. XPS is not affected by moisture.

Generally in cold areas, you want the vapor barrier on the inside of the insulation. In hot areas, you want the vapor barrier on the outside (nearer outdoors) of the insulation.

 

[wwhitney]

The critical consideration here is that Redgard is a vapor barrier, and you want at most one vapor barrier in the wall assembly. So no facing on the batts behind the Durock behind the Redgard.

In other words, yes, the proposed assembly should be copacetic.

Cheers, Wayne

 

[Jhtx]

The critical consideration here is that Redgard is a vapor barrier, and you want at most one vapor barrier in the wall assembly. So no facing on the batts behind the Durock behind the Redgard.

In other words, yes, the proposed assembly should be copacetic.

Cheers, Wayne

Thank you, this is exactly what I was wanting to clear up. I was hoping to already be going on the tile install but the tub install took me forever. Sure goes slow working alone lol.