I'm remodeling a bath, upon demo I found water damage behind the tiled shower stall, located on an exterior wall corner. It seems the original big box builder didn't take the correct steps to ensure a quality job. The insulation in place had no Kraft paper, nor any plastic vapor barrier, it was unfaced insulation with green board and cement board directly attached to the studs.

Now I'm in the rebuilding process, and I keep reading conflicting information regarding insulation, and a vapor barrier for a bathroom.

Conflicting Info Examples
- Use both Kraft paper insulation, and a 6mil poly vapor barrier
- Never use two vapor barriers next to each other, they will create a moisture trap and cause issues
- Inspectors won't allow faced insulation installed, and will require kraft paper removed.

I'm planning on using cement board and re-tiling, but first question, what to do about the insulation and vapor barrier.

Any input regarding the correct/best method to insulate would be appreciated.

Jim

Need to water proof the tile board, that will be your vaper barrier.

Ok, then do I use insulation with or without kraft paper?

As Joe said---waterproof the face of your cement board----best insurance you can buy---if you do---then use unfaced insulation----

Question Oh' Mike... Do you need a vapor barrier on the entire bathroom (Ceiling, shower area, non-shower area (sink, toilet, etc))? Or does it only need to be in the shower area?

Waterproofing is only done on the face of the cement board in the wet areas----ceilings and other walls should use insulation with a vapor barrier-----

1. Where are you located?

2. Is the bathroom above/below grade?

3. Describe the exterior wall make-up...

Gary

1) Located Cincinnati
2) Above grade 2nd floor
3) Exterior: Vinyl siding, sheathing, stud/insulation

Jim

Find your location on the map for Zone, read:http://www.buildingscience.com/docum...commendations/

No vapor barrier/retarders in basements: http://publicecodes.cyberregs.com/ic...001_par003.htm

Same with greenboard: http://publicecodes.cyberregs.com/ic...002_par013.htm

Gary
PS. May need to find closest city for Zone below the map in list, here; http://publicecodes.cyberregs.com/ic..._11_par002.htm