Replies

1. 
   CaptainMayhem | Feb 03, 2010 01:11pm | #1

   What climate are you in?? put your vapor barrier whare it would normally go, and use moisture resistant drywall on the walls, normal 5/8th on the lid and tape properly... DEFINITELY install a ventilation fan... 80cfm's are great for an "average" bathroom...

1. 
   CCI | Feb 03, 2010 03:00pm | #2

   I am in the Northeast - Long Island, to be precise.

   I have the fan installed.

   I am not sure where the vapor barrier would normally go - that is my problem.

   I read it should not be behind the tiled portion of the drywall, for example. True or false?

   Thanks.

2. 
   wane | Feb 04, 2010 08:38am | #3

   the vb goes on the warm side of any exterior surface, so put one over the "Batt insulation in exterior wall - kraft faced" .. some will complain that the kraft faced is a vb, but it's a poor one at best, to be sure just slash it with a utility knife. Seal the vb with acoustical caulk to the corner studs, top and btm plates. You don't mention ceiling, if it is an attic this should have a vb as well.

1. 
   CCI | Feb 04, 2010 08:44am | #4

   The ceiling is finished already and it is below an attic so I am stuck with the kraft facing for that.

   The poly sheet over the slashed kraft faced exterior wall is no problem - what is acoustical caulk? Is that different than silcone or painter's caulk? Where would I find it?

   So, no vapor barrier behind the backer board in the shower area? I thought that was needed.

   Thanks.

1. 
   wane | Feb 04, 2010 01:00pm | #5

   acoutisical caulk is available almost anywhere, no vb behind the backer. I think your confusing vb with a waterproofing membrane like dittra, that is required btwn the baker board and tile in wet areas.

1. 
   Eldan | Feb 04, 2010 07:04pm | #7

   It is? I've been looking all
   It is? I've been looking all over for it for months and all I can find is the low-VOC stuff that won't stick to polyethylene.

2. 
   HerrBag | Feb 04, 2010 02:47pm | #6

   VB SHOULD have gone behind backer. Kerdi or 2 coats of Redguard (or similar) can be used instead of VB just under tile.

3. 
   Jeff_Clarke | Feb 04, 2010 11:39pm | #8

   The moisture barrier (which is what it is with respect to the shower installation) goes behind the backer board per TCNA details. Has nothing to do with climate unless you are now talking about an exterior wall without tile/backer in which case climate is the determining factor.

   I read it should not be behind the tiled portion of the drywall, for example. True or false?

   Without direct exposure to moisture (ie shower compartment) a LI climate does not suggest using a vapor barrier in an outside wall.

1. 
   CCI | Feb 05, 2010 08:38am | #9

   None of the walls are covered yet - everything is doable except the ceiling.

   So-

   Poly sheet vapor barrier behind the backer board in the shower?

   Poly sheet behind the drywall (interior wall) if it is painted?

   No poly sheet behind the drywall (interior wall) if it is tiled?

   No poly sheet behind drywall on exterior wall no matter what is on it?

   I have heard and read so many conflicting things that my head is spinning.

   Thanks.

1. 
   wane | Feb 05, 2010 08:57am | #10

   STOP STOP STOP Everyone .. come on ..

   vb = VAPOUR BARIER, only on EXTERIOR SURFACES ..

   waterproofing membranes only on wet surfaces between substrate and mud/tile

1. 
   CCI | Feb 06, 2010 12:21am | #11

   Now I am even more confused.

   Poly sheet on exterior wall top to bottom regardless of tile or paint.

   No poly sheet anywhere else.

   Apply backer board to shower area directly to studs and cover backer board with redguard before tiling,

   Yes?

   No?

   Maybe?

   Thanks.