Replies

1. 
   JamesDuHamel | Apr 12, 2002 07:59am | #1

   I'd have to say they are mistaken.

   USG (the makers of Sheetrock brand drywall) have no such stipulation on their water resistant drywall.

   What exactly ARE these tapers recommending?

   James DuHamel

   J & M Home Maintenance Service

   "Southeast Texas"

1. 
   JeffBuck | Apr 12, 2002 08:09am | #2

   the only No-Go I know of is not to use on a ceiling. Jeff   *  Jeff J. Buck/ Buck Construction/ Pittsburgh, PA  *    

   2nd Generation Buck Const, 3rd generation Craftsman                         

1. 
   BossHog | Apr 12, 2002 03:41pm | #5

   Why not on a ceiling.

   That's one I've never heard.

   Truss Designer Extraordinaire

1. 
   Mongo | Apr 12, 2002 05:39pm | #6

   Boss,

   The additives in the gypsum core that make it "moisture resistant" also make the core more susceptible to "creep" which means it can sag.

   They do "allow" you to use it on ceilings, but at a recommended 12" oc. Easiest way, if you want to stick with the manufacturer's specs, is to run conventionally spaced framing and then furr the ceiling at 12" oc.

1. 
   BossHog | Apr 12, 2002 05:53pm | #7

   OOPS

   Didn't know that. I did my bathroom at home with green board on the ceiling. The dang place is so small you have to open the door to blow your nose so you don't blow out the window. So I figured it would be simplest to just have one size/type of drywall.

   Guess I'll find out how big a problem it is one of these days........

   Truss Designer Extraordinaire

2. 
   JeffBuck | Apr 12, 2002 11:30pm | #9

   ditto. Jeff   *  Jeff J. Buck/ Buck Construction/ Pittsburgh, PA  *    

   2nd Generation Buck Const, 3rd generation Craftsman                         

2. 
   CliffJohnson | Apr 12, 2002 12:21pm | #3

   Don't cross the path of a black cat. Don't walk under a ladder. Don't step on crack's in sidewalk. This is just great.Now I've got something else to worry about!!!!!

3. 
   BarryE | Apr 12, 2002 02:57pm | #4

   I had not heard this either and we routinely install greenbd over a vapor barrier.

   But I found this on GP's site.

   " Do not install vapor retarders directly behind ToughRock Fireguard Moisture-Guard Gypsum Board. In retrofit, old coatings or covers must be penetrated effectively or removed to prevent a double vapor barrier. "

   http://www.gp.com/gypsum/contractors/submittals/trfiremoisture.html

   ---

   It's not the habitat, it's the inhabitants.

   Won't you be my neighbor

   ---

1. 
   BillHartmann | Apr 12, 2002 07:42pm | #8

   I noticed that the link that Barry posted was specifically for the fire rated version.

   I got the one for the regular green board from http://www.gp.com/gypsum/pdf/trsubmittals/trmoistureguard.pdf

   It does not mention anything about vapor variers.

   Now I am not a building pro and I don't know anything about tiles and interior walls. But I have read a lot about moisture control, flashing, and water control due to some issue that I have on the outside of my house.

   So don't laugh TOO much at what I am going to say.

   AFAIK there is no problem with having two vapor barriers in a wall if they are next to each other. The problem is when you have other wall material between then that can soak in the moisture.

   Now, on the outside, I am a firm believer in the using flashing and overlaying to deflect water way and then have a secondary path to let any watere out that has gotten past the first top layer.

   Here is why I think that they may be going with this. On the inside wall a "vapor barrier" usually means sheet plastic, which is also a bulk water barrier. If even a drop or two of water get past the tile/grout there is no place for it to go, but be soaked up by the gyp board.