Greenboard not ok on bath ceiling?


  #1  
Old 01-30-06, 04:09 PM
Bill Syms Jr.
Visiting Guest
Posts: n/a
Greenboard not ok on bath ceiling?

Was involved in a bathroom remodle last year. The drywall guys came in and installed greenboard to the entire bathroom, including the ceiling.

When the city (Glendale CA) inspector came out he made the customer remove the greenboard from the ceiling of the bathroom and replace it with regular drywall.

We were all standing next to each other (and ourselves) trying to figure out since the ceiling of a bathroom collects the majority of moisture why it was not supposed to be up there in the first place.

Does anyone know why this is?
 
  #2  
Old 01-30-06, 05:27 PM
Doug Aleshire's Avatar
Member
Join Date: Feb 2002
Location: United States
Posts: 4,679
Received 0 Votes on 0 Posts
Bill,

Moisture resistant (MR) gypsum board may not be used in the following locations:

1. Over a vapor retarder.
2. In areas subject to continuous high humidity such as saunas or steam rooms.
3. Ceilings where frame spacing exceeds 12 inches for 1/2 inch gypsum board and 16 inches for 5/8 inch gypsum board.
4. All cut or exposed edges, including those at wall intersections, must be sealed as recommended by the manufacturer

If ceiling insulation was kraft faced then greenboard cannot be used. Kraft faced is considered a vapor barrier.

Any vapor barrier behind greenboard will cause it to deteriorate prematurely. Suprisingly, regular drywall applied to ceilings does not get damaged within bathrooms.

Hope this helps!
 
  #3  
Old 01-30-06, 05:29 PM
F
Member
Join Date: Aug 2005
Location: San Francisco, CA
Posts: 749
Received 0 Votes on 0 Posts
Greenboard is heavier than regular drywall. Perhaps the code in your area does not permit this due to a falling hazard.

If you use a good primer and semi gloss paint, typical bathroom/shower moisture on the ceiling will not be an issue (provided you have a fan).

Greenboard is mainly used in areas that will potentially see large amounts of water; i.e. laundry rooms or behind kitchen sinks.
 
  #4  
Old 01-30-06, 05:58 PM
Bill Syms Jr.
Visiting Guest
Posts: n/a
Interesting

Thanks for the info, been scratching my head untill now.

This was in a master bath / bedroom addition.

I'll pass this info along to the DRYWALL CONTRACTOR!
 
  #5  
Old 01-30-06, 06:14 PM
Doug Aleshire's Avatar
Member
Join Date: Feb 2002
Location: United States
Posts: 4,679
Received 0 Votes on 0 Posts
Bill Syms Jr.,

Many years ago, I was placing MR on the exterior wall of a bathroom. I was asked to remove it as there was premature breakdown of the MR due to creating a double vapor barrier. I even inquired about the use of vapor barriers and MR rock with USG. It's amazing where we can and cannot use this stuff. We just assume since it is MR drywall that it can be used where we assume it should be placed. That is the problem - we need to look at the manufacturers installation guide and read. I, as well as many in the trade, failed to read. I don't do that anymore!!

As Fuente mentioned, which I must correct, you CANNOT use MR on any exterior wall that has a vapor barrier on it. That is a definite No-No!

The word here to note is VAPOR BARRIER - whether it be kraft-faced insulation or poly.

Years ago, mold wasn't such an issue but the inspector that I knew at the time, was also a International Inspector - very bright and knew his stuff. Mold was very prevalent back then but not to the point of todays lawsuits and the like. I was asked to see a home that was being totally gutted - I couldn't believe the damage that had been done to the MR rock and then to see what the mold growth had covered. This home had been remodeled just 2 years prior!!

Your drywaller should be up on this stuff as I see many not installing the right product in the right places. Some inspectors just ignore it but others, and I think it is becoming more today, are really keeping an eye on the applications.

Hope this helps!
 
  #6  
Old 01-30-06, 09:34 PM
F
Member
Join Date: Aug 2005
Location: San Francisco, CA
Posts: 749
Received 0 Votes on 0 Posts
Thanks for the tip Doug. I was not aware of the double vapor barrier issue.
 
  #7  
Old 01-30-06, 09:38 PM
Doug Aleshire's Avatar
Member
Join Date: Feb 2002
Location: United States
Posts: 4,679
Received 0 Votes on 0 Posts
fuente,

You're welcome! I was surprised when I got informed of it and it is a common mistake made by many. I was one of them that made the mistake as well!

Another day, time to call it a night
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: