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drex 01-12-2011 10:26 PM

Bathroom: Bare Green Drywall & Moisture
 
I had re-dry-walled my bathroom a few weeks ago. A friend had passed away and never finished the bathroom. I'm going to try to get it done this weekend. All I did was hang the green drywall. Did not tape or paint it. It's been two to three weeks. We have been using the bathroom and taking showers since then and am a bit concerned about the moisture to an unfinished wall.

Should I be concerned?
As a precaution, should spray a mildew solution on the drywall before I start taping and throwing up joint compound? Before I tape, do I caulk
the joints?

Three of the walls are plank boards, no wall cavity. The other wall is a standard 2x4 wall that is unfinished on the other side. Ceiling I'm more concerned with, as part of the ceiling does not have attic space. That section is right above the shower. Behind the drywall wall , is rigid foam with an air channel between the roof sheathing and foam.

Thanks

Termite 01-12-2011 10:50 PM

Green drywall is appropriate for use in a bathroom, but NEVER in an actual wet area like a shower or tub surround. Cement board tile backer is the product you need to use under the tile. If you're using a Kerdi membrane under the tile you can apply it over drywall.

Green drywall is not designed to get actually wet, so if it is in your shower and you've exposed it to direct contact with water you can rest assured that it has absorbed a good amount of it. If that's the case I'd advise you to remove it from the wet area and start over with the proper product. If there's a band of drywall above the tile then the green drywall is appropriate, provided it is in an area that isn't going to get wet.

The modern I-codes actually prohibit gypsum wallboard in wet areas, for good reason.

AndyGump 01-12-2011 10:56 PM

thekctermite is correct, just one caveat though, according to the IBC greenboard should not be used on ceilings as it is possible that if a leak happens above the greenboard it could possibly hold enough water to cause a sudden catastrophic collapse of the ceiling instead of a gradual leak through.

Andy.

drex 01-13-2011 10:42 AM

Sorry I should of have been more clear. The area surrounding the tub I had already tiled in the past and used cement board. I had used green for the rest of the bathroom. So the area above the tile and the surrounding walls is greenboard.

So my concern was with moisture for the surrounding walls and ceiling.
Is there a concern with the moisture in the room for the bare green board?

As far as the ceiling, what should have I used?
It's a tub and not an enclosed shower. I thought regular drywall on the ceiling would be a bad idea due to the moisture rising above the tub/shower.



Thanks

mrgins 01-13-2011 04:30 PM

MR board will sag on a ceiling. Do not caulk the joints! Just tape and sand then use drywall primer and a top coat of something like Permawhite.

Michael Thomas 01-13-2011 06:48 PM

Quote:

Originally Posted by AndyGump (Post 568988)
thekctermite is correct, just one caveat though, according to the IBC greenboard should not be used on ceilings as it is possible that if a leak happens above the greenboard it could possibly hold enough water to cause a sudden catastrophic collapse of the ceiling instead of a gradual leak through.

Andy.

Andy,

Do you have a cite for the code commentary which discusses the "collapse" issue with Water Resistant Drywall?

Not doubting that it could be the case, it's just a new issue to me (I know that WRD requires max 12" support spacing when installed on ceilings, but I've always been told this was to reduce "pillowing"), and I'd like to know more about it.

MDT

JohnFRWhipple 07-08-2012 08:02 AM

Quote:

Originally Posted by Termite (Post 568986)
Green drywall is appropriate for use in a bathroom, but NEVER in an actual wet area like a shower or tub surround. Cement board tile backer is the product you need to use under the tile. If you're using a Kerdi membrane under the tile you can apply it over drywall....

In Vancouver drywall is not approved in any shower - covered with Kerdi or not.

In a steam shower drywall is not listed as an approved backer board by either the TCNA or the TTMAC

Drywall anywhere in a wet zone is a foolish idea.

JW


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