# greenboard or hardibacker



## hms (Feb 12, 2008)

I have taken down the fake marble shower walls in my bathroom and there is greenboard already there. I am going to be installing 16" tiles. Do I need to remove the greenboards and put hardibacker or something else in there to do it right? Can I just put the tile up on the greenboard and get on with the tiles and save time and money? If I need to cut out the greenboard, why is this necessary?


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## AtlanticWBConst. (May 12, 2006)

Yes, remove the MR (aka Green Board), unless you plan on re-doing that tile again in the future.
MR board *will rot* when it gets wet. It was never designed to be used for showers. It was manufactured as a wax-surface-treated sheetrock, to be used in areas that were prone to Moisture VAPOR. At the time, there was a common misconception (which still exists today) that it is "water-proof". *It is not*. We have ripped it out from behind, literally, hundreds of tiled tubs and showers, because it has rotted and softened to the point that it starts to fall apart.

Rip it off to the studs. Install a Vapor barrier (15 pound roofing felt or 4 mil poly)over the rough framing, and then install your Cement board. Be sure to use the proper cement board screws when attaching it. Silicone all seams.

"Rock-On" brand cement board screws are sold at all the Big Home Improvement Stores. I know at HD, both the 1/2" cement board and the screws are sold together (in the Tile Supply area). There are different screws for different brand cement boards. Good Luck

Here are some helpful links (general information & installation instructions):

http://www.askthebuilder.com/199_Cement_Backer_Board_.shtml

http://www.usg.com/USG_Marketing_Co...uides/DrckCement_Board-Installation_Guide.pdf

http://www.nationalgypsum.com/literature/110831.pdf

http://www.johnbridge.com/vbulletin/archive/index.php/t-576.html


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## IREnergy (Feb 29, 2008)

*Greenboard- don't use it for showers!*

Here's what you'll get behind tile using greenboard!


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## AtlanticWBConst. (May 12, 2006)

THANKYOU!...
A picture is worth a thousand words.

That's a shower wall, that is actually in better shape than most. 
That must have had a fiberglass shower surround. 

Failure behind tile is much worse.


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## IREnergy (Feb 29, 2008)

*Shower mold, greenboard*

Nope, actually you are looking at a plastic vapor barrier wearing an impressive looking coating of mold, infiltration where the penetrations in the plastic were allowed it to progress into the greenboard.

This was the easiest tile demo ever. All of it was out of there in about 10 chunks. It was easy because the greenboard had been doubled up. The picture shows the interior layer.


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## MrLinux (Jan 19, 2008)

Just to double check... I am gong to tear out my shower... there is some 
moisture and plumbing issues. I don't know if I'm going to re-tile it myself
or not... but I might be able to get a deal on some 'hardibacker' board. 
If I go ahead and tear out the tile/greenboard that is there, fix the damage
can I attach 1/4 hardibacker board directly to the studs ( I'll put down a
moisture barrier over the studs ) or does the hardibacker board need to be
attached to something like sheetrock? I was going to remove the 
tile/greenboard and put up 1/2 cement backer board.. but I might be able
to get some free 1/4 hardibacker board and save me a bit of $$$. 

Thanks - jack


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## kgphoto (Dec 2, 2007)

Don't use 1/4 inch on the walls. That is not what it is made for.


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