# Green board & V.Barriers



## angus242 (Oct 20, 2007)

CBU can be covered with a waterproof membrane before tiling removing the need for poly behind it.


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## fishaf36 (Oct 29, 2012)

Last shower I did... I used wedi board... really good and easy to use was impressed with how sturdy it was... think the wedi system was introduced in Europe. It is Styrofoam board with mesh and cement on both sides.. caulk the seams ( with supplied wedi caulk) and u r ready to tile


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## EthanB (Sep 28, 2011)

Angus are you still using DensArmor? What are you using for a waterproof membrane?

I feel like there entirely too many options in shower wall construction at this point.

The worst part is that most of them work but the one that DOESN'T is what almost everyone is still using. Every supplier in this area has huge stocks of cbu and greenboard but almost nobody stocks enough fiberglass drywall, waterproof membrane, kerdi or nobleseal.


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## Part Time Taper (Sep 2, 2012)

Lots of people here use kerdi but when they see the price they tend to shy away. If I re did my own shower that what I would use.


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## Denny Rossi (Oct 16, 2012)

*Denseild*



fishaf36 said:


> Has anyone tried denshield in a shower?


It works great, but wont really know for 5 to 10 years


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## EthanB (Sep 28, 2011)

Denny Rossi said:


> It works great, but wont really know for 5 to 10 years


What won't we know?


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## Greg from K/W (Jan 28, 2010)

There is no drywall that is a VB at all. So yes you have to put it under everything here. If not you fail your insulation inspection. What you put on the surface does not matter. If you use kerdi or some other product to waterproof the surface does not matter they want to see the VB on every square inch with the seams tapes at all times except the interior partition walls. 

You can argue till your blue in the face about double vb it does not matter a cows fart.


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## Inner10 (Mar 12, 2009)

Greg from K/W said:


> There is no drywall that is a VB at all. So yes you have to put it under everything here. If not you fail your insulation inspection. What you put on the surface does not matter. If you use kerdi or some other product to waterproof the surface does not matter they want to see the VB on every square inch with the seams tapes at all times except the interior partition walls.
> 
> You can argue till your blue in the face about double vb it does not matter a cows fart.


That's an Ontario thing Greg.


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## B.D.R. (May 22, 2007)

BC too.
You may not agree, but do it anyway.


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## Greg from K/W (Jan 28, 2010)

I just find it funny what some consider a VB when its not. If you put vb behind the drywall and then a membrane on top what water vapour can penetrate it? Fact is none. So why bother not putting it in? The only time the double VB matters or is wrong is when you have it on both sides of the insulation. 

Its a better idea to have in continuous in a bathroom with tapes joints to prevent the moisture getting to the studs. Why take a short cut that can cause the owner problems in 6 months?

I mean isn't the bathroom fan supposed to help take away part of the problem too?


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## EthanB (Sep 28, 2011)

My understanding of the issue is that older systems of installation such as cbu and mesh-and-mortar would allow moisture to penetrate from the shower, through the grout, through the substrate and into the wall cavity. The VB was necessary to stop the moisture and funnel it down to the pan.

Newer systems focus on stopping the moisture before it can penetrate to the substrate so a secondary VB is unnecessary. If it's unnecessary then why do it?. I use both waterproofing and urethane grout so I can't imagine how the 30# with about a million holes in it is going to improve my product.


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## Tom M (Jan 3, 2007)

Porcelin tile and urethane grout will never allow water to the substrate anyway.
In fact I have to check but I was under the impression that it takes a 20 min shower (which is above average) just for water to penetrate a porus grout. So under abusive conditions even with a treated cement grout your still pretty safe.
I would say most failures stem from expansion joints and of course windows. How much time & money is invested to get a cement board covered with a liquid? Denshield is a done deal. Not as perfect as a liquid applied surface but depending on the user and the prep it may never be a factor.


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## angus242 (Oct 20, 2007)

Greg from K/W said:


> I just find it funny what some consider a VB when its not. If you put vb behind the drywall and then a membrane on top what water vapour can penetrate it? Fact is none.


Fact? No. The _real_ fact is a vapor barrier is nothing more than a vapor retarder. Vapor _will_ get through. It might not be a perceivable amount but the fact is, it's getting through.


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## angus242 (Oct 20, 2007)

Tom M said:


> Porcelin tile and urethane grout will never allow water to the substrate anyway.


The Canadian issue is about vapor, not moisture. There is a difference.


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## Tom M (Jan 3, 2007)

There is a difference between barriers and retarders. Poly,liquid and most pre finished boards are barriers.

You know that,am I misinterpreting you?


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## Big Shoe (Jun 16, 2008)

I'm stay'n outa this one! :scooter:


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## Zack78 (Dec 1, 2009)

EthanB said:


> My understanding of the issue is that older systems of installation such as cbu and mesh-and-mortar would allow moisture to penetrate from the shower, through the grout, through the substrate and into the wall cavity. The VB was necessary to stop the moisture and funnel it down to the pan.
> 
> Yes if the moisture gets to framing will grow mold on it.
> I think regular shower is not as critical as steam shower. With steam shower you really want schluter I think that is the only one which will work.


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## Zack78 (Dec 1, 2009)

AARC Drywall said:


> the best product that i have found is den-shield.....and this is the reason
> Cement board, if you read the instruction, says to hang a poly barrier first. This is because the cement board is porous, and water will wick over time and potentially rotting out the studs.
> Green board, mould board, bath board, are all garbage in this application. It is a cash grab for the home owners and do it your selfers. If you have questions, ask a tile installer, one that does high end homes, one who knows his shi...t.


I think you are 100% right just get someone who knows because it can turn to health issue. Mold is bad for us unless you got lots of pain and you like pain killers grow on your walls


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## Inner10 (Mar 12, 2009)

Zack78 said:


> EthanB said:
> 
> 
> > My understanding of the issue is that older systems of installation such as cbu and mesh-and-mortar would allow moisture to penetrate from the shower, through the grout, through the substrate and into the wall cavity. The VB was necessary to stop the moisture and funnel it down to the pan.
> ...


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## Zack78 (Dec 1, 2009)

Inner10 said:


> Zack78 said:
> 
> 
> > So Schluter is the only one that will work eh? Interesting....:jester:
> ...


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