# Vapor barrier behind Hardi backer?



## Isaacsycamore (Jun 2, 2015)

I'm doing a repair in a shower for a customer. The previous installer used a vapor barrier behind the Hardiebacker instead of a waterproof membrane behind the tile. If you screw the hardibacker to the studs won't that cause a leak around the screws? I've always used a membrane.


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## ccoffer (Jan 30, 2005)

It's a shower, not a swimming pool. Aquabar is the best thing to use because it gives the condensation a place to hang out instead of it running like it does on plastic. It's tried and true, but building a dry shower is better for several reasons.


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## Isaacsycamore (Jun 2, 2015)

Only asking because when I pulled the bottom row of tile the hardibacker was saturated.


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## ccoffer (Jan 30, 2005)

I'm guessing they used polyethylene. Is it a real shower or is it a receptor? Not that it matters. A dry shower is the better method.


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## ccoffer (Jan 30, 2005)

Was it done with glue or thinset? If it was done with the glue from the red bucket, the failure at the bottom is totally normal.


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## Isaacsycamore (Jun 2, 2015)

It was set with thinset. The pan I was told is a tile redi shower pan. The pan is also springing when you step on it. Seems to have let go from the adhesive they used to set it with.


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## Morning Wood (Jan 12, 2008)

Sounds gross.


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## TNTRenovate (Aug 19, 2010)

Isaacsycamore said:


> It was set with thinset. The pan I was told is a tile redi shower pan. The pan is also springing when you step on it. Seems to have let go from the adhesive they used to set it with.


Sounds like someone stepped on it when the mud under the pan was setting.


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## Big Shoe (Jun 16, 2008)

Hung hundreds of showers if not thousands. Never once saw a vapor barrier. There was talk of 30lb. behind cement board 10yrs. back , but never saw that either. (Maybe a couple times.)

Hung Hardie backer once............but never again.


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## MIKE ANTONETTI (Jul 17, 2012)

I turned down two shower installs the past week, one friend, one friend of friend, time involved/ vs. profit is too low for taking time from other projects.

I used to use visqueen and felt paper years back, then switched to redguard, I've got about 20 gallons of waterproofer on hand.

Something is better than nothing, wet hardibacker does not damage it like drywall, mud beds get wet as well, I call that functional.


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## avenge (Sep 25, 2008)

I used 6mil plastic behind all cement backer before membranes became readily available, that's the method that was supposed to be used.


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## Isaacsycamore (Jun 2, 2015)

Wouldn't the vapor barrier need to drain into the pan and not stop at the subfloor like they have it? Could be a dumb question but like I said I've always used a membrane.


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## Isaacsycamore (Jun 2, 2015)

I forgot to mention this shower was installed less than a year ago.


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## illbuildit.dd (Jan 7, 2015)

We're doing a shower now where they insisted on vapor barrier. Used 6mil I had laying around. It's weird because they act like they know everything there is to know about showers and construction. Weirdos


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## Isaacsycamore (Jun 2, 2015)

Don't you just love those kind of customers?:no:


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## illbuildit.dd (Jan 7, 2015)

Isaacsycamore said:


> Don't you just love those kind of customers?:no:


These guys are the worst I've had in my whole career. No joke. And they had the nerve to ask me to remodel another room in the house. Not just no but NOOOO THANK YOU


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## SLSTech (Sep 13, 2008)

Yes the plastic is in the wrong spot though some code officials insist on it - also a membrane or fluid applied should still be used making sure moisture goes back into the pan


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## Isaacsycamore (Jun 2, 2015)

That's what I thought. Thanks


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## ccoffer (Jan 30, 2005)

_Yes the plastic is in the wrong spot_

WTF? Where should it be? On the roof? The method is as old as tile. You put paper or plastic over the studs and then make sure the bottom laps over the pan liner. It's pretty rudimentary stuff. This is described literally in detail in that mysterious thing called the TCA handbook and has been since before most of us were born.


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## Isaacsycamore (Jun 2, 2015)

Unfortunately my handbook walked off and my new one hasn't arrived yet. I appreciate all the feed back guys.


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## MIKE ANTONETTI (Jul 17, 2012)

I thought there was a picture of it out of place, I looked back at the posts three separate times, I almost said this stupid app, and was checking the post #'s. Thanks for the confirmation Chuck.


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## ccoffer (Jan 30, 2005)

I don't understand what you're saying. I'm sorry.


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## MIKE ANTONETTI (Jul 17, 2012)

*Vapor Barrier Behind Hardi Backer?*

I thought someone posted a picture that the barrier was in the wrong place, not overlapped or some discrepancy.

What happened to the old Chuck(sorry, I is right next to u)that argued with everyone?


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## SLSTech (Sep 13, 2008)

ccoffer said:


> _Yes the plastic is in the wrong spot_
> 
> WTF? Where should it be? On the roof? The method is as old as tile. You put paper or plastic over the studs and then make sure the bottom laps over the pan liner. It's pretty rudimentary stuff. This is described literally in detail in that mysterious thing called the TCA handbook and has been since before most of us were born.


I will have to take your word that it is still in the TCA handbook as mine also has walked... & I really haven't seen the need to get a new one

With that, sorry it is wrong, especially in todays newer houses as the tolerances for any little failure are quickly dropping to zero. I can't tell you how many I have ripped out over the years were everything was soaked but hey we have done it this way for years. 

You have a few issues here - first the vapor barrier is in the wrong spot unless you believe that the main water penetration area is in the wall cavity. Number 2 is once you applied the screws through said vapor barrier it essentially stopped being one - sure it might eliminate diffusion, but diffusion is not the issue - it is the 1+% of water getting through the tile / grout.

Can it still work - yes if you are super anal about the install (though I would say you are still rolling the dice) and better yet also use non-porous grout & tiles. Sure they can seal everything, but they have to keep on it I don't know how many homeowners really are that good about it.


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## Isaacsycamore (Jun 2, 2015)

There was nothing super anal about anything on this instal. It looks like Ray Charles and Ronny Milsap grouted it in. Wholes in the grout and wide to narrow joints everywhere. They also used unsanded grout and told the home owner it never needs to be sealed. I feal bad for the home owner for this shower was built for there handicapped kid and it's not if it's going to fail but when.


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## ccoffer (Jan 30, 2005)

_With that, sorry it is wrong, especially in todays newer houses_

Huh? It's hardly "wrong". It's been done this way forever. Or recommended anyway. Surface applied waterproofing membranes are a superior method, but not because the other method leads to failure. The wet shower method stays wet. The backer, the pan mud, the curb, etc. It all stays wet, so over time it becomes a mold producing entity. It takes a long time for a properly built wet shower to do that, but it eventually happens.

Most shower failures are due to the abject stupidity of the proud jackasses who put them together. Guys who don't use boots, don't bother to put a damn thing behind the backer, nail friggen backer board to a curb and about a thousand other dumbass things I routinely see done by people who think they're God's gift to tile because they had the wherewithal to acquire five gallon bucket and a trowel.


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## MIKE ANTONETTI (Jul 17, 2012)

There he is.

If you're a member of NTCA, they send you the handbook every year, the 2015 is 450 pages, other privileges as well worth it.


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## CarpenterSFO (Dec 12, 2012)

Trying to repair a badly done shower is iffy. If the vapor barrier drains down outside of the pan (you mentioned it going to the subfloor) and the pan is wobbly when you step in it, how can you repair it? A problem with trying to repair a bad shower install is that you don't know what else is wrong.

Many, including me, won't repair a shower, only re-do it.


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## Isaacsycamore (Jun 2, 2015)

I've explained that to the home owner. I've left the tile off and she is contacting the origanal installer. Thanks


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## madmax718 (Dec 7, 2012)

Pan is wobbly, thats says tear out to me on some level. Vapor barrier behind cement backer has to drain into the shower/bath tub. I wouldn't screw plastic anyways, but I do staple, then use tape over the staple. Your CB will still get screwd in, so your fubared on some level. Thats why the membrane keri/durock or paint over redguard is superior- there's less stuff that is "wet" all the time. 

Whats wet the old way:
Thinset, cement backer

Whats wet now: 
Thinset

Whats wet the old shower pan way:
Thinset, a few inches of bedding mortar. Stays pretty much wet all the time.

New way:
Thinset

Its like wearing a rain coat over your sweater. vs wearing a sweater over your rain coat. Done correct, you'll stay dry both ways, but it takes a heck of a lot longer to dry out.


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## Isaacsycamore (Jun 2, 2015)

Home owner is giving them a chance to tear it out and start over.


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## Jbonk (Jun 28, 2019)

What is everyone's take on using an intelligent plastic barrier such as "membraine" behind the cement board for a shower wall? Also, this shower wall is a double left curb and the two corner walls are exterior walls. We used mineral wool Ultrabatts by Owners Corning in the exterior walls. Advice please!


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