Vapor Barrier in showers? [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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09-23-2001, 10:21 PM
I'm installing a shower completely from scratch in my basement. 2X4 studs, 1/2 inch durarock, then 8x10 wall tiles. Is there any need to put a vapor barrier layer between the studs and durarock or does the tile do all the vapor barrier work for me?

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Rob Z
09-23-2001, 10:39 PM
Hi Aeronutt

Yes, the vapor barrier is needed in addition to the tile and cement board. You can use 6 mil poly or 15 pound roofing paper as a vapor barrier.

You will also want to seal the bottom edge of the cement board will silicone to prevent wicking.

What do you do in the USAF?


09-24-2001, 05:32 AM
Thanks Rob, I will do the poly method since I've got lots of that laying around.

I'm a computer programmer. Mostly Oracle DBA type work, but I've done just about everything else too.

John Bridge
09-24-2001, 05:47 AM
Welcome aboard. May we have your first name?

The folks here will give you everything you need to complete your shower in a first class fashion.

As an old Army veteran, I want to personally thank you for serving in the Armed Forces (even if it is the AF :D)

Thank You.

09-25-2001, 09:49 PM
Thanks for the welcome John. My name is Ron and I've had the pleasure of working with many soldiers in my years of fighting wars. In spite of our good natured inter-service rivalry, we've always managed to get the missions accomplished (We drop bombs, you catch bullets :-)

As for my tub/shower, I noticed that the Durarock comes in 3X5 foot sheets with instructions to mount it on 16" centers. 16 inches does not divide evenly into either 3 or 5 feet. Do I put in an extra stud to support the joint or cut the sheets down to match the studs? Does it matter if I install them long side up or short side up? How precise do I need to be when fitting the sheets since the mud and tile will cover it anyway?

The tub that my wife picked out for this project is a roman style whirlpool tub. She wants a step in front of it as well as the (very expensive) tile surround. I'll build the step with a couple of 2X8 studs with vertical supports every 16 inches. Should I also cover this with plastic and Durarock before tiling?


Bud Cline
09-25-2001, 10:26 PM

Is your tub a standard 5 footer?

If so, lay the Durock on its 5' side, no big deal. Keep in mind the Durock will not be sufficiently supported on anything greater than 16" centers. Don't cut the Durock just to hit studs anywhere but in the corners. Set the 5' wall (if there is one) first.

As far as the joints, you won't be graded on penmanship and you must tape the joints (with fiberglas tape) and fill the joints (with thinset) anyway. Silicone the Durock/tub juncture.

John Bridge
09-26-2001, 05:44 AM
Hey Ron,

Lose the step idea. When you think about it, the step is a hazard. You get in and out of the tub by either steping over the rim or sitting on it and swinging the legs in or out. The step is in the way of either action. If you step up on it, you then have to step back down. All this with wet feet. Makes no sense whatever except in a model home where no one uses it.

09-26-2001, 06:21 AM
Bud, It's a 6 foot tub. I'll add a stud at the 12 inch point to catch the joint. Studs are cheap.

John, I think you might be on to something with the step advise. Losing the step would add 8 more inches of useable floor space too.


Rob Z
09-26-2001, 06:49 AM
Hi Ron

John and Bud have taken care of you. The only thing to add is that I deviate from the standard USG cement board installation instructions and omit the tape and thinset in the corners.

The reason I do that is on the theory that if there is movement between two of the walls, I want those two planes of tile to be be independant of each other. I fill in this joint with silicone caulk.

This past statement will cause some debate to follow. You can decide for your project which method you wish to pursue.


PS Do you have any connections to some of the NCOs that load bombs into B-52s? If so, maybe I can get an extra special message to bin laden chalked on to one of the bombs.

Bud Cline
09-26-2001, 05:54 PM

That's a good idea, the message thing that is, but where would they find room to include your well wishes? Don't you know those materiel are already full of greetings and salutations from the troops?

09-26-2001, 07:27 PM
Hi Ron,

Might as well throw in "I'm an old Army Signal Corps Veteran" before I add my 2cents.

I don't know why but I've decided to crusade, er campaign for use of Dens-Shield in lieu of DUROCK and similar cement-type CBUs, since I recently switched to its use and found that its feature/benefits were too good to pass up. These include:

a. built in water vapor barrier
b. score & snap with regular utility knife
c. easily saw holes, ells, etc
d. 1/3 lighter than DUROCK
e. 20 year guarantee
f. manufactured by Georgia-Pacific
g. competitively priced

The only negative that I've experienced is its lousy marketing by G-P; You have to track down distributors and retail outlets. Google your way to Dens-Shield and explore a variety of sites and articles/reports.

Best of luck.

09-27-2001, 12:34 AM
Makes for a bit of a problem.

09-27-2001, 05:28 AM
True, for gypsum. Have you seen or tried Dens-Shield?

I've masticed and thinset two pieces of tile to a test piece of Dens-Shield, immersed it in a bucket of water and for the last three weeks noted no apparent deterioration.
Gypsum wouldn't have cut it.

What more do you want? I also researched sites on the Internet and found, for example, that the State of Indiana specifies for tiling wet areas both DUROCK and Dens-Shield in their building construction standards.

Please offer factual rebuttals rather than innuendo. If it's truly bad, I'd like to know so I don't do it again and back off my Dens-Shield forum comments.

John Bridge
09-27-2001, 05:40 AM

I've said it a number of times. Denshield is garbage. You've asked Chip to defend his remarks, but I'll ask you to defend your assertions instead, the best of which is that Denshield is easier to use. That doesn't quite cut it with me. Start a post in the deep end and we'll take it up there.

Rob Z
09-27-2001, 06:44 AM

I'll use my immense powers as moderator and start the topic up for you over on the other side.

You're hanging with the Big Boys now!


09-28-2001, 08:02 AM
John & Rob,

I'll do my best to defend my "assertions" and personal experiences, as a DIY'er.

I'm not grasping your vernacular. What means "start a post on the deep end" and "over on the other side"??

Bud Cline
09-28-2001, 02:26 PM

We refer to the Professional's Hangout Forum as "the deep end" and "on the other side" as compared to the Tile Forum/Advice Board.

We try to keep the tech talk, debates and controversy at that location so as not to further confuse the advice seekers.

Sorry for the confusion.

Your topic has been moved by Rob to: Professionals Hangout/Densshield Debate.

[Edited by Bud Cline on 09-28-2001 at 04:32 PM]