DIY Home Improvement Forum banner
1 - 6 of 6 Posts

·
Registered
Joined
·
95 Posts
Discussion Starter · #1 ·
I'm working on adding wall tiles to my bathroom.

I am using hardibacker cement boards and after looking at their instructions, I found some discrepancies with other sites:

http://www.jameshardie.com/homeowner/products_backerboard_halfInch.shtml?openTab=jsnavLink4

1: In a shower wall installation, it does not mention using a vapor barrier behind the cement board. Does that mean I don't need a vapor barrier?

2: For flooring on top of plywood, I've read from other places that I should apply thinset on the plywood, the backerboard, then thinset to tiles. The hardibacker does not mention adding thinset between the plywood and cementboard. It states that I could directly screw in the cement board on top of the plywood.

Curious on your opinions.

Thanks
 

·
Retired Moderator
Joined
·
25,769 Posts
The thinset under your Hardie is a MUST. It's so springy that it will bridge low spot worse than Durrock type boards---Making it absolutely a must.

Big debate about vapor barriers--I'll remain silent and let Bud or Jazz handle that---I've been waterproofing the whole shower lately--so I don't need a vapor barrier.
 

·
Tileguy
Joined
·
10,705 Posts
Keep in mind that product manufacturers want to sell products and have no vested interest in the success of your project. The more steps they include in an installation process the more likely a potential customer is to go to a different path-of-least-resistance product.

ALL manufacturers of backerboard recommend the use of thinset under the boards. I don't have time to chase it down at Hardi right now.

The Tile Council (TCNA) recommends it. The NTCA (National Tile Contractors Association recommends it. The Marble Institute of America recommends it.

Same goes for the vapor barrier. That has been on the books for decades. The alternative to the vapor barrier to waterproof the face of the boards if the vapor barrier has been omitted.:)
 

·
Tileguy
Joined
·
6,050 Posts
I have removed many wall tiles that had no vapor retarder on the studs. Sometimes there was no sign of mold, sometimes there was. Most publications and associations recommend plastic or tarpaper on the studs, at minimum. I recommend something much better, as Bud also mentioned, surface membrane. I use Kerdi, esp. for showers, and a liquid membrane for tub surrounds.

There are regions of the country where a vapor barrier may not be necessary or even good. The humid south comes to mind, like Luisiana and other swampy areas. Check with local customs if in doubt.

All backer boards installed on floors require a fresh layer of thin set under them. I'd be interested to know where you read different. Perhaps they were talking about wall installations.

But Bud is right that manufacturers may not want to teach everyone the right way to do things since too many details might kill the deal. You, (we) are supposed to know how to do the job already.

Jaz
 
1 - 6 of 6 Posts
Top