Subfloor under tile?

[tvrgeek]

Old school, 1/4 Hardi board. Been there, done that. Never had a problem. Well framed floor with two layers of plywood.

Now, my project I will be using the Laticrete membrane in the zero curb shower. It includes a liquid membrane as well as the cloth.
I was thinking the regular Hardi board and using the liquid, either more Laticrete or red-seal, over the rest of the floor.

Does the cloth and or liquid form a reasonable de-coupling, or should I go to the high tech mats Mapi, Schluter, Laticrete make?

 

[Skymaster]

stay with same brand Laticrete

 

[waitup]

I'm a little confused as to what you are asking. The Laticrete Hydro-ban or Red Guard are brush on waterproofing membranes. The backer board or fancy mats would be the substrate and you would need both. We always use cement backer board unless we're doing a heated floor or it's on a tile slab. In those two cases we use the fancy mats.

 

[JimD]

The important thing is that the subfloor does not move and is not easily damaged by a little water. I've installed tile successfully over two layers of plywood (I used epoxy thin set on that one), 1/2 inch concrete board, concrete (shaky, should have put a membrane over it) and plywood covered with red seal. I had no cracks or other issues with any of them. Which one I use depends on the height of the surrounding floor. If it won't create too much of a mis-match, I use 1/2 inch concrete board over at least one sound layer of subfloor. The least height is the red seal. I used that over a several decade old plywood subfloor.

 

[tvrgeek]

Let me try to explain better:
Cement board and liquid waterproofing WITH the cloth reinforcement mesh through out.
or
Decoupling membrane instead of the Hardi board as it is also waterproof, and only use the mesh and liquid in the shower pan and transition.

I do not have the height to use both Hardi board and the decoupling membrane. Again, two layers of subfloor.

My thought is the brush on waterproofing is somewhat compliant with the correct three coats and the reinforcement cloth embedded. ( I used Red Guard on the walls of a shower I did in my last house) My other thought is the shower tile go over the plastic pan with liquid and mesh, no further de-coupling. The pan sits on only one layer of blocked-up subfloor and is back-filled with thin set as per manufacturer instructions.

I am using the VIM shower pan. I intend to use epoxy grout. A real pain, but I just used the fancy " good as" stuff on a backsplash and the surface texture is much rougher than epoxy. I want the very most durable non-staining.

I want it to be good not just this year, but 20 years from now.

 

[waitup]

Gotcha, if the difference in price doesn't matter I would use the go with the decoupling membrane instead of hardi and just waterproof the shower pan and transition. Epoxy grout is fantastic idea for longevity of looking good.

 

[tvrgeek]

Thanks Matt. I think that is what I will do.