This is my first bathroom diy remodel. I am getting ready to lay down a new tile floor in the bathroom. The subfloor is currently 1/2″ plywood. I plan to use Schlute Ditra; but they (Schulter) indicated I needed to add 3/8″ OSB first. I plan to use a standard 36″ X 108″ Nuheat mat (this will add approximately 1/8″ height to the floor), but I have two areas that will not be included. My question is what do I need to do to make sure the floor is level before laying down the Ditra. Do I need to add a 1/4″ hardie backer board to the other areas. or just apply more thinset? Any suggestions would be greatly appreciated.
Harold
Replies
Greetings rc,
This post, in response to your question, will bump the thread through the 'recent discussion' listing again.
Perhaps it will catch someone's attention that can help you with advice.
Cheers
when in doubt add garlic
You can simply put down the mat as shown in the installation guide that NuHeat provides. The 1/8" is imperceivable, and it's not that thick.
I have no idea what Schlute Ditra is or how it must be dealt with. All of my tile baths have plywood subfloors, 3/8 Durock tile backer, in most cases the NuHeat mat and ceramic tile.
Harold try posing your question at this excellent tile forum
johnbridge.com
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
As already stated, the thickness of a Nuheat mat is small enough that it probably won't matter. If you are setting polished marble you might see a "jump" in the reflections as you move over the tiles but it will be negligible for ceramic tile. You should provide a small notch in the plywood for where the two wire leads come out of the mat. That area is thicker than the mat and will affect the lippage.
A more interesting question is what kind or mortar to use. Schluter recommends modified on plywood but dry set on top of a heat mat. Since your heat mat only covers part of the floor should you mix two types of mortar? Schluter could not give me a good answer so I use two mortars mixes. I also use a plastic notched trowel when working on top of a heat mat to prevent cutting the wires.
To the best of my knowledge you should have a minimum of 1" floor thickness to prevent the floor from 'moving' and cracking the tile. Unless you have very substantive floor joists on 12" centers I would not like to tile over a 1/2" subfloor.
I'd recommend a minimum of thinsetting and screwing down a layer of 1/2" cement board, screwing directly to the joists wherever possible. I know the argument continues as to whether or not a layer of cement board actually 'stiffens' the floor all that much, but better than bare 1/2" ply.
Let's not confuse the issue with facts!