porcelain tile challenge

efdupont · 11-12-2011, 09:19 AM

I have a basement flooring project. We live on a rocky hill with concrete subfloor on 1/2 of the basement and wood on the other half (pine tung & groove over 16-18" joists). I'd like to put down a uniform floor, so am thinking about porcelain tile. Am I asking for problems? Wondering:

• what thickness of Wonderboard to use, particularly on the wood floor
• if I use 1/2" wonderboard over the wood it will raise the level of the floor above the concrete. Do I use a patching material?
• I'm assuming the entire floor be prepped and level before starting. What if there's a drop off in one corner? Could be 2-4"

thanks.
EF

JazMan · 11-12-2011, 01:08 PM

Hi EF,

Quote:

I have a basement flooring project. We live on a rocky hill with concrete subfloor on 1/2 of the basement and wood on the other half (pine tung & groove over 16-18" joists). I'd like to put down a uniform floor, so am thinking about porcelain tile. Am I asking for problems? Wondering:

If both sides start out at an even plane, that is not a good situation to proceed, cuz...... You need plywood over the t&g planks before you can install a concrete backer or membrane. Depending of the width and condition of the planks you may be able to go with 1/2" underlayment grade ply. Then install 1/4" backer or a membrane such as Ditra or one of Noble's.

Alternatively you might consider removing the planks and replacing with 3/4" t&g making everything in plane. Then install the membrane on both surfaces.

Quote:

• I'm assuming the entire floor be prepped and level before starting. What if there's a drop off in one corner? Could be 2-4"

Prep first on the concrete and the wood if you use a membrane. If you use a concrete backer on the wood you will make the floor flat after. 2-4" is a tremendous amount to be off.

Also remember the floor needs to be flat, not necessarily level.

Jaz

efdupont · 11-13-2011, 04:43 PM

Hi Jaz,

Thanks for responding! Your suggestions are in line with, and may be more complete than what I'm hearing from the two masons I'm talking with.

•*One mason suggested 1/2 plywood with a wire mesh on top (no membrane) then "mud" into which we'd set the ceramic tile, which he sez can be used to level out remaining inconsistencies.

• Another recommends 1/2 inch Wonderboard. Is Wonderboard as good as the 1/2" plywood? And if you use Wonderboard, do you still need a membrane?

I'm tempted by the idea of removing the subflooring and putting down a 3/4" plywood, as there is a low ceiling in the basement. And I'd like to not lose the extra 1-1.5" of headroom.

Your thoughts?

Thanks again!

EF

JazMan · 11-13-2011, 08:26 PM

Hi Frank,

I'd like to know if both side are in perfect plane where they meet. Very important.

I don't like either method your masons suggested, (masons, why masons to set tiles?), but some clarification is needed in the first method.

Quote:

• One mason suggested 1/2 plywood with a wire mesh on top (no membrane) then "mud" into which we'd set the ceramic tile, which he sez can be used to level out remaining inconsistencies.

The term "mud" is sometimes thrown out to confuse. Mud in tilework is a mix of sand and Portland cement placed about 3/4"-1 1/2" thick, or thicker, as the base for tiles. However, often the word "mud" is used when thin set mortar is used instead. Thin set is the adhesive used to bond tiles in either case, it is NOT "mud".

It sounds as if you've been told about what is know as a "Jersey Mud Job", it's not a good thing. Please let us know more about what he was proposing with this method.

Quote:

• Another recommends 1/2 inch Wonderboard. Is Wonderboard as good as the 1/2" plywood?

You can NOT install any tile backer direct over plank subfloors or on a concrete slab.

So, let me know if the two areas are in plane in which case I'll most likely again suggest replacing the planks with 3/4" ply and then using a membrane over both.

Jaz

efdupont · 11-13-2011, 10:28 PM

Jaz,

The two sides are close to alignment, not perfect, with the concrete around 1/8" above the T&G wood subflooring. Other complications, the concrete actually slopes a bit from a high spot to the line where it meets the wood, and there's not a simple straight line between the concrete side and the wood side.

I should send you a picture. Or better yet hire a tile man familiar with the Ditra/Schluter system, which sounds great (as you describe) over 3/4" plywood and the concrete.

Thanks, I think I'm getting it.

Frank "EF"

JazMan · 11-13-2011, 11:37 PM

Quote:

Thanks, I think I'm getting it.

From what I've gathered I think replacing the planks with 3/4" t&g ply glued and shimmed to meet the concrete will do the job. You are then left with making the floors flat. Sounds like the slab may need some help which of course would run into the wood side too.

I'd have to be there or have pics with details to xplain better.

Jaz