Replies

1. 
   klhoush | Feb 10, 2009 04:34am | #1

   Soapstone on a floor? Isn't that a bit soft and easy to scratch?

   There was a thread recently on newfangled underlayments that break the old 1 1/8" total thickness under tile rule. I never trust a new product, too many don't work.

   OB

2. 
   davidmeiland | Feb 10, 2009 04:48am | #2

   You can use 1/4" backerboard on subfloor. 1/2" is needed on walls where you are bridging studs.

3. 
   BillHartmann | Feb 10, 2009 05:07am | #3

   Ditra

   .
   William the Geezer, the sequel to Billy the Kid - Shoe
4. 
   EricPaulson | Feb 10, 2009 05:43am | #4

   Any well known brand name modified thinset will give superior adhesion to plywood.

   You don't need ditra or cement board or hardi.

   Try it on some scrap.

    

1. 
   BillHartmann | Feb 10, 2009 07:55am | #6

   For CERAMIC tile the TCA does not show a method for install tile over single layer of plywood over board sub-floor.Not saying that it won't work, but it is not specified.They so have methods for over 2 layers of plywood. And various backerboard and decoupling membrains over a single layer of plywood.But this is stone. And the TCA only recommendation is to get the spec from a stone group.IIRC it is the Marble Institute..
   William the Geezer, the sequel to Billy the Kid - Shoe

5. 
   Mongo | Feb 10, 2009 06:18am | #5

   I think everyone has already hit all your options. The ply needs to be fastened to the planking roughly 8" oc in the field.

   Thinnest obviously is to tile right on the plywood. If you tile on the ply, use an unmodified thinset and modify it yourself with a latex admix. That will give you a better bond than using modified thinset right out of the bag.

   Next thicker would be using an uncoupling membrane like Ditra over the plywood and tiling over the Ditra. The Ditra itself is about 1/8" thick.

   Thicker than that would be cement board over the ply. You could use either 1/4" or 1/2". First you trowel (1/4" square notch) unmodified thinset on the plywood, then set the cement board in the thinset. Then fasten (nails or screws) the cement board to the plywood. Tile over the cement board. The thinset between the ply and the cement board is not so the cb will stick to the ply. The fasteners do that. The thinset is to prevent any up/down flexing of the cement board due to small voids between the ply and the cb.

1. 
   rktect | Feb 10, 2009 04:24pm | #8

   Thanks to everyone for your suggestions.  I think I'm going to use the Ditra system just to be safe.  An extra 1/8" height isn't going to be too obtrusive.  I've heard too many negative things on other forums about laying the stone right on the plywood.  Thanks again.

6. 
   tom21769 | Feb 10, 2009 12:44pm | #7

   I'm curious why you decided on soapstone.
   I like the idea over a radiant slab but am concerned about wear. How does it compare to hardwood?

1. 
   rktect | Feb 10, 2009 04:29pm | #9

   I decided on soapstone tiles for the floors because I'm using the same stone for the countertops and wanted to have consistency between the two.  I'll have to post a note on here after I install it to let you know whether or not I'd recommend soapstone tile for kitchen floors.

1. 
   Mongo | Feb 11, 2009 01:12am | #10

   I'll pass this along to you...Dark floors show EVERYTHING. Every bit of dust, every streak of grease, every smudge, every tracked footprint. Now that can be good, because when you see it you can clean it. Or that can be bad if you're the type that doesn't want to know it's there.

1. 
   davidmeiland | Feb 11, 2009 01:58am | #11

   Have to say I agree with you. I'm putting in a prefinished oak floor right now, it's a very dark brown/black, almost opaque. It's gonna need sweeping or vacuuming every five minutes. Sure does look cool, though.

7. 
   Pelipeth | Feb 11, 2009 04:18am | #12

   Just tile to the plywood with "good on wood" thinset, Mapei has products for this application. When I tile over plywood I have a Mister at hand and soak the plywood prior to putting down the thinset and tile. Prevents the wood from sucking the moisture out of the thinset, enableing a proper cure.