Tiling over tile? [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile

PDA

View Full Version : Tiling over tile?


RDREW
04-26-2006, 05:30 AM
Hello all~

Looking for a bit of direction on a small floor space that I'll be tiling. The area is a medium sized bathroom which leads to a small hallway. The flooring now is old mosaic tiles, no cracks, still in very good shape. Question is this: is it acceptable to tile over old tile, or should I remove the old stuff? I don't mind doing the work, just looking for the best route. I plan on using a natural stone on the floor, a nice colorful slate, or something like it. The existing tile was installed directly onto plywood subfloor probably about 30 years ago.

If I should remove the old tile, are there any tricks getting up old thinset and making the floor level once again for the new stuff? Following removal, should I use something like Ditra or some other isolation membrane to separate from the plywood?

Thanks so much once again!!!!

~Rob

Sponsored Links


bbcamp
04-26-2006, 06:19 AM
Rob, the first thing we gotta check out is your floor structure. Natural stone needs a floor that is twice as stiff as ceramic tile. We need to know the size, spacing and maximum unsupported span of the joists, and the thickness and type of subfloor. If those are OK, we can proceed.

RDREW
04-26-2006, 06:23 AM
Hey Bob,
Thanks for the quick reply, will check when I get home today (at work now). I can see the joists from the basement, but how will I guage the thickness of the subfloor? Should I drill a hole?

~Rob

bbcamp
04-26-2006, 06:25 AM
You can do that, but first, try to locate an existing penetration, such as a HVAC register, or the like. If you gotta drill, try not to hit something valuable. ;)

RDREW
04-26-2006, 02:48 PM
Ok, got the necessary info. The joists are 2x10's, and are 16" OC. The longest unsupported length is 12', and the thickness of the subfloor is 1/2 inch. How should I proceed from here? Thanks guys

Rob

JTG
04-26-2006, 03:12 PM
Rob
If you just have the 1/2" and the tile set on that it won't work for stone and I'm kind of surprised it worked for the tile that is there now. Have you tap tested to see if they are all secure? No hollow sounds.
Note above where is says " Deflecto " you can click on that and input your floor informations and get an idea on what it will work for. Daltile makes a number of porcelain tile that look like slate and you can get by with much less floor build up. :goodluck:
JTG

RDREW
04-26-2006, 03:34 PM
Hey Jerry,

Thanks for the reply. If I were to want to continue with the slate, what would I need to do? How much underlayment will I need to add? You should know that there is slate in the front hallway (opposite side of house), and is still intact. I wouldn't mind a reducer going into the next room, but obviously don't want too drastic a drop off.

Thanks again!

~Rob

RDREW
04-27-2006, 04:33 AM
Hi guys,

forgot to respond to Jerry's earlier question. I did do a tap test, and everything seems secure. How to proceed from here?

Thanks

mosquito
04-27-2006, 06:45 AM
Your joists will work for tile but not for stone. You will need to place additional support if you're stuck on slate. What is the makeup of your 1/2" subfloor? 1/2 ply directly on the joists? Like Jerry said, its lucky your tile held up on that. If you want to go the stone route, that will have to be beefed up too.

So now the ball is in your court, how much work do you want to do? For slate you need to add a beam or sister your joists, pull up the old tile and add about 3/4 inch ply. Some of the others may be able to tell you more about the subfloor, but I think a total of 1 1/4" is what you aim for under stone.

bbcamp
04-27-2006, 10:18 AM
Are your mosaics set on a mud bed, or backerboard, or what?

I'm not ready to give up on tiling on top of the existing tile.

RDREW
04-27-2006, 11:44 AM
Well, there is a small area which isn't tiled (used to be a cabinet sink, is now a pedestal), and from what I can tell, they were set directly on plywood. I may be wrong about the floor thickness, I check the closest heating vent to this space, but maybe I oughta drill a hole to be sure. What do you think?

Rob

bbcamp
04-27-2006, 12:26 PM
With stone, you need to be sure. ;)

...there is a small area which isn't tiled ... and from what I can tell, they were set directly on plywood.
And now, I'm giving up on setting the stone over the tile.

RDREW
04-27-2006, 12:41 PM
haha, gotcha. Will check floor thickness by way of drill... then get back to ya.

Thanks

RDREW
04-27-2006, 02:59 PM
Ok, drilled a hole, much to my dismay, I was correct: subfloor is only 1/2 inch thick, and was tiled directly to the ply. At this point, I'm willing to forget the stone tile and go with a ceramic/porcelain. I assume I'm going to need to pull up the old tile~ no problem there, but do I need to add some more plywood? or can I just lay ditra on top of the 1/2 inch and tile to that, or would it be better to lay backerboard on top of the existing ply?

One final question: anyone have any tricks for getting a nice even surface after ripping up old tile? Thanks

Rob

RDREW
04-27-2006, 07:16 PM
Bueller? Anybody? Bueller?

John Bridge
04-27-2006, 07:16 PM
Hi Rob, :)

I can't explain how anything managed to hold up over 1/2 in. ply, but I'm telling you you'll need more. The minimum any manufacturer will allow is 5/8, and that's pretty skimpy.

RDREW
04-27-2006, 07:25 PM
Hi John,

Thanks for the reply. What would you recommend? Another layer of 1/2 inch, then ditra, then tile? or could I get away with 1/2" CBU then tile?

Thanks again

Rob

bbcamp
04-28-2006, 06:00 AM
I'd go with the 3/8" and Ditra for ceramic tile, or 5/8" and Ditra for stone. CBU doesn't offer any structural strength.

RDREW
05-03-2006, 05:19 PM
Alright guys, sorry. I made a mistake on the measuring. As it turns out, the subfloor IS a full inch. 2 sheets of 1/2 inch ply. So, I think i'm back to the idea of laying stone (Slate). Can I lay ditra right over the existing mosaic tile? If so, do I have to scar it up with an angle grinder? And is there a special thinset for doing this? Thanks again for all the input!

Rob