About two years ago, I laid some 12 x 12 marble tile in a small bath (5 x 5), over new 3/4 T&G ply and 1/4 Hardi backer. Now some of the tiles are loose, and I am wondering why.
Joists are old true dim. 2 x 10 hem? spanning about 11′ on 16″ centers. Staple-up pex radiant heat, if that matters.
Any thoughts?
Bear
Replies
Can you post a pic of the back of a loose tile, and the area it was removed from?
"Joists are old true dim. 2 x 10 hem? spanning about 11' on 16" centers. Staple-up pex radiant heat, if that matters."
Maybe
All the full size framing lumber I get is green
If yours was too, it shrank, leaving nails in the ply standing proud for some buckling between ply and hardi
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Edited 11/28/2007 7:38 pm ET by Piffin
Joists are old true dim. 2 x 10 hem? spanning about 11' on 16" centers.
All the full size framing lumber I get is green
I'm reading just old Paul, not green, but who knows.
I'm not a fan of Hardi, the surface does not seem dense to me. almost talc-ish.
I do know that Wonderboard (or cement board is not to be fastened to the joists for the reason you state. I'm sure the same holds true for Hardi.[email protected]
Silly me. How did I miss that word OLD?
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Your mind blocks it out.
If your view never changes you're following the wrong leader
I do know that Wonderboard (or cement board is not to be fastened to the joists for the reason you state.
Please say a bit more about this. According to the warranty requirements, Wonderboard is to be secured with thinset AND SCREWED DOWN. That seems to conflict with what you are saying - am I misunderstanding something?
It should be evenly adhered to the subfloor. Spot securing to joists only will increase stress at those points.Logic says that there were one of two mechanisms at work in this failure.Either there was some sor tof structrual movement under it all where the flaexing caused more stress than the bond could tolerate, or the bond was poor to begin with either from bad mix or letting it skin over
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add to the bad bond reasons, dirt , dust, possibly oily tile backs.
They can't get your Goat if you don't tell them where it is hidden.
I forget where I got that besides here...........someplace important I saw it. Fastened in the field yes, but not to the joists directly.[email protected]
is it possible your thinset was mixed to thin originally?
David is right -- post a photo of the back of a tile. It will help us determine whether there was a good bond between the tile and floor that later broke, or whether the initial bond was faulty.
Did you put thinset under the 1/4" hardi?
Could the thinset have been mixed too dry or was it allowed to skin over before you set the tile? Did you back butter the tile? Was the radiant heat on when you did the job?
Billy
Bear,
Usually 3/4" ply isn't enough to tile over. I knoe you added the hardie, but hardie does not contribute to the structural strength of the floor. So, flexing could be a problem.
The hardie should have been thinsetted to the 3/4" ply, then screwed. And the screws should no go over or into the joists. Thinsettig the hardei to the ply prevents and up/down movement of the cement board as the thinset fills any voids between the hardie and the ply. Even with a stiff floor, no thinset could cause flex failures due to the cement board moving vertically.
Thinset for the marble. A modified? Or unmodified?
The staple-up shouldn't be a problem.
the tiles that failed...are they related to each other in terms of location, or is one here, another there?
Tile substrate is too thin. 3/4 ply and 1/4 hardi is not enough. That would have been a good base for sheet vinyl but never ceramic tile.
If you used a modified thinset made to allow a little flex, scratch coated both surfaces prior to mudding and setting, and the 1/4" hardy was put down flat and well secured, then I'd be surprised.
My guess is your thinset wasn't scratch coated on the marble prior to being set and you had a poor bond, compounded by a lack of moose milk. Am I close?
Cheers
Beer was created so carpenters wouldn't rule the world.