cracks in new travertine floor: advice needed!

[White Room]

Was the Tile backers board fixed onto adhesive before screwing down...

 

[Rich]

There are so many things that could have gone wrong, I will wait to see what the builder comes back with but my feeling is that the cement boards have been screwed down without any adhesive under them?

Also is there any chance of some pics? What ever happens the tiles are going to have to be lifted, if we could get some detailed pics of the cracks, the tiles before and after they have been lifted and the floor itself, we can get a much better idea of what has happened.

 

[KateME13]

Hi--

Here are some photos, but they don't really do it justice! Have been in touch w builder, hopefully will have some answers tomorrow. Thanks so much for all the posts so far.

 

[White Room]

A decoupling membrane may have helped, travertine and ufh..

 

[The Legend; Phil Hobson RIP]

Sorry to hear of your dilemma, as above so many possible causes, pics would help. Hope you get sorted

 

[Rich]

A decoupling membrane may have helped, travertine and ufh..

Never a bad idea. My money on either a joint in the chipboard with a bit of bounce (not sat over a joist) or no addy under the cement boards. Will have to wait and see what Mr builder comes back with.

 

[bugs183]

I'm guessinfg its one of two things.
a. The floor is not secured enough to the rafters below, so is flexing.
b. and I'm with Whitebeam on this, no un/decoupling membrane has been used.For tiling over a wooden floor there is no substitute for a decoupling membrane, Trouble is not many tradesmen, tilers included have heard of these so they get sold backer boards. What you have is 'defraction within the substrate', This means whatever you are tiling to is moving, If you were to dig straight down through the tile along the crack you will find this crack will 9 times out of ten be above a joint in the backer board. Wood moves, and backer boards stress at their joints,and unless its glued with flexible adhesive and screwed at least every 100mm centres it will crack. A de or uncoupling membrane if fixed above the wood will takes the stress within itself thus relieving the stresses in the wood. It is also recommended now that any underfloor heated floor has a uncoupling membrane included, though this happens rarely due to cost.

Google Schluter Ditra Matting and you'll see info on these kinds of mats. We NEVER tile to a wooden floor without them, and we've fixed hundreds of meters with no problems.

Solution, well it may stabilise, or it may continue to crack. I'd inform the builder of your problem, then decide if you want to leave it a while for the floor to stop moving (could be damp flooring or timbers), or there really is no other way than to dig the floor up, if its flexing its needs fixing, and its too late to add a membrane because of the height difference between the old and replaced tiles.
Ooh and if you fobbed off with 'its the tiles' it's not because the cracks are in an adjacent straight line, so this proves things aren't too happy under the tiles.

 

[One Day]

Bugs 183 - great sum up.

I've nothing to add really except the main problem (in my opinion only) is using a builder instead of a professional tile & stone fixer.

Builders build. Except mine didn't. My garage roof fell off.

 

[charlie1]

Always a good idea to use decoupler with such a fragile stone when tiling on wooden subfloor however, in this case I think the root problem is the flex (up&down movement) in the floor, decoupler will only address lateral expansion. I think the floor will need to come up, along with subfloor and see whets going on with these joists

 

[KateME13]

Hi - Thanks for all your suggestions so far -- am still trying to find out the make of tile backer and whether it was laid with gaps. (May be a dumb question but if the tiles are fixed to the backer and the backer expands, won't the tiles detach?)

Meanwhile, last night we measured out where all the cracks were in relation to the joints of the tile backer boards and in relation to the chipboard t&g boards below those. In short, the cracks (about 14 m of them in total) run almost exactly along where we think the joins of the tile backer boards must be. The only exception is where we think they cross the middle of a board to join to cracks that correspond to joints at either side (as the boards were laid in a brick pattern - hope that makes sense). Is that information helpful?

In reply to Stewart's question of yesterday -- I think they fixed the tiles with dollops of the brown adhesive and then allowed liquid grout to run under the tiles and take up any space. I'm not 100% sure about this so will need to check with the builder.

Thanks again for all your help -- I really feel as though we are getting somewhere.