Marble Floor Tiles - Hairline Cracks - Tile Advice

[Alzak]

Hi All,


Is probably not the problem I would like to talk about but looks like me and my dad mess something up with my bathroom flooring …


Floor was put down about 3 weeks ago and yesterday I noticed some tiles do have cracks.


Tiles are cappuccino marble and subfloor is wood boards 15mm on wood joints.


We used 6mm plywood board and 6mm cement backer board to strengthen subfloor, first we installed tile backer board and then ply board ply was in one piece (as it is relatively small bathroom) and then ply was screwed to subfloor with around 200mm spacing between screws, on top of ply we used acrylic sealant.


Following day we installed electric heating mat covered with mapei self-levelling compound (around 7mm) on top of this we used white flexible adhesive followed by marble tiles.


Not sure where we made mistake ? is it too thin ply ? or anything else ?


One thing we did about week ago we used electric chisel to dig some concrete in kitchen right beneath bathroom not sure if vibrations caused by hammer may got something to do with floor damage ?

 

[J Sid]

hi, sorry to you have problems

those tiles are very weak and need the right prep and fixing method.

your biggest mistake was using ply, 6mm is far to thin and only any good for sold floor coverings. Why use it?
slc over ply has made the ply expand and as it dry's will move.
if you had to, the sides and back need sealing and then it's still no good under ufh wires.

should of :
insulation board
ufh
slc
uncoupling membrane
tile

will fail and sadly needs to be done again, hope you haven't pay him yet

 

[Alzak]

Hi


No I do not paid my dad for this and he is not and was not expecting payment …


That’s the thing tiles cracked in the middle of bathroom rather than on edges.


Ply was properly sealed with acrylic BAL sealant (sides were not unfortunately)


When you say this would fail what is the worst thing may happen ? as I would really want to avoid lifting all tiles just to get this done again…

So basically PLY in my instance is reason for failure ?

 

[Lou]

Yes you needed a tile backer board or something instead.

 

[Alzak]

ah well shame really as I was thinking about using 12mm tile backer instead of 6mm of backer bard and 6mm ply as we used, but I thought 6mm ply in one piece would add some strength to floor beneath marbles ...

 

[J Sid]

backerboard is moisture stable, ply is not so moves with moisture (living)
18mm ply back and edges sealed and an uncoupling in top, be it a sheet membrane or insulation board.

given time it will break up and probably just lift out as I'd be surprised if it's stuck properly. Needs a 100% bed, anything less it will fail anyway

 

[Dan]

As above. Plywood in general these days shouldn't be used for tiling to. There are too many types, and suppliers often don't know which one they have and whether it's good enough for tiling to (although they often say it is). And 6mm shouldn't be used for anything really it's far too thin. I'd even opt for 15 or 18 for solid floor coverings because nobody wants a wibbly wobbly wavy floor.

Ideally it needs ripping up and retiling with the right stuff.

 

[Alzak]

That's the thing floor is solid (it was solid previously with ceramic tiles) no cracks at all in grout etc.

When we fitted this tiles some broke during cutting (rubi wet DU-200 with stone cutting wheel used ) so I was little bit worried tiles may be part of my problem as well.

So if I decide to leave this floor as it is what is the worst may happen ?

 

[Bathfix Bob]

I'm sick of this now, we have all had issues with floors, I Know I have and this is after doing everything right.
Every bathroom I've done and I go back to do other jobs, my eyes are all over the floors checking for the hairline cracks. I recommend all floor tiles are porcelain now to my customers as Im sick of stressing, everytime my phone rings I'm paranoid I'm going to have to rip a floor up.

Granted I've only really had two fail over Hardiebacker joins and the second one is only one line.

Just having a general rant OP, I mean what forces are really at work to pull a tile apart? in the OP's case the ply shrinking?

I saw another floor recently done by a guy with a fantastic reputation who tiled a floor and the grout has huge long linear cracks through most of the joins so much so you can wiggle the grout out like a loose tooth.

 

[Dan]

I dare say ceramic tiles will be a bit more forgiving. Marble with it being natural will split easier I think.

Point is, it's split down the middle, probably where a join is? Or at least flex is?

 

[Dan]

I'm sick of this now, we have all had issues with floors, I Know I have and this is after doing everything right.
Every bathroom I've done and I go back to do other jobs, my eyes are all over the floors checking for the hairline cracks. I recommend all floor tiles are porcelain now to my customers as Im sick of stressing, everytime my phone rings I'm paranoid I'm going to have to rip a floor up.

Granted I've only really had two fail over Hardiebacker joins and the second one is only one line.

Just having a general rant OP, I mean what forces are really at work to pull a tile apart? in the OP's case the ply shrinking?

I saw another floor recently done by a guy with a fantastic reputation who tiled a floor and the grout has huge long linear cracks through most of the joins so much so you can wiggle the grout out like a loose tooth.

You're kind of hiding the problem if you use porcelain. All the same stresses and deflection will still be there. You're just prolonging the problem. The tiles might pop off one day.

You're making the structure of the floor be the porcelain tiles. Which will help to a degree. But the floor should be structurally sound before the tile.

Love the rant though lol

 

[Bathfix Bob]

Can you live with the cracks Alkaz? theres no easy fix.

 

[Old Mod]

This is NOT a fix, it's a way to cover up the cracks, possibly.
If they're not too prominent you could colour match the marble with Akemi and actually repair the cracks and maybe pass them off as natural fissures, maybe!
No idea how long it would last, would depend entirely on floor movement and fitting technique used. Might be worth exploring if you don't want to rip it out.

 

[NZ_Tiler]

Following day we installed electric heating mat covered with mapei self-levelling compound

Was it mapei fibreplan you used over the floor?

How did you commission the UFH?

As above though, ply is to thin.

 

[Time's Ran Out]

Under floor heating, marble and no uncoupling membrane - just a disaster waiting to happen.