Hi All,

I have tiled an en-suite floor and subsequently a line of tiles have cracked. I have lifted these tiles and noticed that the crack line follows a join in the ply sheets underneath (which has a 2mm gap between the pieces). I noticed (and said to the owners) that there was a bow in the floor when I tiled it across the area where the crack has appeared.

The door to the en-suite was removed prior to tiling and cut to clear the tiled floor - this door was scraping across the tiles before I lifted the cracked ones.

I use BAL rapidset flexible and BAL superflex wide joint grout on top of Ply.

I have previously tiled the kitchen and utility room floors using the same materials and the door between them was cut to clear the tiles again and has no problems.

This all leads me to believe that the floor is expanding with the heat and humidity.

This is the first time this has happened to me and I am looking for help in identifying/confirming the problem and a solution to fixing the replacement tiles back down without it happening again.

Any help would be great :-)

Cheers
Broughty Tiler

what thickness of ply did you lay on the floor

I believe it is only 6mm ply as it had to be level with a solid wooden floor in the bedroom.

it sounds as if theres movement in the floor,did you test it for any bounce?

the ply needs to be a minimum of 15mm which isnt generaly available so its 18mm min for overboarding fixed at 300 centres

Originally Posted by BroughtyTiler

I believe it is only 6mm ply as it had to be level with a solid wooden floor in the bedroom.

no use whatsover for tiling unfortunately,it would probably have sucked the moisture out to quickly,to keep the height down you should have removed the floorboards/t@g and replaced with 25mm ply and extra noggins if the floor wasn't stable enough,if it was you could have used 6mm cement boards

I did try testing the bounce in a couple of areas.

I was thinking I could cut out the current ply and try to screw the subfloor down a bit then replace some new ply and tile over it with BAL Fastflex which is more flexible.

with the 6mm ply i would be surprised if this doesn't happen again in the near future,i think you would be quicker re-doing the floor

I don't generally lay the ply, the majority of the time a joiner has done this prior to my arrival and I have not had a problem so far.

Another question I have is what joining strips would you put down between say a carpeted floor and a tiled floor with 15/18mm ply plus adhesive plus tiles - in other words... a step up

schluter reno v

a chrome or brass tile to carpet bars come with raised sides to accomodate this

If you didn't lay the ply in preparation of tilng why not? That's the only way I'll put my name to a job if I prepare it.
You shouldn't have tiled on 6mm plywood so who's to blame - is it a new property that is drying out - substrate settlement.
I'd ask more of the preparation if I was you.

as mike says schlutre reno -u or tk

6mm is imo for vinyl and other materials, defo not 4 tiles just look how bwndy and flexible it is? so why would they put it on the floor, prob cheaper for the joiner??? he should foot the bill aswell and you shouldnt have tiled the floor???

6mm ? asking for trouble laying tiles on that mate.

12mm ply the dita matting then tile. this stops cracking but as a tiler you should know this a!!

hi broughty. personally i wont use ply anymore myself for exactly the same reason.....i dont trust the quality of ply i was getting from either the merchants or b and q sometimes the sheets were split /sheering even before fixing.....and with the temperature differences in bathrooms and the humidity i dont think imo that ply has any place in a bathroom now.

i use cement boards it is slightly more costly i can only advise you to do the same

its only been the last 6 months really i have been called to so many jobs where this has happened with the ply

where the gap between ply fil with hard as nails then smooth down,let it set,then tile again

Originally Posted by sgd tiling

where the gap between ply fil with hard as nails then smooth down,let it set,then tile again

Don't fill the gap between the ply with hard as nails, its an expansion gap.