Four months ago I tiled my kitchen floor with large floor tiles some of which now sound a bit hollow and others are starting to move a bit.

Background: Firstly I screeded the concrete kitchen floor to level it after removing old tiles. When the screed had dried it was sealed with PVA. The tiles were laid on top of Wickes ready mixed floor tile adhesive for concrete floors. I replaced two of the tiles in January because they had started to move a little bit and the grout between the tiles was cracking. When I had taken these tiles out the floor sounded hollow when I knocked on top of the screed bed. Now some more of the tiles are sounding hollow and the grout around them is cracking a little bit.

Does anyone have any ideas why this is happening?

Hello and welcome...

This could be a number of things....

Has the adhesive bonded to the tiles.....what type of tile is it...cermaic/porcelain etc..?

Dave

They are ceramic tiles. When I lifted the two tiles, the adhesive was only stuck to about half of each tile BUT it had bonded completely to the screed.

If the screed is sounding hollow where you have lifted tiles it sounds like a failure to bond between the screed and concrete floor below it, you say that the adhesive has bonded to the screed completely, but only partially onto the tile, if you look on the back of the tile and also the space it came out of, what amount of coverage was there, how much tile was touching adhesive ?

Also, was the screed lifted with the tile when taking them up ?

The adhesive had completely bonded to the screed. No screed lifted at all from the concrete floor. The back of the tile had about two thirds adhesive sticking to it. The rest of the tile was clear of any adhesive.
Thanks

Originally Posted by tiger11

The adhesive had completely bonded to the screed. No screed lifted at all from the concrete floor. The back of the tile had about two thirds adhesive sticking to it. The rest of the tile was clear of any adhesive.
Thanks

In that case sounds like 2 things haven't happened, the screed hasn't bonded to the concrete ( was it primed / devoid of dust etc ) and a 'simple' coverage problem whilst fixing the tiles, maybe a level problem ?

Another option ...could be that the tiles are cut to tight around the perimeter of the room ...i.e against the skirting...this dosen't allow for expansion and can cause the tiles to tent...debond from the substrate...

There weren't any problems with the level at all. The screed is stuck fast to the concrete with no loss of adhesion even when lifting the tiles. Any ideas as to why parts of the tiles themselves are not sticking to the adhesive as the missus has pointed out that other tiles sound a bit hollow now, especially in areas of foot traffic. Can anything be done? I don't really want to have to lift the whole floor.
Thanks again.

With it bieng a ready mixed adhesive then it might have skinned before you had time to lay the tiles....Not sufficent adhesion to the tile...

Without seeing it , i would say it will probably be a re-tile but use bagged adhesive that you mix and not tubbed gear...but as we cannot see the extent or how much is loose or is going to come loose then the call is yours i'm afraid..

I reckon Dave is right, its skinned and prevented sufficient bonding. Did a quote where a bloke had the same problem and had used that unibond floor tub stuff.