Help - Floor tiles coming off !!

[SarahW]

2 years ago we had a slate floor laid on to concrete, the concrete had been down about 4 months and the tiler used a flexable adheshive. after about 2 months some tiles started to sound hollow, then they started to crunch when you walked on them and now they are coming up. In some parts of the room they are raised up by about 4mm, when we took some up they lift clean off, the adheshive has stuck to the concreate but not to the tiles. Does anyone know why this has happened?

 

[Gazzer]

Sounds like the tiler did not clean the slate before fixing

 

[Benny]

Could be that the open time of the adhesive had expired when the tiles were placed on it, in other words skimmed over or the slate was dusty on the back, or that the base was still wet and the contraction as it dried caused the tiles to de-bond ?

:huh2:

 

[SarahW]

I'm fairly sure that he didn't clean the tiles before they were laid - would this be enough for them to not stick ?
The concrete seemed dry, it was kicking up a lot of dust - should he have tiled on to new concrete?

 

[DHTiling]

How big is the floor area that was tiled..?..

Was it tiled up to the skirting or under..?..

 

[SarahW]

the room is about 7m by 5m

It was tiled up to the walls which had been replastered and then the skirting board was put on afterwards

 

[Benny]

New concrete should be left 6 weeks minimum, unless using special adhesive.

 

[DHTiling]

It sounds like the tiles have debonded due to expansion in the floor...the tiles have come loose as they were not correctly adhered to the adhesive bed.......you should really wipe the back of the tile with a sponge etc...to remove surface dust and create a good bond and in most cases the tile is back buttered to achieve this with slates.......

 

[sWe]

I'm fairly sure that he didn't clean the tiles before they were laid - would this be enough for them to not stick ?
The concrete seemed dry, it was kicking up a lot of dust - should he have tiled on to new concrete?

The longer you wait, the better, when it comes to newly cast concrete, but as long as you use materials specced for the age and type of concrete you're using them on, you'll be fine. Vacuum cleaning, or atleast brushing off, dusty surfaces, is definatly something to recommend when tiling. Dusting off tiles before using them is also something I'd strongly recommend.

My guess is that the tiler didn't dust of the tiles properly before using them. It is also very possibly that the tiler didn't use a correctly specced adhesive, in combination with exceeding the open times of the adhesive.

 

[mz30]

I personally don't think it has anything to do with ,cleaning the slate or the amount of time the concrete was left,i have seen this in the past and it was all down to the thickness of the serrator the tiler used,if he has used a thin notched serrator on the floor they tend not to adhere to the slate instead they stick to the conrete and the tiles are only held in place by the grout until you get some traffic on it .

Not saying thats it but i have seen it a few times with slate and the reason has only been down to the depth of the bed.

 

[SarahW]

Should he have put anything on the concrete like a primer ?
Why have they raised up ?

 

[DHTiling]

If they have raised up sarah...they are tenting...how tight did he cut them to the walls......

 

[sWe]

Should he have put anything on the concrete like a primer ?
Why have they raised up ?

Wether or not to use primer depends on the adhesive one's using. Some adhesives are "primer free" on certain surfaces.

As for the tiles raising, I'd say the same as Dave. Did he leave expansion joints/space along the walls?

 

[Benny]

We all know that floor tiles should be solid bed fixed, in other words no voids or do we? sounds like your tiler didn't.

And priming is always recommended on dusty and porous surfaces.

 

[SarahW]

Not very,but the skirting board is on now so I can only see in a few places

But the walls had just been plastered and that didn't go all the way to the floor because there would be skirting board.