Grout coming out and crackling noise under some tiles

[Sachin Parab]

Dear All,

I have recently has procelain tiles laid in my downstairs area which is around 80sq.m. We have UFH (water based) installed as well.

The builder has was Lafarge (anhydrite) screed. He has allowed enough curing time (3 weeks) and heating was commissioned in the right way (starting lower first and gradually increasing and then turning down 48 hours before tiling commenced). Following the tiling we started noticing movement in the tiles and following further investigation by the builder it was found that a primer was not used. to bond the adhesive.

The builder has then removed all the tiles. Floor was then checked with hygrometer for mositure which had all the right readings. Floor was then sanded and primed with 2 coats (1st coat 1:5 left for 12 hours and 2nd coat 1:1 left for 12 hours). UFH was turned off 48 hours before priming the floors. Tiles were laid and UFH left off for 3 weeks and now turned on gradually. The adhesive used was Mapei flexible keraquick adhesive and mapei flexible grout.

A few days before the UFH came on I noticed one area of grout coming out. Since the UFH has come on the grout has started to come out in a few tiles and about 4 tiles are showing movements at the edges.

The builder has raised a complaint with CEMEX and an investigation has been initiated.

I will be grateful if I could get any advise on any steps have been missed and if anything else can be done.

The fortunate thing the builder has accepted accountability and has assured he will get it sorted whatever needs be, but the problem I have is that all my work has been completed and all furniture in place now, but I guess I will have to deal with it.

Thanks in advance

Sachin

 

[Andy Allen]

Did the builder back skim the tile with a layer of adhesive before fitting the tiles?

 

[Sachin Parab]

Thanks Andy for your prompt reply.

I am not sure about that but will ask. As far as I am aware when I was watching he tiler was apllying the adhesive to the floor and placing the tile on it and then filling void areas with adhesive again.

What do you exactly mean by back skimming?

 

[Andy Allen]

Porcelain tiles are very low in porosity, so to gain the maximum adhesion the adhesive should be spread on the floor using a notched trowel then a thin skim of adhesive spread on the back of the tile, when the tile is fitted this adhesive sandwich ensures you gain a maximum bond between tile and substrate.

 

[Andy Allen]

Of course this is just one theory, there could be many reasons as to why it failed.. ....
Floor not dry...... As in bone dry
Laitence not removed..... Sanded... Hovered..
Primer issue..... To thick or to thin.
Thermal shock..... Heating turned on to soon or to quickly..

You need to remove a tile and establish if the adhesive has stuck to the floor but not the tile.. Or to the tile and not the floor..... This would be a start to finding the problem..

 

[Sachin Parab]

Hi Andy,

As mentioned

The dryness of the floor has been checked using hygrometer.
Primer used is line with the adhesive requirement as confirmed by the technical representative of the company
Latince was removed as I mentioned the floor was cleaned and sanded before laying the tile
Not sure about thermal shock.

The first time when it failed the adhesive was stuck to the tiles and not to the floor. Not sure this time.

One of the explanations given by the builder that the grout has not been pushed in well as only the edges are showing slight movement.

 

[Qwerty]

What primer was used

 

[Andy Allen]

If the edge of the tile is moving then there must be voids under the tiles....... We're the tiles just Fixed using dabs of adhesive?

 

[Sachin Parab]

No the adhesive was spread on the floor and the whole area of the tile was covered with reinforcements to the edges as needed.

 

[Sachin Parab]

It was mapei G1 primer

 

[Andy Allen]

No the adhesive was spread on the floor and the whole area of the tile was covered with reinforcements to the edges as needed.

So he spread adhesive on the floor using a notched trowel then put blobs of adhesive onto the back of the tile...?

 

[Flintstone]

This isn’t an error due to not back buttering. It’s a problem with the bond to anhydrite. It’s a solid floor so if there is any grout coming out or any movement at all in a tile then the tile has come loose.lift a tile and look what’s happening, I’m sure it will be adhesive stuck to tile but not the floor. What were the moisture readings? What did he use to sand the floor? 3 weeks before tiling one of these screeds is not a long time at all, they can take many months to dry out.

There’s some good gypsum based Adhesives out there, not sure why he didn’t use one!

 

[Flintstone]

I don’t use primer g but perhaps someone who does can confirm, on gypsum based surfaces you need a neat coat of primer to create a barrier between the gypsum and the cement based adhesive,

 

[Andy Allen]

Andy......re- Read the ops post..
This is the second time it's been tiled... .

 

[Flintstone]

Yeah I know!