HELP Hairline cracks in grout

[DavieA]

Well I have a serious problem that ive never experienced on any of my other tiling jobs. Tiled a bathroom floor with flexible SPF and flexible Grout onto 12mm ply screwed to death over chipboard done by builder but have found that after grouting that in a couple of areas ther is small hairline cracks appeared. Ive done nothing different from what I normally do so am in real need of advice.
The grout mix was correct and i did not over wet the mixture and cant see how there could be a movement problem...

Please help as in racking my brains with how to cure this issue.

Thanks again all.

Dave

 

[DHTiling]

Hi Dave.

Did anyone walk on the floor before the grout cured..?

 

[DavieA]

HI,
No not that im aware of , asked builder and he said noboy had been on it. But who knows really I wasnt there so cant say for sure.

Possible the customer may have to have a wee look after I was gone.

 

[mikethetile]

might be deflection in the floor

 

[DHTiling]

It is either deflection issues or the tile biscuit has drawn the moisture to quick and caused the grout to crack...are the cracks at the tile edges or all over the joints.?

 

[DavieA]

Yeah thought of that too but the floor seamed solid and no bouce that I noticed. Is there any cure if worst case senario it was deflection?

Trying to cover all bases and cases..

 

[DavieA]

tile edges mainly Dave and just in one area that ive noticed.

 

[DHTiling]

Ok.. Best bet is to rake out and re-do... which grout was it..? just seeing if you can add some additive to increase the adhesion and flexual strength.

 

[DavieA]

It was Mapei Ultracolor Plus Grout,

 

[DHTiling]

That is a very strong grout and will be very hard to use a grout rake...

I would just re-do the cracked area's and take it from there.

 

[DavieA]

Quick question Dave whats the difference in causes between cracks all over joint or along the edges of tiles?

 

[DavieA]

Tried grouting over the hairline cracks but they re appeared, Any idea or you still recon best bets to take out damaged grout and try again?

 

[DHTiling]

It is was all over the grout..

It could be bad batch or incorrect mix or even bad delfection to break up that easy.


When it is cracks on the tile edge, it is more likely small deflection from being walked on or moisture absorption from the tiles biscuit.

But not something i have come across wi th mapei grouts.. i have with BAL stuff but not ultra colour.

 

[DHTiling]

Tried grouting over the hairline cracks but they re appeared, Any idea or you still recon best bets to take out damaged grout and try again?

I didn't mean grout over, i meant just rake that area out and re-grout that bit.

 

[kilty55]

just out of interest mate what was the adhesive type you used? only ask as i saw a similar issue recently