Cracking in Tile Grout

[Ajax123]

To be fair it probably isn't their problem but a mid diagnosis is unhelpful in dealing with the issue. Is there any movement either side of the crack if you put your epweight either side of it.

 

[Stef]

Laitance - hired a floor grinder.
Primer - one coat diluted 50-50 in one direction then another coat undiluted in other direction
Used BAL Prime APD

Why would this make a difference to grout cracking though - the tiles are not moving, they are completely solid, no hollow sounds at all anywhere. Or are you suspecting they are moving with cracks forming?

I had to use Bal rapid set on top of an anhydrite screed to push a job on, I only ever use a compatible addy (AnhyFix),
I gave that 6 coats of primer.
I personally haven't used Bals rapid mat & I don't think I ever will as I can't truly understand how it works as I use Ditra & when you see the technical side of it you realise how that works & how it decouples.
I would get someone to stand on a tile & move their weight whilst you check very closely to see if there is movement in the tile.

 

[Andy Allen]

Yes sorry, Bal rep did say tiler should have added GT1 to grout. Weber says its better not to add it as its already flexible.

Don't know why bal rep would suggest that when they don't recommend adding gt1 to there own modified grout ( super flex)

 

[jesteh]

I did consider using gypsum based adhesive. Problem is no mat manufacturer will say their mat is compatible with it. If you ask Schluter whether you can use Ditra with gypsum adhesive, they'll say they do not recommend it. Same with BAL Rapid Mat. So you are going against manufacturer recommendation by using that. I did ask both before the job started.

As far as using 6 coats of primer - why only 6? Again, if I asked Bal or Schluter whether to use 6 coats of primer they will say we do not recommend this - use 2.

I am not saying you are wrong. But you are going against manufacturer recommendation. Probably because you know better.

I on the other hand don't have a clue. I am not a tiler, I don't years of experience or time or inclination to start testing different mats with different amount of primer and different adhesives and see what works best. My tiler also has no interest in material science - he buys tile adhesive in bulk whatever works out at good price. Which is fair enough.

So what I did was to select a supplier and follow their instructions to the letter, trusting that they know what they are talking about. Where I am getting ****ed off is that now I have a problem, they are very quick to say its nothing to do with them and walk off. The entire investigation from BAL consisted of knocking on the tile (it was solid) and poking a nail at the grout. Then blame vertical movement for crack an say that grout is not flexible enough.

I am not saying its a problem with BAL mat or adhesive, I have no idea and neither do they right now. What I am saying is that BAL have shown no interest in finding the root cause which right now puts a very low value on their 25 year material guarantee.

 

[Rich Midge]

The arrogance of these big manufacturers is a joke. We've had similar problems with Norcros. They actually came out and inspected floors in a new build, produced a detailed plan of how we should tile including location of expansion joints, primer, adhesive and even what size spacers. Needless to say the floors failed, not just cracking but lifting in all areas. They came out to it and diagnosed vertical movement so not in any way their fault! The main contractor sent some adhesive samples off for independent testing which found a low polymer content so said manufacturer did their own test. Surprise surprise that test showed the adhesive to be perfect in every way. Vertical movement, a licence to get away with all sorts.

 

[Ajax123]

Can you put a picture on ... That'll make it much easier to diagnose.

 

[Stef]

I did consider using gypsum based adhesive. Problem is no mat manufacturer will say their mat is compatible with it. If you ask Schluter whether you can use Ditra with gypsum adhesive, they'll say they do not recommend it. Same with BAL Rapid Mat. So you are going against manufacturer recommendation by using that. I did ask both before the job started.

As far as using 6 coats of primer - why only 6? Again, if I asked Bal or Schluter whether to use 6 coats of primer they will say we do not recommend this - use 2.

I am not saying you are wrong. But you are going against manufacturer recommendation. Probably because you know better.

I on the other hand don't have a clue. I am not a tiler, I don't years of experience or time or inclination to start testing different mats with different amount of primer and different adhesives and see what works best. My tiler also has no interest in material science - he buys tile adhesive in bulk whatever works out at good price. Which is fair enough.

So what I did was to select a supplier and follow their instructions to the letter, trusting that they know what they are talking about. Where I am getting ****ed off is that now I have a problem, they are very quick to say its nothing to do with them and walk off. The entire investigation from BAL consisted of knocking on the tile (it was solid) and poking a nail at the grout. Then blame vertical movement for crack an say that grout is not flexible enough.

I am not saying its a problem with BAL mat or adhesive, I have no idea and neither do they right now. What I am saying is that BAL have shown no interest in finding the root cause which right now puts a very low value on their 25 year material guarantee.

You are doing everything by the book & that should be enough to cover you for a guarantee but they will find anyway out of it as you have found out.
I don't phone technical now as some of the things they recommend I don't agree with.
This forum is the best place to come for advice but it's normally when someone has a problem like your own case.
It's all well & good us surmising what has led to failure but unless you physically look at the job then it's a guessing game.
I hope you get to the bottom of it.

 

[J Sid]

Like Stef says, they wouldn't admit to anything that would mean there product has failed.
I had this with another adhesive manufacturer who's adhesive failed on some jobs the company I was working for had done. The adhesive company claimed all the normal things, mixed with to much water, not enough water, all the standard excuses.
End of the day, some samples were sent to be tested at an independent chemist. Result, the product was not suitable for what they claimed. The product was withdrawn from sale.
If you believe that any product that was used on your project has not performed as you understood it would or should, sadly it will be down to you to prove that a product has not performed as claimed.
You will get possible reasons for your failure from knowledgeable people on here and hopefully it will point you in the right direction to sort your problems.

Has the floor temperature been taken around the cracked tile for hot or cold spots, which could put undue stress on an already stressed cut tile?
Did the angle of the internal cut have a radius, to reduce the point Load? or is it a sharp point on the internal angle?
Has the max actual floor temperature be measured in the areas of the cracked grout? I know the Weber grout mixed with to much water is very weak, and can be easily done and should be an easy test. If so a re grout of the floor is not a major job.

 

[jesteh]

Thanks very much for all the responses.
I am actually not that bothered about the cracked tile - while a bit annoying its also straightforward to fix. Its only one tile thats been cut and is in a funny place. If it cracks again, it can also be replaced by two smaller pieces - its really not that visible either way. When tiler is back to look at it, we'll lift the tile and see whats happening underneath which will hopefully provide a few ideas.

Its the grout that I am more concerned about. The cracks are very small, really more a hairline fractures and they appear lengthwise either on the edge of the tiles or down the middle of the grout line (rather than across the grout). Grout is also not cracked in every single grout line but it is cracked throughout the whole tiled area. Its not limited to big sections where there is lots of movement. Even in the small separate utility room which is 3m x 1m there are cracks appearing. Cracks are also small enough that you have to get down and look closely to notice them - just walking around the room they are not visible. I only noticed when I started looking for problems after noticing cracked tile. I'll get some pictures done later today.

Is this a major issue?
Is it normal for flexible grout to develop these hairline fractures with UFH?
Should the decoupling mat have prevented this bearing in mind that its advertised as being able to take horizontal movement in milimeters.
Should I leave it for now (grout seems solid and stable enough otherwise) or do I have to regrout?
Does the grout cracking indicate potentially that tiles may start moving too?

As far as quality of grout job - I didn't do it myself so I can't say whether it was done right but the guys who did it were experienced. I actually watched them mixing the grout, they did it by feel - i.e. mixed grout in small amount of water then kept splashing in bit more water while mixing with a paddle mixer at slow speed until it felt right. I wouldn't trust myself to do it that way but its down to experience - they've been doing this for 30 years so I wasn't about to make them measure it out on kitchen scales .

 

[jesteh]

Thanks very much for all the responses.
I am actually not that bothered about the cracked tile - while a bit annoying its also straightforward to fix. Its only one tile thats been cut and is in a funny place. If it cracks again, it can also be replaced by two smaller pieces - its really not that visible either way. When tiler is back to look at it, we'll lift the tile and see whats happening underneath which will hopefully provide a few ideas.

Its the grout that I am more concerned about. The cracks are very small, really more a hairline fractures and they appear lengthwise either on the edge of the tiles or down the middle of the grout line (rather than across the grout). Grout is also not cracked in every single grout line but it is cracked throughout the whole tiled area. Its not limited to big sections where there is lots of movement. Even in the small separate utility room which is 3m x 1m there are cracks appearing. Cracks are also small enough that you have to get down and look closely to notice them - just walking around the room they are not visible. I only noticed when I started looking for problems after noticing cracked tile. I'll get some pictures done later today.

Is this a major issue?
Is it normal for flexible grout to develop these hairline fractures with UFH?
Should the decoupling mat have prevented this bearing in mind that its advertised as being able to take horizontal movement in milimeters.
Should I leave it for now (grout seems solid and stable enough otherwise) or do I have to regrout?
Does the grout cracking indicate potentially that tiles may start moving too?

As far as quality of grout job - I didn't do it myself so I can't say whether it was done right but the guys who did it were experienced. I actually watched them mixing the grout, they did it by feel - i.e. mixed grout in small amount of water then kept splashing in bit more water while mixing with a paddle mixer at slow speed until it felt right. I wouldn't trust myself to do it that way but its down to experience - they've been doing this for 30 years so I wasn't about to make them measure it out on kitchen scales .

 

[Dave]

Morning..

If as you say the tiles are stuck solid and there is no tenting of the field tiles or any signs of debonding , then I would be looking at the water to powder ratio of the mixed grout.
If this was over watered , then this can produce a weaker product , thus can be the cause of the light cracking due to shrinkage of excess water evaporation , so,worth looking at that option as well.

The cracked tile , this could simply be a stress crack to an L cut , this can happen IMO and a replace as you say is simple enough.


Just another option to consider on the info you've provided.

Dave.

 

[Rich Midge]

I think Dave is spot on. Even if the grout was mixed correctly and to the letter the cracking you describe could be down to excess water when washing down. Really could be as simple as not squeezing enough water out of the sponges, be it washboys or by hand.

 

[J Sid]

Weber Grout mixed to wet or washed to soon or to much water...... Post #8.
Seen it may times on ufh, but what do I know...

Turn ufh off, remove grout and regrout.
Adhesive and grout should be mixed as manufacturers instructions, otherwise they will not perform at designed and your warranty will be void.

Heard it may times, 'been doing it 30 years, I know how to mix it' hopefully they mixed the adhesive correctly!
You now know it has not been mixed as instructed, ask them to redo it at there cost.
On the information you have supplied, weak grout look like the problem.