Cracking / Soft Grout

[Bill Beyer]

It's been a while... Thanks to the help of some of the advice on this board, I installed tile in my kitchen/hallway/bathroom about 1 1/2 years ago. The tile is holding up well. The grout however is not!

It's a long story, but the bottom line (I think) is that either I installed the grout wrong, I got a bad batch or there was some kind of interaction between the thinset and the grout.

I first noticed hairline cracks around the edges of some tiles about 6 months after the tile was installed. I called the place I purchased the grout from and they came out to take a look. They then called a rep out from Schluter because I used Ditra. They both inspected everything I did and came to the conclusion that the install was done very well. They said the floor was solid and complimented me on the install (I'm not exadurating). The only thing they could come up with was that there was an interaction between the grout and thinset. They suggested I skim it over again to fill in the cracks in hopes that whatever caused the problem is gone - finished.

I'm finally getting around to cleaning the grout to skim it over and something is up. The grout seems very soft/weak. Using a stiff wet brush, I can actually wear away at the grout with very little effort. I get the sand and color to come up. With a screwdriver I can very easily push through it and chip away at it.

I would like to get this problem behind me... I presume that I should remove the old grout, but before I do I have a few questions:

1. Should I try wetting the floor for a while to see if it will cure?
2. What type of grout should I use to replace it? Is there a more resiliant type of grout?
3. Is there an additive I should mix with instead of or in combination with water?

Oh and I should tell you that the grout was LATICRETE Tri-Poly Fortified Sanded Grout (1500 Series). My tile is porcelain over Ditra. I followed the recommendations on this board on the thinsets to use and the Schluter rep agreed with it.

[tilelayer]

hmm thats odd....im not the best on here im sure theres guys that know alot more than me, actually im positive. sure, wet it you can mist it but i dont think it will do much. portland cement never stops drying so you can wet it alittle. i hate laticrete grout, i just dont like it. I think hydroments awesome because it cures up really hard. i also like TEC and Mapei. I would try to regrout if the grout comes out that easily, its gonnna be alot of work cause it sounds like its a big area. i would use a latex additive instead of water to mix it up this will make it cure harder and i believe if not mistaken help with flexing. when u grouted did u pack the joints real good with grout? it sounds like you did though because of ur pro install of everything else.

[Bill Beyer]

Thanks for the reply "tilelayher".

Yes I did pack the joints as best I could. In a couple of spots I dug it up and it is in there all the way.

Thank you for the recommendations on the grout. I will take the list with me if/when I buy the new stuff.

I just finished cleaning up another small area and my hands have the feeling after you play with portland. Yes the area is pretty big - about 450 sq ft.

[tilelayer]

there should be some more guys along though that know much more than me wait to hear what they have to say especially big jb himself

[Jason_Butler]

Skimming over the existing won't do much good. You need to remove about a third of the grout ( minimum height) for re-grouting to work.

The first thing that comes to mind in this case ( Ditra and porcelain) is the time you waited between setting and grouting.

If you have some of the grout left over, mix it with water and then let it set overnight. See if it is soft after a few days

Jason

[Bill Beyer]

Jason - thanks for reminding me... When I first noticed the cracks, I did just what you recommended. I took some of the same grout, mixed it the same and let it sit for a few days. It was the same as what is on my floor. In fact, I took some to work to show some of the DIYers and they didn't think it was normal. It crumbled in our hands when you squeezed it between your fingers (you had to squeeze pretty hard).