Cracking grout and tiles on floor

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  #1  
Old 08-11-05, 07:03 PM
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Cracking grout and tiles on floor

My ceramic floor was installed about 6 months ago. I've now noticed a few cracked tiles and cracks in the grout in various areas. What causes this - a bad tile job? Does a cracked tile mean that there was not good adhesion with the thinset? Same thing with the grout? The house is 40 years old so I doubt there are any settling issues. The old tile I ripped out (including the mud bed) had been in place since the 80s and there weren't any cracks. The new subfloor is 3/4" plywood screwed down with 1/2 cememt board over it. The tiles are 13" sqaure with 1/4" grout lines. Not sure what brand the thinset was, but I know it was mixed with water. The grout is sanded Polyblend. The guy that did this job and he says he's been doing floors for 14 years. Any advice here? I did not seal the grout - would this have helped prevent cracking?

thx, Don
 
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Old 08-11-05, 07:37 PM
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Several possibilities here.

Was the cement board set in a layer of thinset? It should have been.

What kind of plywood was used? CDX is the wrong answer, it is rated as sheathing not underlayment, the "D" layers have too many voids that can compress. Should be CC plugged or better yet BCX grade.

Are the tiles tight to the walls or are there gaps? Were the gaps filled with grout along the walls before the baseboard was put in? It could be pressure from the walls moving around is pushing on the tiles. The cracking would most likely appear in the middle of the room but about anywhere is possible.

What is the size and spacing of the the floor joists and what is its unsupported span? It could be the mud held everything together enough to keep from deflecting enough to cause cracks.

Was the tile job done in hot weather or in the sun where the thinset could have dried out before being covered by a tile? Was a modified thinset used? Was a proper sized trowel used to spread the thinset so as to get full coverage on the backside of the tile?

I'm sure there are other possibilities, but my brain is fried from the heat and I need to get some sleep. Maybe some of the others will shed more light, but at least investigate the above items and let us know wht you can find out.
 
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Old 08-12-05, 01:20 PM
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Answer all of Bobs questions, sealing the grout wouldn't have done a thing, there's movement somewhere or lack of thinset coverage or like Bob said, many other factors could have caused this also, he screwed up big time somewhere, this will all have to be redone, I would call him back, everyone I know guarantees their work for at least a year, let him deal with this.
 
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Old 08-14-05, 03:29 PM
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"Was the cement board set in a layer of thinset? It should have been."

Yes, there is thinset under the CB

"What kind of plywood was used? CDX is the wrong answer, it is rated as sheathing not underlayment, the "D" layers have too many voids that can compress. Should be CC plugged or better yet BCX grade."

I don't remember, could be CDX (3/4".) Under the mud bed was planks on the joists - they looked pretty old, as if they used scraps when the floor was originally done (original structure mid 60s, remodeled 1988.) My installer screwed the heck out of the plywood, probably a screw every 4-6 inches. Prior to that I put down more screws in the planks to make sure they were solid to the joists. So, we tried to do a good job of getting the subfloor solid.

"Are the tiles tight to the walls or are there gaps? Were the gaps filled with grout along the walls before the baseboard was put in? It could be pressure from the walls moving around is pushing on the tiles. The cracking would most likely appear in the middle of the room but about anywhere is possible."

There are gaps between the wall and tile and there is no grout between the tiles and wall. I left the baseboards in place, just took up the shoe.

"What is the size and spacing of the the floor joists and what is its unsupported span? It could be the mud held everything together enough to keep from deflecting enough to cause cracks."

Joists I believe are 2x10 16" oc.

"Was the tile job done in hot weather or in the sun where the thinset could have dried out before being covered by a tile? Was a modified thinset used? Was a proper sized trowel used to spread the thinset so as to get full coverage on the backside of the tile?"

The tile was done in Feb, so it was cold. I believe it was modified thinset, and the trowel was 1/2 sq. notch


Some more info - Tiles are laid on 45 deg. The entire floor goes from the entry, through part of the LR, and into the kitchen, a total of about 550 sq ft. There are 3 cracked tiles, and several spots with obvious grout cracks. The most worst grout cracks are in the doorway into the kitchenThe other grout cracks you can't see from standing, but on my hands and knees I can see hairline cracks here and there in all areas of the floor - some in the middle of the grout, some along the edge of the tile.

Can this be grouted over the top without cutting out the old grout?
Should I wait for the cracks to get worse (within 1 year of the installation) to make sure see everything?
If there is a problem with the floor system are cracks going to reappear?
If there are expansion issues does it matter if the grout is redone in the sumer or winter?
Sholud an additive have been used with the grout? My installed told me it wasn't necessary, and that it would cost more because with the additive it shrinks when it dries and would have to be grouted over again to fill it in.



thx, Don
 
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Old 08-15-05, 06:12 PM
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Polyblend IS a modified grout, don't know what your installer is talking about.

What was the temp. of the floor when it was installed, this is indoors, yes, heated room?
 
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Old 08-16-05, 06:57 AM
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Yes, indoors, heated to about 68 deg.
 
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Old 08-19-05, 08:43 AM
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Tileguybob - any more comments?

Bump - any other suggestions based on the additional info I provided?

thx, Don
 
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Old 08-19-05, 10:54 AM
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Don't sound like such a bad installation to me since we don't know what plywood he used,maybe he used the right stuff--maybe not. I would get the guy back though and while he was taking up the cracked tiles I would look at the coverage on the back. If it was poor I would figure this was the cause of the crack and hopefully when it was fixed it would not reappear. I would be concerned about the rest of the installation though. A 1/2 inch notched trowel held at the wrong angle will not give adequate coverage. Thinset for large tiles is supposed to be trowelled a certain way and the tiles laid a certain way to insure complete coverage

The grout could have been mixed a little wet----shrunk and cracked.

Did anybody walk on this too soon---guess not.

I think there are probably a lot of floors installed worse than this one that never crack assuming there is adequate coverage on the back of the tiles.
 
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Old 08-19-05, 02:14 PM
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thx joneq

No, we didn't walk on it too soon - this was done before we moved into the house.

If there was too much water and that is causing the cracking grout, can it be grouted over the old, or does it need to come out?

don
 
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Old 08-19-05, 03:21 PM
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Take it out with a grout saw[home depot]--not too bad. Be careful not to come out of the grout joint and onto the tile. I would let the guy do it, as a matter of fact I wouldn't touch anything.

The guy did tape the seams right? Are the cracks parallel to the floor joists or prependicular.Are they all in the same direction? Some long kitchens may need an expansion joint in the middle of the room if it is long enough---I think 20 ft.

Where,in relation to the middle of the floor joists span, are the cracks? If it is not near the middle I doubt it is a deflection problem. I would defer to the tile experts on this ,but it just seems natural.

I would also be asking for an extended warranty[in writing] at the very least. Maybe 1 more year. Since you already have problems I think it is reasonable to expect more time to see that everything is all good.

If he balks ask him how much he would charge to rip out this installation and do it over with you paying for everything--new plywood , cement bd, tile, grout. You may also want to ask him how long he thinks it should last---you have already had problems.

As far as I am concerned I, as a home owner, should never have to deal with any of the same problems even after the warranty is up if they are the same problems that appeared before the warranty ran out. Hope that's clear to you and the contractor.

Lastly--cracked tile and grout have proven that there is at least something wrong with this installation, unless of course it always happens with his installations. Maybe you should ask if it happens all the time, if not --what happened here.
 
  #11  
Old 08-31-05, 08:18 PM
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I have some cracking grout in my house and I found out it is due to the foundation moving. It doesn't seem to take very long for the foundation to move slightly and cause a bunch of problems. I noticed just in a month (of dry weather and not enough foundation watering on my part) that the foundation moved enough to crack some grout. I am having the house leveled in a few days so hopefully I can start fixing that stuff soon.
 
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Old 09-01-05, 01:00 PM
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How are they going to level the house? Never heard of that, just curious as to what is involved.
 
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Old 09-01-05, 03:00 PM
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Dmestan, what is the span of the floor joists?
 
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