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Thread: Cracked Grout

  1. #1
    Don Jackson's Avatar
    Don Jackson Guest

    Exclamation Cracked Grout

    Hello, My first post. I "inspected" a friends home, meaning he wanted me to come over and take a look at his kitchen floor. I didn't take any of my equipment. Anyway, he has a tiled floor that has a 1/16" crack in the grout and spands diagonally across the kitchen floor (50 feet).

    I thought maybe it was poorly mixed grout, but it is a single crack. The home is on a slab foundation and I see no cracks. There are no cracks at the doors or windows.

    Could this be just a poorly installed tile floor or is there an underlying, more critical problem?


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  2. #2
    Join Date
    Oct 2003
    Rockwall Texas

    Default Re: Cracked Grout

    If he's got a crack in the floor of 50ft. I'd suspect he's had some type of foundation movement.

    Cracks in the grout are quite common but 50ft. may be a indicator of something more serious.


  3. #3
    Join Date
    Aug 2007
    Memphis TN.

    Default Re: Cracked Grout

    Welcome to the Board Don,

    A single crack as you describe could very well mean foundation settlement.

    I'd check to see if the floor had a low spot toward the middle of the crack.

    Also check if there is a temperature differential from one area to the other on the floor to check for a possible water leak in or under the slab.

    You can turn off all the water fixtures, water heater supply line and check the water meter
    trickle needle as an indication of a water leak.

    It Might have Choked Artie But it ain't gone'a choke Stymie! Our Gang " The Pooch " (1932)
    Billy J. Stephens HI Service Memphis TN.

  4. #4
    Join Date
    Mar 2007

    Default Re: Cracked Grout

    So what you are saying is that the tiles were layed on the diagonal, Not square to the kitchen, and there is a small crack that follows the grout joint across the room. No cracked tiles?
    How old is the house?
    How high are the tiles above the floors adjacent to the kitchen?
    My point is this. If the tiles were not set properly on a cement board base, which would add generally 1" above the other floors then the tiles may have just been glued down to the wood subfloor.
    This always causes what you are describing.
    Or are we talking about a house set on slab?
    There are many causes to what you are asking and you have not given enough info for a good opinion.
    The more info you give us gets you a better answer

  5. #5
    Join Date
    Mar 2007
    Philadelphia PA

    Default Re: Cracked Grout

    Quote Originally Posted by wayne soper View Post
    Or are we talking about a house set on slab?
    From the original post: "The home is on a slab foundation"

  6. #6
    Join Date
    Mar 2007
    Fletcher, NC

    Default Re: Cracked Grout


    Would you update your 'Location' to include what part of Florida - we are a big place.

    Sounds to me like the slab cracked (typically not a big deal and is to be expected. Concrete does two things: 1) it gets hard, 2) it cracks. That's why 'control joints' cut into slabs - to do nothing other than try to 'control' where the crack goes.

    The problem is actually quite common, the tile (if properly laid and set) is in rigid adhesion to and with the concrete slab, the slab cracks, and the tile has nothing to do but move with the slab. Typically, the 'tile' crack along the slab crack, but if you are lucky, the crack will show up in the grout joint, meandering step-like approximately along the same angle as the crack goes.

    When the grout cracks, it indicates that the tile was not fully bonded to the slab as it should have been (faulty work comes out in your favor this time), however, that means to be aware of potential future loosening of the tile, and even of tile 'tenting'.

    There are two basic methods to control cracks so they do not crack the tile: 1) *proper* use of a tile crack control 'separation membrane', however, that really should then have another 1" to 1-1/2" of mud on it then the tile laid to that mud - "typically" these are just glued to the slab and the tile thin set laid on the separation membrane ... not the right way, and usually not the right membrane either; 2) wait a year or two for the house to settle and then tile the floor *after* the slab cracks - yeah, right!

    In South Florida, the way the builders typically handled this was to come back at the end of the first year's warranty period and replace the cracked tile with extra tile they left on site (usually in the attic) just for this purpose.

    Don, try 'tapping on the tile' with your knuckles (I used to just carry a golf ball and drop it around the floor) you will hear the 'hollow loose sound' where the tile is not fully bonded to the slab, and you will here the 'solid thud sound' where it is (the golf ball works great, so does a wood dowel with a rubber leg end on it - but the golf ball is easier to carry around, and I always got a smile from my clients when I would say 'I now have to get my most expensive and high tech tool to check for loose tile' and then I would pull a golf ball out of my tool bag. Heck, I even carried several golf balls and let my clients go around bouncing the ball and check for loose tile - they liked doing it.

    Typically, the places you will find cracks are at inside corners radiating out from the point of the corner, and in long narrow slabs at the center or 1/3 or 1/4 points of a long narrow slab - depending on how long it was.

    Typically, though, this is not a structural problem.

    This is typically caused by: a) the bottom of the footings not being fully compacted enough; b) the concrete block walls (or two story walls) carrying *ALL* of the load to the perimeter of the slab, with no load on the center of the slab, the perimeter moves downward slightly, causing cracks from the perimeter - concrete does not like to flex.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired


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