Multiple Tiles Cracking in a Straight Line


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Old 08-08-08, 11:22 AM
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Multiple Tiles Cracking in a Straight Line

My wife noticed, as she was washing the tiled kitchen floor, that a crack has appeared in virtually every tile in a more-or-less straight line (oriented the same as the floor joists) in our kitchen. The tiling was done just prior to our buying the house in late '06, so it's still fairly new. The cracks are growing - at first, you had to wash the floor to see them, but now, they're visible on their own. She first noticed them about three, maybe four months ago.




We've also found a second crack, parallel, about 51" away from the first one. Same kinda idea, but shorter, because it's in a doorway.

The tiles appear to have been set properly - there's 3/4" plywood underneath the tile, on top of the usual floorboard, so stiffness ought not to be a concern.

Here are my questions:

1. Anybody have any idea why this might've happened?

2. Is there a recommendation for some way to seal the crack?

Thanks in advance,

B.
 
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Old 08-08-08, 02:27 PM
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It's got to be all torn out and done correctly.

Tile does not get installed over plywood.

Your joists system needs to meet deflection requirements to find out if its suitable for tile.

We need your floor joists size, spacing, and unsupported span to get a calculation.

Tile needs to be installed on a underlayment, like cement backboard or other membrane.

There are no sealers for tile cracks. The tiles are cracking because of movement in the subfloor.
 
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Old 08-08-08, 03:24 PM
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bk

Tile cracks from movement. Movement can be caused by different things.

The tiles appear to have been set properly - there's 3/4" plywood underneath the tile, on top of the usual floorboard, so stiffness ought not to be a concern.
Not sure what you have here. Are you saying you have 3/4" plywood subfloor over joists, or are you saying you have 3/4" plywood underlayment over dimensional floorboards that are attached to the joists? What is the exact composition of the floor? Start with the joists, we need the size, on center spacing and unsupported span from below? We need to know what the layers of flooring are, by material, thickness and how they are oriented and installed?

Can you tell if the cracks are also over a plywood seam where 2 sheets of plywood meet also? Do you know if the 3/4" plywood was butted at the edges or a gap was left between sheets for movement?

Was a cement board or isolation membrane underlayment used or was the tile set directly to the plywood? If cement board was used, was it installed according to manufacturers instructions, proper spacing, mud & tape joints, nail patterns etc?

Can you see the joists from the room or basement below? Do the joists where the cracks are appear to be in good condition? Do they have holes or notches cut in them to accomodate plumbing, heating etc? Can you see the subfloor material? Can you tell us exactly what it is, material, thickness and any other markings?

Is there a recommendation for some way to seal the crack?
You need to find the cause of the cracks first. Anything you put in the cracks will be a temporary bandaid, as they will continue to get worse. Filling the cracks with any kinda material won't look good.
 
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Old 08-08-08, 03:42 PM
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Also, do you have a cantilevered deck outside your kitchen? I have found this on occasion when the cantilevering was not sent back far enough into the room and not sistered properly.
 
 

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