ceramic tiling - grouting problems

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  #1  
Old 07-02-03, 09:39 PM
BobV
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Unhappy ceramic tiling - grouting problems

My son-in-law and I laid tile in his kitchen, and the grout began to crack (very badly). we determined that the problem was that the substrate was too flexible. He just finished taking up the tile, and adding a hardi-backer substrate. He then tiled over it, and sadly the grout is cracking again. What would you suggest we do next?
 
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Old 07-03-03, 08:38 AM
J
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Hardibacker, or any subfloor material, cannot compensate for joists with too much flex. You need to determine the size of the joists (e.g., 2x10), the spacing between them (e.g., 16") and the span between supports (e.g., 12'). Give us this information and we can tell you if there is hope.

Another common cause of grout cracking is mixing it with too much water.

And what is he using to adhere the tile to the floor?
 
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Old 07-03-03, 06:44 PM
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Talk about paying for your education in tile 101!
You paid twice for the class

Hardibacker is not meant to add strength to the subfloor. It is there for wood subfloors contraction and expansion, not up and down deflection.

Maximum 16" joist centers, with 2x12's and cross bracing.

Engineered floor trusses on 24" centers, won't cut it.
 
  #4  
Old 07-04-03, 06:47 AM
floorman
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also need to look at the width of the subfloor,you need a minimum of 1 1/4" of subfloor after the c.b.u.Make sure you read the instructions and screw or nail as specified every 2" on the seams and every 4 to 6" in the feild,thin set under neath the c.b.u. to fill voids and help flatten and tape the joints when finished screwing.Get back to us on the subfloor and let us know what you have
 
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Old 07-04-03, 07:22 AM
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Originally posted by floorman
also need to look at the width of the subfloor,you need a minimum of 1 1/4" of subfloor after the c.b.u.

I'm pretty sure floorman meant to say...

you need a minimum of 1 1/4" of subfloor under the c.b.u
 
  #6  
Old 07-04-03, 07:30 AM
floorman
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the minimum requirements for a tile installation is 1 1/4 inches of subfloor after the c.b.u a total width of 1 1/4 ,3/4 on the subfloor,1/2 on the c.b.u. for a total of1 1/4 that is a min.providing the joists are 2x12 on 16" centers
 
 

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