Laying cement board and tile over Luan


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Old 01-09-18, 06:34 AM
J
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Laying cement board and tile over Luan

Good Morning,

This is my first post on this forum and I am hoping you guys can help. I am looking to tile my floors in my Kitchen and Bathrooms. I have removed my vinyl flooring in my bathroom and noticed that it had Luan under layment below it. I was going to rip it out and noticed that it is glued down and stapled to the floor. Can I lay 1/4 inch cement board over the Luan and then lay my tile? Or do I have to rip out the Luan? Thanks!
 
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Old 01-09-18, 08:07 AM
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It also needs to go.
1/4 underlayment is not approved for use under tile.
 
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Old 01-09-18, 10:09 AM
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oh this is going to suck.. ok.. Then go with a 1/2 cement board?
 
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Old 01-09-18, 01:09 PM
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What do you have for sub floor, joists size, joist spacing/span?
 
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Old 01-09-18, 04:40 PM
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1/2" cement board is for walls, 1/4" is for floors set in a troweled bed of thinset mortar. I doubt the luan is glued, but stranger things have happened. Luan has too many voids to be acceptable as an underlayment for tile. Previous questions are still valid as we need to know the makeup of your subfloor. Size, spacing and span of your joists as well as the thickness of the subfloor. Needs to be beefy enough to last in a tile install.
 
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Old 01-09-18, 05:55 PM
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What is the problem with attaching the 1/4 cement board over the existing luan?
 
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Old 01-09-18, 06:11 PM
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Luan has voids in the plys. They can collapse and cause tile failure.
 
 

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