To luan or not to luan...


Old 01-31-10, 01:57 PM
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To luan or not to luan...

Three quarters through building an addition to our house, we decided to go with a ceramic tile floor rather than vinyl.

The subfloor is 3/4" plywood over 2x10'', 16" O.C.

I had purchased 1/4" luan mahogany to be used under the vinyl. Should I lay this over the plywood for under the tile? the luan cannot be returned.

Any advantage one way or the other?

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Old 01-31-10, 06:41 PM
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The advantage is if you ever decide to pull up the tile, you won't have to pull up the whole subfloor. Plus, it will raise the floor an 1/8" (or whatever size they are making it now). That could be a good or bad thing
Old 01-31-10, 08:42 PM
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You absolutely do NOT want any 1/4" ply, especially luan anywhere near a tile installation. Luan is very unstable and is specifically named as a non acceptable underlayment by every thin set manufacturer that I know of.

If you subfloor system is sturdi enough for tiles, you need to install a cement backer or a membrane over the subfloor. What is the unsupported span of those joists? Do you know the species and grade? Tell us what you're doing and with what.

Old 01-31-10, 09:17 PM
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1/8 or 1/4" luan IS generally noted as not being stable enough for subfloor, yes, but this won't be the only subfloor. he stated that he already has a 3/4 ply down.

I always tile with the DITA membrane. It's stronger and I get better results. But if he has the luan and wants to use it, will it still be an issue even over a 3/4" ply?

It would need to be installed correctly with the proper stapling/ nailing.

He doesn't need to use it. He is asking if it will pose a problem if he does. I've used it on top of a stronger structure without issues. Again, the only advantage would be in tearing up the floor in the future.

Is it an issue even if its over top of a better sub?
Old 02-01-10, 09:57 AM
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Jaz is right on here. Luan doesnt belong anywhere underneath tile period. It will definitely do more harm than good. Don't use it. If your subfloor meets deflection standards, use an islolation membrane or cement board the plywood subfloor.
Old 02-04-10, 08:56 PM
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Luan is specifically noted on thinset bags as a product that tile cannot be set onto, no matter what is under it. The luan is a soft wood and is too compressive. it used to be mahogany but now can be made of various types of wood, all of which have oils inherent in the wood that inhibit the proper bond of thinset. Vinyl trade associations do not want luan under their product either.

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