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mjbraun
ceramic tile underlayment requirements?

My kitchen/dining/utility rooms have two layers of 3/4" plywood.

I would like to remove one of the layers of plywood and replace it with 1/4" cement board before installing ceramic tile.

Would this be an acceptable amount of underlayment?

Or should I use Ditra (which I would prefer not to use only because of the really high cost).

A little more info...I want to remove one layer of the plywood because this would allow me to have a smooth transition between the new ceramic tile and the adjacent hardwood floor. Currently there are two layers of 3/4" plywood and one layer of vinyl on top of that (which is a smooth transition to the hardwood). My joist spacing is 16" on center, joists are 2x10, and 16 feet long.

bp21901
Re: ceramic tile underlayment requirements?

If you go to www.johnbridge.com they have a deflection calculator that you can use to see how "bouncy" your floors are and see if anything needs to be done before installing the tile.

mjbraun
Re: ceramic tile underlayment requirements?

didn't see the deflection calculator anywhere on that site

mjbraun
Re: ceramic tile underlayment requirements?

how much of a difference would it make to use the 1/2" cement board rather than the 1/4" cement board

bp21901
Re: ceramic tile underlayment requirements?

http://www.johnbridge.com/vbulletin/deflecto.pl

Here is the link to the deflection calculator. I don't think cement board adds any stiffness to a floor so 1/2" vs. 1/4" won't do anything structural for you. A 3/4" subfloor is a minimum thickness in my opinion. Read through the johnbridge forums for all the answers you could ever want about tile jobs.

jboller56
Re: ceramic tile underlayment requirements?

That calculator is great, thanks guys.

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