What to do with subfloor prior to 6x24" tiling


Old 07-23-13, 08:14 PM
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What to do with subfloor prior to 6x24" tiling

I've been searching for stuff online about this all night and am getting incredibly frustrated and irritated with all of the conflicting info about this.

I have a ~60sqft entryway that had ceramic tile in it that I am replacing. Old tile is torn up and about 1/3 of the old thinset has been scraped off. The existing subfloor is 1" plywood. New and old tile is the same thickness.

What, exactly, do I need to do with this? I know the tiles are 6x24" so they will crack more easily under pressure than the smaller ones. It would be nice just to be able to put cement board over the existing floor, but I'm reasonably sure that if I did that and then tiled on top of it that the door wouldn't be able to open because of the increase in height.

Do I need to rip out the whole subfloor and do 1/2" ply and 1/2" cement board? Wouldn't that only give 1/2" of support? Can I just tile over the plywood like it was before? The previous tiles were 8x8 and not cracked even after 30 years.

Also, if I do have to replace the subfloor, I'm assuming the edges won't line up with the joists because the entryway goes through three doorways. What would I do with the edges that don't end on a joist to keep them from flexing?
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Old 07-24-13, 05:30 PM
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Your saying it's a 1" subfloor, but what is the exact make up?
2, 1/2 layers, 3/4" then a layer of 1/4"?
1/2" plywood is useless as a subfloor, only good as an underlayment.
1/2 tile board is not used or need as an underlayment, 1/4" is all that's needed. It's just for something for the tile to stick to, not for support.
Old 07-25-13, 02:39 AM
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There's good information. There is a fascination with larger/longer tile nowadays. Not sure what it is. You will arrive at a point to where you have to split a tile lengthwise. How will you do that? Tile saws won't accept them as they are too long. Most tile cutters won't, either. As you say, they will tend to crack more readily than smaller tile will.
Old 07-26-13, 10:41 AM
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I know you didn't have any problem with the old tiles but I always like to start with the basics: what's the size, spacing and unsupported span of the floor joists?
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