Floor flatness expectations

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Old 11-17-10, 06:45 PM
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Floor flatness expectations

Question regarding ceramic tile job over subfloor with cement backer board (1/4").

The original subfloor is anything but flat. What should I expect from a professional perspective as far as backer board installation and surface prep for flatness before thinsetting the tile?

Would it be crazy talk to expect good finished wall to wall tile flatness from a pro installation?

Area is a small half bath, using 12" tiles centered with a 7" surround. Room was gutted to bare subfloor.

My question is primarily regarding typical obtainable flatness and floor prep.

Thanks.
 
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Old 11-18-10, 05:55 AM
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Most of this can be corrected with SLC (self leveling cement). You would install your cement board per manufacturers instructions, then pour the SLC over that. Depending on the size of the unevenness, you may just get away with skimming over these areas with extra thinset.

The other option is to pull the subfloor and correct the flatness that way. Sistering up joists to bring everything in line and installing new plywood.

Speaking of plywood, what type and how thick is your current subfloor? What size floor joists do you have, their spacing, and unsupported span?
 
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Old 11-18-10, 08:14 AM
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You say the floor is down to bare subfloor, but forgot to say what it is. You can make the floor flat by doing what Mark suggested. But that's a lot of extra work for such a small room. You should hire a tile setter that can do a real "mud" job on that floor. He'll mix sand/cement and apply it about an inch thick making the floor flat, then set the tiles.

Jaz
 
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Old 11-18-10, 04:57 PM
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Joists are 2x10 on 16" centers. Sufloor appears to be 3/4 or 7/8 ply.

Thanks for the input. I wasn't sure if my expectations were out of line. Hired a local floor company to do a small bathroom. The overall layout looks great with the pattern and grout joint width consistentcy, but they did a lousy job at flattening the floor which was something we discussed in advance.

I have some tiles that either dive or crest depending upon how you want to look at it. Going into this as a first tile experience, I didn't have much of the installer lingo down and didn't realize how deeply I had to specify this project with this particular vendor (the customer shouldn't have to if they're a good installer). They'll come back and pop a few tiles for reset, but at what compromise to the rest of the floor I don't know.

Needless to say, for the cost of the labor and the raw materials markup, I could have purchased a nice wet saw. Next floor will be all mine. I don't see the point in paying good dollars to farm this out. I think as long as I do the design on paper first and do a dry layout before cutting anything, along with some good common sense prep work, I'll come out far ahead.

Regards,

GT
 
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Old 11-18-10, 05:46 PM
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Sorry your floor didn't come out as flat as it could have. Who did the rip out and prep and when was it done?

Jaz
 
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Old 11-18-10, 08:03 PM
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I did the rip out to subfloor. Old floor was vinyl over 1/4" backer. Got it all cleaned out, all the staples removed. It was a clean surface when the dealer started.

Floor dealer put down the cement board and took it from there up.

Just like painting cars or anyting else... the finish product is only as good as the prep time put into the base materials. If the substrate isn't flat, you can't expect to get a flat tile layup. Not sure how a pro can miss this.. but... That's why there's loads of DIY'ers. I'm up for some tiling...

Cheers!
 
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Old 11-18-10, 08:38 PM
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You didn't answer when the rip out was done.

What I was getting at is that sometimes the salesman or tiler looks at the job before the customer does the demo because the customer wants to save money and do it himself. So they quote a low price that does not include any leveling or any other extra work. Then they get there and they go with the floor they are presented because it's supposed to be flat within standards.

This may not be how it happened in your case, I don't know. The problem is that if they realize the floor is not flat, they'd have to change gears and either install a SLC to level the floor or change the entire installation method. This would likely add another days labor which the customer might bulk to wasting more time & money.

In the end the installer should have checked, stopped and added the extra cost to do the job right, but that would have to be agreed to in advance. Sometimes the owner is not around, or they think the customer won't pay for the work, or any number of other reasons. You mentioned the possibility of extra prep was talked about. Can you explain that?

Jaz
 
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