What's the proper way to tile a concrete slab floor?
#11
We have a house in Florida that's built with concrete black walls on a concrete slab, as is the typical case there.
We want to rip up some carpet and put ceramic tile down on the floors.

Given that the floor is flat, what's the best way to do install the tile. On plywood subfloors, I always put down backer-board attached to the concrete with thin-set, the the tile on that with thinset. Is backer board needed on the concrete slab floor to prevent the tile from cracking? Or do i need a membrane type install?
Thanks,

 Fred
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#12
When we moved into our house in Texas we pulled up the carpet on the  downstairs.  The people laying the tile laid it on the slab.  They did snap some lines to keep the lines square.  One thing also the made sure the slab was very clean with no paint.
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#13
(06-03-2019, 04:17 AM)frule Wrote: We have a house in Florida that's built with concrete black walls on a concrete slab, as is the typical case there.
We want to rip up some carpet and put ceramic tile down on the floors.

Given that the floor is flat, what's the best way to do install the tile. On plywood subfloors, I always put down backer-board attached to the concrete with thin-set, the the tile on that with thinset. Is backer board needed on the concrete slab floor to prevent the tile from cracking? Or do i need a membrane type install?
Thanks,

 Fred

When I did that in my laundry room, all the recommendations for tiling over just about any floor was to use Schluter's Ditra under the tiles.  Schluter had a great site full of easily downloaded and printed info. for installation on just about any surface. 

Good luck,
Paul
Paul
They were right, I SHOULDN'T have tried it at home!
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#14
Assuming the concrete flloor is clean and not moving (active cracks), there's no reason to use an underlayment. Schluter makes great products but none of them are better than a clean, flat concrete slab. If the floor is actively cracking, I would use the Schluter as it helps float the tile floor so any cracking beneath it won't transfer to the finished grouted tile.

Again, assuming the floor is flat, clean and stable.. I'd use a polymer modified thinset directly on the concrete. Unmodified will work but modified has better bonding properties and is easier to trowel and clean up. IMHO, it also sets a little slower allowing for more working time. I'm not a pro so working time is important to me. A pro can mix a bucket of thinset and knock it out before it sets up... but a pro also has someone cutting tiles, cleaning tools and buckets. I try to only mix enough thinset that I think I'd use in about 40 minutes.

Some tips:
* If you are using a light colored grout, use white thinset. If you are using a dark grout, use a gray thinset.
* I've done quite a bit of tiling and have learned that I use a wet-saw for about 1% of my cuts. 90% are done with a simple snap cutter. Lowes has a decent one for $119.00
*Most small notches or circle cuts can easily be done with a 4 or 4-1/2" Diamond Blade on a cheap angle grinder. I think I pair $19.00 for my black and decker angle grinder and have been using it for years.
* I do own a wet-saw but rarely use it unless I'm working with marble or I need to make a cut which is either too risky or impossible to do with a snap cutter or diamond blade on the angle grinder.
* For floor tiles (particularly large format tiles), I would only use porcelain tile. It is much less prone to chipping and cracking vs. ceramic tile.
* I've become a big fan of tile lashes for large format tile. It will make a novice's job look like a pro did it. Tile Lash part A
Part B
You'll still need to use your desired sized spacers with tile lashes.
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#15
Thinset it and tile it. If it's bigger tile go medium set. (yes it's not all called thin set as it refers to the body of the mud for the tile size)

 The only issue is if the slab was polished with a whirlybird or it has a sealer on it you may need to rough it up and at least apply an adhesion promoter. As for cracks.... Well I have seen fast food buildings that had a crack in the floor and one side of the room was 8' lower than the other. They would blend the crack and slope with self leveling filler and tile over it. 5 years later no cracks or grout issues. Look at other commercial buildings they are all full of tile laid on concrete and it will be there for 30 years or more. 

  Schluter makes great products but some act like it's the end all and be all of tiling systems and it can only be done their way and hold up. I have seen many tile installations over bare plywood that had stood the test of time with no issues as well.

Oh and a tile leveling system is also a great idea. There are many out there and many ones that are junk on amazon. They will not pull up the tile like some think they will pull the tile down. If the commercial guys would spend the $ to use it they wouldn't have to pull up and redo so many tiles for lippage.
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#16
The only thing I've ever done was apply the thinset and lay the tile...no underlayment.
I started with absolutely nothing. Now, thanks to years of hard work, careful planning, and perseverance, I find I still have most of it left.
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#17
My son laid tile directly on a concrete slab (walkout basement) about 8 years ago and has had no issues. But the slab was about 30 years old and had no cracks in it. If it had cracks or was fairly green cement, I'm not sure there wouldn't have been issues. I'm sure ditra or another decoupling membrane could keep a small crack from telegraphing but probably wouldn't prevent problems in larger separations.
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#18
Thanks for the replies,folks..........good info.!
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#19
(06-03-2019, 07:55 AM)fredhargis Wrote: The only thing I've ever done was apply the thinset and lay the tile...no underlayment.

+1
Steve

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#20
I lay 1/4" cement board over wood floors. But I've never tiled a wood floor that I thought was in good enough condition to do without an underlayment. My current house has engineered I-Joists. They bounce, I'm doing underlayment (1/4" cement board). If it had a decent, solid floor.. I'd put down luan and tile it.
Neil Summers Home Inspections




" What would Fred do?"

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