Does my Floor have to be Level to Install Tile?

by Roger

Before installing tile on your floor you must make sure your floor is properly prepared.  A properly prepared floor does not have to be level. It must, however, be flat.

The only time the levelness (is that a word?) must be taken into consideration is when drainage is an issue, such as on a porch or in a shower. In those cases you must make sure your floor is not level – it has to be angled toward a drainage area.

If your floor will not be subjected to water regularly, such as a kitchen or bathroom floor, it does not necessarily have to be level. That does not mean you can have a 45 degree angle from your door to the cabinet (although I suppose you could if you wanted), it just means if your floor is not absolutely level it will not negatively affect your tile installation.

One of the things you must make sure of, among other things, is that your floor is flat. If it is not it will be difficult to set your tiles without what we call “lippage”. That’s a ridiculous word, isn’t it? Lippage simply describes the difference in the height of two adjacent tiles. If you have a tile that sticks up higher than the tile next to it you have lippage. You don’t want that. Starting with a flat floor helps prevent it.

When prepping your floor for tile trade your level for a straight edge. Don’t be concerned with how level your floor is, be concerned with how flat it is.

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Daylyn

We are DIY-ing our floor tiles now. The level showed the floor is level when we started, but as we are installing the tiles, we found that we are using more and more cement to make the tiles finish with a perfect level. (We were worried that if we just follow the existing floor level, we will have to cut the baseboard corners in angles when we put it back afterwards, or the ball rolls to one side of the house when we play fetch with the dog etc…)

Do you have any suggestion on how to level the floor now, beside putting more and more cement under each tiles like we are doing now? We are reducing the amount of cement each row now because we don’t want super thick floor at the other side + it has taken a lot of time! :cry: )

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Michelle

Hello,
I have a sea(3,200sq/ft) of 20X20 shiney floor tiles that I would like to get rid of & replace with ceramic wood looking tiles (I found a line that makes a mix of long/short w/hand scrapped appearance). The existing sea of floor tiles are in good condition, no broken, cracked or lifting tiles. When you walk across them there is a solid sound (no hollowness). Here’s is the problem…they are FLAT but not level (UGH!)! How can I make the floors flat…leveling cement is expensive…I have heard of using glued down sheets of plywood…
Can I have the existing tiles prepped with acid to remove the shine and have tile installed over them? I have talked with several installers, and the consensus is always split…if they are prepped properly shouldn’t the new tiles be fine? My friend ripped her tiles out, new installation of tiles & hers are separating from the floor….so it seems that it’s a 50-50 chance of good install v. poor install.
Thank you!!!
Michelle
background – house is in south florida, barrier island (sand), original home is built on pilings w/the addition on slab that I had secured with pilings 4 years ago.

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Michelle

Correction!!! How can I make the floors LEVEL – they are flat

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Roger

Hi Michelle,

If you want it level then slc is about the only choice short of hiring a pro to mud it. That is placing and forming deck mud over the existing substrate. This will add a MINIMUM of 3/4″ to the height of your floor.

I do not go over existing tile, but it can be done just fine provided the existing tiles are properly prepared and a proper thinset is used.

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KP

Hi Roger,
I finally found a contractor that prepared a correct subfloor in a hallway, but
the threshold into a dinning room wood floor doesn’t meet evenly with the
subfloor. We have 1/4 to 1/2″ difference end to end on about a 5′ opening. How can this be corrected? They’re just starting to lay tile &trying to figure out what to do without removing some of the wood floor. HELP PLEASE
Kathy

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Roger

Hi KP,

That needs to be leveled so there is a flat plane from room to room. That may entail slc or something else, depending on the tile substrate being used. What are they bonding the tile to?

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Jennifer

Hi Roger,

We’re tiling a 12×24 room with 12″ porcelain tiles. The floor is tongue and groove OSB. The room is built on many sonotubes and as such has some potential for movement. The floor has a high spot that could create some “lippage”. Would you recommend ditra or Cement board and any thoughts on how to address the high points at the tongue and groove junction? (maybe a planer or sanding).

Thanks so much!
Jennifer

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Roger

Hi Jennifer,

You need to place another layer of plywood over the existing osb, offsetting the seams. Then I would use ditra, although properly installed cement board will work as well. The offset layer of plywood, plus the mebrane or backer, will adequately compensate for any movement.

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Karen

I have a ~15 sqft entryway that I would like to tile, but it looks like it was tiled previously before being pulled up and replaced with carpet. There’s hunks of I think mortar still on the concrete, concrete is kinda cracked too. Maybe I can take some sort of mortar chisel to get most of it off, but I doubt it will ever be smooth. Will this be a problem for lippage? Will the morter flatten things, like being thinner where there’s bumps of mortar still, and thicker where there isn’t, resulting in an even floor? I also have to do this myself apparently because it seems no one will take on such a small job.

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Roger

Hi Karen,

Yes, a mortar chisel will work. And yes, the mortar will level it out as you’ve described.

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Lynn

Hi!
I want to install tile in our hallway into the kitchen. We originally were going to do laminate but they said when the current floor is pulled up it may leave the subfloor damaged, due to the current floor being glued directly to the subfloor. They said they would have to replace part of the subfloor…will this also be an issue when laying tiles?

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Roger

Hi Lynn,

Yes, it will. You need a proper, solid substrate beneath your tile. If the subfloor is damaged when removing the existing flooring it will need to be repaired first.

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JayDee

Hola Elf
Cant describe all the horrible problems on current job, grout joints 1/2″ +, leaks in several places, mold etc.
…A previous contractor??? Replaced part of bath floor and shimmed his 5/8 ply with strips of 5/8 ply, so I am now trying to get back to orig floor that is in other half of bathroom. It has 1 by 6 with 3/4 ply over that. I am going to use HB so I need 1+1/4″ min my question is can I use sm pieces of ply I have on job? I have been adding 2/6 and 2/8 blocks to the joists anywhere that even looks questionable
Also I am installing 16″ tile and the only trowel I could locate is a 5/8 U shape. I sent the homeowner and he looked all over town, so will it work? Thanx Elf, ur a character :lol: :lol:

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Roger

Hi JayDee,

Yes, you can use the small pieces of ply. Just ensure that you use thinset beneath your backer and it’ll be fine. That trowel is frickin’ huge! Try the internet, I’ve heard you can buy stuff off of it. :D Look for a 3/8″.

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Alec

Hi Roger,
I’m about to install about 1000 Sq.Ft. 6×24 porcelain tile with a wood look, it’s going in the basement with cement floor. There are expansion cuts all over the cement floor.
1. Do I fill them all, what do I use?
2. I’m planning on using flexbond polymer-modified mortar, is that right?
3. Will I experience crack later on in the tile? How do I prevent the cracking?
4. With this specific tile, what trowel size do you recommend?

Thank you in advance

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Roger

Hi Alec,

The search box in the upper right corner will lead you to every answer you seek.

1. No, you don’t fill them. You can use a membrane over them to be able to relocate your soft joint, but you don’t fill them, they are there for a reason.
2. Yes, that is one right answer. It’s a good thinset.
3. Not if you properly prepare and install your tile, with soft joints and perimeter joints.
4. Whichever gives you the proper coverage.

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Alec

Roger,
Can you just tell me how to used that membrane and which one should I use. I can’t find it in your search box

Thank you
Alec

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Roger

Hi Alec,

Which particular membrane would that be? Ditra? If so it just goes down on the substrate with thinset, then the tile is installed over it. It’s super easy.

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jmd

Greetings. I have a 30sq ft powder room i will be tiling. I used my 4 ft level to check for flatness, but i have no idea if the surface of the level is flat. Do you have any recommendations on an inexpensive straight edge? Also what is the tolerance for flatness. I have 23/32 osb that will be covered by 11/32 ply, covered by schluter ditra covered by 30cm x 60cm porcelein tile. Great site.
Thanks

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Roger

Hi jmd,

I’ve never seen an unflat level. :D Yardsticks are cheap and flat. Your floor needs to be within 1/4″ in ten feet.

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