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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Jared Duplantis

Hi, I’m wanting to lay ceramic tile from my kitchen into my living room however. The cement slab where the kitchen and living room meet are different hieghts. About 3/8″ to 1/2″ difference. The living room was an add on so the slab wasn’t poured at the same time. What can I do? Also, considering staining the living room maybe. Thanks :censored:

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Nate

I have a bathroom floor in a basement we are finishing. The floor concrete and we have poured self-leveler over it to deal with a small peak at a seam. Can I tile directly over the self leveler, or do I need to put something like DITRA down over the self-leveler first? (The room is 5×7)

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Roger

Hi Nate,

You can tile directly to the slc.

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Rick

What is the best method to obtain a flat subfloor. The subfloor is 5/8″ plywood and there are a couple low spots, about 1/8″ to 1/4″ max. I believe the knuckleheads who built the house put a couple joists crown down. Shingles and roof felt followed by 3/8″ plywood followed by 1/4″ durock; or 3/8″ plywood followed by 1/4″ durock and then the low spots filled in with SLC? Thanks for your help.

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Roger

Hi Rick,

No shingles or roofing felt. The ply, durock with slc over it (thinset beneath the durock) will work just fine.

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Kathleen A Ferraro

The contractor who replaced the tile in our bathroom after it was damaged by water and chemicals used to put out a fire wrote in his insurance proposal that they would remove and replace 1/2 inch cement board and 3/4 inch BC plywood. The bathroom had been installed in 2002, and we had had no problems with the tile or grout until the fire. The height difference between the tile floor and the wood floor in the bedroom was less than 1/4 inch. We indicated we wanted it to be restored to its pre-fire condition.

The new floor is about an inch higher than the original one. The contractor cut the bottom of the door to fit. The door is now 3/4 inch shorter and there is barely 1/4 inch between the bottom of the door and the floor. In addition the floor feels kind of lumpy underfoot. I am also concerned that the height difference might create problems with our curbless shower.

The wall tile job is also terrible. I have not paid the contractor’s final payment and don’t plan to. My guess is the contractor did not replace the old cement board and plywood before installing the new floor, but could something else have caused the height difference? I can send photos.

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Roger

Hi Kathleen,

I think you’re probably correct. That’s a huge height difference. He likely just went right over what was already there.

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Kathleen A Ferraro

Thanks, Roger. A floor inspector came today and was able to look below the new plywood and found it had been installed over the old subfloor. The contract says remove and replace subfloor, so I believe this is a breach. The inspector also said the floor is moving and has bumps in it. I am waiting for his report on the floor and the wall tile and plan to send the contractor a letter saying I will not pay until he fixes the problems with the floor and also the poor workmanship with the wall.

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angel barros

Hi, First I want to congratulate you for keeping this page, it helps a lot to installers like me.
I have a project of 4500 sf on a second floor. the substrate its a lightweight concrete over wood beams, and needs a lot of prep. i’m planing on patching cracks and then self leveling the floor and install a ditra underlayment and then lay tile with 12″x24″
My questions is, if the lightweight concrete its going to support the weigh of the tile, I’m worrying about doing a good installation that can fails in a year with a bunch o crack tiles or worst.

Reply

Roger

Hi Angel,

If you are talking about gypcrete – yes, it’ll support it just fine. Be sure to use the primer for the slc to ensure a proper bond to the gypcrete.

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Albert

I live on the second floor in a condominium. I am replacing the marble tiles with 24″X24″ rectified polished Porcelain tiles. The existing area has plywood sub floor with 3/4” concrete over. I am tiling the foyer, kitchen and the powder room. The floor slopes down from the entry door toward the kitchen of about 1”. I am confused of how to tile the area with the existing condition. Does my floor have to be level to install tile? Some installers have suggested to remove the concrete and use Hardie Backboard for tiling. Others have different way of leveling the area which is to use paper on plywood, pour cement mortar and thinset and then tiles. I am really confused. What is the correct way of handling this project? I appreciate your help?

Reply

Roger

Hi Albert,

The best solution is self-leveling cement. I highly doubt it’s actual concrete, it’s likely gypcrete (lightweight concrete). Your floor does not need to be level, but it does need to be flat.

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