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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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.


Ashley Green

I am attempting first time bathroom reno. The cement backboard isn’t a perfect 90 degree angle at the bottom, so the shower pan won’t marry up to the backerboard just perfectly. Thus, the tile can’t sit over the flange on the pan. Someone told us we can just fill in the gap with mortar/cement and place the tile on top of the flange and mud up the walls to correct the imperfection of the wall unevenness. The shower pan is about 9-10mm out in the corner. True or false? Is this a recipe for disaster or can we make it work? Thanks!



I’m installing tile on a concrete basement floor. I’m using ditra underlayment for crack prevention, but the concrete is sound. The only problem is that it is not consistent or flat as you would say. I can’t use floor leveler because I need to maintain the slope of the concrete to the floor drain which is at the center of the floor. The floor is out a flatness a maximum of 3/16″ to a feather when using a straight edge in the area I want to tile. I was going to simply us polymer modified thinset to fill in the low area and make it consistent (flat). I’m going to wet the concrete before and make sure to work it in. I’m not sure if I’m going to use a primer on top of the concrete? Does this approach make sense or would you have another approach?




I have a 3/4″ sub floor down, glued and screwed. I am planning on using 1/8″ ditra over that. The problem is, that the sub floor has a slight dip of about 1/16″ to 1/8″ running the length of the 4×8 sub floor plywood. The tile is 6×24. Does that need to be filled with leveler or will the thin set fill it in sufficiently? The tile will run parallel to the low spot and not perpendicular to it.



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?



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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