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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Wayne

Roger,

I am planning to tile approximately 950 sqft with a 6×24 porcelain plank tile over a concrete subfloor. The most intimidating part of this whole job is getting the subfloor flat enough to prevent lippage. What is the best method to flatten a large area like this? I have looked into SLCs but they are very pricey. Do you have other suggestions?

Also, I was planning to lay down Laticrete’s Strata Mat to isolate the tile install from the concrete. Is this necessary or can I use something else to create the isolation. I saw an install online where they used something over just the cracks in the concrete. I assume that would only isolate horizontal movement. Again isolation membranes like Strata Mat are very pricey. I don’t want to sound like a cheap hack but I also don’t want to do like many DIYers and spend money where it is not necessary. Any advice would be very much appreciated.

Reply

Roger

Hi Wayne,

SLC is your best option to get a concrete slab flat. Strata mat is not required, but always a very good idea over concrete. What you’ve seen is a crack-isolation membrane, it only deals with in-plane movement (as any membrane will) but only over where it is placed. The properties of strata mat or ditra that do the same thing do it for the entire installation.

Reply

Dave

Hi Roger,
I have a customer I have done a couple of tiling jobs for, nothing spectacular. However he is very intent on hiring me to tear out some marble tile in his personal residence, a rather intimidating house, and replace it with large 24″ porcelain tile. I believe it would be around 700 – 800 sq ft. I feel overwhelmed by the prospect, and yet also would like to tackle a job of that scale. My main concern is that I have heard rumors from guy who saw the current marble installed, that the sub-floor is very uneven and needed a whole lot of building up with mud in order to keep the floor flat. I am not terribly experienced with real large tile installation and am not sure how I would address the sub-floor. Since this would be a remodel, I have other floor transitions to match. Was wondering if you run into a lot of these types of situations and appreciate any advice you could think to give me. Also, which brand of snap cutter would you recommend? I would like to purchase one for larger tile. Thanks so much.
– Dave

Reply

Roger

Hi Dave,

I’ve done a few of them. Your best bet is to remove EVERYTHING beneath the marble, down to the substrate. At that point determine what method would best help you achieve a flat floor with smooth transitions. Deck mud is actually my preferred method, but an SLC may suffice. It just depends on how much buildup you may need.

And I use Sigmas. They are the best I’ve ever used, and never let me down.

And DO NOT undercharge for this! Don’t underestimate the amount of work involved. I had to pay for that lesson a couple of times. :D

Reply

Adam

Hi Roger,

Thanks for your guidance, I found a deck mud that can be between 1/2″ and 1-1/2″. I don’t know if I can get it where I am, but at least I know deck mud exists.

Thanks for the guidance and the website,
Adam

Reply

Roger

Hi Adam,

If you take a bucket and mix 5 parts sand to one part cement then deck mud will exist in your bucket too. Can you get sand and cement where you are? :D

Reply

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