How to Install a Tile Floor on an Uneven Subfloor

I love the look of tile compared to cheap, laminate flooring. But since ceramic tile isn’t flexible, I’ve wondered how to install a tile floor on an uneven subfloor.

So I decided to research it and here’s what I learned:

For subfloors with only minor variations, under 1/4 inch, it is acceptable to simply use additional thin-set mortar to even out your floors. However, for variations greater than 1/4 inch, you will want to use a self-leveling floor compound to ensure your tiles go down on top of a perfectly level subfloor.

But there’s a lot more to know about how to get great results for your floor tile project if you don’t have a perfect subfloor to start with.

So in this article, we’re getting into all the problems you might run into as well as the tips and tricks you need to know to have your new floors look perfect.

So let’s dive in.

Can you tile on an uneven floor?

The short answer is yes, but you’ll need to use some sort of self-leveling floor compound to make the subfloor even first.

After all, ceramic, granite, and other types of floor tiles aside from vinyl floor tiles have no flexibility whatsoever. So they’ll crack if they get stepped on in places where they aren’t perfectly adhered to the subfloor underneath.

Plus, the finished job will look terrible if some tiles stick up above the others.

So take the time to properly prepare your subfloor so all the work you are about to put into laying the tiles will be worth it in the end.

Can you use mortar to level out a floor?

This is a common question among homeowner DIY types.

After all, you’re already using mortar to stick the tiles to the floor, so why not just lay down an extra thick coat where you need it, right?

Well, that can work if the variations in the subfloor are small; under 1/4 inch. 

But if the subfloor varies by more than 1/4 inch, thin-set mortar usually isn’t recommended by the pros. In this case, it’s better to use a flexible floor leveling compound.

So go to Sovereign Chemicals to see the best selection for your job.

Can I put new subfloor over old subfloor?

The short answer is yes. Just be aware that depending on how high your doors are off the ground, you may need to trim them once the new subfloor is attached.

There’s a lot of reasons you might want to lay a new subfloor over an old one, such as:

  • Improve insulation on a pier and beam house
  • The old subfloor has excess glue or other adhesives that are extremely hard to get up
  • The current subfloor is uneven

Plywood works great for the new subfloor. Just make sure to use some leveling compound first so the new subfloor can lay perfectly flat.

Also, ensure that the joints of the new subfloor are not lining up with the subfloor underneath. But don’t just screw the new floor into the old. Gluing the new floor down will help ensure a perfectly flat floor that won’t creak or buckle as the weather changes. 

And that level subfloor is critical when you install tile on top of it. Otherwise, you risk the tiles cracking and your new floor looking terrible after just a short time.


A perfectly level subfloor is critical to having a beautiful new tile floor.

If you’re lucky enough to already have a level subfloor, tile away! But for the rest of us, especially those of us who live in older houses or pier and beam houses, often leveling compound is needed to ensure a perfectly level subfloor.

I know you’re eager to get started and my telling you to take a whole day for this extra step is frustrating. But trust me. For the long-term look of your new tile floors, this is not the place you want to cut corners!

Jeff Campbell

Jeff Campbell is a husband, father, martial artist, budget-master, Disney-addict, musician, and recovering foodie having spent over 2 decades as a leader for Whole Foods Market. Click to learn more about me

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