I want to put tile down in my basement. The floor is concrete and feels like a basement with some furniture on it. I’m hoping the tile will change that. I measured the level of the floor by putting my laser level on a shelf then measured the distance from the level line to the floor throughout the room. It turns out the floor is way out of spec compared to the 1/4” per 10’ guideline. But, I wouldn’t have known it was out of level without measuring.

Can I get away with slapping tile down on the uneven and unlevel floor or will variations become more noticeable once it’s finished?

  • 1
    A level floor and a flat floor is two different things. Tile wants a floor that you can lay a long straight edge down and do not see any difference. You want a pool table to be level. A floor can have as much of a slope as you can live with.
    – crip659
    Commented Mar 9 at 16:43
  • If the floor is wavy/has dips/ridges, not flat, that needs to be fixed first. Tile does not bend. A self levelling compound or similar can be used. A nice simple flat slope you did not notice before, will not be noticeable after.
    – crip659
    Commented Mar 9 at 18:33
  • @crip659, i didn't notice the undulations of the floor until i pulled out a laser
    – holmeski
    Commented Mar 9 at 19:22
  • It might not matter much with the small(penny size tiles), but larger tiles do not bend if the floor is not flat. One reason why upper floors often require an inch plus sub floor above the joists for tiles. Tiles break/crack easily if not fully completely supported under the tile.
    – crip659
    Commented Mar 9 at 19:32
  • Depending on the size of the tiles, it may not be an issue. Some lack of flatness can be overcome with the thinset layer, and if the tiles aren't too big vs. the "bumps" you could even simply follow the bumps with the tile.
    – Huesmann
    Commented Mar 10 at 23:31

2 Answers 2


If you didn't notice the floor was out of lever before, you should not notice the floor is out of level after tile.

The process for tiling may need to be tailored to the tile that you are putting down.

Tiles that are rectified have a square edge and need to be installed with some type of Tile leveling system There are a number of different types, but they all work with the same principal of raising or lowering the edges of tiles to match each other. Needing to use a leveling system will add time and money to your project. Getting the floor ready to start tiling can be more work depending on how much the floor dips and slopes. ( How to compensate depends on how bad the floor is and we don't know that exactly.)

If you were to use a tile without rectified edges, or edges that are beveled to allow a slight variation in installed height differences, you will eliminate the need for a leveling system. ( If my basement it would be my choice.)

From your description that the floor was not noticeably sloping, I would be confident that I could install non-rectified tile on the floor with a good result. Ask questions of the professionals you intend to purchase the tile from as to what size trowel to use and what type of thinset mortar for the tiles you like before making a final decision.


As tile size increases, a wavy floor causes more and more lippage (where one tile edge--a lip--sticks up compared to its neighboring tile's edge). You can cope with a wavy floor, then, by choosing smaller tiles.

I've never used those 4 ft long faux wood tiles before, but I've seen credible advice stating that a tile leveling system can be necessary to pull waviness out of these tiles to get a very nice install (with minimal lippage). Generalizing the idea, maybe you could use a tile leveling system to make larger tile work nicely? My instinct is that this only works for tiles that are relatively short in one direction but long in the other direction (like the faux wood tiles). Otherwise you'd generally be trying to deform tiles into strange saddle shapes instead of simple 1d curves.

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