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  1. #1
    Join Date
    Aug 2007
    Posts
    9

    Default Tile on uneven basement floor

    I am re-finishing my basement after fixing a drain tile issue. I am adding a bar area and would like to add tile around the bar area. When the interior drain tile was replaced the contractor did not level the concrete the best to match up with the existing slab. The high point starts at the wall and slopes slightly downward until it meets up with the original slab. So I am looking at about 12-14 inches of concrete with about 1/8", maybe 3/16" of slope. To correct the slope and have level tile can I simply use a thicker bed of thin set to compensate or will this affect the tile affect the tile in the future. Or do I have to grind down the concrete. The rest of the floor will be carpeted so I don't think the transition would be highly notable if I were able to use a thicker bed of thin set, just not sure if that is permissible.

    Thanks,

  2. #2
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    6,321

    Default Re: Tile on uneven basement floor

    So your question is basically which one is better: 1. to raise the entire field to the highest point of the elevated tiles, or 2. to grind down the few raised tiles to the level of the rest of the field.

    My guess would be #2, it will be less work since you only have a few raised tiles.

  3. #3
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Tile on uneven basement floor

    Quote Originally Posted by jloesch View Post
    I am re-finishing my basement after fixing a drain tile issue. I am adding a bar area and would like to add tile around the bar area. When the interior drain tile was replaced the contractor did not level the concrete the best to match up with the existing slab. The high point starts at the wall and slopes slightly downward until it meets up with the original slab. So I am looking at about 12-14 inches of concrete with about 1/8", maybe 3/16" of slope. To correct the slope and have level tile can I simply use a thicker bed of thin set to compensate or will this affect the tile affect the tile in the future. Or do I have to grind down the concrete. The rest of the floor will be carpeted so I don't think the transition would be highly notable if I were able to use a thicker bed of thin set, just not sure if that is permissible.

    Thanks,
    You can but depends on how far.
    I would take a straight edge and a level and see how much impact the level of the tiles will be further away from the wall where it meets with an adjoining floor surface.
    For example -- lets say the slope is 1/4" per foot. At four feet you will have a difference of 1" between the low and high points.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  4. #4
    Join Date
    Dec 2010
    Location
    Houston Texas
    Posts
    2,918

    Default Re: Tile on uneven basement floor

    Most brands of thinset have a maximum depth of 1/4". A medium set mortar can be as deep as 3/4" max.

    Do check the slab to make sure it will absorb water. If it doesn't, the scarfiying the surface will be necessary.

  5. #5
    Join Date
    Jan 2008
    Posts
    1,915

    Default Re: Tile on uneven basement floor

    If you need the drain, you need to retain the slope toward it. In an area that is expected to be dry I will go with as little as 1/8" per foot slope which will still drain deeper water quickly but not shallow water which might require mopping to clear completely. This slope will not present a problem with stools wanting to tip over which becomes marginal at or over 1/4" per foot, and it will still leave the drain functional.

    You can safely exceed the maximum recommended thickness of the tile-set mortar slightly in small areas, say less than 1/2 of any given tile sitting on it not to exceed 10% or so of the entire tiled area. If more than that is needed grind or otherwise level the concrete before setting. More than anything, tile needs as flat a surface as you can give it to sit on, whether it's level or not is a far lesser concern. Also be sure to seal the grout when you're done, renewing that every couple years or so.

    Tiling is a great DIY project and not hard to do though it is a bit tedious if you're tiling a large area.

    Phil

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