What would be the correct way to level a basement floor that is this much uneven, so that I could build a sublfoor consisting of delta-fl and plywood ?

enter image description here Thank you for any help !

  • what do you plan on using as the final flooring? – Steven May 31 '16 at 18:18
  • It would be either one of theses two solutions : dri-core squares or a combination of delta-fl + plywood or osb. flooring will be vinyl click planks – Rémi Fortier May 31 '16 at 18:22
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    You're nearly an inch out of level, is that right? – The Evil Greebo May 31 '16 at 20:17
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    I'd want to know why the corner broke and sunk that much. There could be a larger settlement issue that is important to deal with. I would cut out enough of the broken concrete to get a good look underneath. Look for any foundation or water problems. If there is nothing needing repair, look for a gap under the concrete slab that hasn't broken yet, You may want to add some support under it so it doesn't eventually break, too. There are various ways to get supporting material under the slab. (cont'd) – fixer1234 May 9 '17 at 0:31
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    If the problem is just that corner, there's a good chance of a water problem eroding what's under there. If you don't want to investigate or fix it, add enough stone to raise the settled area to slab level before restoring the slab. – fixer1234 May 9 '17 at 0:31

If you plan on using dri-core then you don't need to level the floor with self-leaving concrete or any similar method. Instead, you'd just shim the dri-core panels to make them level.

If you are just going to put down standard OSB then you'd want to use self-leaving concrete.

A big advantage to just shimming the dri-core is that most basement floors slope towards a drain and with shims, you'd maintain this slope so any water that gets beneath the dri-core would still drain properly instead of sitting underneath the OSB. And of course this is why dri-core has a rubber bottom layer.

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    Good suggestion, but would a 15/16" slope over a 2.5' distance be too much to shim correctly ? – Rémi Fortier May 31 '16 at 19:09
  • Almost an inch over 2.5' is definitely too steep. Typically your drainage slope should be 1/8" over 1', so for 2.5' that should be 5/16". – The Evil Greebo May 31 '16 at 20:18
  • 3/8" per foot for a small section? I cant see why you couldn't shim this... – Steven Jun 1 '16 at 13:20

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