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How do I level a sloped floor?

jenniferz5 | Posted in General Questions on

I recently turned my sunroom into a kitchen.  The sunroom was (I think) formerly a sunporch that was enclosed at some point.  The slate tile floor is in great shape, but it slopes about 1.25″+/- over 10′.  Since the floor is also cold to our feet in winter, I plan to add a floating cork floor with insulation and moisture barrier, so now is the time to even up the slope, if possible.  Any ideas?  I have over an inch at the termination of the slope to work with.

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  1. Expert Member
    NICK KEENAN | | #1

    Take a bunch of 10' 2x4's, cut them on an angle so it is 1.25" at one end and 0" at the other. Space them 16" apart. Cover the whole thing in 5/8" plywood and then put your floating floor over that. I think you could float the whole thing over the slate.

  2. Expert Member
    BILL WICHERS | | #2

    You could use floor leveler here. You have a pretty big slope to work with, but if you put in a temporary curb you should be able to use floor leveler to even out this floor. Once that’s done, you can install whichever floor you like on top.


  3. user-723121 | | #3

    What is the cause for the slope? Is it a concrete slab? If not, I would inspect the support (foundation) to see what happened. It could have been sloped intentionally to let rainwater drain out, the foundation may have settled or it could have been a slab converted to a sunroom with a direct earth connection. More details please.

  4. jenniferz5 | | #4

    Thanks for your replies. I would rather not use floor leveler, as I want to keep the original floor intact. The floor is intentionally sloped, as it was an outdoor porch. Would it be possible to just add some insulation to the floor, sloped in the correct direction? The cork flooring is about 1/4" thick, the underlay is also around 1/4".

    1. Expert Member
      BILL WICHERS | | #5

      I see no reason you couldn’t use foam insulation rated for compressive strength in this application, but I think it would be a massive hassle to try to trim it to a thin wedge shape. It would probably be easier to rip some “joists” of the right shape and build a plywood subfloor over them instead.


    2. Expert Member
      NICK KEENAN | | #6

      I don't think you could cut insulation to that slope. Nor does it have the strength to span a gap unsupported. But consider this:

      The slope you have described is 1.25" over ten feet, or 1/8" per foot. Over 4' it's 1/2". So if you had 4' wide pieces of subfloor they would be horizontal if the lower edge was shimmed a half inch. I'm thinking three steps, of 4', 4' and 2'. The top step has no insulation, the middle step has 1/2" and the bottom has 3/4". That gives you a flat floor, you can add more insulation on top if you want. Depending on what you use for the subfloor you will need additional shims, half inch plywood can span 16" and 3/4" can span 24".

      1. jenniferz5 | | #7

        This makes sense! Thank you.

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