I'm contemplating both worthwhile solutions from this less specific question. However, I'm concerned about my ability to nail down hardwood flooring after using a leveling compound, and am reluctant to expend the effort to rip out and replace the subfloor per the second answer.

In my specific case, I need to level the floor in an upstairs room where one of the floor joists is, I'm assuming, 3/4" higher than the rest of them. Along one side of the room, the subfloor is 3/4" higher. It drops to the height of the rest of the room over about the first twelve inches of each subfloor board.

I am contemplating purchasing 3/4" thick plywood boards and attach them to the existing subfloor except for the elevated area. Then, along the twelve inch strip, I would use leveling compound. I could then stagger the hardwood flooring to avoid nailing into the leveling compound.

Is this a reasonable approach?

  • What is your plan for dealing with the 3/4" plywood offset plus the additional 5/8" to 3/4" offset when you get to the door of the room?
    – Michael Karas
    Commented Nov 16, 2013 at 15:43
  • The problem joist extends out the door into a hallway, then conveniently disappears under a wall. I have a small section of hallway that I will also have to raise to keep everything level. Commented Nov 16, 2013 at 16:06
  • I'm not clear why you don't want to nail through the self leveler. If its deeper than 1/4 to 3/8 inches thick, the substructure should be corrected.
    – HerrBag
    Commented Nov 16, 2013 at 16:28
  • I'm assuming that the self-leveller, once dry, has the consistency of concrete and is such impossible to nail through using my air nailer. Commented Nov 16, 2013 at 16:39
  • You can nail through it, its aggregate is very fine. It will crack a bit around the nail, but will still support the flooring properly. Take a look at the new-ish silicone paper moisture barrier. Any self-leveller install thicker than 1/2 inch deep should have some lath embedded in it for strength (more typical for under tile installs).
    – HerrBag
    Commented Nov 16, 2013 at 16:54

1 Answer 1


One solution is to cut subfloor on either side of the offending joist, plane the joist down, sister 2x6 nailers alongside the perimeter of the exposed opening. Then replace the subfloor with new 3/4 ply.

  • 1
    That is what I did for my problem spot in my floor earlier this year, worked like a charm. It took about 2 hours to fix after all materials and tools were assembled
    – Jack
    Commented Nov 17, 2013 at 2:11
  • 1
    If you follow the excellent advice from HerrBag, and don't yet own a planer, now's your chance to justify getting one. I just bought one myself, a 3 1/4" Bosch for $109 at Home Depot based on the excellent reviews it received. I used it to strip the finish off some oak flooring boards and it was quick and easy.
    – getterdun
    Commented Nov 17, 2013 at 3:11

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