I need to patch the subfloor after moving the plumbing from under the floor to the wall, in the bathroom. To support the new OSB patch, I've added floating 2x4s and now plan to put the board down with 2" screws and PL400. Now I'm sure you see the 1/2" gap between the old and new board at one spot.... what can I do about it? I don't plan to cut a new board but here's what I'm considering :

  • Fill in some foam to ensure seal from underneath (prevent air, moisture, or bugs from passing through) OR
  • Fill out the gap on the board first with Bondo and then lay it down. What would you all recommend?

PS: I plan to lay down LVP (20 mil wear layer thickness) directly on top. Pictures : https://imgur.com/a/Ijodslm

  • Can fill it in, but the planks will probably not be bothered with a small piece missing if the rest of the floor is flat.
    – crip659
    Commented Apr 2 at 17:48
  • Got it. Yes, the rest of it is mostly flat... I'm not too worried about the LVP on top but plan on sealing the gaps anyway to prevent air, moisture, or bugs from passing through
    – bsong
    Commented Apr 6 at 19:24
  • Mostly flat might not be good enough. Planks usually want flat within a few mm/16ths. The installation instructions should give the range of non flat is allowed.
    – crip659
    Commented Apr 6 at 19:31


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