I bought a condo (900 sq ft) that was carpeted (now all removed along with baseboard and all kitchen cabinets and appliances). Under the carpet is particle board. There are many uneven spots (including a few places with plywood, which is a slightly less thick). I've used some floor patch on the worst places, and on the bigger holes created when the carpeting was pulled.

Initially I thought putting the spec'd 3mm padding and then floating a 1/2" click engineered hardwood floor would be okay, figuring the 3mm foam padding would help forgive some of the unevenness.

But now I am wondering if I should put OSB over the particle board to allow a smoother surface for the engineered hardwood floating floor. If I attached the OSB to the particle board using #8 coarse sheetrock screws... would that hold? And, if I did that, should I put flooring paper between the particle board and the OSB to reduce potential squeaks?

Removing the particle board would be a lot of work, and noisy too. I believe the particle board runs under the walls. (The building was industrial in the early 1900s, and converted to condos in the mid 1980s.)

So, I wondering if I should be okay with just putting the floating floor on the slightly uneven particle board that's there, or if that is asking for trouble and I really should do OSB on top. OR... will putting OSB on top of particle board potentially cause more problems?

Your thoughts would be appreciated.


  • 1
    Floating floors can withstand some unevenness, but usually limited to less than 3/16 inch within some distance(read instructions). If the particle board is in good condition, then OSB/plywood over it should not be a problem.
    – crip659
    Mar 3, 2023 at 22:48
  • Thank. Any thoughts on it being better to add flooring paper in between the OSB and the particle board?
    – Scot
    Mar 4, 2023 at 0:14


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