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Thread: Hardwood flooring over particle board subfloor?

  1. #1

    Hardwood flooring over particle board subfloor?

    I'm tearing up carpet and putting down 3/4" solid hardwood, but have found that the subfloor is 3/4" particle board (yes, particle board, not OSB) on top of 1/2" plywood. From googling, I've learned this was common in the 70s-80s to bring a carpeted floor up to the same level as other tile flooring.

    So, what to do?

    I'm know the "right" thing would be to tear the particle board out and put down 1/2 or 3/4 ply. But that's a huge amount of additional work and cost.

    I've read that some people will nail the hardwood down to the particle board, so I guess that's the other option. I was planning to use Primatech cleat nails, 2", which are barbed, and should go all the way through the 3/4 particle board, 1/2 ply, and 3/8" into the joists (which I'll try to hit, and will run the flooring perpendicular to).

    I will only be in the house another ~4 years, so am not necessarily looking to do this the same way that I'd do this in a "forever" house. Existing wood flooring in the house is already pretty squeaky, so I'm willing to accept that potential bad outcome. I'm not worried about water wrecking the particle board. That said, I don't want to be the jerk who does it wrong and makes a mess for later.

    If this was your project, what would you do?

  2. #2
    Quote Originally Posted by Dan Friedrichs View Post
    ...I'm know the "right" thing would be to tear the particl board out and put down 1/2 or 3/4 ply....
    I will only be in the house another ~4 years, so am not necessarily looking to do this the same way that I'd do this in a "forever" house...
    I'm not worried about water wrecking the particle board...

    If this was your project, what would you do?
    First thing I'd do would be to fire you.
    "Anything seems possible when you don't know what you're doing."

  3. #3
    Join Date
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    I would take the particle board up. How is it fastened down?

  4. #4
    Join Date
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    I definitely would not put hard wood on particle board.

  5. #5
    Join Date
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    Dan,

    I think by your statement, you answered your own question but don't want to accept it.
    Ken

  6. #6
    Join Date
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    Modesto, CA, USA
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    What is under the wood?

  7. #7
    If I were to install the hardwood on top of the particle board, the finished assembly would be 3/4" solid wood, 3/4" particle board, 1/2" ply, and barbed cleats running through the entire sandwich and out the other side into the floor joists. I have a hard time believing it wouldn't be stiff enough. I worry about the pull-out strength of cleats in particle board, but since the cleats go all the way through and through another 1/2 of ply, certainly that has some holding strength?

    I don't feel good about it, but I'm trying to understand the problems that may arise so I can make a decision based more on logic and facts than feelings.


    Quote Originally Posted by andy bessette View Post
    First thing I'd do would be to fire you.
    Thankfully, I'm both the boss and customer on this one

  8. #8
    Join Date
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    I'd like to understand what the issues are with nailing the hardwood floor on top of the particke board? What can go wrong?

  9. #9
    Join Date
    Feb 2003
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    I'm wondering about the depth of penetration of those cleat nails. The ones I used when I put in floors (in my house) went in at an angle, so they don't go 2 inches deep. If my math is correct, and the cleats go in at a 45 degree angle, that gets them 1.4 inches down, which means only about halfway into that 1/2 inch plywood, and well short of the joists. If the hardwood flooring boards are perfectly flat, and don't need much holding, that'd be fine, but I found (only 3 rooms worth of experience, though) that a lot of the boards weren't so perfect. Would cleats mostly in particle board hold unruly boards?

    But perhaps my math is off or I'm missing something. Wouldn't be the first time

    Ken

  10. #10
    Join Date
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    When I started building houses in 1973, for a living, this is the way they were typically done for a couple of decades, so I have some feel for the materials. I'm assuming that the thickness of the floor below the tongue, and the angle of the cleat is accounted for (edited to add: I typed that before Ken had posted his response, which included the math). The cleats have barbed sides. The holding strength that the particle board will offer will approach zero. 1/2" sheathing plywood, which is not really a half inch thick, whether 3-ply, or 4-ply, will not have much better holding strength than the particle board. That leave the 3/8" in the joists, at best. That's the little pointy end of the cleats.

    Knowing the stiffness of this flooring system, which has been increased in later decades, even in the cheapest built houses, it's going to flex some between the joists in the process of living on it. Things will loosen, and squeaks will be terrible. They were bad enough with flooring installed on thin subflooring, without the particle board.

    I always snapped lines, and put every cleat in a joist, which also added another factor in selecting boards to lay out in each row, so that no two ends met towards the middle of the span between joists.

    I just don't see anything good happening for the future of a floor installed on top of 1/2" sheathing, and particle board underlayment. That old particle board underlayment is even sorrier than what particleboard furniture people might be familiar with these days.

    This just my opinion after a couple of decades of experience with that type of construction.

    Only recently, I've seen the biggest shift in desired flooring ever. There are two million dollar houses built these days, on the lake here, with nothing but luxury vinyl all through the house. This just in the past few years. I almost always used 5" White Oak solid wood for floors in the spec houses I built here for 33 years, but built my last spec house in 2007.

  11. #11
    As long as the particle board is in good condition I don't see anything wrong with putting a hardwood floor over the top. It would probably be best to run the flooring perpendicular to the framing in case the sub-floor ever gets wet. That would be the only issue. If the particleboard gets rotten the flooring could sag between the framing if you run it parallel. I just did a remodel where the pine 1x6 sub-floor was rotten and they took up the hardwood floor and people were stepping through the sub-floor. If they hadn't taken up the hardwood floor nobody would have ever known there was an issue.

  12. #12
    Quote Originally Posted by Tom M King View Post
    When I started building houses in 1973, for a living, this is the way they were typically done for a couple of decades, so I have some feel for the materials.
    Thanks, Tom. You perspective and experience are very much appreciated.

  13. #13
    Join Date
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    Where I live, solid hardwood flooring has fallen out of favor. Instead, people are choosing "engineered" hardwood planks, and the "luxury" vinyl that Tom mentioned. I used the engineered hardwood in my new house and have been very pleased. I much prefer it to the solid red oak flooring in my old house. It doesn't squeak and it doesn't expand and contract showing cracks with the change in seasons. If you don't remove the particle board, I would suggest the use of that material, which is glued down rather than nailed.

  14. #14
    Join Date
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    Rent a toe-kick saw, cut the particle board around the edges, then dig up all the nails holding down the particle board. BTDT--it's a LOT less effort to dig nails than to try to pry up the particle board. It will just break into small pieces. I would then glue and screw 1/4" OSB (1/2" plywood would be much better) through the subfloor into the joists.

    And I second the comment that particle board has zero holding strength. I helped a friend and his FIL lay hardwood in a modular home. Someone messed up a few pieces, and I remember that we were able to just pick up the offending pieces by hand even though they had already been nailed down (with 2" cleats).
    Jason

    "Don't get stuck on stupid." --Lt. Gen. Russel Honore


  15. #15
    Are you sure there is 1/2" ply under the particle board? There are some houses I've seen where the subfloor is only 3/4" particle board that was glued to the joists.
    Lee Schierer
    USNA- '71
    Captain USN(Ret)

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