I am hoping someone will be able to give me advice on how to proceed with my project. I am installing vinyl flooring and noticed the particle subfloor was rotten in a spot. I decided that I wanted to remove it and replace it with plywood. When ripping it up it looks like it was screwed and glued onto risers (planks of wood - not sure what they're called).

Is it best for me to take these risers up and just place 3/4" plywood on top of the existing plywood? I assume I would have to glue as well right? Or should I get 1/4" plywood and lay that on top of the risers?

Any advice you could provide would be greatly appreciated as I clearly have no idea what I am doing. Here is a picture of what it looks like:

picture of floor

Wider view of what's being replaced (don't mind the mess :))

Wider Image

Thanks in advance!


  • It's a little hard to tell what you're replacing. Just the area over the shims? A full overlay? A wider shot with some perspective would be great. The short answer is that it doesn't much matter as long as it's solid.
    – isherwood
    May 7, 2020 at 18:49
  • Thanks - I added a wider image. My terminology is likely incorrect but I think it's 1/4" particle board underlayment on top of those shims. Under the shims is the plywood subfloor. I want to take the whole particleboard off and replace it with plywood as it's rotting.
    – deved out
    May 7, 2020 at 18:55

2 Answers 2


If I were you I'd keep those risers there. You don't know if they're glued on the bottom and you might damage the plywood underneath. Sand those risers to get rid of the glued particle board remaining on them. Then replace the particle board with plywood of the same thickness and make sure you glue it to the risers in addition to using a fastener. Fastener does all the structural work and the glue prevents squeaky floors.

  • Thanks, sounds like a good idea to me. The only concern I have is that the risers feel a bit loose. I don't have enough of the particle board down yet to know whether or not they're glued or just 'floating'. If they're floating should I glue them down and just get the same size plywood? or take them up? or hire someone :)?
    – deved out
    May 7, 2020 at 19:34
  • I don't think you need to hire someone. What you're doing here is more aesthetic than anything else, so have fun with it. I'd keep the risers there even if they're loose. The reason being that it'll be better to have the board resting on the skiny(er) risers than a continuous flat surface. You could get air bubbles caught in there and the floor could delaminate if that makes sense?
    – represton
    May 7, 2020 at 19:38
  • Thanks again for your help This was very helpful. One last question - what kind of plywood would you recommend? It looks like the particle board I am replacing is 1/4" and the plywood is .205". Will that .05" make a big difference?
    – deved out
    May 7, 2020 at 19:46
  • It might with that thin vinyl. If you're having trouble finding something close you could always go with the particle board again.
    – represton
    May 7, 2020 at 19:51
  • Cut off a piece of the existing particle board and bring it into home depot. Try to find the closest thing.
    – represton
    May 7, 2020 at 19:52

I'm not an expert, but I had a similar situation when installing laminate flooring. The particle board subfloor ran under the framing and I was concerned damaging it could be cause more series issues so I decided not to replace it. Your particle board doesnt look like its in terrible shape.

  • I was so tempted to leave it too but basically committed now. The top right corner of the wider picture is (for a lack of a better word) mushy. And it's no where being close to being level. We put the flooring down and it was very obvious something was wrong.
    – deved out
    May 7, 2020 at 19:45

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.