I am replacing downstairs flooring that had three layers before the subfloor. Linoleum, Cement Board and Tile. All flooring had to be removed down to the subfloor due to water leak. Since the cement board was screwed it, it is causing uneven areas as the screws are pulled/removed. Should I lay 1/4" or 1/2" plywood underlayment on top of subfloor before installing LifeProof vinyl plank flooring?

If so, what do you recommend? Should I also glue this new underlayment on current subfloor and screw down as well?

The goal is to not have any transition pieces from room to room, while making sure flooring is level with no dips or valleys.

  • If your existing plywood sub-floor is in good shape, I would say no. And putting 1/4 or 1/2 inch plywood over an existing, uneven floor could lead to squeaks and eventual low spots. A couple of years ago I had a rental I remodeled. I pulled up all the floor coverings and particle board underlayment (it was in poor shape) and used a leveling compound to patch and even out any low spots. Then installed a pretty high end product (LVT) and it turned out great. The most important part is to get a solid, level floor. May 22, 2020 at 15:31
  • Thanks. I wouldn't say it is "unlevel" per say. There are some low spots and marks in the wood from screw removal
    – afeddy05
    May 22, 2020 at 16:25
  • My floor had some def. dips that would have shown thru to the finished floor. It needed to be leveled. If you are level AND solid, just patch the low spots and significant gaps. Home Depot has good installation instructions for your product. images.homedepot-static.com/catalog/pdfImages/9f/… May 22, 2020 at 16:48
  • What is the subfloor made of?
    – FreeMan
    Jun 21, 2020 at 16:15
  • downstairs = cement floor?
    – DMoore
    Feb 16, 2021 at 19:50

1 Answer 1


I prefer underlayment On top of sub flooring if there are a lot of bulges from the screws I would put a thin layer of spackel or self leveling cement down then the sub flooring. If you use a pad the vinyl plank may be fine on the existing Sub floor but when redoing my houses I want it nice so I would use an underlayment.

The problem with plywood is knot holes and blows will end up showing through over time with some floors underlayment is cheaper and better for this case. Always stagger the seams don’t put any new seams over the old ones.

  • 1
    If you use “underlayment grade” plywood that is “plugged and patched” you’ll eliminate all those missing knot holes and blows. A little more expensive but worth it.
    – Lee Sam
    Oct 14, 2021 at 20:29

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