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Adding subfloor reinforcement

I am remodeling a big room in my house.  I just ripped out a bunch of tile.  Currently the floor/subfloor is 1/2 in plywood with 3/4 in particle board over it.  I am planning on ripping up the particle board and installing engineered hardwood flooring, but I would like to keep it at the level it is.  My questions are:

1. Can I leave the 1/2 in plywood subfloor and just add another 3/4 in more plywood on top with some screws and liquid nails?  Or should I rip it ALL out and add a single layer of 1 1/4 inch plywood?  Do they even make that?

2. For this type of application should I be considering OSB or plywood?

Thanks in advance!
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Posted 2017-01-10T05:08:24+0000  by Skeletor11 Skeletor11

Hello Skeletor11 and welcome to the Community.

First of all, I would read the installation instructions and requirements provided by the manufacturer of the engineered flooring, that you are planning to install.  They will specify the acceptable sub floor materials.  This information can usually be found on Home  by clicking on the Specification tab below the photo of the product.  Under the (Product Overview) heading and to the right, you will see a sub heading of (Info & Guides).

There is no such thing as 1 ¼” plywood.  It should be alright to add a layer of 3/4" (23/32”) plywood or OSB on top of the existing 1/2" plywood if it is secured together well with the liquid nails and screws. 

Check that the subfloor is within flatness tolerance. For example - It must be flat with no visible bumps or low spots; the subfloor should be flat to within 1/8” in 6 feet span or 3/16”in 10 feet.

A moisture barrier with or without padding, should be used between sub-floor and engineered flooring.

Thank you for your inquiry.


Posted 2017-01-10T17:15:09+0000  by Char_HD_CHI
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