Probably asked and answered but still not sure

Discussion in 'Floor Preparation' started by Baf3472, Aug 14, 2019.

  1. Baf3472

    Baf3472 New Member

    I am getting ready to install mohawk 4.5mm click vinyl flooring, glued down, in my home. The house was built in 1989 and had carpet everywhere but the kitchen and bathrooms. I don't plan on living in the house forever but will be here for a few years. I tore up the carpet in one of the rooms and saw that it has 5/8" particle board underlayment. Tore that up and got to the 1/2" plywood subfloor (not T&G). This is the part that is kind of throwing me for a loop. They installed the 1/2" plywood, nailed only on the perimeter to the joists and I don't believe they glued it to the joists, built the walls, then installed the particleboard and nailed that thru the plywood to the joists every 6-8". The subfloor seems kind of flimsy after i removed the particleboard even after I nailed the plywood to the joists. The floors felt very solid before I removed the particleboard. I would like to stiffen it up but not quite sure how to proceed. I'm thinking I could lay 1/2" OSB over the plywood and screw that thru the plywood to the joists as well as in between and then staple 1/4" plywood to glue the vinyl down. I can float the vinyl floor but with a big rowdy dog and a lot of sunlight, I'd prefer to glue it down. Ive spoken to mohawk and they suggested just using 1/2" plywood on top as an underlayment, screwed to the joists and in between and then using a seam patch to fill the gaps and screw heads, but that doesn't seem right. I know removing the 1/2 subfloor and adding 5/8" T&G would be the correct thing to do, but Im not planning on staying here forever and that kind of work on 2000 sf is not worth it to me in this house. Anyone ever run into this type of situation before?
  2. Jim McClain

    Jim McClain Owner/Founder Administrator

    Sounds to me like the only extra work there is to doing it the right way is to pull up the half-inch subfloor. And that doesn't seem too difficult if, as you said, it's only fastened around the edges and may not even be glued to the joists.

    Once the old subfloor is removed, you would have to add a few 2x6 blocks to the joists next to walls to support the new subfloor material. Then you can get subfloor material (T&G), install that by gluing it to the joists and fastening it with deck or galvanized screws every 6" along all joists. Add that layer of quarter-inch underlayment so you can glue down your vinyl flooring... OR, if you select a pretty smooth 3/4" subfloor plywood, you could fill the imperfections with cement based patching compound and glue the vinyl planks/tiles to that, saving the work and expense of the underlayment.
  3. Mike Antonetti

    Mike Antonetti Senior Member

    I’m not sure I would glue down a floating designed floor. It doesn’t need 1/4” for smooth but something sturdy subfloor/substrate.
  4. Baf3472

    Baf3472 New Member

    Thanks for the reply. I would still need to add a second sheet of plywood if I decided to rip up the 1/2" and install 5/8" T&G to get up to the door jamb height. Would adding the 5/8" T&G OSB on top of the half inch work?
    Last edited: Aug 14, 2019
  5. Jim McClain

    Jim McClain Owner/Founder Administrator

    OSB is a horrible underlayment. It's a mediocre subfloor material, so you would have to install a decent plywood on top of it for underlayment. But you indicated this was all just to get you out from under in a few years. So, save money and labor by using a thicker plywood subfloor (if you need thicker than 3/4", it's available (1-1/8 CAT PS1-09 Tongue and Groove Douglas Fir Plywood at Lowe's).

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