Subfloor with sub-optimal plywood?

Discussion in 'Floor Preparation' started by Bulldogg629, May 14, 2018.

  1. Bulldogg629

    Bulldogg629 New Member

    DIYer and first time homeowner, I just bought a house with a terrible asbestos tile floor.
    Ultimately I want to put down Cali bamboo, but surprise projects have made money tight. I wanted to at least put down subfloor to encapsulate the asbestos and make this place feel less disgusting. A local guy on craigslist was selling what he billed to be "1/2" plywood half sheets" but what they actually are, are low quality plywood 1/3 sheets, used to ship honda engine parts over, varying in thickness between .35 and .55" and wavy.
    2018-04-07 19.23.04.jpg 2018-04-07 19.23.43.jpg

    I bought 2 stacks hoping to use it for workshop walls, a workshop floor, new garage roof sheathing, and the subfloor for the house. I'm sure it'll work for the first 3 things, but is the thickness variance going to cause trouble as a subfloor in the house?
  2. kwfloors

    kwfloors Fuzz on the brain Charter Member I Support TFP Senior Member

    The plywood they use for shipping is that way, used for shipping. Its junk, probably has rocks and crude in it also. I would build a dog house out of it but that's about it. Spend the money and get the good stuff that will last.
  3. Commercial Floor Rep

    Commercial Floor Rep I Support TFP Published

    No way I'd use this for a subfloor. You have no idea what it's contaminated with or how it was constructed. It may not be put together with the proper adhesives and when you put patch or adhesive on it, it could delaminate and swell.

    I'm curious what the subfloor underneath the tile is, concrete or wood?
  4. Bulldogg629

    Bulldogg629 New Member

    Wood under the tile, its a crawlspace house. Being asbestos tile I have to do a floating floor, so no adhesive on the subfloor.
  5. Commercial Floor Rep

    Commercial Floor Rep I Support TFP Published

    Thanks, I've seen folks try to install subfloor over concrete and it can be disastrous, that's why I wondered.
  6. Chris 45

    Chris 45 Director of P.R. on some deserted island. I Support TFP

    How well are the tiles stuck to the floor? Sometimes they are barely held down by little more than gravity. If that’s the case, I’d pop all those tiles up then either skim coat the existing adhesive or possibly cap the whole floor with 1/4”. Then you would have other options besides floating floors. Those tiles are non friable which means you don’t have nearly the concern with asbestos. As long as you don’t sand, grind or do something that would otherwise release the asbestos, you are fairly safe.
  7. Bulldogg629

    Bulldogg629 New Member

    Chris, some sections are letting go. The house sat empty before I bought it and it seemed like the winter heating cycles made them start popping up. I did want to fill those spots with self leveler before putting down plywood. Pouring 1/4" over the whole house would require a lot of other projects to be done... remove the cabinetry, build new cabinetry, new door frames, an hvac duct mess. Covering it with plywood would let me cover most of it, and patch in spots later as I go.
  8. Chris 45

    Chris 45 Director of P.R. on some deserted island. I Support TFP

    No self leveler. 1/4” plywood. The box stores have sheets of something close to 1/4” for around $15 each. I’m thinking budget wise for ya. Not perfect but certainly better quality than your crate wood. I just wouldn’t be comfortable shooting a million staples through the existing VAT.
  9. Jim McClain

    Jim McClain Owner/Founder Administrator

    I remember what a pain in the ass that can be sometimes. Old VAT can be as hard as stone and deflect most staples you try to drive into it. Some will bend in a way you can't even tell - between the VAT and bottom of the plywood - until you notice a small bump in the surface, or a noise when you walk on it.
    • Agree Agree x 3
  10. Bulldogg629

    Bulldogg629 New Member

    Why no self leveler? Wont the 1/4" ply warp to the unfilled indentations under it over time? And if I cant shoot staples through the tile, how should I secure the ply down?
  11. Commercial Floor Rep

    Commercial Floor Rep I Support TFP Published

    Most self-leveling products are not designed for use over wood substrates by themselves. If they are used, then you'd have to put down diamond mesh metal lathe prior to use. Think of it as "tiny rebar".

    There is just too much flex in a wood subfloor which would lead to cracking of the self-leveling if done without the lathe.

    There are self-leveling products that can be used over wood substrates but it's not typically something you'll find in a box store. Self-leveling is also not as easy as it sounds, especially if you've never done it before.
    • Agree Agree x 1
  12. Mark Brown

    Mark Brown On The Surface Flooring I Support TFP

    You got that right...

    we just leveled a second floor on osb... oh jeebus. Floor was out of whack by over 3/4 in 5" and laminate was going down. Now it's glass.... but it took me and my partner the better part of 3 days to get it that way and over 45 bags of leveller. Good times had by some.
  13. Commercial Floor Rep

    Commercial Floor Rep I Support TFP Published

    A lot of DIY folks, and for that matter many pros, don't take into account the amount of weight that they are adding to a, very possibly, over stressed wood subfloor. The first questions should be can the floor support the additional weight? If not, bracing and support should be addressed first.

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