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Community and Q&A

Ordered Advantech Subfloor – Got Sheathing, OK?

maine_tyler | Posted in GBA Pro Help on

I ordered some Advantech subflooring from a local lumber yard. They delivered Advantech sheathing. I should have known seeing as I asked for the 19/32 subfloor panel and they got pretty confused and said it was 5/8. I thought it was just a ‘nominal’ thing.

Is the sheathing appropriate to use as a subfloor. I’m actually doing a two-layer floating over foam application). What’s the difference between the products? 

It looks like the subflooring is actually a bit cheaper (and 19/32 IS thinner than 5/8, so…)

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  1. Expert Member
    NICK KEENAN | | #1

    If the product is rated for use as subfloor it will have an APA stamp on it that says so. You're kind of asking for trouble using a structural product in a way it's not rated.

  2. Expert Member
    Akos | | #2

    Subfloor should be T&G. Sheathing is square edge. I guess in a pinch if your concrete is flat and you take a bit of care to make sure the edges are screwed down the same, you can make the square edge OSB work.

    I'm not sure if this is worth your while though, if you ordered subfloor, have them exchange and deliver the right material.

  3. Expert Member
    BILL WICHERS | | #3

    Plywood is made to metric thicknesses in most cases, so you end up with those "nominal" inch sizes, which is where the funky "19/32" stuff comes from -- it's a close(ish) approximately to a metric thickness, and "true" 5/8" plywould would be 20/32". That's common though, and has been the case for a long time. That in itself is not something to be concerned with.

    5/8" subfloor is the minimum acceptable thickness, 3/4" is a better option. I would double check to see what you actually ordered. If you ordered 3/4", then do NOT accept 5/8" as a substitute!

    I'm with Akos here -- if they didn't ship what you ordered, that's the lumber yard's problem to fix. Have them come pick up the incorrect product and deliver the correct material. You don't have to suffer for your supplier's mistakes here. The only possible exception would be if subfloor was unavailable for some reason with a very long lead time, in which case they might be trying to help you out and ship a substitute. You can use regular plywood for subfloor too if you can't get the T&G material intended for this purpose.


  4. maine_tyler | | #4

    This actually is tongue and groove. Apparently the 5/8 sheathing comes with that option. I wish I knew what the difference between products was.
    I'm floating this on foam, two layers, so feel pretty good about 5/8" thickness.

    I suppose I could have them pick it up, but I'm worried they simply don't carry the subfloor. I'll call em tomorrow. If this works I'm tempted not to deal with the hassle of redelivery

    1. Expert Member
      Akos | | #6

      If it is T&G and won't be exposed to weather, I would have no issues using it in this case. There is no spanning capacity needed, so I don't think even a very picky inspector will have issues.

  5. user-5946022 | | #5

    Might be worth a call to Advantech

  6. Expert Member
    Michael Maines | | #7

    Edit: I was thinking Zip sheathing, not Advantech sheathing.

    Huber has a whole tech document for floating subfloors:

    Original comment:
    I don't know why they use the same product name for the sheathing and subfloor, as they have different qualities. The subfloor material has more wax in it and if I recall correctly, a different mix and orientation of adhesives than the sheathing product, so it is significantly more resistant to water and swelling than the sheathing product. If you are already dried in, I wouldn't rule out using their sheathing product for a floating double subfloor, but I think you'll find that screws don't hold well enough in 5/8" sheathing. Advantech subflooring has been in short supply around here, so they may not have it. There are a few competitors that are almost as good, though I haven't seen anything yet that matches that magic of Advantech subflooring.

  7. maine_tyler | | #8

    This is what the advantech support said:

    "Thank you for your inquiry. AdvanTech Sheathing is designed for roof, wall, and 2-layer floating subfloor systems. There is no difference between AdvanTech Subflooring and sheathing from a performance standpoint. Unlike the sheathing, AdvanTech Subflooring has a fully sanded panel surface. I have linked below a couple resources regarding AdvanTech in a 2-layer floating floor application. Feel free to contact me with any questions or concerns."

    I am dried in. It sounds like I'll be OK. Not sure if the lack of sanded surface will matter for hardwood floor...?
    I figured 5/8 would be plenty for screwing but my mind may have been thinking more in terms of plywood. Perhaps if I use glue as well I'll be ok.

    The yard doesn't stock the 19/32 subfloor but does have the 3/4 (or whatever /32 that is near). I was trying to avoid that little bit of extra height and cost, which sounds silly but is where my head was at.

    1. Expert Member
      MALCOLM TAYLOR | | #9


      Just use enough fasteners to hold it flat while the glue sets. It will be fine.

    2. Expert Member
      BILL WICHERS | | #10

      I don't see the lack of a sanded surface being an issue for a hardwood floor, especially if you're doing a floating floor with some kind of foam between the hardwood and the subfloor. Even the very thin ~1/8" backing I use with the bamboo flooring I like is enough to absorb small imperfections like the ocassional nail head that has a a bit of an attitude problem, and it prevents the flooring from being disturbed. You should be fine with what you have. I do like Malcolm's idea using some extra fasteners and glue. It's sooo much easier to put in a solid floor from the beginning than it is to deal with a squeaky floor later...


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