Sub floor joints must be feather filled?

Discussion in 'Vinyl Flooring Q&A' started by Dylan Flaherty, Dec 30, 2017.

    • Material: Hallmark LVP, Polaris Erickson Maple, 5.5mm
    • Subfloor: 3/4" OSB
    • Underlayment: 1mm Eternity high density rubber sheets
    • Tools: Bullet Shear Laminate cutter, tablesaw, pullbar, t-floor spacers, tapping hammer.
    According to the installation instructions from Hallmark (manufacturer of my planks):
    "Sub floor joints must be feather filled with a Portland based patch and allowed to dry. The patch may be ¼” deep or more in the joint between two panel edges. Note that it will not dry as quickly as a surface patch.... Sub floor tolerance for a flat surface is 3/16” within a 10’ radius and 1/8” in a 6’ radius."
    Question: Is this really necessary? Seems like extreme overkill for the ~.25" gaps between boards... Especially in light of how comparatively thick my planks are and the fact that I'm laying down underlayment...
  1. Mark Brown

    Mark Brown On The Surface Flooring I Support TFP

    You could skip it and PROBABLY get away with it but for the little bit of time and effort it is, you are best to go ahead. More importantly is that they aren't peaked all that bad. High spots in your subfloor will cause hollows under the product.

    ....I COULD run my car without back breaks bit seeing as pads were 60 dollars I opted to put them on :)
  2. Thanks for the reply Mark. Any suggestions for *how* to do it quick and easy?

    I started filling the gaps with a puddy knife and a small bucket of pre-mixed patch product but that has been incredibly slow and tedious.
  3. Chris 45

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

    Mix up some patch in a bucket then spread it with either a broad knife or a flat trowel. If you have any thicker gaps to fill, hit those first then hit them again when you are done with the rest of the floor. Ultimately I like to hit all my seams twice. If they don’t warrant two times then they don’t need to be hit at all in my mind.
    • Like Like x 1
  4. Mark Brown

    Mark Brown On The Surface Flooring I Support TFP

    Like Chris said, small flat trowel or a 6 inch knife. It isn't something to sweat over, basically all you are trying to do is leave a small enough depression that your floating floor will never settle into it. Chances are you have that now and you are just paying for insurance.

    ....full disclosure. I don't think I have ever patched the seams on a floating LVT job. I have done the entire floor, I have filled damage but I cannot think of a time when I did the seams. I know I have sanded a lot of them down however.

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