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I'm planning on installing LVP in my bathroom - it is about 68 sqft of flooring. The floor is unlevel, sloping 3/4" at the worst location. A floor joist had been cut straight through by the previous owners which is where the largest dip in the floor is located. I had sistered that joist when I started my bathroom renovation to repair it, but didn't think to raise the height of the joist when I did the repair. Removing the sistered joist and raising it isn't an option as I secured it with a ton of structural screws and heavy duty construction adhesive.

So now I am left with a sloped bathroom floor that needs to be leveled within 3/16" per the LVP manufacturer. I mocked up a sketch of the room with the measured dips. The back left corner of the room is the high point. The floor does not slope much length-wise (3/8" at the worst). I plan to install the LVP lengthwise as well. The LVP is 8"x48" planks.

My question is how do I go about leveling the subfloor? I was planning to use this self leveling compound. Upon reading the instructions, it calls for metal lath to be installed with a minimum pour depth of 1/2" for single layer plywood subfloors. I wanted to level the entire floor so that would mean I'd need to pour 1/2" of leveler at the high point over the lath, then 1 1/4" of leveler at the high point. That is a ton of leveler to use and I'm wondering if there's a simpler or at least more cost-effective way to level the floor?.

The options I considered are:

  1. Install 1/2" plywood on top of the area of the floor that dips 5/8" and 3/4", install the metal lath, pour self leveling compound on the entire floor. Still would require a lot of self leveler, but would save me a few bags at least.

  2. Install metal lath and pour self leveler everywhere except the back wall of the room. Not pouring 1/2" of self leveler over metal lath there will save me from adding another 1/2" of leveler everywhere else in the room. I'd come back in with feather finish compound and feather out the patch.

  3. Install metal lath and pour 1/2" of self leveler to entire room to create a flat surface. Only considering this option since the width of the planks are only 8" wide and may be able to tolerate the slope of the room over each individual plank. Not so confident it would work but I am considering it.

My floor joists are 2x8", 16" OC. Existing plywood subfloor is 5/8" exterior grade plywood.

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  • I've added ply and door skin and then done sika leveler which can be feathered to zero thickenss. never done an SLC that required diamond lath ! After I had a tenant do vinyl tiles in a bathroom i'd never do something with a seam again. Smelled like an outhouse. Feb 29 at 3:38
  • Regarding option 3, do you mean you want to pour self leveler out to still have a slope? Won't the self leveler... level itself whether you want it to or not?
    – Joel Keene
    Feb 29 at 5:49
  • Joel - that’s an interesting point that I hadn’t considered. I think the risk would be that I create a valley between the high and low point, worsening the problem?
    – Niko
    Feb 29 at 10:29

1 Answer 1

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If the slope of the room does not bother you, use your option 3.

That option is the easiest and gives you a FLAT floor. LVP needs a flat floor not level. It can easily handle a slope on a floor.

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  • Isn't the self leveler going to try to level the floor, even if that isn't what you want?
    – Joel Keene
    Feb 29 at 5:49
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    Self leveler can be manipulated, (moved) with a rake if not mixed extremely thin. It can be used to make a floor flat.
    – RMDman
    Feb 29 at 12:50
  • I wonder if LVP on a non-level floor is more likely to migrate into the overage area left at the walls.
    – Huesmann
    Feb 29 at 17:08
  • @ Huesmann, what is an "Overage area"? I've been installing LVP for over 7 years now and never heard of this term or any issues related to it.
    – RMDman
    Mar 1 at 1:01

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