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kyle_austin65

Need help leveling concrete substrate w/ paint over black mastic

Kyle Austin
3 years ago

I have an addition in my house that sits on its own concrete slab (no basement underneath). We want to redo the flooring in the addition (roughly 125 sq. ft.) with luxury vinyl plank, but need to correct some leveling issues first.


However, back when we bought the house a year ago, we'd ripped up the thin carpet in this addition only to discover black mastic adhesive remnants underneath. Deciding to play it safe, we just assumed it contained asbestos (house built in 1948, uncertain of when the addition was built, but likely before cutback adhesive w/ asbestos was banned from use) and, desiring a quick fix, painted over top of the mastic with oil-based concrete paint to seal it.


Now that we want to update the flooring, we're up against a wall here, as:

  • we need to correct the leveling issues for LVP to work as intended
  • self-leveling compound will not bond with a painted concrete substrate
  • we cannot scarify the substrate without disturbing the asbestos fibers
  • we're reluctant to try and remove the paint with a chemical stripper, as we're unsure of how the chemicals would affect the mastic, and research leads me to believe that use of these chemicals can also negatively impact SLC bonding


Is there any other way to go about leveling this floor that I'm just not seeing? (Outside of going the commercial abatement route, of course, as that's far beyond what we're able/willing to spend on this project.)


My only lead is a product called PerfectPrimer, which claims to be applicable over both black mastic and painted concrete, with the result being a surface suitable for SLC application and bonding. It's an expensive product at $130/gallon, and outside of the customer reviews on the manufacturer's website (taking those with an entire shaker of salt), I can't find any solid info on this product or verified user success stories, which makes me very wary of rolling the dice.


Any help would be greatly appreciated!

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