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I am installing (floating) 3/8" engineered hardwood over a concrete subfloor with 1/8" underlayment. After grinding high spots and filling in larger voids with self-leveler, I have occasional 1/8" or less dips that I have come across while laying the floor. I have read here and elsewhere that roofing shingles can be used on a wood subfloor to raise small valleys.

  • Can shingles be used on a concrete subfloor too?
  • What are the concerns with using them on concrete if an adhesive like Liquid Nails is used to secure them in place?
  • Roofing shingles seem very thick to me. What type of shingle are you referring to, exactly? – JPhi1618 Jul 8 at 19:50
  • I guess I'm not a shingle expert (or any kind of expert when it comes to what I'm trying to do!). I think just normal (non-architectrual) asphalt shingles. – Bill Jul 8 at 20:07
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    Hmm, yea I looked at your link that that seems to be talking mostly about wood subfloors where I could see bigger gaps happening. A new asphalt shingle can probably get closer to 3/16". Maybe a very cheap shingle would be 1/8", but even then you would have to buy a whole bundle. Can you just use a feather-edge concrete patch? – JPhi1618 Jul 8 at 20:10
  • "The subfloor doesn't have to be absolutely in the same plane to prevent squeaks, but voids of 1/8 inch or more can cause problems." - you have 1/8" or less.... Party on, Dude. – Mazura Jul 9 at 1:33
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I've done things like this on a number of occasions, and the problem is that you'll create more bumps than you resolve. Only the inner portion of your depressions measures 1/8", and fairly quickly they taper up to a smaller dimension. This means that the edges of your shingles are almost always too thick for their position.

Also, they're crunchy. For at least a while after installation you'll hear it underfoot.

You're much better off skimming with a leveling compound.

  • Would not recommend construction adhesive or anything that attaches or has the potential to attach the floor to the sub floor as this is a "floating" floor and any place that is attached can be a point at which the floor buckles in the future because it cannot move. On a floating floor an 1/8 inch isn't even going to be noticeable as the sound deadening foam on some of these floating floors is that thickness. – user1946891 Jul 8 at 21:44
  • That's a fair point. When I wrote this answer I was thinking wood subfloor for some reason. – isherwood Jul 8 at 23:12
  • The link: "But shingles can be hard to work with and they don't fill the entire hollow spot." If it's less than an 1/8" nothing will fit there, and nothing needs to. If they're that bad the voids should have been feathered, same as the high spots were. – Mazura Jul 9 at 1:40

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