We have a slab foundation on our place. The previous owners put down carpet with pad and there's a fair amount of glue and pad residue on the concrete, as well as some paint overspray. We'll need to level the floor and roll on a liquid moisture barrier before putting down flooring. Two questions:

Do I need to grind off every bit of glue and stuff before putting on concrete leveler primer?


  • Hello and welcome to DIY. Did the post not first read vinyl plank? What flooring are you thinking?
    – P2000
    Apr 28, 2021 at 19:15
  • Product recommendation requests are off topic here. I've removed that portion of your post.
    – isherwood
    Apr 28, 2021 at 19:20
  • 1
    Welcome, and please take the tour.
    – isherwood
    Apr 28, 2021 at 19:20
  • @isherwood I took the original question to mean what type of primer etc... not necessarily which brand. I'd be ok with questions of what type.
    – P2000
    Apr 28, 2021 at 19:25
  • I wouldn't have thought discussion of types of primer to be useful. How many categories can there be? It's a matter of reading labels to find one that fits the need. Feel free to edit further if you disagree. I'm easy.
    – isherwood
    Apr 28, 2021 at 19:28

1 Answer 1


Assuming this is a floating vinyl floor (as originally posted), you need to scrape away the high spots, lay down an underlayment that has vapour barrier with foam and optionally felt to provide a smoothing cushion.

For planks, there's no need to prime or scrape bare.

As for flatness and smoothness, the manufacturer will specify it, but usually anything less than 1/16in is not a problem, and some bowing and bending over several multiples of the plank length or its width is tolerated quite well.

If you are flattening with self-leveling cement, for whatever reason, you have to scrape the concrete bare, entirely.

As for a concrete or cement primer, read the label on the self-leveling cement: some don't need primer and they are more expensive. Others require primer which you can add-in or roll-on to your surface.

Which one you choose depends a bit on how thick the layer will be: anything over 1/4 (very roughly) and it's more economical to roll it on first, otherwise you're just mixing very expensive cement.


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