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Do I need to seal concrete before using self-levelling compound?

Yes, If you are using a cement-based self-levelling compound it is always best to use a sealer on concrete. Even if it’s just because the floor is dusty, sometimes it can be quicker to apply a sealer rather than hoovering it all up, but it’s best practice to do both. Sealing the floor can be done simply with PVA, and a brush and roller.

No, If you are using a latex-based self-levelling compound then there is no need to apply a sealant, which saves you a job. Just hoover your floor covering and away you go. 2-part latex-based Ardex Na is commonly used in the trade. It is easy to use for beginners, and suitable for almost any application (So you don’t need to think too much about the exact type of floor covering).

It is suitable to be applied directly, without a primer/sealer over

  • Concrete
  • cement/sand screeds
  • prepared terrazzo
  • asphalt
  • bitumen
  • any floor tiles
  • quarry tiles
  • porcelain tiles
  • internal steel floors
  • Dampproof membrane
  • Decoupling membrane.

What is self levelling compound?

Self-levelling compound is also known as a floor screed or floor levelling mix. It is a thin layer of a cement-based mixture that is applied to subfloors in order to level out any bumps.

The mix is applied in a thin layer to subfloors such as concrete and floorboards, you use it before laying another floor, such as tile, above it.

It is called a self-levelling compound as it, in theory, self-levels. What this means is that you don’t have to worry about getting the mix perfectly level. It should flow across the floor, and correct any errors.

While this does generally work, there are limits. It doesn’t flow like water so will not perfectly level over a large area and may require a bit of help from you.

Why use self-levelling compound?

You use a self-levelling compound to turn a bumpy, un-even subfloor into a perfectly smooth surface. This is great when you are fitting a solid floor such as tile or wood.

Your floor wont be able to hide the bumps and just sit on them when you fit a rigid floor. Tiles will crack and break and a wood floor will bounce and move. Whereas a flooring like carpet will happily sit on an uneven base.