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How, when and why use primers in flooring jobs

Learn how to choose the right primer and when it has be applied in flooring works

Crucial to know

water primers

acrylic dispersion

epoxy based

PU based

Tools needed


highly absorbent


Step 1

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Why primers?

The role of primers

Primers provide the base for the installation. They bind the dust, increase or create adhesion “bonding-bridge”, create uniform absorbency of the substrate and protect the substrate against moisture of levelling compounds.

  • Additional benefits of some primers: they seals residual moisture and reinforce the substrate.

Relative humidity

Recommended relative air humidity content is below 75%. The higher humidity content the slower SLC drying proces. Optimal conditions for SLC application and usually taken as reference conditions are: air temperature +23°C and air humidity 50%.

Step 2

Type of substrates

Different primers for different substrates

Depending on a kind of substrate, you should use a proper primer.

  • On absorbent and highly absorbent substrates: apply penetration primers – sometimes a few applications are necessary.
  • On non-absorbent substrates: apply a film forming primer – as thick as necessary to build a uniform film.

Step 3

Special purposes

Get the right rimer

Depending on a kind of substrate and special purposes, choose a proper primer:

  • For absorbent screeds and concrete floors use dispersion water-based primer Ceresit R 777 or the universal one – Ceresit CT 17.
  • For absorbent, impervious, dusting and unstable surfaces use PU primer Ceresit R 740.
  • Against rising moisture and for surfaces exposed to mechanical and chemical stresses use epoxy primer Ceresit R 755.
  • For universal purposes use a multi-purpose primer Ceresit R 766 or a universal primer Ceresit CT 19.
  • For difficult substrates (PVC, tile-on-tile, chipboard etc.) use special primer Ceresit CT 19 or Ceresit CN 94.

Tips & Tricks

For professionals

How to strengthen substrate and improve adhesion

Special natural wetting agents provide better coverage and good adhesion on the critical substrate. These liquid softening wetting agents are plasticizing and tackifying resin. Combination of selected dispersions provides durability, flexibility and adhesion. Particles of different sizes help polymers to penetrate even difficult types of surface, resulting in better overall flexibility. Ceresit CN 94 strengthens the substrate surface and improves adhesion.

products used

  • ${/content/heliux/adhesive/ceresit/com/en/products/flooring/central-pdp#/ceresit-cn-94/SAP_0201TNC014A4/searchResult.productFields.MainImageAltText}
    Special primer for reliable bonding of floor levelling compounds, ceramic and natural stones on critical surfaces. 
  • ${/content/heliux/adhesive/ceresit/com/en/products/interoir-finishing/central-pdp#/ceresit-ct-17/SAP_0201JAC014F1/searchResult.productFields.MainImageAltText}
    Primer for surface strengthening of all absorbent substrates for indoor and outdoor application, prior to fixing ceramic tiles, pouring floors or fixing thermal insulation boards. 
  • ${/content/heliux/adhesive/ceresit/com/en/products/tiling/central-pdp#/ceresit-ct-19/SAP_0201SOC014F8/searchResult.productFields.MainImageAltText}
    Fast-acting special primer for a secure bond between ceramic coverings, natural stones, wall & floor screeding compounds and on difficult substrates. 
  • ${/content/heliux/adhesive/ceresit/com/en/products/flooring/central-pdp#/ceresit-r-740/SAP_0201TNC015L9/searchResult.productFields.MainImageAltText}
    CERESIT R 740
    One-component PUR fast barrier primer for absorbent and impervious substrates, suitable for highly absorbent substrates. 
  • ${/content/heliux/adhesive/ceresit/com/en/products/flooring/central-pdp#/ceresit-r-755/SAP_0201TNC015M0/searchResult.productFields.MainImageAltText}
    CERESIT R 755
    Reliable moisture barrier effect: up to 6 CM% on cement screeds, up to 7 CM% on concrete floors. Also suitable for producing an epoxy resin screed. 
  • ${/content/heliux/adhesive/ceresit/com/en/products/flooring/central-pdp#/ceresit-r-766/SAP_0201TNC015M1/searchResult.productFields.MainImageAltText}
    CERESIT R 766
    For absorbent and non-absorbent substrates, ensuring the adhesion of self-levelling compounds or repair mortars to the substrate. 
  • ${/content/heliux/adhesive/ceresit/com/en/products/flooring/central-pdp#/ceresit-r-777/SAP_0201TNC015M2/searchResult.productFields.MainImageAltText}
    CERESIT R 777
    Dispersion primer for absorbent screeds and concrete floors, suitable for directly bonding floor coverings. 

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