Product Codes

  • Grey 30620340


Approx. 4m2 per bag at 3mm depth (depending on the smoothness of the floor surface & application technique)
Blend of cement, organic binders and fillers
+5°C to +25°C
1mm to 10mm
Up to 20 minutes after mixing (depending on ambient temperatures)
Foot traffic: approx. 2 hours. Ceramic tile/textile floor coverings: approx. 12 hours. Resilient floor coverings: approx. 24 hours (<3mm depth at +20°C, depending on ambient conditions)
Store and transport securely. Store for up to 6 months from date of manufacture in original, unopened packaging, clear of the ground, in cool, dry conditions within the temperature range +5°C to +25°C and out of direct sunlight. Protect from excessive drafts, frost, damp, condensation and dew
Dry, free flowing powder
Clean tools and equipment with warm soapy water immediately after use
Typically 30N/mm² after 28 days
Typically 7.5N/mm² after 28 days

Key Features

Excellent flow characteristics
Protein-free & low-odour


Bostik SL C525 SMOOTH is a single part, polymer-modified, cementitious underlayment for the smoothing and levelling of uneven subfloors before laying decorative floor coverings. It is suitable for application by trowel and by mortar screw pump to give an extremely smooth and level floor where required. It can be laid over most common substrates, including cementitious screeds, concrete floors, calcium sulphate screeds, sound, strong asphalt and other solid and rigid subfloors. Bostik SL C525 SMOOTH should not be used over adhesive residues or low strength smoothing compound residue. As Bostik SL C525 SMOOTH is protein-free, it is suitable for biologically sensitive areas. The low-odour formulation makes it ideal for use in occupied buildings. It is suitable for use with warm water underfloor heating systems, provided a surface temperature of +27°C is not exceeded and in areas of high solar gain. It should only be used on subfloors protected from moisture from the ground and residual construction moisture. Do not use before applying surface DPM’s. It is not to be used as a wearing surface and should always be covered with a floor covering. For interior use only.

Case Study
Bostik – Flooring in Healthcare
Bostik – Flooring in Healthcare
Technical advice and quality subfloor preparation products and flooring adhesives from Bostik are said to have enabled the progress of the new hospital building.
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