Bostik Cempolatex Latex Sub-Floor Levelling Compound 20kg

What is Bostik Cempolatex?

Bostik Cempolatex is a cement-based compound presented as a grey, dry, free-flowing powder. When mixed with water, it transforms into an easy-to-apply, self-smoothing liquid with good flow characteristics, designed to level out irregularities in sub-floors. 

This rapid-setting formula is designed for interior applications only and creates an ideal, sound surface, ready to receive floor coverings. It is not intended for use as a final wearing surface.

Applications & Suitable Substrates

Bostik Cempolatex is ideal for smoothing and levelling a variety of common interior sub-floors before laying new floor coverings. It creates a stable base for textile coverings, resilient flooring (vinyl, LVT), ceramic tiles, and wood flooring.

Suitable substrates include:

• Properly prepared concrete sub-floors
• Sand/cement screeds
• Stone, brick, and terrazzo (firmly bonded, unglazed)
• Calcium sulphate-based screeds (gypsum)
• Mastic asphalt (consult Bostik for specific priming requirements)
• Rigid and stable flooring grade plywood (minimum 15mm)
• Firmly bonded unglazed ceramic and quarry tiles

Important Limitations:

• Not suitable for use over existing adhesive residues or water-soluble contaminants.
• Must always be covered with a suitable floor covering; it is not designed as a final wear surface.
• For interior use only.

Benefits

• Enhanced Flexibility: The latex modification provides good flexibility, helping to accommodate minor movements and vibrations, especially beneficial for suspended timber floors.
• Rapid Setting & Drying: Allows for light foot traffic in approximately 4 hours and the application of many floor coverings within 16-24 hours (at 20°C, 3mm thickness), facilitating quicker project turnarounds.
• Excellent Adhesion: Achieves a strong bond to a wide range of correctly prepared substrates.
• Self-Smoothing Properties: Offers good flow characteristics for ease of application and achieving a consistently level finish with minimal trowelling.
• Protein-Free Formulation: Reduces the risk of adverse reactions with sensitive adhesives and is suitable for use in environments where protein content is a concern.
• Underfloor Heating Compatibility: Suitable for use over piped, warm water underfloor heating systems when applied as a levelling compound (subject to specific conditions).
• Versatile Application Thickness: Typically applied between 3mm to 12mm in a single application for self-levelling purposes. It may also be used for deeper patching repairs up to 100mm in isolated areas (specific application techniques may apply) and as a floor topping/concrete re-surface with the addition of Bostik SBR.

Substrate Preparation & Considerations

Underfloor Heating Systems (Warm Water):

• Bostik Cempolatex is suitable for use with embedded warm water underfloor heating systems when applied as a self-levelling compound.
• The heating system must be switched off at least 48 hours prior to application, remain off during application, and for a further 48 hours after the compound has been laid.
• After this 48-hour post-application period, the heating can be gradually turned up (e.g., by a few degrees per day) to its normal operating temperature to prevent rapid dehydration of the levelling compound.
  
  

Note: This product is NOT suitable for this application if used as a filling compound, floor topping, or over mastic asphalt/contaminated surfaces in conjunction with UFH. For electrical underfloor heating systems, please contact Bostik Technical Services for advice.

Wooden Surfaces:

• Can be applied over mosaic and wood blocks that are directly and firmly bonded to solid sub-floors, provided an effective damp-proof membrane (DPM) exists in or beneath the sub-floor.
• Suitable for stiff, suspended floors constructed of flooring grade plywood (minimum 15mm thick). Ensure adequate ventilation beneath the floor.
• Timber substrates must be solidly fixed, clean, and free from movement. Plywood should be screwed down at 150mm centres. Do not apply over flexible surfaces like plain edge boards.
• The timber structure must be capable of supporting the additional weight of the compound, adhesive, final floor covering, and in-service loads without deflection.
• Due to lack of ventilation and consequent risk of decay, do not use on boarded floors where joists are fixed directly to concrete.
  
  

Priming

• Priming the sub-floor prior to applying Bostik Cempolatex is essential.
• Priming minimises rapid water absorption from the levelling compound into the substrate, reduces the risk of pinholes appearing in the finished surface, and extends the working time, all contributing to an ideal surface finish.
• Always use a primer recommended by Bostik for the specific substrate. Refer to the relevant primer Technical Data Sheet for application instructions and drying times.

Mixing & Application

Mixing:

• Gradually add the Bostik Cempolatex powder to the specified amount of clean, cold water as detailed on the product packaging (ensure you refer to the packaging for the precise water ratio).
• Mix with a suitable mechanical mixer (e.g., a slow-speed high-torque drill with a power whisk attachment) for at least 2 minutes, until a smooth, lump-free, and consistent workable mortar is achieved. Do not over-water.

Application:

• Pour the mixed compound onto the prepared and primed sub-floor without delay, as the working time is approximately 20 minutes.
• Spread to the desired thickness (between 3mm and 12mm) using a steel smoothing trowel or float. The product is self-smoothing, but gentle trowelling will assist flow and ensure an even coverage.
• Maintain a wet edge to ensure seamless integration of subsequent mixes.
• For larger areas, using a spiked roller immediately after spreading can help release any trapped air and further improve the surface finish.