Bostik Cempolay Deep Floor Levelling Compound Grey 20kg

What is Bostik Cempolay Deep?

Bostik Cempolay Deep is a high-strength, protein-free floor levelling compound, expertly formulated for efficiently tackling subfloor imperfections. It excels in deep applications, capable of raising levels from 5mm up to an impressive 50mm in a single pour. 

Based on a sophisticated blend of cements and organic binders, this compound is designed to transform uneven subfloors into perfectly flat, durable surfaces, ready for a wide array of floor coverings in light to heavy-duty interior environments. Its versatility also makes it ideal for filling substantial depressions or creating precisely sloped screeds.

When mixed with water, this specially developed cement-based powder becomes a smooth, free-flowing, and easily workable mortar. A key advantage is its protein-free formulation, which significantly reduces the risk of harbouring bacteria, rendering it a suitable sub-base choice for hygiene-sensitive areas once the final floor covering is installed.

Applications & Substrates

Bostik Cempolay Deep is designed for interior use only and is ideal for:

• Levelling Uneven Subfloors: Correcting irregularities in concrete or screeded floors.
• Raising Floor Levels: Building up floor height significantly in a single pour.
• Filling Depressions & Trenches: Effectively filling localised low spots or channels in subfloors.
• Creating Sloping Screeds: Can be used to form gentle slopes for drainage or to transition between different floor levels.
• Smoothing Over Existing Hard Surfaces: Suitable for application over well-bonded, sound subfloors such as: 
  • Concrete
  • Sand/cement screeds
  • Stone
  • Calcium sulphate-based screeds (anhydrite) - with specific priming and thickness limitations.
  • Unglazed ceramic tiles, terrazzo, and quarry tiles (must be firmly bonded and meticulously prepared/primed).

Not Suitable For:

• Application over existing adhesive residues, water-soluble contaminants, wooden floors, or mastic asphalt.
• Use as a final wearing surface - it must always be covered with a suitable floor covering.
• Exterior applications or areas subject to constant water immersion.

Benefits

• Wide Application Thickness: Can be applied from 5mm up to 50mm in a single application, perfect for significant levelling or raising of floor heights.
• High Strength & Performance: Creates a robust, durable surface suitable for light to heavy-duty internal traffic before the application of a floor covering.
• Protein-Free Formulation: Ideal for use in environments where hygiene is a priority, such as healthcare or food preparation areas (once covered).
• Excellent Workability: The mixed compound flows well for easy application and smoothing, with a working time of up to 20 minutes.
• Versatile Substrate Compatibility: Adheres well to a range of properly prepared subfloors including concrete, sand/cement screeds, stone, and even existing unglazed tiles.
• Underfloor Heating Compatible: Suitable for use over piped, warm water underfloor heating systems (when specific protocols are followed).
• Smooth Finish for Floor Coverings: Provides an ideal surface for the direct application of vinyl, carpets, tiles, and other floor finishes.
• Rapid Setting Properties: Allows for light foot traffic after approximately 90 minutes, helping to speed up project timelines.

Surface Preparation

Subfloor preparation is absolutely critical for the optimal performance and adhesion of Bostik Cempolay Deep.

• Cleanliness & Soundness: The subfloor must be thoroughly clean, structurally sound, and completely dry (Relative Humidity <75%RH). It must possess adequate tensile and compressive strength to support the levelling compound and final flooring.
• Remove Contaminants: All laitance (a weak, dusty layer on new concrete), dust, dirt, oil, grease, paint, old plaster, polish, existing adhesive residues, curing compounds, or surface hardeners must be completely removed. Mechanical preparation (e.g., scabbling, shot blasting, grinding) may be necessary.
• Defects & Repairs: Inspect for any cracks, holes, or structural defects. Clean out and repair any significant cracks or voids using a suitable repair mortar like Bostik Rapid Repair Mortar. Allow repairs to dry fully.
• Temperature Control: The temperature of the floor, the product, and the application environment must be stable and maintained between +5°C and +27°C throughout the application and drying period. Avoid draughts during early curing.
• Conformity: Ensure the subfloor preparation conforms to the relevant sections of BS 8204 (Code of practice for concrete subfloors).

Mixing & Application Guide

• Water Addition: Pour exactly 3.5 litres of clean, cold water into a clean mixing bucket. Using the correct water ratio is vital for performance.
• Mixing: Gradually add the full 20kg bag of Bostik Cempolay Deep powder to the water whilst continuously mixing with a heavy-duty electric drill (minimum 650rpm) fitted with a suitable mixing paddle.
• Continue mixing for at least 2 minutes until a smooth, lump-free, homogeneous mixture is obtained. Do not under-mix.
• For optimal results, allow the mixed material to stand for 1 minute to mature, then briefly re-mix for 1 minute.
• Ensure all material from the sides and base of the bucket is incorporated.
• Caution: Adding too much water will weaken the compound and may cause separation and poor strength development. Do not attempt to re-temper (add more water to) the mix if it begins to stiffen.
• Working Time: Do not mix more compound than can be used within 15 to 20 minutes, as the mixture will remain workable for approximately this long under normal site conditions (+20°C). Higher temperatures will reduce working time.

Application Process

• Pouring: Pour the mixed Bostik Cempolay Deep onto the primed subfloor in a continuous operation. For larger areas, it can also be applied by a suitable pump.
• Spreading: Using a clean steel trowel or float, spread the compound evenly to the required thickness (between 5mm and 50mm). Work efficiently to maintain a wet edge.
• De-aerating: While the compound is still fluid (typically within the first 10-15 minutes of pouring), use a spiked roller to remove any entrapped air and to help smooth out trowel marks, promoting a more uniform surface.
• Protection: Protect the freshly laid surface from foot traffic and any site activity until it has sufficiently hardened. Ensure the compound is fully dry according to the recommended drying times before applying any floor covering.

Drying Times & Readiness for Floor Coverings

Drying times are approximate and will vary depending on application thickness, substrate absorbency, ambient temperature, and humidity. Good site ventilation will aid drying.

• Light Foot Traffic: Approximately 90 minutes at +20°C.
• Loose Lay Floor Coverings (e.g., some carpets): Approximately 4 hours at +20°C.
• Bonded Floor Coverings (e.g., vinyl, adhered carpet, wood): Allow approximately 24 hours per 5mm of application thickness at +20°C.
• Ceramic Tiles:
  • For <10mm Cempolay Deep thickness: Approx. 3 to 4 hours.
  • For >10mm Cempolay Deep thickness: Minimum 24 hours.
• Textile Coverings: Approx. 24 hours per 10mm of application thickness (for a 5mm application at +20°C).

Always ensure the levelling compound is thoroughly dry (<75%RH when tested with a hygrometer) before installing impervious floor coverings like vinyl or resin finishes to prevent trapped moisture.