What is a Self-Levelling Compound?
A self-levelling compound is a specialized cement-based mixture designed to create a smooth, level surface on uneven floors. Also known as a floor screed or floor levelling mix, it is applied in a thin layer—typically between 3mm and 10mm—to rectify imperfections in the subfloor. Once properly applied and dried, this compound provides an ideal base for various flooring types such as luxury vinyl tiles (LVT), ceramic tiles, laminate flooring, or carpets.
Why Use Self-Levelling Compound?
The primary purpose of using a self-levelling compound is to transform a bumpy, uneven subfloor into a perfectly smooth and stable surface. This is especially crucial when installing rigid floor coverings like tiles or hardwood, which require a flat base to prevent issues such as cracking, bouncing, or premature damage. In contrast, softer flooring options like carpets can generally accommodate minor unevenness without problems.
Limitations and Precautions
While self-levelling compounds are formulated to self-level, they are not perfect solutions for large or complex discrepancies. They are most effective in thin layers and can crack if applied too thickly or over unstable substrates. Notably, self-levelling compounds should not be used as a finished floor surface unless specifically designed for that purpose. Special versions are available for such applications, but standard mixes are intended solely as a preparatory layer.
Causes of Cracking in Self-Levelling Compounds
Cracking can occur in self-levelling compounds due to two main reasons:
- Poor adhesion to the substrate: If the base surface is dusty, oily, or unevenly prepared, the compound may fail to bond correctly, leading to cracks.
- Subfloor movement or instability: Movements in the underlying structure—such as shifting concrete or timber expansion—can cause stresses that result in cracking.
Both issues can often be mitigated by using a high-quality, latex-enhanced self-levelling compound that offers improved flexibility and adhesion. These formulations tend to bond more effectively to various substrates and accommodate minor movements, making them suitable for first floors, suspended timber floors, or areas prone to movement.
Choosing the Right Self-Levelling Compound
Traditional cement-based self-levelling compounds mixed with water are more prone to cracking under stress. Conversely, latex-modified self-levelling compounds contain polymers that enhance flexibility, adhesion, and durability. They are particularly effective when applied over:
- Concrete subfloors
- Wooden floors or chipboard
- Existing uneven surfaces requiring correction
Application Tips for Optimal Results
To ensure a successful application:
- Prepare the substrate thoroughly, removing dust, oils, and loose debris.
- Use the appropriate thickness as recommended by the manufacturer, typically between 3mm and 10mm.
- Mix the compound with the correct amount of water or latex additive for consistency.
- Pour the mixture steadily across the surface and use a spiked roller to eliminate air bubbles and enhance adhesion, especially over larger areas.
- Allow sufficient drying time before installing your final floor covering, as specified by the product instructions.
Additional Resources and Frequently Asked Questions
- How thick can you pour self-levelling compound?
- Can you use self-levelling compound outdoors?
- Is it suitable for application over asphalt?
- Can layers be built up to a greater thickness?
- What type of paint is compatible for sealing or finishing?
- Should concrete be sealed before applying the compound?
- Can expired or old self-levelling compounds be used?
- Is a spiked roller necessary during application?
- Can it be applied over chipboard or bitumen surfaces?
- What is the typical drying time?