Guide to Applying Self-Levelling Compound in Multiple Layers

Applying Multiple Layers of Self-Levelling Compound

Most self-levelling compounds are designed to be applied in multiple thin layers, especially when significant height build-up is required. If you need to raise your floor level substantially—say, more than 10-12mm—building up in layers is highly recommended. This approach not only ensures better adhesion and stability but also prevents cracking or uneven settling over time.

For cement-based self-levelling compounds that require mixing with water, it is crucial to allow each layer to cure fully before applying the next. Once the first layer has dried and cured properly, proceed with surface preparation by applying a diluted PVA primer (mixed with just enough water for easy spreading). When the primer becomes tacky, you can then apply the subsequent coat of self-levelling compound. This process improves adhesion and ensures a smooth, durable finish.

In contrast, if you are using a two-part latex self-levelling compound—such as Ardex NA—these are supplied with a latex additive that can be mixed directly with the compound. For such products, you can usually apply the second coat directly over the first without additional priming, provided the first layer is fully cured and properly prepared.

Important note: Self-levelling compounds are generally intended for thin applications, typically between 3-6mm, and can sometimes be built up to a maximum of 10-12mm. Applying thicker layers requires incorporating aggregate or a different mix, effectively transforming your floor into a concrete slab. Always consult the manufacturer’s datasheet for specific guidelines related to your chosen product.

Understanding Self-Levelling Compound

Self-levelling compound, also known as a floor screed or levelling mix, is a cementitious material used to create a smooth, even surface on subfloors. It is typically applied over uneven substrates such as concrete slabs or wooden floorboards before laying the final floor covering. The key feature of self-levelling compounds is their ability to flow and settle into a flat surface with minimal manual leveling, hence the name “self-levelling.”

While they are formulated to spread evenly across the floor, they do have practical limits. They do not flow like water over large areas and may require some assistance to achieve a perfectly flat surface, especially over extensive spaces. Proper application techniques and surface preparation are essential to achieve the best results.

The Benefits of Using Self-Levelling Compound

The primary purpose of self-levelling compound is to transform a bumpy, uneven subfloor into a smooth, solid foundation. This is particularly advantageous when installing rigid floor coverings such as tiles, hardwood, or laminate, which require a stable, level base. Without proper leveling, these floors can develop issues like cracking, cracking, or bouncing, leading to damage and reduced lifespan.

Conversely, softer floor coverings like carpet or vinyl can tolerate more uneven surfaces without issues. Therefore, choosing the right leveling approach ensures the longevity and aesthetic quality of your finished floor.

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