Complete Guide to Self-Levelling Compound

In the intricate realm of flooring installation and renovation, ensuring a surface that is impeccably smooth and level is of paramount importance. For those who seek to attain perfection in flooring, self-levelling compounds are indispensable. These compounds, a blend of cementitious materials and often polymers, serve as the preliminary layer in flooring, rendering uneven or rough surfaces perfectly smooth and flat.

Self-levelling compounds are specifically formulated to improve the flatness and uniformity of the substrate. Thereby creating an ideal base for the final floor covering, be it tiles, carpet, or wood. This guide explores the facets of self-levelling compounds, including their composition, modes of application, and inherent advantages.

These compounds are essentially the synthesis of cement, polymers, aggregates, and additives. Each plays a pivotal role in ensuring the compound’s performance, workability, and durability. Polymers augment the compound’s flexibility and adherence properties. On the other hand, the additives are integrated to modulate the flow, set time, and enhance other functional properties. The amalgamation of these components ensures that self-levelling compounds effectively rectify any substrate discrepancies, delivering a uniformly levelled surface ideal for any flooring type.

In the ensuing sections, we will delve deeper into the intricate details of self-levelling compounds. We will explore their diverse types, application methodologies, and the pivotal role they play in flooring installation

What is a self-levelling compound and what is it composed of?

A self-levelling compound is a highly specialised, hybrid flooring solution primarily utilised to rectify and mitigate imperfections in the substrate, creating an impeccably smooth, and level canvas for subsequent floor installations. It is a fluid material that autonomously levels out, filling in depressions and eliminating protrusions, hence, used extensively to correct surface irregularities like dips, bumps, or cracks on subfloors.

Detailed Composition:

The composition of a self-levelling compound is predominantly comprised of the following components, each contributing to its unique properties:

  • Cement: Acts as the foundational base of the compound, providing rigidity and structure.
  • Polymers: These are incorporated to enhance the compound’s flexibility and adhesion, enabling it to bond efficiently with diverse substrates, accommodating minor movements and fluctuations in the substrate without compromising integrity.
  • Additives: Specific additives are integrated to modulate and optimise the flow characteristics and setting time of the compound, ensuring a seamless, even spread over the substrate and aiding in the attainment of a flat, uniform surface.
  • Aggregates: These are granular materials that provide bulk, stability, and structure to the compound, aiding in achieving the desired consistency and thickness.
  • Pigments: Some compounds may contain pigments to impart colour to the compound, which could be advantageous in certain aesthetic or functional applications.

Upon application, the self-levelling compound spreads and levels itself out due to its low viscosity and optimised flow properties, filling in low spots and levelling high spots, thus, creating a uniform, smooth surface. The refined balance of components in the compound ensures that it maintains its shape and structure once set, providing a stable and reliable base for subsequent floor coverings.

This foundational layer is pivotal for the longevity and quality of the overall flooring system, as it rectifies substrate irregularities, preventing future issues such as cracking, debonding, or uneven wear in the final floor covering.

Types of self-levelling compounds

There are three major types of self-levelling compounds. Understanding their composition dictates their use. Residential properties and commercial spaces will have different requirements, however, the ultimate goal is to achieve dimensionally stable and level surfaces.

Water-based compounds
  • Application: Ideal for residential and light commercial spaces due to their cost-effectiveness and ease of application.
  • Characteristics: These are usually less viscous, user-friendly, and emit lower VOCs (Volatile Organic Compounds).
  • Substrates: Suitable for concrete, wood, and other standard subfloor materials.
  • Limitation: They might not be suitable for areas with heavy loads or extreme conditions due to lower strength and resistance.
Latex-based compounds
  • Application: Preferred for surfaces prone to movement or vibration, such as wooden floors, due to their enhanced flexibility.
  • Characteristics: They exhibit superior adhesion and flexibility, reducing the risk of cracking or debonding.
  • Substrates: Ideal for substrates like wood, which may exhibit movement or dimensional instability.
  • Curing: Latex-based compounds often require longer curing times compared to their counterparts.
Epoxy-based compounds
  • Application: Predominantly used in industrial settings where high strength and resistance to chemicals, impact, and abrasion are required.
  • Characteristics: They are characterised by high compressive strength, chemical resistance, and durability.
  • Substrates: Best suited for concrete and steel substrates in demanding industrial environments.
  • Limitation: These compounds are more complex to mix and apply and are usually more expensive than water and latex-based compounds.
Polymer-modified compounds
  • Application: Suitable for a wide range of applications with enhanced performance characteristics.
  • Characteristics: They combine the properties of polymers and cementitious compounds for improved adhesion, flexibility, and water resistance.
  • Substrates: Can be applied to a variety of substrates including concrete, wood, and tiles.
  • Versatility: They can be customised with additives to achieve specific performance requirements.
Fast-setting compounds
  • Application: Ideal for projects with tight timelines where rapid setting and curing are crucial.
  • Characteristics: They offer quick drying times, allowing for the swift progression to subsequent construction stages.
  • Substrates: Suitable for most standard substrates including concrete and wood.
  • Consideration: The fast setting time requires a quick and efficient application to avoid premature drying and curing.

EWI Store’s products

EWI-250 Self-Levelling Compound ProLevel Fibre: Reinforced Flexible Floor Leveller
Internal Flooring Internal Use
Manual or machine application Manual application
Quick set in 2 hours Set in 3 hours
Thickness – 2 to 100mm Thickness 3 – 75mm
Basic surface levelling including cement, concrete, load-bearing anhydrite screed, etc Excellent flexibility for timber floors and underfloor heating systems
Tile after 8 hours
  • Self-levelling ewi 250
    Quick View

    Self-Levelling Compound, Ultimate Leveller (EWI-250)

    £13.48 Excl. VAT
  • ProLevel Fibre: Reinforced Flexible Floor Leveller
    Quick View

    ProLevel Fibre: Reinforced Flexible Floor Leveller – 20kg

    £14.61 Excl. VAT

Application steps

1. Surface Preparation

Before embarking on the application of a self-levelling compound, it’s critical to meticulously prepare the substrate to ensure optimal adhesion and performance of the compound. Start by thoroughly cleaning the surface, and removing any traces of dust, dirt, grease, oil, or any loose and deteriorating materials. This step is imperative as any contaminants left on the substrate can impede the adhesion of the compound, leading to potential failures in the future. For surfaces with stubborn contaminants like oil or grease, consider using a degreasing agent or an industrial cleaner.

Once the cleaning is complete, assess the substrate for any cracks, holes, or other damages and repair them using a suitable patching compound. After repairs, the application of a primer is crucial. A primer enhances the bond between the substrate and the levelling compound, preventing issues such as pinholing and bubble formation. Ensure that the chosen primer is compatible with the levelling compound and apply it as per the manufacturer’s instructions, allowing adequate drying time before proceeding to the next step.

2. Mixing the Compound

The mixing process is a pivotal step, and precision is key here. Accurate measurement of the compound and water (or any other recommended liquid) is essential. Follow the manufacturer’s specified ratio diligently to avoid inconsistencies in the mixture. Use a mechanical mixer to achieve a lump-free, homogenous consistency. Avoid overmixing as it could introduce air bubbles into the mix, which can lead to problems during application. Once mixed, the compound should be used immediately, considering its rapid-setting nature.

3. Application of the Compound

Pour the mixed self-levelling compound strategically, starting from the furthest point of the room and working your way towards the exit. The compound should be poured evenly over the surface, allowing it to flow and level itself out. Utilise a squeegee or a gauge rake to assist in spreading the compound to the desired thickness, ensuring it covers the entire area uniformly. Adhering to the manufacturer’s recommended application thickness is crucial to avoid issues such as cracking or insufficient coverage. For areas that are hard to reach or for detailing, a trowel can be used to manually spread the compound.

4. Curing Process

After application, the self-levelling compound requires a sufficient curing period to achieve its full strength and properties. The drying time can vary depending on the type of compound used, ambient conditions like temperature and humidity, and the thickness of the application. Generally, it ranges between 1 to 3 days. During this period, it is paramount to avoid any traffic or disturbance to the area to prevent imperfections or damage to the freshly applied compound. Adhering to the manufacturer’s recommended drying time ensures the compound is adequately set before installing the final floor covering.

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Advantages of self-levelling compounds

Uniform and Smooth Surface

One of the primary advantages of self-levelling compounds is their ability to provide a highly uniform and smooth surface, an attribute that is crucial for the optimal installation of final floor coverings. These compounds meticulously fill in the depressions and rectify undulations on the substrate, eliminating irregularities and imperfections. The attainment of a smooth, flat surface is indispensable for the longevity and performance of floor coverings such as tiles, laminate, or carpet, ensuring they are laid evenly and securely.

Rapid Application and Setting

The application of self-levelling compounds is relatively swift and straightforward, which can significantly reduce the downtime in construction or renovation projects. Many of these compounds are formulated to set and cure rapidly, allowing for the progression to subsequent stages of the flooring installation in a shorter timeframe. This expedited setting is particularly advantageous in commercial settings, where minimising operational disruption is often a critical consideration.

Enhanced Durability and Strength

Self-levelling compounds are imbued with properties that impart enhanced durability and strength to the floor structure. They serve as a robust intermediary layer between the substrate and the floor covering, distributing loads and stresses more evenly across the surface. This uniform distribution of stresses mitigates the risk of cracking, deformation, and other structural damages to the floor covering, prolonging its lifespan and maintaining its aesthetic appeal over time.

Versatility and Compatibility

Self-levelling compounds exhibit immense versatility, being compatible with a variety of substrates including concrete, wood, and tiles. This versatility is augmented by the availability of different types of compounds, each tailored to meet specific requirements and conditions of the project. Whether it’s a high-traffic industrial floor requiring chemical resistance or a residential space needing aesthetic appeal, there is a suitable self-levelling compound that can cater to diverse needs and preferences.

Accommodates Varied Floor Coverings

The use of self-levelling compounds is not restrictive to specific floor coverings. Once cured, these compounds can accommodate varied types of floor coverings including tiles, carpet, vinyl, and wood, providing ample flexibility in choosing the desired aesthetic and functional attributes of the final floor. This ability to adapt to different floor coverings allows for greater design freedom and customisation, enabling the realisation of distinct architectural visions and preferences.

Things to consider

Substrate Condition and Preparation

Before applying a self-levelling compound, it’s crucial to thoroughly examine the substrate’s condition. Any presence of contaminants, loose materials, or structural damage on the substrate can compromise the adhesion and performance of the compound. Proper preparation, including cleaning and repairing the substrate, is fundamental to achieving optimal results. Substrate moisture levels should also be evaluated, as excessive moisture can lead to failures such as debonding or blistering of the compound.

Material Selection

Choosing the appropriate type of self-levelling compound is essential, considering the specific requirements and conditions of the project. Factors such as the substrate type, environmental conditions, desired drying time, and the intended floor covering should influence the selection. For instance, epoxy-based compounds may be more suited to industrial environments due to their enhanced strength and chemical resistance, while latex-based compounds might be preferable for surfaces prone to movement due to their flexibility.

Manufacturer’s Instructions

Adherence to the manufacturer’s instructions is paramount throughout the process, from mixing to application. Instructions typically include guidelines on the proper mixing ratios, drying times, and application thickness. Deviations result in inconsistencies, poor performance, or failures of the compound. Reading and following the product datasheet and guidelines ensures that the compound is prepared, applied, and cured correctly, optimising its performance and durability.

Ambient Conditions

The environmental conditions during the application and curing of the self-levelling compound can significantly impact its performance. Temperature and humidity levels should be within the recommended range to prevent issues such as improper curing, cracking, or poor adhesion. Protecting the area from direct sunlight, wind, or precipitation is also essential, particularly for outdoor applications, to avoid rapid drying or contamination of the compound.

Health and Safety

Given that self-levelling compounds contain chemical components, prioritising health and safety is crucial. Utilising appropriate personal protective equipment such as gloves, goggles, and masks is essential to prevent exposure to harmful substances. Adequate ventilation should be ensured in enclosed spaces to avoid the inhalation of fumes or dust. Additionally, any spills or residues should be promptly cleaned, adhering to the recommended disposal methods to mitigate environmental impact.

Budget and Cost-effectiveness

Economic considerations should also play a role in decision-making. While self-levelling compounds are a valuable investment for achieving high-quality floors, balancing the cost with the project requirements and budget is essential. Opting for cost-effective solutions without compromising quality and performance is crucial. Exploring various products and their cost implications can aid in making informed, economically sound decisions.


2 thoughts on “Complete Guide to Self-Levelling Compound

    1. Hi Will, the best way to do this is to use a spiked aeration roller. It will disperse the compound and force the air pockets out, ensuring totally flat coverage.

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