Any construction work, including tiling and EWI, requires a flat surface. Unfortunately, not all substrates will be innately flat. Some may have old render peeling off, whilst some may have large cracks. This is the same for floors; concrete floors crack over time and therefore, require levelling prior to any work. That leads us to the question of how to level floors and walls. At EWI Store, we stock materials to take you through every step of levelling floors or walls, including all the tools to ensure your surface is totally flat.
The terms you will often hear in reference to levelling floors and walls is ‘screed’ or ‘screeding’. Screed is a thin layer of material that is placed on top of a concrete subfloor. Usually, screed consists of cement and sharp sand. However, where a more industrial version is required, coarse aggregates can be added to create a thicker layer.
The difference between levelling floors and walls
Gravity plays a significant role in differentiating the processes of levelling floors and walls.
Floor levelling needs to counteract the pull of gravity, as it tends to exaggerate the dips, bumps, and irregularities on the floor surface. In contrast, wall levelling has the advantage of gravity pulling the levelling compound downward, which helps spread it over the surface. However, it simultaneously poses a challenge as the mixture needs to be thick enough to adhere to the vertical surface and not sag or run down.
The purpose and function of the surfaces also significantly differ:
Floors need to be levelled to ensure safety and comfort. An uneven floor can be a tripping hazard, making it difficult to install furniture or appliances. It also causes problems when laying floor coverings like tiles, hardwood, or carpet. The levelling process should result in a smooth, flat surface that can bear weight and resist wear and tear.
On the other hand, walls need to be levelled primarily for aesthetic reasons. It is also required to facilitate the application of finishes like paint, wallpaper, or tiles. While they also bear weight (especially in the case of load-bearing walls), their levelling doesn’t typically involve supporting regular foot traffic.
Levelling Mortar for Walls
Levelling a wall starts with the application of a levelling mortar. This is typically a mixture of sand, cement, lime, and water that provides a firm, even surface upon which to work. It’s ideal for fixing uneven plasterwork or preparing walls for a new layer of tiles, wallpaper, or external wall insulation systems.
The process begins with applying the levelling mortar onto the wall. Once the mortar has been applied, it’s smoothed out using a trowel. This is usually done by holding the trowel at an angle and dragging it across the surface in broad, sweeping strokes. The finishing touch is generally given with a damp sponge or cloth, used to smooth out any small imperfections and create a uniformly even surface.
It’s essential to work methodically across the wall, therefore ensuring every part has been adequately covered. The mortar is then allowed to dry for a specified period before any further work can be done.
Self-levelling compounds for floors
For floors, self-levelling compounds are typically used. These compounds are a blend of cement, sand, and other additives mixed with water. Once the self-levelling compound is mixed, it should be poured onto the floor as soon as possible. The liquid compound naturally flows and fills in the low spots on the floor, thereby ‘seeking its level’. This behaviour is due to the gravitational pull and the specific rheological (flow) properties of the compound facilitated by its ingredients.
Self-levelling compounds are ideal for dealing with uneven concrete subfloors or preparing floors for laying tiles, carpets, or wooden flooring. Once the compound is mixed to a pourable consistency, it’s poured over the floor and spread out using a floor screed trowel.
After pouring the self-levelling compound, it’s essential to go over the surface with an aeration roller. This tool helps to eliminate air bubbles that can potentially weaken the final surface and disrupt the self-levelling process. As the compound starts to cure, it forms a flat, smooth surface. The curing process involves a chemical reaction, called hydration, which occurs when the cement component of the compound reacts with water. This reaction generates heat and results in the hardening of the compound.
It’s worth noting that self-levelling compounds are not a remedy for extreme dips or structural problems in the floor; in these cases, more extensive repairs or interventions may be necessary.
Specialised tools: aeration rollers and floor screed trowels
To ensure optimal results, specific tools are used in the process. An aeration roller is one such tool, primarily used when applying a self-levelling compound. It helps remove any trapped air bubbles in the compound, which promotes a smoother, more even finish.
On the other hand, a floor screed trowel is used to spread the self-levelling compound across the floor. This tool helps ensure that the compound is evenly distributed, resulting in a uniformly level surface. It’s usually a flat, rectangular tool with a handle, allowing precise control while spreading the compound.
EWI-250 Self-Levelling Compound has an added benefit. It is machine compatible therefore the application process is much quicker. It is also far simpler to cover the whole area when using a machine as you need to spend less time spreading the compound across the whole area. Spiked aeration rollers remain absolutely crucial as any air trapped inside the screed must be removed.
Leave us a comment below if you’ve had experience with our Self-Levelling Compound!