Leveling the floor with a self-leveling mixture: rough level, topcoat, warm floors

Recommendation points

• Surface preparation
• Classification of self-leveling mixtures and their manufacturers
• Cooking tools and materials
• Tools and overalls
• Calculation of the consumption of dry mixes
• Work order
• Making a subfloor from self-leveling mixtures
• Surface priming
• Finishing layer
• The use of self-leveling mixtures for underfloor heating

In new buildings and in old houses, during repairs, before laying the topcoat, you need to hide all the irregularities and level the floors. The easiest way to do this is using self-leveling compounds. Let’s take a look at the types of mixtures and talk about how to choose and use them correctly to get the desired result..

The subfloor may not always be leveled at one time. If there is a significant level difference in the floor, uniform or pit, as well as deep cracks, work must be performed in several stages..

Surface preparation

Since a layer of a self-leveling mixture cannot be too thick, with significant unevenness in the floor, the screed is first performed on a cement (up to 50 mm) or gypsum (up to 100 mm) base. To do this, the floor is cleaned of debris and materials that are destroyed by slight mechanical stress. After that, a screed is performed according to the marks and left for some time until it dries completely. The drying time depends on the layer thickness, the moisture content of the solution and the air parameters in the room and is 10-30 days.

After the prepared base has completely dried, you can start working with a self-leveling mixture.

Classification of self-leveling mixtures and their manufacturers

Fine-grained self-leveling mixtures according to their basic composition are divided into:

• cement;
• gypsum;
• polymer.

Cement (more expensive, suitable for indoor and outdoor use) and gypsum (only for dry rooms) are used when a perfectly flat and horizontal floor surface is required. These are base mixes. Polymer themselves serve as a finishing coat when installing glossy self-leveling floors.

Mixtures of different composition are designed to solve various problems:

• primer mixes improve adhesion and are applied to even floor slabs before finishing mixes;
• finishing mixtures are applied to the entire area of ​​the room, forming a layer no thicker than 5 mm;
• special compositions are used for local filling during “patching” repairs – expensive and with good adhesion;
• mixtures for underfloor heating are designed for increased operating temperatures.

Two-component polymer mixtures are basically:

• polyurethane – for residential premises;
• epoxy – for utility rooms.

High-quality, demanded cement-based mixtures are widespread “Weber.Vetonit”, “Ceresit”, “Bolars”, “Horizon”, etc. Among the gypsum plaster can be distinguished “Glims”, “Knauf”, Bolars. The best known primers are Knauf, Beton-Base and Betokontakt. TM mixes are well suited for the manufacture of warm floors. “Weber.Vetonit”, Alfapol. For self-leveling floors use mixtures “Epital”, “Texil” and “Streamline Chemicals” (different grades are made on the basis of epoxy resins and polyurethane).

Cooking tools and materials

Before starting work, you need to purchase (borrow) the necessary tool and buy the required number of packs of mixtures for the rough and finishing layer as needed.

Tools and overalls

Since some mixtures contain harmful substances, which decent manufacturers indicate on the packaging, when working with them, you need to protect the respiratory system and skin. Therefore, you will need: a respirator, rubber gloves, closed shoes. When performing a finishing layer or self-leveling floors, experts recommend wearing a sole with spikes on shoes, which does not spoil the quality of the finished surface.

From the tools you will need:

• container for mixing the solution;
• drill with mixer attachment or construction mixer;
• wide spatula-equalizer (for large volumes of work it is more convenient on a long handle);
• needle roller (preferably on a long handle);
• a roller with a dense nap for a primer (may not be needed);
• guide rails and bench marks for level control (may not be needed).

The height of the needles in the roller should be 1–2 mm greater than the thickness of the leveling layer, which must be taken into account when purchasing.

Calculation of the consumption of dry mixes

To avoid unnecessary costs, but the mixture was enough for work, you need to calculate in advance the expense for the rough and finishing layer. Manufacturers on the packaging, as a rule, indicate the consumption of dry mix per 1 m² layer 1 mm thick. For the rough layer, you need to determine the minimum and maximum thickness (in mm) and multiply the arithmetic mean by the area of ​​the room, and multiply the result by the recommended consumption.

For example, the difference between the highest and lowest point is 30 mm. The arithmetic mean of the alignment thickness is 15 mm. Layer above the maximum point – additional 10 mm.

Total: layer thickness 25 mm. The manufacturer recommends a consumption of 1.6 kg / m² for every millimeter of layer thickness. Consumption for 1 m² will be 25 x 1.6 = 40 kg / m². Floor area – 20 m². The consumption for the sub-floor will be 40 x 20 = 800 kg of dry mix. The resulting amount of the mixture must be rounded up to the standard package, which in most cases is 25 kg. In our example, you need to buy 800/25 = 32 packs of 25 kg. Experts recommend buying material with a 10% margin, since it is impossible to accurately calculate the volume. This means that for our case you need to purchase 35 packages.

The thickness of the finishing layer is taken according to the recommendations for the mixture. Let’s look at an example for the same room. Manufacturer’s recommendation: 1.5 kg / m² per 1 mm of layer thickness, maximum layer thickness – 5 mm. Total: 5 x 1.5 / 20 = 150 kg mix or 6-7 packs.

Work order

The order of work when making a subfloor, a finishing layer for floor coverings, installing warm and self-leveling floors is somewhat different.

Making a subfloor from self-leveling mixtures

After cleaning the floor from dust and debris, you need to lay a tape of elastic material between the future screed and the wall, which will prevent cracks between the wall and the floor.

For a rough floor, if it is laid on a surface with a significant slope, it is advisable to pre-set the guide-beacons, installing them horizontally with a level and fixing them with cement mortar along the room. The extreme guide strips are fixed at a distance of 20 cm from the wall, the rest at a distance of 1-1.2 m along them.

The mixture is prepared according to the ratio indicated on the package. In this case, the water should be cool, the mixture is poured into a measured amount of water, and not vice versa, and double mixing is performed with a technological pause of 3-5 minutes. The prepared composition is poured onto one of the formed “paths” and quickly, but neatly, is smoothed out by the rule moving along the guides. You need to start work from the window. If part of the diluted mixture did not have time to be used, and it began to dry in the container, it will have to be thrown away. It is unacceptable to dilute the mixture with water again, the quality of the layer will be unsatisfactory.

Drying must not be forced after finishing work. The room must be isolated from direct sunlight and drafts.

If the subfloor is done correctly, the finishing layer does not need beacons, as it is thin and made from a more fluid solution. If a “warm floor” system is installed on such a base and it is poured with a self-leveling mixture, then beacons will be needed, since the layer is not so thin as to neglect the possible deviation from the horizontal.

Surface priming

If the subfloor has not been completed due to the good surface quality and slight slope, then the surface must be primed before the finishing layer. It is needed to improve adhesion and prevent accelerated drying of the finish layer due to the increased rate of moisture absorption by the concrete floor. The primer mixture is prepared in the proportions indicated on the label and is applied evenly over the entire floor area with a short-nap roller. After a while, a second layer is applied. The finishing layer is applied in the interval from 4 to 24 hours after laying the second layer of primer.

Finishing layer

When pouring the finishing layer after priming, you will need benchmarks, the millimeter scale of which allows you to set the thickness of the poured layer, starting from 0.3 mm. Benchmarks are installed throughout the room at some distance from each other and consist of support legs, in the center of which there is a flat-head screw. The screw sets the distance from the floor – the future layer thickness, and the level, laid on the caps of adjacent benchmarks, controls the horizontal position. If pipes pass through the floor, they must be carefully insulated to avoid interfloor solution leaks..

After the beacons are displayed, you need to dilute the mixture, strictly adhering to the instructions on the package. To do this, you need cool water, a container for the solution and a drill with a mixer attachment. Stir the solution for at least 3 minutes for homogenization, then 2 minutes – a technological pause and mix again for 3 minutes. The solution is smooth and homogeneous, with a consistency resembling thick paint.

Quickly but carefully, the mixture is poured onto the floor in small portions, starting from the window, and, guided by the beacons, smooth it with a spatula, remove the benchmarks and pass over the entire area with a needle roller, releasing air bubbles out. The whole floor must be poured at one time – the mixture hardens quickly, and during this time it is necessary to pour, level and remove air bubbles.

If the finishing layer is performed on a perfectly horizontal base layer of the subfloor, then a primer is not required and beacons can be omitted.

The use of self-leveling mixtures for underfloor heating

At the first stage, a screed is performed, leveling the base for the installation of a warm floor. Then a heating system is installed – electric or with hot water as a heat carrier. When the frame and pipes (heaters) are laid, you need to fill the structure with a self-leveling mixture. Most often, gypsum-based mixtures are used for this, which can be applied in a thicker layer and at the same time they are cheaper than cement ones, which are used only for floors in rooms with high humidity..

To fill the solution, professionals use a filling machine with a hose that serves the mixture, evenly moving it over the heated floor areas. In this case, it is advisable to use reference beacons. After this base layer has hardened, a floor covering is laid on the floors or, as a finish, a self-leveling floor is made from a mixture based on polyurethane.

A warm floor can be covered with a self-leveling cement-based mixture according to the same principle as the subfloor was performed: with guides and a rule.

If the floors are initially even, then the self-leveling mixture can be applied using a metal “ruler”.