Do-it-yourself self-leveling floor screed. Floor screeds dry and liquid

Let's visually examine two types of flooring - semi-dry and wet (liquid) made using the usual method for subsequent laying of the finishing coating (tiles, porcelain stoneware, laminate, linoleum). The main causes of cracks are described on this page. Screed with cracks The photo of the screed with cracks was borrowed from the forum of finishers “City of Masters”.

Disadvantages of “liquid screed” - low strength, high shrinkage and numerous cracks

This is what a regular one looks like wet screed. The photo clearly shows shrinkage cracks caused by an excessive amount of moisture in the cement mortar, the strength of such a screed does not meet the standards for subsequent laying of the finishing coating; when walking or loading in the area of ​​the seams, individual pieces may move, you can feel the deflection and bending of the screed, a dull sound, and buckling. When such a surface is fully exploited and laying tiles or linoleum on it is not permissible, it risks dismantling the flooring that serves as a “clean floor”

A screed made using the semi-dry screed method, reinforced not with a steel mesh, but with fiber fiber, looks completely different, has a smooth surface, is resistant to compression and tearing, and has good adhesive properties to the surface when laying floor coverings.

The work in these photographs was carried out by our company at the construction site of the MIPT IT Technopark

The technology of such a screed differs from the usual amount of water in the preparation of the solution, which is only sufficient to hydrate the cement. Also, the semi-dry screed is laid on a separating film, the film cuts it off from the overlap, preventing rapid absorption of moisture from the solution into the ceiling and adhesion of the solution to the base, which gives a floating effect, i.e. the screed is non-contact and does not have adhesion to the base, the only requirement which is prohibited from being neglected when laying on polyethylene film, the thickness of the screed must be at least 40 mm. You can read how we make such a floor surface

Self-leveling screed is famous for being very easy to fill. To do this you don't need to have great experience in construction. In addition, this type of screed allows you to achieve a perfectly flat surface, which is ideal for any type of coating. But few people know how to properly prepare and apply self-leveling mixtures to the floor.

Most mixtures for self-leveling screeds are cement-based. Gypsum is also used. Such mixtures contain sand or limestone. In addition, modern mixtures contain plasticizers, components that retain water, improve strength and other characteristics.

As for the choice of composition, you should be guided by the following criteria:

1. Humidity. If the room was and will be damp (nothing can be done about it), it is necessary to use exclusively cement-based mixtures. If the room is dry, you can buy both gypsum and cement compositions;
2. Base. If you have to deal with concrete, sand (using cement) or anhydrite base, it is better to buy special mixtures. These are produced, for example, by the Ceresit brand;
3. Deadlines. If deadlines are running out, you can purchase so-called mixtures for urgent repairs. Their main feature is that they can dry in literally 6 hours (some in 10, which is still very fast);
4. Required layer. Standard height layer of self-leveling mixture is 1 cm. But there are special mixtures that allow you to make a layer of 8 cm or more. An example is Ceresit Moment Flat floor;

Most experts do not recommend using self-leveling mixtures if the layer height is expected to be more than 2 cm. In this case, it is better to make a rough screed from ordinary mixtures that do not level on their own.

1. Proposed screed coverage. If you plan to paint the screed in the future, it is best to take Horizont brand self-leveling mixtures. Judging by the reviews, they are the best for paint and varnish coatings;
2. Required insulation. In cases where it is necessary to achieve high sound insulation and heat retention, it is better to use Bolars brand mixtures. If fire resistance is important, buy mixtures from KNAUF.

There are a huge number of manufacturers of such mixtures, but when you are in the store, be sure to pay attention to the characteristics of each of them. Usually, all the features of each mixture are described on the bag.

Let's assume that in our case the humidity in the room is normal and the height difference in the room is 0.5 cm. Then the required layer of screed will be equal to 1 cm. The base is concrete, the deadlines are not pressing. Linoleum will be laid on the screed; increased insulation is not required. In this case, we only need to pay attention to the thickness of the layer (indicated on the bag). Let's take one of the most popular mixtures, Thomsit DD from trademark Ceresit.

As you can see, the layer thickness and characteristics are indicated directly on the bag (on the right bottom corner). It says that the composition is environmentally friendly, suitable for interior work and other. In the same way, the bags indicate that the mixture has increased noise insulation, high drying speed or other characteristics.

How much mixture should I take?

To answer this question, you need to take the estimated height of the screed layer in millimeters, multiply it by the area (number of square meters in the room) and multiply it all by 1.5. Then you get the number of kilograms of screed. The fact is that with a layer height of 1 mm per one square meter you will need 1.5 kg of mixture.

This can be expressed in the following formula:

M – mass (quantity) of the screed, kg;

H – height of the screed layer, mm;

S – room area, sq. m.

As we said above, in our case the height will be 1 cm, that is, 10 mm. Let's assume that the area of ​​the room is 15 square meters. m. Multiply 10 by 15 and 1.5, we get 225 kg of screed. Considering that almost all such mixtures are sold in 25 kg bags, we need to divide 225 by 25. This also applies to the Thomsit DD we chose as an example. We will receive 9 bags.

Some mixtures require different flow rates. Therefore, before purchasing, be sure to pay attention to everything written on the bag.

Required Tools

So, we have already purchased the mixture. In addition, we will need the following tools:

• a bucket of at least 20 liters;
• It is advisable to take a drill with a mixer to stir the mixture (otherwise it will turn out with lumps);
• spatulas of different lengths;
• roller - you need to take a needle roller.

It is also advisable to take a special extension handle for the roller, so as not to step on the poured mixture, but to level it from a distance.

This is what a needle roller looks like.

And here is the pen for him.

As for water, in most cases a minimum of 7 liters is required per bag. In some cases, the bag will indicate a different dosage.

Do-it-yourself self-leveling screed step by step

This process begins with preparing the base. As part of your preparation, you must do the following:

Be sure to look at the bag to see how long the cement should dry. Under no circumstances should a screed be applied to wet or even slightly damp cement, otherwise both mixtures will mix, and then a depression will form in place of the crack.

After priming the floor, you must let the base dry again. Otherwise, the self-leveling mixture will mix with the primer and will not be able to bond firmly to the floor. That is, the primer will not fulfill its main purpose.

Interestingly, the technology allows adding a small amount of primer to the screed mixture. But the floor still needs to be primed.

Self-leveling floor screed makes it possible to perform high-quality surface leveling. For this, a special mixture is used, which makes it easier to create the necessary evenness. This option has advantages over a simple cement screed, which is much more difficult to pour and has a fairly long drying time.

A screed with a self-leveling effect has undeniable advantages that make it stand out among standard options:

Compared to competitors, self-leveling coatings have the shortest drying time

Of course, there are many more advantages, which makes this solution quite popular for creating a smooth floor covering.

But with all the positive properties, these compounds also have disadvantages:

• Impossibility of quick dismantling. Indeed, such coverage will require a large number of time for complete removal.
• The screed is performed only on a horizontal plane. If you need to create some slope, according to the design intent, this is simply impossible.
• Not the highest strength. This parameter is explained by the small thickness, which often ranges from 5 to 15 mm.
• Possibility of numerous cracks. This problem arises due to poor surface preparation and violations of installation technology.

Self-leveling floor requires careful preparation bases, otherwise the coating will be irretrievably damaged

Thus, the majority negative points due to non-compliance the right technology fills.

Types of mixture

The leveling screed has different kinds according to the created thickness. Each option is suitable for a specific task:

Important! It must be taken into account that, despite the ability to correct defects using a self-leveling screed, a careful approach to preparing the base for pouring is required.

In addition to the division according to the method of application, there are varieties that differ in composition:

Gypsum and cement self-leveling mixtures are equally suitable for both water and electric heated floors

Thus, there is a wide choice of materials, which gives this screed additional advantages over other options.

Material consumption

All work starts with correct calculation required quantity self-leveling mixture. To obtain this indicator, numerous factors should be taken into account:

1. First of all, it is measured total area the room that will be poured.
2. The condition of the foundation is determined. If the surface has significant defects, it is recommended to eliminate them during preparation. The fact is that solutions with a self-leveling effect can correct many defects, but this significantly increases their consumption.
3. Desired thickness of the poured layer. This indicator is determined depending on the type of product and the existing irregularities.

Even minor curvatures of the base lead to serious consumption of expensive self-leveling floors

Each manufacturer indicates on the composition label the calculation rules depending on the conditions. But there is a standard calculation method: with a layer 10 mm thick, taking into account minor surface deviations, the total amount of dry mortar will be 1.5–2 kg.

Pouring process

This process begins with careful preparation. The self-leveling mixture is applied primarily as a final coating, so any imperfections will significantly complicate the work. General principle preparation is as follows:

• cracks and potholes are expanded and sealed with putty compounds;
• the surface is cleaned of dust and dirt, a layer of primer is applied;
• if required, a fiberglass reinforcing mesh is stretched and fixed with glue;
• When creating a layer more than 20 mm thick, special beacons are installed.

The base is prepared in stages, and each stage is equally important.

They are set according to measurements taken to determine the maximum unevenness and lines marked along the entire perimeter.

Additionally, the necessary tools for the job are prepared. It must be taken into account that the process should be carried out at a temperature of 15 to 30 degrees and air humidity of no more than 65–70%.

A self-leveling screed is created as follows:

1. Prepare the solution. It is kneaded using a mixer or drill with a special attachment. Due to the fact that the composition has high speed setting, all work is completed quickly.
2. The prepared mixture is poured onto the surface and distributed using a spatula. When you need to quickly spread the composition over a large area, you can use a squeegee for greater convenience.
3. To achieve uniformity, a needle roller is used to expel air bubbles. All work must be completed within half an hour.

Stages of self-leveling floor installation

Thus, it is possible to quickly level the floor surface with minimal labor costs. It is important to consider that the solution sets within an hour, but installation decorative materials You can start after a few days.

A major renovation of any residential space begins with the renovation of the floor. An old concrete floor is usually a depressing sight. Height changes, potholes, chips, cracks... You cannot lay a new coating on such a base. How to fix this?

The traditional solution is a cement-sand screed. It has a number of significant disadvantages: high consumption material, leveling it is very difficult without skills and experience; hardening of concrete takes at least a month. It is much easier and faster to use a modern self-leveling screed - you can start finishing the next day.

Self-leveling screed is a method of leveling the floor, which involves the use of a special mixture. It contains not only the main substance (cement, gypsum) and binder (sand), but also glue and plasticizers, thanks to which the mixture becomes much more plastic than ordinary concrete. It acquires the ability to independently fill in the defects of the main coating and spread over the entire area of ​​the room. If necessary, it can be supplemented with pigments and become a decorative coating.

IN different conditions operation, one of several types of self-leveling mixtures can be used. The choice must be made based on the following factors:

• indoor humidity;
• likelihood of direct contact with moisture;
• Is the floor required to be resistant to aggressive chemicals?
• whether a decorative covering will be laid on top of the screed;
• type of base;
• the need to give the floor additional properties - noise absorption, thermal insulation, anti-slip.

There are not many types of mixtures for screed - it will not be difficult to choose. They are classified based on the variety of constituent components:

• Cement. The cheapest and weakest option, most often used as a primer. If you need to create a full-fledged screed, it is better to supplement the cement with acrylic. In this case, it will be durable, frost-resistant and undemanding to the properties of the base. However, like ordinary concrete, cement strainer It will take several weeks to gain strength.
• Plaster. It is stronger than cement, does not require preliminary leveling of the base, and conducts heat well. Eco-friendly. It can be of any thickness and is perfect for underfloor heating systems. The base must be dry, since gypsum absorbs moisture very well.
• Epoxy. The screed is durable and resistant to chemicals, but does not withstand abrasion. May crack when hit with heavy objects.
• Polyurethane. Best suited for industrial and commercial premises. Resistant to all types mechanical impact, changes in temperature, humidity. Long service life. The main disadvantages are demands on the condition of the foundation and high cost.

Pros and cons of this alignment method

Self-leveling screed has many advantages:

• Easy to use. The dry mixture just needs to be diluted with water, stirred and poured onto the floor. It will spread on its own and create a perfectly flat and smooth surface.
• Fast drying. You can walk on the screed within a few hours after pouring; it gains full strength in just a day.
• High strength, resistance to the most different types influences.
• No shrinkage.
• Minimum screed thickness – 5 mm.

It also has disadvantages:

• The base must be prepared - cracks sealed, dust and debris removed, surface dried.
• It is very difficult to remove a failed screed.
• Relatively high cost.
• Toxicity. Plasticizers can release chemical compounds harmful to health into the air, so during drying the room should be well ventilated, and work must be done with the mandatory use of personal protective equipment.

Characteristics, manufacturers, approximate price

One of the main properties of the screed in question is the smoothness of the resulting surface. It is ensured by the use of fillers having dimensions of no more than 260 microns. They are bound by plaster or cement. Additional properties - elasticity, fluidity, ability to adhere to the base - are imparted by various plasticizers. They can be polymers or minerals. The exact composition depends on the manufacturer of the mixture, and specifications materials.

When choosing, you need to pay attention to the range of permissible screed thicknesses (for example, 3-60 mm), the time of initial strength gain, the possibility of use for outdoor work, strength (indicated in MPa).

Today's market for self-leveling mixtures is represented by the following manufacturers:

• Knauf(Knauf) is the undoubted leader. The basis of the product is high-strength gypsum mixtures with the addition of fine quartz sand, improving performance characteristics screeds – adhesion to the subfloor, abrasion resistance. Price - approximately 220 rubles. per package 20 kg.
• Vetonit. Mixtures based on cement and limestone can be used to create finishing floor. Screed thickness – up to 5 mm. High strength and wear resistance. The initial strength gain takes only 3 hours. Consumption – 1.5 kg/m 2 /mm screed. Price - 360 rub. per bag 25 kg.
• Ceresit. Ceresit mixtures are suitable for making screeds on any base and under any finishing coat. Suitable for heated floors. A dry base is required. Screed thickness – up to 60 mm. Fast drying. Price - 400 rub. per bag 25 kg.
• Bolars. The mixtures differ in that with their use it is possible to create a heat and sound insulating screed. Price - 300 rub. for 25 kg.

Calculation of material quantity

You can calculate the required amount of mixture using the consumption information provided by the manufacturer. The mass of the mixture required to form a screed 1 mm thick is indicated. For example, if the packaging indicates a consumption of 1.5 kg per m2, then to form a screed 5 mm thick in a room of 10 m2 you will need 1.5 * 10 * 5 = 75 kg of the mixture, or three bags.

Such a calculation will be fair only in ideal conditions– when the base of the floor does not have height differences. If the surface has depressions even after rough leveling, you should add a little mixture. Additionally, you need to take into account the volume of materials such as insulation and reinforcing mesh, if used.

Work order

Leveling the floor using this method is carried out in several stages:

1. Preparing the base. Cracks need to be repaired, the floor dried and cleaned. Then the primer is applied in two layers.
2. Preparation of the solution. The mixture must be diluted in accordance with the recipe specified by the manufacturer on the packaging of the material. In order for the mixture to be of high quality, it is necessary to maintain the room temperature within 15-30 degrees. You need to stir the poured mixture quickly, without lumps, so this should not be done manually, but using a drill with a spatula attachment.
3. The finished mixture is poured onto the floor surface. You should start from the far corner of the room, gradually moving towards the exit. If necessary, you can walk on wet screed using paintshoes - special shoes with spikes.
4. You need to go over the entire area with a needle roller to remove any air bubbles that have formed.
5. Then all that remains is to wait for the screed to gain strength. It is not recommended to overdry it, so you should protect the floor from exposure to sunlight, heat sources, and drafts.

If a self-leveling screed is formed in large room, you don’t need to make a lot of mixture at once. It will dry out very quickly, and the unused material will have to be thrown away. If there is no assistant, you can work alone in sections - the screed does not shrink, so areas that dry at different speeds will not differ in height.

In the following video you can clearly see how to work with such a mixture with your own hands:

How long does it take to dry?

Depending on the manufacturer and brand of the mixture, the initial strength gain may take 3-8 hours. After this period it will be possible to walk on the screed. You can apply the decorative coating in 1-2 days. The screed will reach its maximum strength (indicated on the packaging in MPa) in 28 days.

In contact with

In a house under construction, everything must be done conscientiously so that a person feels comfortable and calm. In my opinion, the floor, as a structural element, plays one of the main roles. Therefore, in order to achieve a smooth and reliable floor, it is worth familiarizing yourself with the axioms of laying screed

A screed is one of the layers of the future floor, due to which a flat surface is achieved on which the floor covering is directly laid.

The concrete screed is designed to achieve greater strength of the floor, which after many years will be able to withstand the weight of not only furniture, but also industrial equipment.

There are two options for laying a concrete floor screed:

Dry floor screeds

It is considered a new way of leveling. It prevails because it is easy to style. When choosing this method, you will be spared the need to prepare solutions, for fear of “flying over” with the proportions of the components, and smoothing the surface for an incredibly long time. After completing the installation of such a screed, the floor is immediately ready to receive the finishing coating. Accordingly, you save significant time. They make a layer of all kinds of “dry” slabs, chipboard sheets, gypsum fiber board, fine-grained expanded clay.

Liquid floor screeds

They are made using liquid mixtures, which turn to stone after a short time. When hardening, the cement screed will certainly shrink, so do not forget about shrinkage joints during the work, especially if the area covered by the screed is more than 30 m2, and the side length is more than 6 m. After complete hardening concrete screed, it is necessary to seal these seams so that the floor looks monolithic. A floor with such a screed is more durable.

Preparing floor screed

When making floor screeds, the main thing is to arrange the liquid mixtures so that chips and cracks, as well as elevations/depressions exceeding 2 millimeters, do not appear.

To decide on the materials for the screed, let’s find out the purpose of the room. In factories and workshops, the floor will become more reliable when used in concrete screed. In apartments, special mixtures are often used to ensure not only reliability, but also heat retention. They are rarely used in private homes because the floor always remains cold.

Currently, in the manufacture of concrete screed in residential buildings, preference is given to cement-sand mixtures. They are quite common, and purchasing them is not a problem. Usually this is a bag of powder gray, which is diluted just before starting work.

Before using the mixtures directly, prepare the surface. The quality of preparation depends on what will play a role flooring. If you plan to lay tiles on the floor, there is no need for a screed at all.

Choosing a floor screed

When choosing a floor screed, carefully read the product description given by the manufacturer on the mixture packaging. Pay attention to such points as the method of diluting the mixture, room temperature, humidity, drying time.