How to make a floor screed: characteristics of types of screeds, we make a screed with our own hands step by step. Choosing the optimal thickness of the floor screed Prices for cement screed

Types of screeds: 1) Adhesive screed in contact with the concrete slab. The screed is laid directly on the floor slab and adheres to it. For such a screed, the thickness can be small, from 2 cm, but exceptional important role plays adhesion to the base. When producing such screeds, it is important to thoroughly vacuum the surface, use good primer, ideally Betokontakt, and ensure that the base does not become dusty during the work. 2) Screed on the separating layer. The solution is laid on a thin separating material: plastic film, roofing felt or waterproofing. 3) Floating screed. Placed on a layer of heat and soundproofing material. This can be regular or extruded polystyrene foam, dense mineral wool, rolled polyethylene foam, including foil, expanded clay bedding. Each type of screed has its own advantages and disadvantages. The disadvantage of adhesive screed is poor sound insulation. The advantage is the smallest possible layer of screed and the possibility of combined leveling using finishing levelers in areas with a thin layer. At the same time, there is practically no danger of cracks appearing at the junction of materials. The screed on the separating layer, during the development of strength, is protected from moisture extraction by the overlap and improves waterproofing properties, but it should not be less than 3 cm thick and requires reinforcement. A floating screed also cannot be thinner than 3 cm, and the optimal layer is 5 cm and must be reinforced. Pros: good noise and heat insulation, leveling possible large differences without increasing the load on the floors. Cons: Significant increase in price and greater thickness. When choosing a pouring method, you need to take into account the unevenness of the base, and remember the fact that the weight of the screed is 20 kg per cm of thickness per square meter, i.e. a layer of 5 cm weighs 100 kg/sq.m. Reinforcement is made in one of the following ways: 1) Metal welded mesh, rod diameter 4 mm, cell 100x100 or 50x50. The mesh is placed on supports so that after pouring the mesh is in the center of the layer. The meshes are laid overlapping and tied with wire. When installing cable heated floors, it is convenient to fasten the cable to the mesh with wire or electrical ties.

2) Fiberglass mesh. I haven’t used it myself, but I know that it is cheaper, lighter and more durable than metal, it’s a pity that it’s practically not represented on building materials databases

3) Metal fibers, polypropylene, basalt or fiberglass. This method of reinforcement is good, but only if the fibers are evenly distributed when mixing the solution. As a rule, fiber fiber is added to the automixer when leaving the concrete plant. During the journey to the object, the fibers manage to be well distributed throughout the volume of the solution. It is difficult to achieve such uniformity at home.

Even with reinforcement, the screed, in the process of gaining strength, shrinks and “pulls” it, which large areas leads to the formation of shrinkage cracks. To prevent this from happening, expansion joints are made. In apartments, it is better to place seams in the area of doorways and at the junctions of different floor materials. The expansion joint can be laid when pouring with any thin separating material, or cut after pouring in a still fresh mortar that has not yet gained strength. The reinforcement at the seams is interrupted

A little about lighthouses. Beacons are made so that the floor level is perfectly level. For a high-quality screed, the deviation should not exceed 2 mm at a 2 meter level applied at any point on the floor. These are the requirements of any laminate and parquet board manufacturer. This is also an excellent base for laying tiles. I won’t tell you much about how lighthouses are made, I’ll just say that you shouldn’t use gypsum compounds to make them. Especially if there are tiles on the floor. The fact is that gypsum, with increasing humidity, increases in volume, which can lead to cracks on the surface of the tile.

The screed should not come into contact with the walls and columns, therefore, before starting work, a dividing tape made of foamed polyethylene or its equivalent is laid along the wall. One of the important points in the construction of the screed is the water-cement (W/C) ratio. The more water in the solution, the stronger the subsequent shrinkage of the screed. The W/C can be reduced by adding a plasticizer to the solution, as well as by using the “semi-dry screed” method, when the cement-sand mixture is mixed with a small amount of water. The solution turns out to be crumbly and if it is left in the container for several minutes, no moisture will be released on its surface. To prepare such a solution, you cannot do without a powerful mixer, since it is very dense and non-plastic.

To level the solution, use the blunt side of the rule and add material in the right places. Also for leveling, it is convenient to use a yellow polystyrene foam grater

A significant advantage of the semi-dry method is the fast drying time and the acquisition of primary strength. You can make mortar beacons and level the floor on the same day. You can immediately walk on a freshly laid screed wearing special shoes with wide soles, similar to snowshoes. You can walk in regular shoes after 6-12 hours. Tiles on such a floor can be laid every other day, and laminate and parquet boards after 5-10 days, depending on the thickness of the layer and the moisture meter readings. In order for the screed to properly gain strength, on the first day you should protect it from drafts and cover it with film, and periodically moisten it for the next 2-3 days. In industrial premises and wherever floors are used without coating, they are rubbed with special trowelling machines to strengthen the top layer

Installing a floor screed is a process that, with good repairs and especially construction, no one can avoid. And with this process, a lot of dusty, dirty and wet work is usually done. After them, the screed should be left to “mature”, “helpfully” moistened for several days, and not walk on the floor for quite a long time. Not to mention the money spent.

To ensure that the result is pleasing to the eye, and the process occurs in an organized and fast manner, we suggest that you read this article, which will tell readers how to make a floor screed yourself. Moreover, there is nothing supernatural or prohibitively difficult in this, which we intend to convince our readers of.

A floor screed is an intermediate layer that is placed between a base and the final floor covering. Why do you need a screed?

To give floors the required rigidity and strength in accordance with expected loads.
To level the floor horizontally or, conversely, to give the required slope in some areas, for example, in shower stalls.

No matter how funny it sounds, screed is sometimes made for thermal insulation, since some of its types are capable of this.
The screed in heated floors plays the role of a large radiator, therefore, we can say that it is needed for the necessary heat absorption and distribution.
For covering elements of engineering systems: electrical wiring, heating pipes and underfloor heating coils, sewer pipes.

To cover and protect the thermal insulation layer from mechanical loads.

In some cases, the screed itself is also the final floor covering. For example, in garages, any technical or production premises, where no other covering will be laid in the future. Then, we can say that such a screed - single-layer .

In many other cases, ties are made two-layer .

The first layer levels the surface horizontally, or gives required slopes. It is usually made from a cement-sand mixture or concrete. It is commonly said that the first layer is rough screed . In the future, you can lay tiles or porcelain stoneware on it.
The second layer is called finishing screed . It already makes the surface perfectly flat for the final floor covering, for example, laminate, parquet, carpet. Very often the finishing screed is performed , giving an ideal surface when used correctly.

The screed can be laid on different substrates: compacted soil, concrete or even wood. Depending on the connection with the screed bases, you can divided into the following kinds:

Tied tie , which is characterized by the fact that it is firmly bonded to the previous layer. More often it is a concrete screed on a concrete floor slab. The necessary adhesion and uniformity of this design also provide excellent mechanical strength. Such screeds can only be made in rooms where the humidity of the base will not be high. They are used on the second and subsequent floors of various buildings.

Screed on the separating layer . This design should exist when two different materials come into contact. For example, when a concrete screed is made on the ground. Or in the case when gypsum or dry screed is laid on concrete. And also the use of a separating layer is mandatory if the humidity of the underlying layer is higher than normal. Various bitumen-based roll materials (roofing material), polymer films or coating compositions can be used as a separator. Obviously, the screed will already be a separate structure, so it is advisable to reinforce it and make it at least 3-5 cm thick.
Floating floor screed is a further continuation of the previous one. It must be arranged if any insulation is required. The floating screed is separated from the base by a layer of insulation along with waterproofing. It must also be separated from the walls. This could be insulation, but of less thickness, or a special damper tape. Warm water floors are necessarily accompanied by a floating screed, since in addition to mechanical loads, such a screed will also change in size due to temperature effects. Working in such conditions forces the use of reinforcement and a thickness of at least 5 cm.
Prefabricated or dry floor screed. In our country this is a relatively new phenomenon, but in Europe it has been used for a long time. On the prepared and insulated base of such a screed, filler is poured in the form of dry bulk material. The most commonly used is granular, which is good warmth- and a sound insulator. Sheets are laid on top of it gypsum fiber plates fastened together. This type of screed can be installed very quickly and this is its main advantage. However, dry screed can only be done in rooms with guaranteed low humidity and with low or medium load on the floor.

Screeds can also vary in installation methods. Let's list them:

Continuous floor screed performed using the “wet” method . This is the most common, one might even say the classic way. The solution, mixed with water, is applied to the prepared base and leveled according to the beacons using the rule. Since the main binder for wet method 95% is cement, then such screeds gain full strength only after 28 days, which is a big drawback.
Continuous floor screed performed using the “semi-dry” method . This direction began to develop relatively recently. The point of this approach is that exactly the amount of water that is necessary to hydrate the cement is added to the working solution. Such screeds dry faster - the next day you can already walk, and lay the tiles within a week. A plasticizer is introduced into the solution, which improves mobility and ductility during installation. In addition, micro-reinforcement with fiber (polypropylene or basalt) is often used in semi-dry screeds. Screed with fiber has better strength, wear resistance, tensile and bending properties than with classic wire mesh reinforcement. The technology for laying semi-dry screeds is more complicated; preparing the solution requires strict adherence to the recipes.

Laying, leveling and sanding of semi-dry screed - all in one day

Continuous floor screed using self-leveling mixtures . This method also applies to “wet”. As we noted, this method is very convenient for making a finishing screed. Such screeds are made in a thin layer of 0.5-20 mm, primarily for economic reasons, since dry mixtures for preparing solutions are very expensive. But the installation technology and the result observed later are above all praise. The working solution is simply poured over the surface in strips, rolled with a needle roller to remove bubbles, and that’s all.
Dry or prefabricated floor screeds. We have already mentioned them earlier. You can read more about them on our portal.

All floor screeds, with the exception of prefabricated (dry) screeds, are made using based on two main binders component - cement or gypsum. There are also others - magnesium, bitumen, anhydride - but they are not used for residential construction, and therefore will not be considered. Let us note the weak and strengths these two basic materials.

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cement strainer

Cement based screeds They have high strength, durability and, most importantly, resistance to water. The weaknesses of such screeds are the tendency to shrink when drying and the long maturation time.
Gypsum-based screeds strong enough and durable. The solutions are very plastic and do not shrink when dried. have good thermal insulation properties. Can be applied to any substrate, including wood. The maturation period is several times shorter than that of cement screeds. But there is one main disadvantage - this is the “fear” of water.

Naturally, in addition to the astringent component, which is the main one, the composition of any modern solution or dry mixture also includes other components: fillers and modifiers, both of natural origin and those obtained in chemical production. Therefore, modern mixtures cannot be called only cement or gypsum. It's more correct to say cement-polymer or gypsum-polymer .

In cement screeds, polystyrene foam chips are often used as one of the fillers, which gives the coating thermal insulation properties. The load-bearing capacity and rigidity of such screeds is less, this must be taken into account. In this case, a second leveling and strengthening layer with more durable fillers is also required.

If you need to create a screed with thermal insulation properties of great thickness, then another material comes to the rescue - expanded clay, obtained by firing clay. This is an excellent filler that has good thermal insulation properties, it is inert, does not decompose with water and is quite durable. Another advantage of using expanded clay as a filler is a significant saving of cement and a reduction in the labor intensity of laying the screed.

With the help of fillers and modifiers, modern cement screeds dry faster and shrink less, and gypsum screeds partially overcome the “fear of water.” But, it must be said that “hereditary diseases” still remain in one form or another. Therefore, cement-based screeds are still the most versatile. Gypsum-polymer also has a place, but only in dry rooms, where exposure to water in any form is excluded.

Let's move on to the practical part of implementing the floor screed. To do this, we will divide this process into stages, each of which will be considered separately. What are these stages?

Preparation of the base;
Display of beacons;
Preparation of the solution;
Floor screed device.

At each stage, we will try to explain the entire process in detail, accompanied by photos and video materials. So let's begin.

Preparing the base for a floor screed

We will consider only three types of foundations: soil, old floor screed and concrete surface. Wooden base We will not deliberately consider it, since we believe that it is easier to install floors on it without a screed, using other levelers: plywood or OSB sheets.

The basis of the screed is soil

The best time to arrange rough screeds floors on the ground - this is the stage of foundation construction. Then all excavation and other work is much easier to carry out. And in modern construction they do exactly that. If you do this in an existing house, then, of course, the task becomes much more complicated, but it is not fundamentally different. Let us note the main stages of preparation.

The first thing to do is to select soil to a depth of at least 50 cm. In each specific case, the depth may be different. The bottom of the pit is cleaned and compacted.
If the soil is clayey or loamy soils, then it is necessary to take care of drainage so that moisture does not “prop up” the floors from below.
Next, the creation of the so-called filtration or drainage layer begins. To do this, sand is poured in a layer of at least 100 mm. More is possible, but note that 100 mm is lower limit. After this, the sand is compacted using a manual tamper or using an electric or gasoline tamping machine.

It should be noted that the maximum permissible layer of sand that needs to be compacted - this is 200 mm. If a larger layer is planned, then the tamping work is divided into stages, but no more than 200 mm at a time. During the compaction process, it is necessary to periodically water the sand with water from a hose.
A layer of crushed stone or coarse gravel is poured onto the sand. The minimum thickness is also 100 mm. This layer is compacted manually or mechanically. Crushed stone or gravel helps to better compact the sand layer and give the filter layer a rigid base.

The next step depends on how much space is left to the level from which the future floor screed will be formed on the ground.

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vibrating plates

If you still have 150-200 mm at your disposal, then you can lay a layer of concrete with the addition of expanded clay on a gravel-sand cushion. This will be the first stage of thermal insulation, but which will still not be enough for most regions of Russia. Per layer expanded clay concrete then a layer of 40-100 cm of “lean” concrete is laid and compacted. It is called “skinny” because it contains a low content of binder – cement. Lean concrete usually has grades M 100 (B7.5) or M 150 (B10). The task of such a layer is not to bear the main load, but to fill the unevenness of the underlying layer, level the surface and prepare it for waterproofing.
Another case in the preparation of ground floors for screed is the lack of 150-200 mm for the expanded clay concrete layer. Then skinny concrete comes to the rescue again. It is laid directly on crushed stone, and the concrete layer should also not exceed 100 mm, 40-60 mm is more than enough. When laying it, be sure to compact it so that the solution penetrates into the space between the crushed stones. Using a trowel, a rule and a grater, it is necessary to form a flat outer surface, which will serve as the basis for the future floor screed.

The subsequent steps are the same for both cases. After the “laying” of lean concrete has dried, it is necessary to carry out waterproofing measures. For this purpose they use bitumen mastics, with which the entire surface is coated in at least two layers. Do not forget that the walls must also be coated with mastic to a height no less than the height of the floor screed. In regions with high groundwater levels, after mastic, a roll based on bitumen or dense polyethylene film laid overlapping would also be useful.

The base of the screed is an old screed

Those who got this option should not be envious, since in most cases the old screed will have to be dismantled. Even if it gives the impression of reliability and impeccability. Even if it does not “bounce” when tapped and has a smooth surface without cracks. Let us present the arguments.

new screed, the “impeccability” of the old one can easily be damaged. Under new conditions, detachment from the base and cracks may occur, which will also affect the top layer.

A new screed on top of the old one is an additional load on the base. This is especially true for floors on upper floors. 1 m² slab cement-sand screed 5 cm thick has a mass of already 110 kg.

Each screed “eats” at least 5 cm of space, which is already quite significant in standard housing. In addition, problems may arise with radiators, pipes leading to them, thresholds and door panels.

Screeds are never made in such a way that they cannot be dismantled. It seems logical to sometimes connect two layers with reinforcing bars or wire, but no. Even connected concrete screeds adhere to each other only due to adhesion and will delaminate quite easily under mechanical stress.

To dismantle the screed, it is best to call a team of workers who specialize in this particular area. From experience, it will be much cheaper. You shouldn’t even try to do this alone, as both the owners and the neighbors will be exhausted if the screed is removed in an apartment building. A professional team arrives immediately with all the necessary chiselling and stone-cutting equipment, shovels, garbage bags, and a vacuum cleaner. They immediately take away all the garbage collected during slotting work and the owner does not have to worry about calling a separate car. The work of the professionals goes on continuously: one or two people dig, another one or two immediately collect the garbage in bags, and the rest take it out and load it into the car.

The main task of the owners is to come to an agreement with everyone to whom the noise may cause discomfort. IN panel houses- this is the whole house. And, of course, make sure that after the team leaves, there are no traces left on the site and in the entrance from the presence of “noisy guys” and dust from old screed.

In private houses everything is simpler; you don’t have to negotiate with your neighbors. You can try it yourself, but you still can’t do it without helpers. To dismantle the old screed, you will definitely need a powerful hammer drill with a non-SDS+ cartridge, and not an SDS-Max. You will also need chisels for the hammer drill. Sometimes jackhammers are used, but this step can only be taken if this tool is in the hands of a professional. Improper use of a high-power jackhammer can easily lead to the breaking of a reinforced concrete slab.

In addition to the hammer drill, a 230 mm grinder with a stone-cutting disc, a construction vacuum cleaner, shovels, brooms, and a large number of durable bags can be very useful. Work must be carried out in work clothes made of thick fabric and a hat, wearing gloves, wearing a mask or glasses. Since there will be a lot of dust, a respirator is required. It is better to protect your hearing organs with headphones, as there will be a lot of noise. Not every craftsman has such a set of tools in his arsenal, but all this is rented in any region. In order not to overpay for rent, it is better to fit all the work into one day, so assistants are definitely needed. Let us describe the main stages of dismantling the old screed.

If electrical wiring, heating or water supply pipes run in the room under the screed, then it is desirable to have a diagram that should remain after installation. If it is not there, then you will have to use a special device - a detector of hidden wiring and metal, with which you need to examine the entire area of the room and mark these places on the surface with a bright marker.
It is better to start dismantling the screed from the entrance to the room and then move deeper into it. This will make it easier to immediately remove the loose pieces of the old screed. But before dismantling begins, it is necessary to carry out “exploration drilling”. To do this, cuts are made in a small area using a grinder with a stone-cutting disk, and then small pieces of the screed are broken off with a hammer drill with a spatula or a jackhammer to get to the next “cultural layer.” If that layer is the right one load-bearing slab, then you need to measure the thickness of the screed to be removed with a tape measure in order to know the reference point.
You need to start breaking off the old screed with low revolutions of the hammer drill engine and first break off small pieces. Further, when the degree of adhesion of the screed to the base is already clear, you can increase the speed and break off in large pieces. Everything will be intuitively clear. When working, you should always take a stable body position and hold the tool with only two hands. There is no need to put too much pressure on the hammer drill or jackhammer; this does not affect the force of the blow, but your hands will get tired faster.
It is better to remove pieces of broken screed immediately with shovels, load them into strong bags and take them to a certain place for subsequent removal. This is another argument in favor of the need for assistants.

When working, breaks are required. This is necessary both for resting your hands and for cooling the instrument. After 15 minutes of work, rest for 5 minutes. It is also desirable that the operators behind the rotary hammer or jackhammer also change. But this can only be done if others have good tool skills.
If the old screed is reinforced with wire mesh, then before dismantling it with a grinder with a stone-cutting disk, you need to make cuts to a depth that would ensure cutting of the reinforcing mesh. The work of the grinder must be combined with the work of the vacuum cleaner, since there was a lot of work from cutting concrete. The surface is “chopped” into rectangles, such that they can be conveniently carried away in bags, and only then chiselling is done.
Those places where pipes or hidden wiring pass, a large hammer drill or jackhammer should be bypassed. In these areas, then after the “heavy artillery” it is better to let a small hammer drill or even a hand chisel and hammer work. You also need to be careful in corners and near partitions, especially if they are made of plasterboard or cellular concrete.
After dismantling and removing all debris, the surface of the base is cleaned with a hammer drill with a wide blade from the remnants of the old screed. Then the room is swept, the floor and air are sprayed with water from a sprayer and 15-20 minutes are given for all the dust to settle. Use a vacuum cleaner to remove remaining dirt.

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polystyrene concrete

It happens that after dismantling the screed, the “cultural layer” laid on the floor is exposed. ceramic tiles. Moreover It happens that this tile was laid back in the 50-60s of the last century. On construction and renovation forums, the question very often arises of what to do with these tiles? Should I fight her off or not? Opinions on this issue vary. Our opinion is clear – beat back!

Tiles laid during the times of developed socialism in the USSR, when dismantled, have two extremes. Either she literally “jumps” from the base herself, or she “stands to the last.” Moreover It happens that tiles behave differently in one area. And all because previously craftsmen did not have tile adhesives with predictable properties in their arsenal. That's why they stuck to whatever they wanted. They used just cement, and cement with PVA, and Bustilat glue, and even epoxy resin and some other “brutal” compositions with ammonia. Moreover, they glued them without any mineral base in the form of sand, chalk or lime. Therefore, dismantling old tiles can be a problem.

Some home craftsmen mistakenly believe that than hit harder perforator, the more readily the tiles will lag behind the base. However, practice shows that a small hammer drill with a sharp blade can cope with old tiles better than the “monster”, but with a more blunt blade. That is, when dismantling an old tile covering, it is not the force that is more important, but the place of its application.

After dismantling the old screed and thorough cleaning, preparing the surface for a new screed will be practically no different from what will be described in the next chapter.

The screed base is a concrete slab

It is most pleasant to do the screed on such a surface when you do not have to deal earthworks or dismantling old coatings. But nevertheless, the surface must be prepared. What steps should surface preparation include?

First of all, you need to provide a workplace good lighting, in which the slightest surface flaws will be visible.
All joints of reinforced concrete slabs (if any) are cleaned, processed, and then sealed with a cement-sand mortar of the same recipe that will be used for the future screed. This solution can also be used to seal the junction of walls and floors where there may be gaps.
All dried splashes of mortar, lime and others on the surface, as well as everything that can be touched with a spatula and hammer, are knocked off and cleaned.
If there are large recesses on the upper surface of the slabs, then they can also be covered with the same solution as the joints between the slabs.
If there are cracks, they are cut to a width of at least 5 mm and then filled with special repair compounds for concrete.

After all the solutions have dried, the room is thoroughly cleaned, and then a primer is applied with a roller. deep penetration. After the first layer has dried, the second is applied. Primer treatment is required in any case, even if the screed is to be made on the separating layer.
If the screed is bound, then it is recommended to use a special composition - “Betonkontakt”, which contains a complex of polymers, cement and quartz sand. After treatment with this primer, the surface becomes rough, to which everyone “sticks with pleasure.” Construction Materials. However, we recommend using “Betonkontakt” after placing the beacons in order to prevent damage to the surface created by this soil.

If the screed has a separating layer, then a dense polyethylene film. The joint of the strips should overlap at least 100 mm, and the overlap on the walls should be the thickness of the future screed plus 20 mm.
A damper tape is glued to the walls around the perimeter of the room, which serves to compensate for temperature expansion.

At this stage preliminary preparation surfaces can be considered complete.

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concretecontact

Placing beacons for floor screed

The floor surface intended for screeding is rarely completely flat. In addition to uneven terrain and the profile of the floor slabs themselves, in most cases the rough surface has a slope in one direction. If in separate room a slope of 3 mm per 1 meter will be imperceptible, but on the scale of the house it can already turn into several centimeters, which is unacceptable. You should always ensure that the floor in the entire apartment or floor of a private house is on the same level. The exception is bathrooms, which should be 15-20 mm lower. Therefore, with proper repairs, it cannot be that in each individual room the screed is done only in its interests. In no case! You can make a screed in some room, but taking into account the entire apartment or the entire house.

In order to prevent the floor level in an apartment or house from “dancing” as it pleases, it is necessary to set the zero level in all rooms. This is very easy to do if you have a laser plane builder at your disposal, which has long ceased to be a luxury. Let's describe the methodology.

A laser level is installed on a tripod in a certain place so that its beam can cover the maximum number of rooms. It is better to install it at a comfortable height for work - approximately 140-150 cm. Mark the position of the beam on the walls of the premises with a marker.

The level is transferred to some room where there is already a mark and is set By her . Next, the position of this mark is transferred to all walls. Use a painter's cord to mark a horizontal baseline.
Similar actions are carried out in all rooms. As a result, it should turn out that a horizontal base line is drawn on all walls, against which the floor level and screed thickness will be calculated.
Measurement points are marked on the baseline at a certain frequency (1.5-2 meters). Then the distance from the measurement points to the floor level is measured vertically and written down with a marker or pencil directly on the wall.

Find the minimum and maximum distance from the base line to the floor surface. In the given example minimum distance 1420 mm, and the maximum is 1445 mm. The height difference is 25 mm.
Let's say the recommended minimum thickness screeds for sand concrete of any brand is 30 mm. This means that you need to set aside 30 mm from the highest point and get that the zero level will be 1420 - 30 = 1390 mm from the base line. The thickness of the screed in this case will vary from 30 mm to 55 mm. This is completely acceptable.

These calculations are very appropriate to apply to the house plan. Such a document will be very useful in the future, since screeding is usually not done immediately in the entire apartment or floor of the house, but gradually, moving from one room to another.

It's time to learn how to place beacons correctly. These actions cannot be called hard physical labor, but a lot depends on the correct placement of the beacons. They are the ones who define the surface of the floor, and from the slightest mistake, all further work can lead, at worst, to further elimination of deficiencies, and at best, to banal excess consumption of dry mixture, from which the screed solution will be prepared.

Let's give an example. Let's say there is an apartment with an area of 100 m² in which you need... For this purpose, sand concrete M 300 will be used, which has a minimum layer size of 30 mm. When beating the zero level, it turned out that the thickness of the screed can be from 30 mm to 55 mm (we gave this example earlier). This means the average thickness of the screed will be approximately (30+55)/2=42.5 mm or 4.25 cm. Average consumption sand concrete M 300 is 20 kg per 1 cm of thickness and an area of 1 m². It turns out that the consumption for the entire apartment will be: 4.25 * 100 * 20 = 8500 kg of dry mixture, which will be 212.5 40 kg bags.

Now let’s imagine that when installing beacons, the master instead of the minimum 3 cm at the highest point set 4 cm with the “iron” argument “the reserve is not enough for the pocket.” Let's recalculate: an extra 1 cm added to the screed over the entire area of 100 m² will result in 20 * 100 = 2000 kg, which will be an additional 50 bags in 40 kg bags. It turns out that the reserve “pulled the pocket.” And the point here is not so much about money, but about the extra load on the floor. The extra 2 tons will lie on the base of the floor. The extra 2 tons will need to be dragged, prepared and laid.

All readers probably know that the most inconvenient load when transporting and especially lifting to floors is a piano. Loaders avoid it “like hell” and charge a special rate. The average weight of one piano is 250 kg. It turns out that plus 1 cm of screed in the considered example is equal in weight to approximately 8 conventional pianos or one conventional Lexus RX 400 SUV.

There are too many ways to display beacons to describe them all in one article. Each master has his own favorite method, which does not necessarily have to be similar to others. In principle, what difference does it make if, using different methods of placing beacons, two masters get equally good results. We propose to consider a method that will be understandable to everyone and even a beginner can reproduce it.

Completely different objects and devices are used as beacons for floor screeding. Some people prefer to make beacons from mortar, others use pipe sections. The ceiling guide profile is very widely used, " borrowed"in plasterboard systems, which we know as PN 28*27 or UD 28*27. Its shape and sufficient rigidity allow it to be used for lighthouses. For example, as shown in the figure.

In the method of placing beacons we describe, we will use the PM-10 beacon profile, originally conceived for plaster, but also successfully used in screeds. It is made of galvanized sheet steel and has a shape that also provides it with good rigidity. The side shelves of PM-10 are perforated to facilitate its attachment to the leveling surface in different ways.

Very often, beacon profiles are fixed using mortars. To do this, on the pre-marked line on which the beacon should be located, at the beginning and at the end, self-tapping screws are screwed into the previously installed dowels. Then using laser level or other measuring tool, adjust the screw heads so that their upper plane is in the plane of the future screed. Along the line of placement of the beacon, slides are made from cement-sand or other mortar at a certain periodicity, and then the beacon profile is placed on them and pressed with a rule, which is pressed against the heads of the screws.

When the beacon profile is pressed into the mortar cushion, be sure to ensure that it is pressed against the rule along its entire length. The excess protruding above the lighthouse is cleaned. When the solution has dried, you can begin the main work on the screed. For a cement-sand mortar, at least 1-2 days must pass for the beacon to be fixed, so to speed up the process, some craftsmen use adhesive gypsum mortars or even alabaster. In this case, the lighthouse is fixed almost instantly and work on laying the screed can begin immediately. Everything seems to be fine, but it turns out that there will be foreign inclusions from other materials in the body of the screed. During the operation of the screed, in those places where there are “strangers”, cracks will most likely form, since the coefficients of linear thermal expansion different materials are different. Therefore, beacons should be installed only on the mortar that will be used to make the screed.

The method of installing beacons on a solution has a main drawback - it is the impossibility of correcting the position in case of an error. Only dismantling the beacon and reinstalling it can correct the situation. Therefore, it is better to use a method that will allow you to easily install and dismantle the beacon and adjust its position. This can be easily achieved using self-tapping screws with dowels and a special fastening – a plastic clip for attaching beacons.

This clip consists of two parts - the clip itself and the lock that secures the beacon. This type of fastening the beacon is good because the clip itself can be attached to the head of the screw after it has been screwed in and adjusted in height. There is a special groove for this. After, already after The beacon is inserted into the clip and is being finally secured with a lock. The result is a very reliable mount, which can also be adjusted in height. The price for such clips is cheap - 100 pieces cost 250-300 rubles.

Let's consider the process placing beacons using plastic clips. For ease of perception, we present it in the form of a table.

Image	Process description
	On the prepared floor surface, the position of the beacons is marked, which should be installed in the direction of pouring the screed from the far wall of the room to front door parallel to the side walls (if the room is rectangular). From the side walls to the guides closest to them, an interval of 200-300 mm should be maintained. The distance between neighboring beacons is 1-1.5 meters. The rule applied to adjacent beacons must still have a margin of at least 200 mm on both sides.
	On the beacon position lines, holes are drilled with a hammer drill at intervals of 500 mm, into which dowels are immediately hammered.
	In the room where the beacons are displayed, there is the highest point, according to previously made calculations. At the corresponding point, the dowel is screwed in with a self-tapping screw, but not all the way. A laser level is installed and aligned along the baseline previously drawn on the walls.
	On direct wooden block a mark is made of the position of the screw head relative to the baseline, but taking into account the height of the beacon (10 mm) and the clip (2 mm). That is, 12 mm is added to the previously calculated screed level relative to the baseline. The block is installed vertically on the screw head and the position of the mark is controlled.
	By screwing in or unscrewing the self-tapping screw with a screwdriver, ensure that the mark on the block coincides with the beam of the laser level. The self-tapping screw at this point can be considered set, and all the others must be aligned with it.
	The laser level is installed on the floor and its beam should be higher than the head of the exposed screw. A long bit is clamped into a screwdriver. Then the bit is inserted into the slots of the aligned self-tapping screw vertically and controlled to ensure that the laser beam is on it.
	A strip of white masking tape is glued to the bat in a circle, then it is again placed vertically in the slots of the screw and the position of the laser beam is marked with a marker.
	Self-tapping screws are inserted into all previously installed dowels.
	Using a screwdriver, all screws are sequentially tightened to the level determined by the mark on the bit and the laser beam.
	Clips are put on the heads of the screws, and the adjacent ones should be oriented opposite to each other.
	The position of the clips is checked using a rule, a level and a laser beam. The rule should be that all clips lie strictly horizontally.
	Beacon profiles are inserted into the grooves of the clips. All profile joints must be made using clips only.
	The profiles are secured in clips with snap locks.
	The room is cleaned with a vacuum cleaner.
	The floor surface is primed with a deep penetration compound.
	After the primer has dried, a semi-dry solution of sand concrete is mixed and all beacons are strengthened with it. The same solution can be used to fix the position of the damper tape.

The proposed method is also good because the level can be set without the beacons themselves, and they can be put on immediately before laying the solution. This is very useful when the screed is reinforced.

Floor screed reinforcement

The question often arises about the advisability of reinforcing the screed, because by its intended purpose it is often not a power element bearing the main load. And this is partly true. But the absence of reinforcement can only be justified in connected screeds laid on a reliable concrete base, and in all other cases it will not be superfluous. Let's consider cases where reinforcement is required.

Screeds in a heated floor system must be reinforced, as they are subject to thermal expansion and contraction.
Floating screeds laid on insulation boards are also necessarily reinforced, since it has a much lower load-bearing capacity.
Ground screeds must be reinforced with reinforcement, since they are usually laid on a loose base. Another reason for reinforcement may be external factors, for example, seasonal swelling.
If heavy objects are installed in the room or the screed is subject to any dynamic loads, then reinforcement is required.
Screeds with a height of more than 5 cm are reinforced to prevent cracking during the drying process.

Can be used for reinforcement various materials. Let's consider which ones.

Reinforcement of screeds with metal mesh

The oldest proven method of reinforcing screeds is steel mesh made of reinforcement or wire. the former are used for heavily loaded floors on the ground, for example, in garages, and the latter in all other cases. Meshes for reinforcing screeds are made from VR-1 wire with a diameter of 2.5 mm to 6 mm. If earlier the frame was formed using thin wire, which was used to twist the laid rods, now meshes are offered, connected by spot welding. Cells can be square or rectangular shape, sizes from 50 to 200 mm. Obviously, the smaller the cell size and the thicker the wire, the more reliable the tie will be. Meshes made from thin wire (up to 3 mm in diameter) can be sold in rolls, and from thicker ones in the form of cards measuring 0.5 * 2, 1 * 2 and 2 * 3 meters.

A very important element in any wire mesh is the presence of notches on the rods, located in increments of 2-3 mm along the entire length. They significantly increase the adhesion area of the frame to the concrete mortar, which strengthens the finished screed. When purchasing wire mesh, you must strictly ensure that all wire intersections are welded, since not all manufacturers do this. And it is also worth checking the mesh for the absence of strong foci of corrosion, which will expand in a highly alkaline concrete solution when it hardens.

There are a lot of sources on the Internet that tell you how to “correctly” reinforce a floating screed with underfloor heating pipes. A wire mesh is placed on the layer of heat and waterproofing, and only then the heated floor pipes are attached to it with plastic clamps. The actions of such “craftsmen” can be seen in the photographs.

Such “reinforcement” is possible at its core - it is hiding expensive wire mesh under a layer of concrete. They do not perform any reinforcing function, since they will simply “roll” under the screed. In order for the reinforcement not to be useless, the meshes must be located inside the concrete, and they must be spaced at a distance from the base protective layer thickness not less than 15-20 mm. In thin screeds, the mesh will be located approximately in the middle, and in thick screeds it is better to place it in the lower third, so it will work better under various loads that arise.

When forming screed frame made of steel mesh be sure to overlap by 1 cell, but not less than 10 cm. For example, if a mesh with a cell of 10*10 cm is used, then adjacent canvases should overlap by exactly 1 cell, and if 20*20 cm, then half of it is enough . To ensure that the mesh is spaced at the same distance from the base, several methods are used:

The mesh is installed on hills of cement mortar - exactly the same as the screed will be poured. Sometimes this is combined with the installation of beacons. This is a completely acceptable method, but its main disadvantage is that the slides and the screed itself do not dry out at the same time. This can lead to heterogeneity of its structure and delamination. It is unacceptable to use gypsum solutions!
The reinforcing mesh is installed on supports made of pieces broken bricks, fragments of concrete or other available materials. This method is also allowed, but setting the grid at the same distance from the base is quite difficult. And then, when they lay the screed and move along the grid, some homemade supports may fly out. The use of wooden blocks is unacceptable, as they will increase in volume due to water and “tear” the screed.
The most modern and best way to install reinforcing mesh is to use special reinforcement clamps. They are made of plastic, have calibrated dimensions and are selected for any type of reinforcing mesh, for any thickness of the protective layer and for any base. Such “implanted” racks do not in any way affect the concrete or cement-sand structure of the screed for the worse. These products can be easily found in any normal building materials store or market. The price for them is cheap: approximately 0.8-1.6 rubles per 1 piece, if taken in bags of 1000 pieces. It is recommended to use at least 8-12 fasteners per 1 m². This depends on the diameter of the reinforcement or wire, the mesh pitch and the base material.

Reinforcement clamps - modern and The best decision for installation of reinforcing mesh

The most common reason, in which screed reinforcement is necessary in residential premises - this is a warm water floor. But placing a metal mesh on the base and then attaching pipes to it is a rather dubious task. The effectiveness of such “reinforcement” is close to zero. The most correct thing is to fasten the pipes to the thermal insulation, and place steel mesh on top of them on the reinforcement clamps.

Let us note the advantages of using steel reinforcing mesh for screed:

Such ties have the highest tensile strength, bending, for stretching and compression.
Excellent resistance to temperature changes over a very wide range.
Steel mesh laid on top of underfloor heating pipes allows temperature gradients to be distributed more evenly, since metal has thermal conductivity many times greater than concrete.
Properly installed screeds with steel reinforcing elements have a long service life.

Steel reinforcement has few disadvantages - high price and the ability to corrode if stored and installed improperly.

Reinforcement of screeds with polymer and composite elements

Progress does not stand still, so change traditional reinforcing steel elements others come from different polymers or composite materials. For a long time there was no alternative to traditional steel reinforcement, but now a worthy “rival” has appeared - reinforcement and mesh made of polymer and composite materials. Let's take a brief look at them and immediately note the advantages and disadvantages.

Composite reinforcement is rods of various diameters, which may have ribs similar to those on steel reinforcement or, for better adhesion, a sand coating is applied to them. The rods are formed from fibers and a polymer binder, which is why such reinforcement is called composite. The fibers used are glass, basalt or carbon, and therefore the reinforcement is called fiberglass, basalt-plastic or carbon fiber.

Composite reinforcement has a number of advantages, we list them:

Let us note the disadvantages of composite reinforcement:

Lower stiffness of composite reinforcement than steel.
Lack of ductility – high fragility.
The heat resistance of composite reinforcement is worse. Fiberglass loses its properties at 150 °C, carbon fiber at 300 °C, and steel only at 500 °C.
When cutting composite reinforcement, a large amount of dust harmful to health is generated. Especially it concerns fiberglass reinforcement.

They work with composite reinforcement in the same way as with metal reinforcement. When knitting frames, wire or plastic clamps are also used, and for installation, clamps or mortar pads are used. The correspondence between the diameters of steel and fiberglass reinforcement can be seen in the following table. The price of composite reinforcement is not lower than that of traditional steel, however, if there are large logistics costs for delivery to the site, then in the end its use may be cheaper. True, when installing the frame and pouring the screed, you must be careful, because composite reinforcement is much easier to break than steel, since it bends much worse.

Prices for fiberglass reinforcement

fiberglass reinforcement

To reinforce screeds located on reliable foundations, plastic meshes are now widely used. They are made of polypropylene or fiberglass with a special impregnation that prevents the effects of the alkaline environment inside the concrete. Nets are produced in a very wide range, with different cell sizes. For screeds, polypropylene mesh with a cell size of 35 to 50 mm is most often used. The width of the canvas is from 50 cm to 4 meters, and the length of the mesh roll is from 10 to 50 meters. Of course it is very convenient. Let us note the advantages of plastic meshes for reinforcing floor screeds.

The only drawback of plastic meshes is the impossibility of using them in rough screeds on the ground.

Fiber reinforcement of screed

Reinforcing the screed with microfibers (fiber) differs from all others in that the frame itself is not visible. But the reinforcement in the concrete mixture is still present in the form of thin fibers, evenly distributed in the solution, and after drying, in the thickness of the screed. They are the ones who reinforce the concrete in all planes, as they are located randomly. Their addition, even in small quantities, significantly increases the grade of concrete, impact resistance and strength. In fiber concrete (this is what concrete with added fiber is called) There is also an almost complete absence of shrinkage cracks. Fiber can be made from different materials:

Steel fiber – represents pieces of high-quality steel wire with a diameter of 0.2-1.2 mm and a length of 25-60 mm. For better adhesion to concrete, the ends of the wires are curved. Steel fiber is the strongest, but is not used in ties. Its purpose is concrete for massive monolithic structures, mainly prefabricated.

Fiberglass fiber significantly improves the quality of concrete, which allows reducing the amount of cement by up to 15% and water by up to 20%. IN monolithic structures and screeds are not used, since the fibers are made from a special alkali-resistant zirconium glass is very expensive. Therefore, glass fiber found yours application in decorative and structural plasters.
Basalt fiber is pieces of basalt fiber with a diameter of 20 to 500 microns and a length of 1 to 150 mm. Reinforcing concrete with basalt fiber increases its strength by 4-5 times, abrasion resistance by 2-3 times, tensile strength by 2-3 times, compressive strength by 1.5-2 times, water resistance by 2 times. This type of fiber can partially dissolve in cement mortar, but from this it only gains strength. It turns out that reinforcement occurs both chemical and mechanical. Consumption – approximately 0.8-1.2 kg per 1 m³ of finished concrete solution.

Polypropylene fiber is the most common a type of micro-reinforcement of floor screeds, since along with the excellent characteristics of concrete (almost like basalt fiber), its prices are lower. Polypropylene fiber does not enter into chemical reaction with concrete mortar and does not change its properties during the entire service life of the concrete. Consumption of polypropylene fiber is approximately 0.6-1 kg per 1 m³ of finished solution.

Adding fiber to a concrete solution is very simple; there are two ways to do this - dry and wet. All types of fiber, except basalt, can be kneaded dry. This means that the basalt fiber is first soaked in water, and then the dry ingredients of the mixture are added. Steel fiber is added only in a dry manner. That is, it is added to the sand, mixed, then cement is added, and then water.

It should be noted that mixing solutions with fiberglass will be of high quality only when this is done mechanically - using concrete mixer or mixer. The mixing time with fiber should be increased by at least 30% so that it is distributed as evenly as possible throughout the volume.

Conclusions regarding the reinforcement of floor screeds

The opinion of the authors of the article regarding reinforcement is clear - it is necessary in any case in one form or another. This is based primarily on personal experience, but also on an analysis of the opinions of professionals on numerous thematic construction forums. Here are the arguments:

Any properly executed reinforcement makes the screed better.
Highly loaded screeds, as well as those made on the ground, must be reinforced with a reinforcement cage.
Composite reinforcement does not provide any advantages over steel at current prices.
Any reinforcing frame must be inside the screed, and the thickness of the protective layer must be from 15 mm.
on a reliable basis, it is sufficient to use polypropylene reinforcing mesh.
It is always better to reinforce with polypropylene or basalt fiber, since the costs for this are disproportionately less than for all other components of the solution, and the result, if used correctly, is obvious.

Preparation of mortar for floor screed

The issue of proper preparation of the solution in the installation of floor screed is extremely important, since both the quality of installation and the period of further operation depend on it. If you “rewind” 20-30 years ago, then this issue did not arise at the construction sites of private houses in the territory of the former USSR. Either simply on the floor surface, or in homemade troughs, a solution consisting of cement, sand and water was mixed with shovels, and then it was laid on the floor surface using wooden graters, slats, and pieces edged boards and other available means. And many of the ties made then still serve today. But this does not mean that we should continue to use these “old-fashioned” methods.

Modern screeds are often made on a layer of insulation, and heated floors are also no longer a luxury item. Accordingly, the requirements for what kind of solution should be prepared also increase. Let us immediately tell readers that mixing with shovels on the floor or in a trough, as some current sources may even talk about, is an unmodern approach. A good screed should have a homogeneous structure, so preparing a solution for it is better to compare with the craft of a pharmacist, which from various containersusing beakers measures accurately required quantity ingredients and then mixes them until smooth. It is clear that the volumes of a pharmacist and a builder are different, but the attitude should be similar. And, of course, the preparation of the solution should be done only using mechanisms - mixers or concrete mixers (concrete mixers).

A drill mixer is a very useful device that comes in handy in household not once

Floor screed solutions can be prepared in two ways, each of which has its own advantages and disadvantages.

The first method is to prepare the solution yourself. At the same time, they are purchased in the required volume necessary ingredients, which are mixed in certain proportions. It should be taken into account that with this method experience or clear instructions are desirable, not to mention the quality of the individual components of the solution.
The second method is to use ready-made dry construction mixtures that are specifically designed for floor screed. This makes the job easier, but costs more.

Let's consider these methods separately and in more detail.

Making your own mortar for floor screed

Modern SNiPs do not at all interfere with self-cooking solution, but its grade must be no less than M-150, which means that each square centimeter of the screed must withstand a load of 150 kg. This is sufficient for simple screeds, but may not be enough for heated floors. In addition to the traditional screed components - cement and sand, it is also recommended to use a special additive - plasticizer . What does this give?

In order for cement to turn into stone, it needs a certain amount of water approximately equal to a quarter of its mass. For 100 kg of cement you need approximately 25 liters of water. But such a ratio will not allow obtaining a plastic and flowable cement mortar with fillers, so an additional amount of water is introduced into the mixture, which makes it possible to conveniently lay the mortar. Plasticizers make it possible to reduce the water-cement ratio to a minimum, which has a beneficial effect on both the rate of hardening and the final strength of the structure or coating.

Plasticizers are not a luxury, but a necessity

The use of a plasticizer avoids the appearance of air bubbles in the body of the screed. This is especially true when pouring heated floor screeds. When laying the screed, the air, due to the plasticity of the solution, freely escapes on its own, and cement-sand mortar better grips the underfloor heating pipeline.
The brand strength of the finished solution when using a plasticizer increases by 20-40%.
Solutions with a plasticizer have a frost resistance 50% higher than without it.
The “lifetime” of the solution, during which it can be worked with when laying the screed, increases significantly. This allows you to make batches in large volume and improve productivity.
The water resistance of screeds with plasticizer is significantly higher than without it.

We hope that we have convinced our readers of the need to use a plasticizer for screed. It can be found easily on sale in liquid or powder form. It can be called differently, but in terms of its chemical composition and in fact in 99% of cases it is a C-3 plasticizer. The liquid form is more convenient, since the plasticizer can be added directly to water to prepare a solution, while the powder requires preliminary dissolution of a certain amount in measured volume of water. All instructions for using the plasticizer are always indicated on the packaging.

Now let's look at how to prepare a time-tested solution for screeds.

Portland cement itself must be used as a binder. common brand M 400. You can also use M 500, then the screed will be even stronger. It is usually sold packaged in 50 kg bags, but for ease of transportation there are also 25 kg bags. Of course, it is necessary to check that the shelf life of the cement has not been exceeded.

It is recommended to use as a filler quarry sand, whose grains of sand have irregular shape with sharp edges. In a screed, such sand will adhere well on its own with you, with cement and foundation. With prolonged exposure to water, river sand takes on a smoother shape, which means it will peel off from the screed more readily.
Only clean water should be used to prepare the solution, free of impurities of petroleum products, fats and other contaminants. Naturally, water containers should also be clean and intended only for it. It should be noted that the required amount of water does not need to be added immediately, since a solution with a very high content can be obtained. This will have a bad effect on the ease of installation and strength of the screed. Sand may already contain some amount of water and the use of a plasticizer also greatly affects the water-cement ratio.

Now about the proportions of the ingredients of the screed solution. The proven “classic” for years is one part cement to three parts sand. We suggest calculating the exact amount using a calculator.

Calculator for calculating the amount of ingredients of a mortar for floor screed

The proposed calculator is very easy to use, requires a minimum amount of input data, and produces results with good accuracy. The only explanation for its use is the point about the difference in height of the screed. This is nothing more than the difference between the highest point of the base and the lowest, expressed in millimeters. We talked about this in our article when we looked at the installation of beacons.

A screed is the upper part of the floor structure, which serves as the basis for laying decorative flooring. Modern renovations, carried out both in new buildings and in apartments in old high-rise buildings, necessarily include work on screeding the floor. In order to start arranging the floors yourself, you need to know what materials will be needed and what thickness of floor screed will be optimal for your apartment. The nature of the work will largely depend on the characteristics of the room and the desired characteristics of the future floor.

Primary requirements

The screed layer in the entire floor structure performs a certain list of functions. With the help of this layer, the dynamic and static strength of the flooring is ensured, and also creates a smooth surface necessary for high-quality styling tiles, laminate or linoleum. The screed allows you to evenly distribute the load on those layers of the floor that are located under it, thereby extending their service life. With the help of a screed, they not only level the floor, but also create slopes provided for by the renovation project.

The screed in a living space must be strong enough to withstand the physical stress that occurs as a result of arranging furniture and moving people living in it around the room. The screed layer must be equally dense over the entire floor; any voids inside it, as well as chips and cracks, are not allowed. If the room is not specifically designed to have a floor with a slope at a certain degree, then in standard cases the surface after pouring should be horizontally flat with maximum slope at 0.2%.

The thickness of the screed has a direct relationship with the service life and strength of the floor structure. A specific number indicating optimal thickness subfloor, no. The thickness of the fill depends on the room in which the renovation is being carried out, what loads the floor is intended for, and what type of soil is used as the base. Both the choice of screed thickness and the choice of cement brand for pouring it, the use or absence of reinforcing elements during the work depend on these indicators.

What kind of screed can there be?

Standardly, there are three types of screed relative to its thickness. The first type includes a subfloor of small thickness. What thickness of screed is used in this case? To fill the floor, self-leveling mixtures are used, which are poured to a height of up to 2 cm. Pre-laying of reinforcing elements in this case is not carried out.

The second type of coating includes a floor with a height of up to 7 cm. This coating requires the presence of reinforcement or reinforcing mesh and is made of reinforced concrete. The third type of subfloor is a screed with a maximum thickness of up to 15 cm, which is a monolith with reinforcement inside. A thick screed is used in cases where it must simultaneously play the role of both the floor and the foundation of the house, connected into one system.

The final thickness of the screed depends on the materials used in the process of arranging the floor. Thus, concrete pouring with the addition of crushed stone can no longer have a minimum thickness. In this case, due to the crushed stone fraction thin layer it is impossible to complete the subfloor. For pouring a thin layer, the best option would be to use self-leveling and other mixtures intended for finishing the floor before laying the floor covering. Using the mixture, a thin and even layer of screed is created, which, after drying, can be immediately used as a base for decorative material.

Particular attention is paid to the thickness of the screed when installing heated floors. It is important here that the filling completely covers the heating elements. With standard pipe sizes of 2.5 cm, the total thickness of the screed for a warm water floor can be from 5 to 7 cm. It is not recommended to pour concrete to a height of more than 7 cm. According to experts, for the normal functioning of the floor and warming up the room, a 4 cm layer of concrete above the pipes is sufficient. A thicker layer will complicate the regulation of heat supply, since it will spend most of the energy on heating the concrete itself.

The maximum thickness of the screed can lead to another unpleasant consequence in the form of wall deformation. When heated, the concrete part of the floor expands and has a mechanical effect on the walls of the room. The thicker the screed layer, the stronger this effect will be. To exclude possible consequences Before pouring the concrete mixture, it is recommended to cover the perimeter walls with special tape.

Minimum screed

According to SNiP, the minimum screed height in a floor structure can be 2 cm. But there is one feature here, which is that depending on the material, the minimum screed height can be different. If the screed is made on the basis of metal cement, then a layer of 2 cm will be quite enough. If no reinforcing element is provided in the fill, then the minimum layer height cannot be less than 4 cm.

This requirement for a minimum screed is due to the fact that the floor covering must be characterized by a certain strength and wear resistance. A thin screed simply will not be able to provide the required performance indicators.

Pouring a thin coating can only be carried out if several conditions are met, which include an existing subfloor, a surface leveled with a rough screed and the absence of reinforcement. Thin screed is not recommended for indoor use technical purpose, and also where the mechanical load on the floors is very high. In an apartment, such rooms include the kitchen, bathroom and hallway - here experts advise pouring a fairly thick screed.

A thin screed is used to create a leveling layer necessary for further work. The sequence of work on a flat ground surface is as follows:

A layer of crushed stone and sand is poured, leveled and compacted efficiently;
Waterproofing is installed, which can be a simple polyethylene film;
A reinforcing mesh is installed and beacons are placed;
The concrete solution itself is poured.

The minimum thickness of a floor screed using reinforcing mesh cannot be less than 4 cm. Due to the presence of the mesh and the small height of the screed, the concrete used for pouring must be made from fine crushed stone. Compliance with this requirement will allow you to pour the solution in a thin layer, and the final screed will be quite strong. To increase the strength of the coating, it is recommended to add special plasticizers to the solution.

Maximum screed

There is no specific maximum possible thickness of the screed. The fill height will depend on many factors: the value is determined separately for each case. In technological terms, a height of more than 15-17 cm does not make sense; structures with such a height are created only when necessary, as they require a lot of time and materials.

It makes sense to thicken the layer if you are arranging the floor in a room where heavy loads are placed on the floor. The most simple example A garage can serve as such a room: the weight of the car and its impact on the floor when moving are large, so a screed height of 15 cm is quite justified.

A high screed is also used in situations where it will be part of the supporting structure. In this case monolithic filling large thickness becomes not only a floor, but a foundation. Experts recommend increasing the thickness of the screed if the base of the floor structure is problematic soil.

Sometimes height concrete pouring increase in order to hide significant differences in the surface. In practice, significant unevenness of the original surface occurs quite often, but a large screed thickness is not the only way to eliminate them.

Before deciding to pour a 15 cm high screed, many builders advise evaluating the possibility of using crushed stone or expanded clay to level out differences. Correct sudden changes with a powerful jackhammer. If surface imperfections can be corrected using these methods, then the need to pour concrete to a greater height will automatically disappear.

A minimum layer of fill will also not work in this situation, however, you will need a much smaller amount of material to screed the floor. If you level huge surface differences of 15 cm in size only with the help of concrete mortar, then your costs for the concrete itself and for paying for the work of builders will add up to a round sum. Most often, large expenses will not be justified, so it is worth doing at least partial leveling using a bulk layer of crushed stone.

Filling a screed of maximum thickness when installing warm water floors is also not financially justified. A large thickness of the cement layer above the heating elements will cause the floor to warm up slowly. The efficiency of such a design will ultimately be low, and heating costs will be simply enormous.

How to fill?

Filling a floor screed can be done in two ways: either with cement mortar or a special dry mixture. With the first method, you will get a concrete screed as a result, with the second - a semi-dry screed. Which option should I choose?

Concrete pouring is the most popular, but to use it you need to know several important points. The solution itself is prepared from cement, sand and water. Experts recommend buying cement of at least grade M-300 - with a particle fraction of 3-5 mm, such material will ensure high quality of the final coating. Using sand sifting rather than sand to prepare the solution will also have a positive effect on the final result: the adhesion of the sifting particles is significantly better.

To increase the strength of the future flooring and prevent cracking and destruction of the screed into crumbs in cement mortar plasticizers must be added. At this point you should pay attention Special attention for those who are going to make a screed for warm water floors. Plasticizers are special additives that increase the strength and ductility of the concrete layer.

The use of plasticizers to prepare the solution is also necessary when pouring thin floors. The minimum thickness of the screed without them can be only 4-5 cm; for a concrete floor of smaller thickness, the addition of plasticizers to the solution is a necessary condition.

Concrete screed requires a long time to dry. The solution must dry on its own; turning on the heated floor for this is strictly prohibited. The floor is dried for a month, and the surface is periodically moistened with water to avoid cracking.

Floor arrangement using special semi-dry mixtures in Lately gain popularity. This screed does not require adding large quantity water, dries faster and is more durable. The range of special mixtures for floor repair work today is quite large.

Unlike concrete mortar, semi-dry screed will take much less time, the main thing is to wait the period specified by the manufacturer. Once it has expired, you can begin installation. decorative covering and turn on the heating system if you installed a heated floor. The use of dry mixtures for pouring floors looks preferable when the time allotted for renovation work, are limited.

Semi-dry screed requires lower financial costs, but the performance characteristics of the final coating significantly exceed those concrete screed. Coatings made from such mixtures have better noise and heat insulation and are more resistant to cracks and peeling. After the material hardens, a perfectly flat surface is obtained, ready for laying laminate or parquet boards.

Or in commercial premises. The solution is prepared directly on site from simple ingredients– sand, Portland cement, water and special additives (anti-frost, plasticizers).

The cement-sand mixture is ideal for foundations where level differences do not exceed 5 cm. In other cases, it will lose its best performance characteristics.

Advantages and disadvantages

Due to its porous structure, cement and sand screed has excellent sound and heat insulation properties. It is quite durable and wear-resistant. Despite its excellent performance characteristics, the material has some disadvantages:

long period of drying and achieving design strength;
difficulties of filling due to the presence of “wet” processes;
significant weight, which increases the load on the floor;
thickness limitation – 5-7 cm;
If the pouring technology is not followed, the quality of the rough foundation is questionable.

Device technology

Before pouring the solution, the base is cleaned of contaminants. Marks are placed along the contour of the room that correspond to the top of the future subfloor. Guide beacons are installed on the prepared base, which will facilitate pouring and distributing the solution over the surface. A damper tape is fixed around the perimeter of the room, which will prevent the destruction of the material due to temperature changes.

To prepare the solution, certain proportions of cement and sand are used, which will create a structure of a certain strength. To increase the service life of the structure, it is additionally reinforced. Fresh solution is distributed between the slats using a rule, and when it sets, they are removed.

How much will it cost to fill a screed in Moscow?

Our company offers the most favorable prices in Moscow for the installation of cement-sand screed in premises of any purpose. In each case, we use the best materials and do not neglect the requirements of technology. The cost of the company's services can be found in our price list.

When renovating an apartment or building a house from scratch, it is important to think through all the nuances so that the final result is not only beautiful, but also of high quality. Much attention needs to be paid to preparatory work, including manufacturing. It is necessary to ensure that the foundation under your feet is strong and reliable, as well as for arranging the finished floor. And its long service life can be ensured only by properly manufacturing it. What is the minimum thickness of a floor screed? After all, making it is not a cheap pleasure, and a small consumption of materials would allow achieving a certain degree of savings.

Screed is an important and even basic element of almost any room. It must be made in any case, since without it it is impossible to properly lay the finished floor covering. The screed also performs additional functions of heat and waterproofing and will provide a good level of noise insulation if done correctly. But its main function is precisely in leveling the rough foundation and correctly distributing the load on the floors.

In order to level the base, that is, to implement the first function of the screed, in certain situations it is possible to make a very thin layer. So, sometimes it is enough to make a screed about 5 mm thick. But in order to achieve the correct distribution of the load on the base, which will depend primarily on the thickness of the layer, sometimes it is necessary to pour a much thicker layer.

On a note! The screed layer must easily withstand a compressive load of 15 MPa. Moreover, the slope of the base should be minimal and be no more than 0.2%.

Thus, the screed must be strong, reliable, have no cracks, and be even. The better this construction element is made, the greater the chance of getting floors that will last without complaints for many years.

What affects the layer thickness?

The thickness of the concrete screed layer depends on the influence of many factors. Let's consider the main ones:

the condition of the base, that is, the floors. This is one of the main factors influencing the final thickness of the screed layer. So, the greater the difference in height of the rough foundation, the thicker the screed will be. Otherwise, it will simply not be possible to achieve smooth floors. Plus, the base may be covered with cracks, have some protrusions - all this will affect the final thickness. That is, for example, if the base has very minor flaws, then the thickness of the concrete layer in the screed, according to SNiP, can be only 4 cm. If the height differences are too great, then you should prepare for the fact that the consumption of materials will increase - get rid of it with a minimum layer will not work;

Important! A screed that is too thin can quickly collapse, even if it is poured correctly. Therefore, when pouring a layer of minimum thickness, you will have to use reinforcing elements as an addition. If they are not used, the minimum layer should be at least 4 cm.

type of solution used. Some materials allow you to achieve a strong, but very thin base. So the mixture used to fill the screed will also affect its thickness. The minimum consumption will be indicated on the packaging. This point applies to all modern mixtures. Using conventional time-tested compounds or making a dry screed, you can expect that its minimum thickness in some cases can reach 8-15 cm. Sometimes you can use a trick - use it as a bedding, which will allow you to achieve the desired level, but at the same time reduce weight screeds and concrete mix consumption;

the presence of insulating layers for various purposes also affects the thickness of the screed layer. For example, the screed can be poured directly onto the floors if their condition allows this. And in this case, sometimes 2 cm of mixture is enough. But if there are layers, the screed will have to be made thicker. Even if only waterproofing is used.

It is important to remember that too thick a layer is not the best option. Excessiveness in this case can cause a decrease in the space between the ceiling and the floor, the material will take a long time to dry, and if used, it will require much more energy to warm up the base than with the optimal or minimum layer. Also, do not forget about the increase in the mass of the floors and the load on the floors. In some cases, making a heavy, thick screed is completely prohibited.

By the way, if you plan to install a heated floor, this also needs to be taken into account when creating a screed. It should completely cover all heat sources. For example, if the diameter of underfloor heating pipes is 2.5 cm, then the thickness of the screed should vary between 5-7 cm. Experts note that sometimes 4 cm of thickness is enough. A screed that is too thick is not an option, since a lot of thermal energy will be spent on heating the concrete itself.

SNiP 2.03.13-88. Floors. Downloadable file (click the link to open the PDF in a new window).

Video - Screed thickness in the presence of heated floors

What type of screed is there?

It was mentioned above that the thickness of the screed is also influenced by what it can be made of. Let's get acquainted with the main types of screeds.

Table. Types of screeds.

Type	Description	Minimum thickness
	Classic. This screed has been used in construction for decades and does not lose its relevance due to its reliability. However, it is quite heavy and cannot be used in all buildings. It is made independently from cement, sand and water.	4-5 cm or less. In the latter case, it is important to use additional reinforcement. When installed on concrete slabs, its thickness is at least 5 cm. If there is no reinforcement, it is at least 7 cm.
	In this case, the screed is made from special compounds that can spread independently over the floor with a little help. You can achieve the thinnest screed layer. Often used as a finishing coat on screeds before laying the final floor. Here the screed turns out to be very level relative to the horizon.	From a few millimeters to 2 cm.
	Ready-made mixtures are very convenient to use, but are not cheap. Often this option goes where more money than to create an ordinary concrete one. But bases made from ready-made mixtures dry faster, and the layer usually requires a much smaller thickness.	In this case, all recommendations for layer thickness should be looked at on the packaging - they are given by the manufacturer; the indicators for different mixtures may differ.
	In this case, the screed is made of expanded clay, special slabs and a number of other elements. It is lightweight and easy to install; it does not need to be dried and can sometimes be used immediately after installation.	The thickness can be approximately 10-15 cm. And the minimum is 3.5 cm, provided that the thickness of the slabs forming the surface is 2 cm.

In some cases, the thickness of a concrete screed can reach 15 cm. This is a monolithic heavy thick floor, within which reinforcement is necessarily used or for additional strengthening of the floors. In ordinary city apartments, this option is not used due to the fact that a significant load is created on the interfloor floors. But in a private house, this screed can itself become both a foundation and a floor at the same time.

The minimum thickness of the screed layer will also increase if bedding is used. It can be crushed stone or expanded clay, poured onto the ground or rough foundation, and then poured on top concrete mixture or fits . The thickness of the concrete layer cannot be less than 10 cm in this case.

Is it possible to make the screed thinner?

In fact, you shouldn’t deviate from the minimum screed thickness recommended by experts, even to save money. This will be unjustified, since a thin layer will be unreliable, and everything will have to be redone over time anyway. Of course, no one forbids saving on materials, but too thin a layer can:

cause rapid cracking of the screed;
serve an extremely short period of time;
be damaged when a heavy object falls on the floor;
cause improper heat distribution when installing floor heating.

On a note! Sometimes you can still get out of the situation - make a thin tie. But a reduction in thickness is allowed only if some kind of plasticizer is added to the mixture - for example, lime, detergent, PVA, etc. There are also a number professional means, which can be bought in stores.

Screed installation: general rules

Knowing all aspects of the design and installation of the screed, you can begin to work. However, it is worth remembering a few rules that must be followed during this process. And they are relevant for absolutely any type of screed.

You should always waterproof. Otherwise, your neighbors may be flooded while pouring the cement screed. And in the future, the possibility of pipe leaks cannot be ruled out. In this case, the neighbor's renovation will again be saved by the waterproofing layer. Also, in some cases, it allows you to get rid of adhesion, which is not always necessary when pouring screed.
Installation of damper tape must be mandatory. The bottom line is that the screed changes its physical parameters during the drying process and can either crack itself or damage the walls. And in any case, it will soften the pressure of the poured base on the walls of the room. It is better to install the damper tape before laying the waterproofing layer.