home

Cement screed in some places 2 cm. Choose the optimal thickness of the floor screed

The arrangement of the floor screed is a process that, with a good repair, and even more so construction, no one can avoid. And in this process, a lot of dusty, dirty and wet work is usually done. After them, the screed should be left to “ripen”, “helpfully” moisten for several days and not walk on the floor for quite a long time. Not to mention the money spent.

To make the result pleasing to the eye, and the process to take place 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 and prohibitively difficult in this, which we intend to convince our readers of.

Floor screed is an intermediate layer that is organized between any base and the floor finish. Why do you need a screed?

To give floors the required rigidity and strength according to expected loads.
To level the floor horizontally, or, conversely, to give the desired slope in some areas, for example, in showers.

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

For shelter and protection of the thermal insulation layer from mechanical stress.

In some cases, the screed itself is already the floor finish. For example, in garages, any technical or industrial premises, where another coating will not be laid in the future. Then, we can say that such a screed - single layer .

In many other cases, ties do two-layer .

The first layer levels the surface horizontally, or gives the desired slopes. Usually it is performed from a cement-sand mixture or concrete. It is customary to say that the first layer is rough screed . On it in the future, you can lay tiles or porcelain tiles.
The second layer is called finishing screed . It already makes the surface perfectly flat, under the floor finish, for example, under a laminate, parquet, carpet. Very often, a finishing screed is performed giving a perfect surface when properly applied.

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

Linked screed , 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 homogeneity of this design also provide excellent mechanical strength. Such screeds can only be done in those 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 be in contact of two different materials. For example, when a concrete screed is made on the ground. Or in the case when a 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 above the norm. As a separator, various bitumen-based roll materials (roofing material), polymer films or coating compositions can be used. Obviously, the screed will already be a separate structure, so it is desirable to reinforce it and make it at least 3-5 cm thick.
floating floor screed is a continuation of the previous one. It is necessarily arranged if any insulation is required. The floating screed is separated from the base by a layer of insulation along with waterproofing. It is also necessarily separated from the walls. It can be a heater, but of a smaller 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 still change in size due to temperature effects. Working in such conditions forces the use of reinforcement and has 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. Most often used granular, which is a good heat and sound insulator. Sheets are laid on top of it gypsum fiber plates attached to each other. Such a screed is equipped very quickly and this is its main advantage. However, dry screeding can only be done in rooms with guaranteed low humidity and with a low or medium load on the floor.

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

Solid floor screed, performed by a "wet" method . This is the most common, you can even say the classic way. The solution, closed with water, is applied to the prepared base and leveled along the beacons by the rule. Since the main binder for the wet method is 95% cement, such screeds gain full strength only after 28 days, which is a big disadvantage.
Solid floor screed, performed in a "semi-dry" way . This direction began to develop relatively recently. The meaning of this approach is that exactly the amount of water that is necessary for cement hydration is added to the working solution. Such screeds dry out faster - the next day you can already walk, and lay the tiles in a week. A plasticizer is introduced into the solution, which improves mobility and plasticity during laying. In addition, semi-dry screeds often use micro-reinforcement with fiber (polypropylene or basalt). The screed with fiber is better in terms of strength, wear resistance, stretching and bending than with classic wire mesh reinforcement. The technology of laying semi-dry screeds is more complicated, the preparation of the solution requires precise adherence to the recipes.

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

Solid floor screed with self-leveling compounds . This method also applies to "wet". As we noted in this way, it is very convenient to make a finishing screed. Such screeds are made with a thin layer of 0.5-20 mm, first of all for economic reasons, since dry mixes for the preparation of solutions are very expensive. But the laying technology and the result observed later are above all praise. The working solution is simply poured over the surface in stripes, rolled with a spiked roller to remove bubbles, and, in fact, that's it.
Dry or prefabricated floor screeds. We have already mentioned them before. You can read more about them on our website.

All floor screeds, with the exception of prefabricated (dry), are made on based on two main binders component - cement or gypsum. There are also others - magnesia, bituminous, anhydrite - but they are not used for housing construction, and therefore will not be considered. We note the strengths and weaknesses of these two basic materials.

cement screed prices

cement strainer

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

Naturally, in addition to the binder 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 obtained in chemical industries. Therefore, modern mixtures cannot be called only cement or gypsum. It's more correct to speak cement-polymer or gypsum-polymer .

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

If you want 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 plus of the use of 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, while gypsum screeds partially overcome the “fear of water”. But, I must say that "hereditary diseases" in one form or another still remain. Therefore, cement-based screeds are still the most versatile. There is also a place for gypsum-polymer, but only in dry rooms, where exposure to water in any form is excluded.

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

Foundation preparation;
Displaying lighthouses;
Solution preparation;
Floor screed device.

At each stage, we will try to explain the whole process in detail, accompanying with photos and videos. So let's start.

Preparation of the base for floor screed

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

The basis of the screed - soil

The best time to equip rough floor screeds on the ground is the stage of foundation construction. Then all earthwork and other work is much easier to carry out. And in modern construction they do just that. If this is done in an existing house, then, of course, the task is greatly complicated, but it is not fundamentally different. Let's note the main stages of preparation.

The first thing to do is to choose the soil to a depth of at least 50 cm. In each case, the depth may be different. The bottom of the pit is cleaned and compacted.
If the soil is clayey or loamy soil, 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 with a layer of at least 100 mm. More is possible, but note that 100 mm is the lower limit. The sand is then rammed with a manual rammer or with an electric or petrol rammer.

It should be noted that the maximum allowable layer of sand you need to tamp - this is 200 mm. If a larger layer is planned, then the ramming work is divided into stages, but no more than 200 mm at a time. In the process of tamping, it is necessary to periodically water the sand with water from a hose.
A layer of crushed stone or gravel of a large fraction 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 more space is left to the level from which the future floor screed on the ground will already be formed.

Prices for vibrating plates

vibrating plates

If there is still 150-200 mm available, then a layer of concrete with the addition of expanded clay can be laid on a gravel-sand cushion. This will be the first stage of thermal insulation, but it 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 has a low content of a binder - cement. Lean concrete usually has grades M 100 (B7.5) or M 150 (B10). The task of such a layer is not to carry the main load, but to fill in the irregularities of the underlying layer, level the surface and prepare it for waterproofing.
Another case in the preparation of soil floors for a screed is the absence of 150-200 mm for the expanded clay concrete layer. Then lean concrete comes to the rescue again. It is laid directly on the rubble, and the concrete layer should also not exceed 100 mm, 40-60 mm is more than enough. When laying, be sure to ram it so that the solution penetrates into the space between the rubble stones. With the help of a trowel, a rule and a grater, it is necessary to form a flat outer surface, which will be the basis for the future floor screed.

The next steps are the same for both cases. After the “laying” of lean concrete has dried, it is imperative to carry out waterproofing measures. For this, bituminous mastics are used, with which the entire surface is coated with at least two layers. Do not forget about the fact that mastic must be coated with walls to a height not less than the height of the floor screed. In regions with a high level of groundwater, after mastic, it will not be superfluous to roll on the basis of bitumen or dense plastic film, overlapped.

Screed base - old screed

Those who got this option should not be envied, 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 “blow” when tapped and has a flat surface without cracks. Let's give the arguments.

a new screed, the "perfection" of the old one can easily be broken. Under new conditions, delamination from the base can occur, cracks that will affect the top layer as well.

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

Each screed “eats up” at least 5 cm of space, which is already very significant in standard housing. In addition, there may be problems with radiators, pipes suitable for them, thresholds and door leaf.

Ties are never made so that they cannot be dismantled. It seems to be logical sometimes to connect two layers with reinforcing bars or wire, but no. Even connected concrete screeds are held together only by 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. From experience, it will be much cheaper this way. You should not even try to do it alone, as both the owners and neighbors will be exhausted if the screed is removed in an apartment building. A professional team immediately arrives with all the necessary mortising and stone-cutting equipment, shovels, garbage bags, and a vacuum cleaner. They immediately take away all the garbage collected during mortising, and the owner does not have to worry about calling a separate car. The work of professionals goes on in a continuous mode: one or two people are hammering, 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 negotiate with everyone who may be uncomfortable with noise. In panel houses - this is the whole house. And, of course, make sure that after the departure of the brigade on the site and in the entrance there are no traces of the presence of "noisy guys" and dust from the old screed.

In private houses, everything is simpler, you don’t have to negotiate with neighbors. You can try it yourself, but you still can’t do without helpers. To dismantle the old screed, you will definitely need a powerful puncher with a cartridge not SDS +, not SDS-Max. The puncher will also need chisels. Jackhammers are sometimes used, but this step can only be taken if this tool is in the hands of a professional. Improper use of a powerful jackhammer can easily break a concrete reinforced slab.

In addition to a puncher, 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 working clothes made of dense fabric and in a headdress, gloves, 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 master 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 in one day, so assistants are definitely needed. Let's describe the main stages of dismantling the old screed.

If there are electrical wiring routes, heating or water supply pipes in the room under the screed, then a circuit is desirable, which should remain after installation. If it is not there, then you will have to use a special device - a hidden wire and metal detector, which needs to examine the entire area of \u200b\u200bthe 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 further move deeper into it. So it will be easier to immediately remove the exfoliated pieces of the old screed. But before starting the dismantling, it is necessary to carry out "exploratory drilling". To do this, in a small area, cuts are made with a grinder with a stone-cutting disc, and then small pieces of the screed are broken off with a puncher with a spatula or a jackhammer to get to the next “cultural layer”. If that layer is the desired carrier plate, then you need to measure the thickness of the removed screed with a tape measure in order to know the landmark.
It is necessary to start to beat off the old screed with small revolutions of the perforator engine and first chip off in small pieces. Further, when the degree of adhesion of the screed to the base is already clear, it is possible to increase the speed and break off in large pieces. Intuitively everything will be clear. When working, always take a stable body position and hold the tool with only two hands. It is not necessary to press hard on the puncher or jackhammer, this does not affect the force from the blow, but the hands will get tired faster.
It is better to remove pieces of a broken screed immediately with shovels, load them into strong bags and take them out to a certain place for subsequent removal. This is another argument in favor of the need for helpers.

Breaks are required during work. This is necessary both for resting the hands and for cooling the instrument. After 15 minutes of work - rest 5 minutes. And it is also desirable that their operators also change behind the perforator or jackhammer. But this can only be done if others have good skills in working with the instrument.
If the old screed is reinforced with wire mesh, then before dismantling with a grinder with a stone-cutting disc, cuts must be made to a depth that would ensure cutting of the reinforcing mesh. The work of the grinder must be combined with the work of a vacuum cleaner, since there were a lot from cutting concrete. The surface is “shredded” into rectangles, such that it is convenient to carry them away in bags, and only then chiselling is performed.
Those places where pipes or hidden wiring pass a large puncher or jackhammer should bypass. 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. And you also need to be careful in the corners and near the partitions, especially if they are made of drywall or cellular concrete.
After dismantling and removing all debris, the surface of the base is cleaned with a perforator with a wide spatula from the remnants of the old screed. Then the room is swept, the floor and air are sprayed with water from the sprayer and 15-20 minutes are given for all the dust to settle. The vacuum cleaner removes the remaining dirt.

Prices for polystyrene concrete

polystyrene concrete

It happens that after dismantling the screed, a “cultural layer” with ceramic tiles laid on the floor is exposed. And it happens that this tile was laid back in the 50-60s of the last century. On construction and repair forums, the question often arises of what to do with this tile? Repulse her or not? Opinions on this issue vary. Our opinion is unequivocal - beat off!

The tile, laid in the days of developed socialism in the USSR, has two extremes when it is dismantled. Either she literally "jumps" from the base herself, or "stands to the last." And It happens that tiles behave differently in one area. And all because before there were no tile adhesives with predictable properties in the arsenal of masters. Therefore, they glued who on what much. Just cement was used, and cement with PVA, and Bustilat glue, and even epoxy resin and some other "brutal" compounds with ammonia. Moreover, they were glued 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 the stronger the impact of the perforator, the more likely the tile will lag behind the base. However, practice shows that a small hammer with a sharp blade can handle old tiles better than a "monster" but with a more blunt blade. That is, when dismantling an old tiled coating, it is not the strength 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 basis of the screed is a concrete slab

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

First of all, it is necessary to provide the workplace with 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 formulation that will be used for the future screed. And also with this solution, you can close up the junction of walls and floors, in which there may be gaps.
All dried mortar splashes, lime and others on the surface, as well as everything that lends itself to a spatula and a hammer, is beaten off and cleaned.
If there are large depressions on the upper surface of the plates, then they can also be smeared with the same solution as the joints between the plates.
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 deep penetration primer is applied with a roller. After the first layer has dried, the second one is applied. Primer treatment is mandatory in any case, even if a screed is made on the separating layer.
If the screed is bound, then a special compound is recommended for use - Betonkontakt, which incorporates a complex of polymers, cement and quartz sand. After treatment with this primer, the surface becomes rough, to which all building materials “stick with pleasure”. However, we advise you to apply " Betonkontakt"After setting up the beacons, in order to exclude damage to the surface created by this soil.

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

At this stage, the preliminary preparation of the surface can be considered completed.

Prices for "Betonkontakt"

betonkontakt

Setting beacons for floor screed

The floor surface intended for screeding is rarely completely flat. In addition to the unevenness of the relief and the profile of the floor slabs themselves, in most cases the rough surface has a slope in one direction. If in a separate room a slope of 3 mm per 1 meter is imperceptible, then on the scale of the house it can already turn into several centimeters, which is unacceptable. It is always necessary to 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 made only in its interests. In no case! You can make a screed in a room, but taking into account the whole apartment or the whole house.

In order for the floor level in an apartment or house not to “dance” as it pleases, it is necessary to beat off the zero level in all rooms. It is very easy to do this if you have a laser plane builder at your disposal, which has long ceased to be a luxury. Let's describe the methodology.

In a certain place, a laser level is installed on a tripod so that it can capture the maximum number of rooms with its beam. It is better to install it at a height that is comfortable for work - about 140-150 cm. On the walls of the premises, marks of the position of the beam are made with a marker.

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

The minimum and maximum distance from the baseline to the floor surface is found. In the example shown, the minimum distance is 1420 mm and the maximum distance is 1445 mm. The height difference is 25 mm.
For example, the recommended minimum screed thickness for sand concrete of any brand is 30 mm. This means that from the highest point it is necessary to set aside 30 mm and get that the zero level will be 1420 - 30 = 1390 mm from the baseline. The thickness of the screed in this case will vary from 30 mm to 55 mm. This is perfectly acceptable.

These calculations are very appropriate to put on the plan of the house. Such a document will be very useful in the future, since the screed 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 properly arrange beacons. These actions cannot be called heavy physical labor, but a lot depends on the correct placement of beacons. It is they who set the floor surface and from the slightest mistake all further work can lead, at worst, to further elimination of shortcomings, and at best, to banal overexpenditure of the dry mix from which the screed solution will be prepared.

Let's take an example. Let's say there is an apartment of 100 m² in which you need. For this, sand concrete M 300 will be used, in which the minimum layer size is 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 that the average thickness of the screed will be approximately (30 + 55) / 2 = 42.5 mm or 4.25 cm. The average consumption of sand concrete M 300 is 20 kg per 1 cm of thickness and an area of 1 m². It turns out that there will be an expense for the whole apartment: 4.25 * 100 * 20 \u003d 8500 kg of dry mix, which will be 212.5 bags of 40 kg.

Now imagine that when installing beacons, the master, instead of the minimum 3 cm at the highest point, set 4 cm with an “iron” argument “the pocket does not pull the stock”. We recalculate: an extra 1 cm added to the screed over the entire area of 100 m² will result in 20 * 100 \u003d 2000 kg, which will be an additional 50 bags in 40 kg bags. It turns out that the stock still "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 have to be dragged to prepare the mortar and lay it down.

All readers probably know that the most inconvenient load during transportation and especially lifting to the floors is a piano. Loaders shy away from it "like fire" and calculate at a special rate. The average weight of one piano is 250 kg. It turns out that plus 1 cm of the tie 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 set up beacons to describe them all in one article. Each master has his own favorite way, which does not have to be similar to others. In principle, what's the difference if, with different methods of setting 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 screed. Someone prefers to make lighthouses from a solution, someone uses pipe segments. The ceiling guide profile is very widely used, " borrowed» in drywall 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 it is done in the figure.

In the method of placing beacons we are describing, we will use the PM-10 beacon profile, originally conceived for plaster, but 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 various ways.

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

When the beacon profile is pressed into the mortar pad, make sure that it is pressed against the rule along its entire length. Excess protruding above the lighthouse is cleaned. When the solution dries, you can begin the main work on the screed. For a cement-sand mortar, at least 1-2 days must pass for the lighthouse to be fixed, therefore, to speed up the process, some craftsmen use adhesive gypsum mortars or even alabaster. The beacon in this case is fixed almost instantly and work on laying the screed can be started 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 for different materials are different. Therefore, beacons should be installed only on the solution with which the screed will be made.

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

This clip consists of two parts - the clip itself and the lock that fixes the beacon. This type of fastening of the beacon is good because the clip itself can be mounted on the head of the self-tapping screw after it is screwed in and adjusted in height. For this there is a special groove. Then, already after the beacon is put into the clip, the final fixation with the lock is in progress. It turns out a very reliable mount, which can still be adjusted in height. The price for such clips is cheap - 100 pieces cost 250-300 rubles.

Consider the process placing beacons with plastic clips. For convenience 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 the 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 laid down for neighboring beacons must still have a margin of at least 200 mm on both sides.
	On the position lines of the beacons, with an interval of 500 mm, holes are drilled with a perforator, into which dowels are immediately hammered.
	In the room where the beacons are placed, there is the highest point, according to previously made calculations. At the corresponding point, the dowel is screwed in, but not completely. The laser level is set and set according to the baseline previously drawn on the walls.
	On a straight wooden block, a mark is made on 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 bar is installed vertically on the head of the screw and the position of the mark is controlled.
	By screwing or unscrewing the self-tapping screw with a screwdriver, the mark on the bar and the laser level beam are matched. The self-tapping screw at this point can be considered set, and all the rest must be set on the same level with it.
	The laser level is installed on the floor and its beam should be above the cap of the exposed screw. A long bit is clamped into a screwdriver. Then the bit is inserted vertically into the slots of the exposed self-tapping screw and it is controlled that the laser beam is on it.
	A strip of white masking tape is glued onto the bit in a circle, then it is again placed vertically in the slots of the self-tapping screw and the position of the laser beam is marked with a marker.
	Self-tapping screws are baited into all previously mounted dowels.
	A screwdriver sequentially tightens all the screws to the level determined by the mark on the bit and the laser beam.
	Clips are put on the heads of the self-tapping screws, and the neighboring ones should be oriented opposite to each other.
	The position of the clips is checked with a rule, a level and a laser beam. The rule must lie on all clips strictly horizontally.
	Beacon profiles are inserted into the grooves of the clips. All profile joints should fall only on clips.
	Profiles in clips are fixed with latches.
	The room is cleaned with a vacuum cleaner.
	The surface of the floor is primed with a deep penetration compound.
	After the primer dries, a semi-dry sand concrete solution is mixed and all beacons are reinforced with it. The same solution can 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 being reinforced.

Floor screed reinforcement

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

Screeds in the underfloor heating system are necessarily 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 bearing capacity.
Ground screeds must be reinforced with reinforcement, as they are usually laid on a loose base. Another reason for reinforcement may be external factors, such as seasonal swelling.
If heavy objects are installed in the room or the screed is subject to any dynamic loads, then reinforcement is mandatory.
Screeds with a height of more than 5 cm are reinforced to avoid cracking during the drying process.

For reinforcement, various materials can be used. Let's consider what.

Reinforcement of the screed with metal meshes

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

A very important element in any wire mesh is the presence of notches on the bars, located in increments of 2-3 mm along the entire length. They significantly increase the area of adhesion of the frame to the concrete solution, which strengthens the finished screed. When buying 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 grids 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 how to “correctly” reinforce a floating screed with underfloor heating pipes. A wire mesh is placed on a layer of heat and waterproofing, and only then pipes of a warm floor are attached to it with plastic clamps. The deeds of such "craftsmen" can be seen in the photograph.

Such "reinforcement" is inherently possible - 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, while they must be separated from the base on a protective layer with a thickness of at least 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 occur.

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

The grid is installed on the slides from the cement mortar - exactly the same as the screed will be poured. Sometimes this is combined with the installation of beacons. This is a perfectly acceptable method, but its main drawback is the non-simultaneous drying of the slides and the screed itself. This can lead to heterogeneity of its structure and delamination. The use of gypsum solutions is unacceptable!
The reinforcing mesh is installed on supports made of pieces of broken brick, fragments of concrete or other improvised materials. This method is also allowed, but it is quite difficult to set the grid at the same distance from the base. And further, when the screed is laid and moved along the grid, some homemade supports may fly out. The use of wooden blocks is unacceptable, as they will increase in volume from the water and “tear” the screed.
The most modern and best way to install reinforcing meshes is to use special reinforcement retainers. 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 the least 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: about 0.8-1.6 rubles per 1 piece, if you take packages of 1000 pieces. For 1 m², it is recommended to use at least 8-12 clamps. It depends on the diameter of the reinforcement or wire, the mesh pitch and the base material.

Reinforcement clamps - a modern and best solution for installing reinforcing meshes

The most common reason why screed reinforcement is necessary in residential premises 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 on top of them already place steel meshes on the reinforcement clamps.

We note the advantages of using steel reinforcing mesh for screed:

Such ties have the highest strength: tensile strength, bending, for stretching and compression.
Excellent resistance to temperature extremes over a very wide range.
Steel grids laid on top of underfloor heating pipes make it possible to distribute temperature gradients more evenly, since metal has a thermal conductivity many times greater than concrete.
Properly mounted screeds with steel reinforcing elements have a long service life.

There are few disadvantages of steel reinforcement - this is a high price and the ability to corrode if stored and installed improperly.

Reinforcement of the screed with polymer and composite elements

Progress does not stand still, so to replace traditional reinforcing steel elements others come from various 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 meshes made of polymer and composite materials. Let's briefly consider them and immediately note the advantages and disadvantages.

Composite rebars are bars of various diameters, which may have ribs similar to those found on steel rebar, or be coated with sand for better adhesion. The rods are formed from fibers and a polymer binder, which is why such reinforcement is called composite. Fibers use 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:

We note the disadvantages of composite reinforcement:

Lower stiffness of composite reinforcement than steel.
Lack of plasticity - high brittleness.
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. This is especially true for fiberglass reinforcement.

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

Prices for fiberglass reinforcement

fiberglass reinforcement

Plastic meshes are now widely used to reinforce screeds located on reliable foundations. They are made of polypropylene or fiberglass with a special impregnation that prevents the effects of an alkaline environment inside the concrete. Grids are produced in a very wide range, with different mesh sizes. For screeds, polypropylene meshes with a mesh size of 35 to 50 mm are most commonly 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. We note the advantages of plastic mesh for reinforcing the floor screed.

The only drawback of plastic nets is the impossibility of their use in rough screeds on the ground.

Fiber screed reinforcement

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

Steel fiber - is a piece 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 screeds. Its purpose is concrete for massive monolithic structures, mainly prefabricated.

Fiberglass fiber - significantly improves the quality of concrete, which allows you to reduce the amount of cement up to 15%, and water - up to 20%. It is not used in monolithic structures and screeds, since fibers from a special alkali resistant zirconia glass is very expensive. Therefore, fiberglass fiber has found his application in decorative and structural plasters.
Basalt fiber is a piece of basalt fiber with a diameter of 20 to 500 microns and a length of 1 to 150 mm. Reinforcement of 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 the cement mortar, but from this it only gains strength. It turns out that reinforcement occurs both chemically and mechanically. Consumption - approximately 0.8-1.2 kg per 1 m³ of ready-made 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 with basalt fiber), its prices are lower. Polypropylene fiber does not enter into a chemical reaction with concrete mortar and does not change its properties during the entire service life of concrete. The consumption of polypropylene fiber is approximately 0.6-1 kg per 1 m³ of the finished solution.

Adding fiber to concrete mortar is very simple, there are two ways to do this - dry and wet. All types of fiber, except for basalt, can be kneaded in a dry way. 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 way. That is, it is added to the sand, mixed, then cement is added, and then water.

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

Conclusions about the reinforcement of the floor screed

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

Any properly made reinforcement makes the screed better.
Highly loaded screeds, as well as those made on the ground, must be reinforced with a reinforcing cage.
Composite rebar offers no advantage over steel rebar 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 a polypropylene reinforcing mesh.
Reinforcement with polypropylene or basalt fiber is always best done, since the cost of this is disproportionately less than for all other components of the solution, and the result, if used correctly, is obvious.

Preparation of floor screed mortar

The question of the correct preparation of the solution in the arrangement of the floor screed is extremely important, since both the quality of the installation and the period of further operation depend on it. If you “rewind” 20-30 years ago, then there were no issues with this at the construction sites of private houses on the territory of the former USSR. Either just on the floor surface, or in makeshift troughs, a solution consisting of cement, sand and water was kneaded with shovels, and then it was laid on the floor surface using wooden graters, slats, pieces of edged boards and other improvised means. And a lot of screeds, made then, are still serving. But this does not mean that we should continue to use these "grandfather" methods.

Modern screeds are often made on a layer of insulation, and warm floors are also no longer a luxury item. Accordingly, the requirements for which solution should be prepared also increase. We will immediately tell readers that mixing with shovels on the floor or in a trough, which some current sources can even talk about, is an outdated approach. A good screed should have a uniform structure, so the preparation of a solution for it is better compared with the craft of a pharmacist, which from various containerswith the help of beakers accurately measures the right amount of ingredients, and then mixes them until smooth. It is clear that the volumes of the pharmacist and the builder are different, but the ratio should be similar. And, of course, the preparation of the solution should be carried out only using mechanisms - mixers or concrete mixers (concrete mixers).

A drill mixer is a very useful device that will come in handy in the household more than once.

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

The first way is self-preparation of the solution. At the same time, the necessary ingredients are purchased in the right volume, which are mixed in certain proportions. It should be noted that experience or clear instructions are desirable with this method, not to mention the quality of the individual components of the solution.
The second method is the use of ready-made dry building mixes, which are specially designed for floor screed. This simplifies the work, but costs more.

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

Self-preparation of floor screed mortar

Modern SNiPs do not in the least interfere with self-preparation of the 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 underfloor heating. In addition to the traditional screed components - cement and sand, it is also recommended to use a special additive - plasticizer . What does it give?

In order for cement to turn into stone, it needs a certain amount of water, approximately equal to a quarter of its mass. Approximately 25 liters of water are needed for 100 kg of cement. But such a ratio will not allow to obtain a plastic and fluid solution of cement with fillers, therefore, an additional amount of water is introduced into the mixture, which makes it possible to conveniently lay the solution. Plasticizers allow you to minimize the water-cement ratio, 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 in the pouring of underfloor heating screeds. When laying the screed, due to the plasticity of the solution, the air freely exits itself, and the cement-sand mortar better “encloses” the underfloor heating pipeline.
The grade strength of the finished solution when using a plasticizer increases by 20-40%.
Solutions with a plasticizer have frost resistance 50% higher than without it.
The “life” time of the solution, in which it can be worked with when laying the screed, increases significantly. This allows you to make batches in a large volume and increase productivity.
The water resistance of screeds with a 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 easily found on sale in liquid or powdered form. It can be called differently, but according to its chemical composition and in fact in 99% of cases it is a C-3 plasticizer. measured volume of water. All instructions for the use of the plasticizer are always indicated on the packages.

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

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

As a filler, it is recommended to use quarry sand, in which grains of sand have an irregular shape with sharp edges. In a screed, such sand will adhere well by itself. with you, with cement and foundation. River sand with prolonged exposure to water takes on a smoother shape, which means it will more readily peel off the screed.
Water for the preparation of the solution should be used only clean, free of impurities of oil products, fats and other contaminants. Naturally, water containers should also be clean and intended only for her. 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 of it can be obtained. This will have a bad effect on the convenience of laying and the strength of the screed. The sand may already contain some 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 “classic” proven over the years is one part cement to three parts sand. We propose to calculate the exact amount using a calculator.

Floor screed mortar ingredient calculator

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

Hello! After reading today's interview, you will find out how to make a floor screed. The right screed is the basis of a good floor, whether it be laminate, parquet, linoleum or tile. Master Vadim Alexandrovich answers all our and your questions today.

Hello, Vadim Aleksandrovich! We want to learn how to do floor screed correctly.

Good afternoon, dear readers! Let's get started soon, I hope my advice will be useful.

Please tell us why we need to do a floor screed at all, because in most cases the floor is already even?
The screed has several purposes. Here are the main ones:

1. Leveling the floor if it is uneven or not level.

2. Alignment of floor levels in different rooms. During construction, this situation often occurs - the floor level does not converge by 1-2 centimeters due to level measurement errors or improper pouring of concrete. Because of this, further work is not possible, for example, laying laminate or linoleum. Yeah, and who wants steps between rooms?

3. Heated floor. Two ties are made - one after the insulation layer, the second after the heating wire.

What types of floor screed are there?

Screeds are of four types:

1. Cement-sand screed. The most common type of tie. A significant advantage of this type over others is the price and simplicity. Most people mean this type when they hear the word "screed".

2. Dry floor screed. This type is still unpopular for some reason, despite its main advantage - the speed of production. No need to prepare the solution, and then wait until it cools down - you just need to lay dry bulk material, lay gypsum boards on top. And everything is ready.

3. Self leveling. But this method is just rapidly gaining popularity. Lighthouses are not needed here, there is no need to level - the mixture itself spreads horizontally. The disadvantage is that only a thin layer (up to 2 cm) can be poured.

4. Combined. Cement-sand + self-levelling. Its main purpose is to get a perfectly flat floor if you need to change the level significantly.

Do I need to prepare the surface in some way?

Yes, it is necessary to prepare the surface, but there are no tricks here - we just remove dust and debris, you can moisten the floor before pouring a cement-sand or self-leveling screed.

Tell me step by step about the screed procedure itself.

Okay, I'll talk about cement-sand and self-levelling screed, dry screed will be discussed in the next interview, since the way it is laid is radically different.

1. It is necessary to set the required level with a water level or a level. Remember that the minimum thickness of a cement-sand screed is 3 cm, and the maximum thickness of a self-leveling screed is 2 cm.

2. Beacons must be installed for cement-sand screed. Most often, ready-made beacons are used, but if they are not there, then you can use the "old-fashioned way" and use the boards. Lighthouses are installed at a distance of just over a meter from each other. We attach to the floor with a thick cement mortar.

3. Next, prepare the solution. The proportions of sand and cement, depending on the brand, are given in the table. Ready-made mixtures are sold in stores, which we simply dilute with water. If you do not have any extreme loads on the floor, then use a solution of brand 150 or 200, depending on finances.

Grade of cement	Proportions	Solution grade
600	1:3	300
600	1:4	200
500	1:2	300
500	1:3	200
400	1:1	300
400	1:2	200
400	1:3	150
300	1:1	200
300	1:2	150
300	1:3	100

4. Fill. We simply pour the self-leveling mortar and wait about two weeks until it dries completely, and pour the cement mortar between the beacons and, as a rule, level the mortar level along the beacons. We lay the solution from the far corner of the room and stretch it towards ourselves, otherwise we ourselves will find ourselves in the corner and will not be able to get out. So that there are no cracks, it is necessary to moisten with water two or three times during hardening. And in a couple of days it will already be possible to walk, and we need to get the beacons and fill in the cracks, otherwise the beacons will start to rust. We wait three to four weeks until it dries completely.

Everything, the screed is ready! If we did all the steps correctly, then we will get a horizontal, even floor without large cracks. Some builders claim that cracks are normal, but this is not true - only small surface cracks are allowed. The rest is bullshit. Well, small cracks in the cement-sand screed can be removed by pouring a couple of millimeters of self-leveling mortar from above.

Thank you, Vadim Aleksandrovich, for your story! Come visit us for more interviews.

Please, I will definitely come. I hope my advice will help people in the repair.

Kira says: 08/08/2013 at 09:36

When I throw a self-leveling screed, I also put beacons. then it is easier to stretch and lies more evenly.

Admin says: 10/17/2014 at 10:56 am

If you are laying tiles, then it is not necessary, only if there are gaps between the walls and the floor, then you can first coat it with a waterproofing solution. If without tiles, then you need to cover the entire floor with a waterproofing solution

Admin says: 10/17/2014 at 17:34

It depends on your solution. if you buy a ready-made composition, then the proportion should be written on the package, if you cook it yourself, then we dilute it to the consistency of thick sour cream approximately - and it will be easy to pull and there will be no cracks during drying

Admin says: 03.11.2014 at 20:01

Depends on the solution. An ordinary cement screed dries for 1-2 days to a state where you can carry out work and walk on it, and before it dries completely, 3 weeks.

Olga says: 08/30/2015 at 08:06

After the cement-sand screed of the floor, not very deep cracks formed in our place. Let's lay linoleum.

Kirill says: 20.10.2015 at 12:05
The hearths would be repaired before laying the linoleum. Then he falls asleep under it and it will be problematic to fix something.

Alexander says: 10/19/2015 at 21:58

Hello!!! The consumption is written on the packaging of the self-levelling screed (for example, for 1 mm of thickness 1.6-1.8 kg / sq.m.), i.e. if I want to make a 1 cm screed, then I need to calculate approximately 18 kg per square. But I'm still worried that the mixture may not be enough. I don’t know how uneven the floor is (suddenly most of the screed will spread to one end and not enough to the other). Moreover, as I understand it, the self-nevilir will fill up at a time. How to calculate how much mixture is needed?

Admin says: 20.10.2015 at 17:32
To begin with, check the level of your floor so that, as you wrote, it does not turn out that everything is glassed into one corner. Measure the maximum level difference and divide by 2. That many mm. more to be calculated. Those if at the beginning of the room the floor is higher than at the end by 4 mm, then in order to fill the screed in 1 cm, you need to add another 2 mm. But it works with a more or less uniform slope. If you have pits or significant irregularities, it may be worth aligning them separately for a start.

Types of ties: 1) adhesive screed, in contact with a 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 adhesion to the base plays an exceptionally important role. In the production of such screeds, it is important to vacuum the surface well, use a 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: polyethylene film, roofing material or waterproofing. 3) floating screed. It is laid on a layer of heat and sound insulating material. It can be ordinary or extruded polystyrene, dense mineral wool, rolled polyethylene foam, including foil, expanded clay bedding. Each type of screed has its own advantages and disadvantages. The disadvantage of the adhesive screed is poor sound insulation. The advantage is the smallest possible screed layer and the possibility of combined leveling using finishing smoothers in areas with a thin layer. At the same time, there is practically no danger of cracks at the junction of materials. The screed on the separating layer, while curing, is protected from moisture by the overlap and improves the waterproofing properties, but at the same time it should not be less than 3 cm thick, and requires reinforcement. The 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, the ability to equalize large differences without increasing the load on the floors. Cons: Significant rise in price and large thickness. When choosing a pouring method, it is necessary to take into account the unevenness of the base, and remember 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. The mesh is laid on supports so that after pouring the mesh is in the center of the layer. Grids are stacked overlapping and tied with wire. When installing cable underfloor heating, it is convenient to fasten the cable to the grid with wire or electrical ties.

2) Fiberglass mesh. I myself have not used it, but I know that it is cheaper, lighter and more durable than metal, it is a pity that it is practically not represented at the bases of building materials

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

Even under the condition of reinforcement, the screed, in the process of curing, has shrinkage, and it is "pulled together", which leads to the formation of shrinkage cracks over large areas. 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 during pouring with any thin separating material, or cut through after pouring in a solution that has not yet gained strength. Reinforcement at the seams is interrupted

A little about lighthouses. Lighthouses are made so that the floor level is perfectly even. 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 manufacturer of laminate and parquet boards. For laying tiles, this is also an excellent base. I won’t tell you much about how lighthouses are made, I’ll only say that you shouldn’t use gypsum compositions for their manufacture. Especially if the floor is tiled. 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 walls and columns, therefore, before starting work, a separation tape made of polyethylene foam or its equivalent is laid along the wall. One of the important points in the screed device is the water-cement (W/C) ratio. The more water in the solution, the stronger the subsequent shrinkage of the screed. It is possible to reduce W / C by adding a plasticizer to the solution, as well as 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 is released on its surface. To prepare such a solution, one 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 pour the material in the right places. Also for leveling, it is convenient to use a yellow styrofoam grater

A significant advantage of the semi-dry method is the rapid 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 in special shoes with a wide sole, similar to snowshoes. In ordinary shoes, you can walk after 6-12 hours. Tiles can be laid on such a floor every other day, and laminate and parquet board after 5-10 days, depending on the thickness of the layer and the moisture meter readings. In order for the screed to gain strength correctly, on the first day it should be protected from drafts and covered with a film, and for the next 2-3 days, periodically moistened. In industrial premises and wherever floors are used without coating, they are rubbed with special trowels to strengthen the top layer.

The screed is the upper part of the floor structure, which serves as the basis for laying the decorative floor covering. Modern repairs, carried out both in a new building and in apartments of old high-rise buildings, necessarily include work on filling the floor with a screed. In order to independently engage in the arrangement of floors, you need to know what materials will be required and what thickness of the floor screed for your apartment will be optimal. 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, as well as a flat surface is created, which is necessary for high-quality laying of tiles, laminate or linoleum. The screed allows you to evenly distribute the load on those layers of the floor that are under it, thereby extending their life. With the help of a screed, they not only level the floor, but also create the slopes provided for by the repair project.

The screed in a living space must be strong enough to withstand the physical stress resulting from the arrangement of furniture and the movement of people living in it around the room. The screed layer must be equally dense throughout the floor, any voids inside it, as well as chips and cracks, are not allowed. If the room does not specifically provide for the organization of the floor with a slope of a certain degree, then in standard cases the surface after pouring should be horizontally flat with a maximum slope of 0.2%.

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

What can be a screed?

As a standard, there are three types of screed with respect to its thickness. The first type includes a draft floor of small thickness. What screed thickness 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 performed.

The second type of coating includes a floor with a height of up to 7 cm. Such a coating provides for 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. So, concrete pouring with the addition of crushed stone can no longer have a minimum thickness. In this case, due to the crushed stone fraction, a thin layer of the subfloor cannot be made. 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. With the help of 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 arranging underfloor heating. 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 heating the room, a layer of concrete above the pipes of 4 cm is enough. A thicker layer will complicate the adjustment of the 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. The concrete part of the floor expands when heated and has a mechanical effect on the walls of the room. The thicker the screed layer, the stronger this effect will be. To eliminate possible consequences, it is recommended to glue the walls around the perimeter with a special tape before pouring the concrete mixture.

Minimum screed

According to SNiP, the minimum screed height in the 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 enough. If no reinforcing element is provided in the fill, then the minimum layer height cannot be less than 4 cm.

Such a requirement for a minimum screed is due to the fact that the flooring must be characterized by a certain strength and wear resistance. A thin screed simply cannot provide the required performance.

Filling a thin coating can only be carried out under several conditions, which include an existing subfloor, a surface leveled with a rough screed and the absence of reinforcement. A thin screed is not recommended for use in technical rooms, as well as where the mechanical load on the floors is very high. In an apartment, such rooms include a kitchen, a bathroom and an entrance hall - here experts advise pouring a rather 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 with high quality;
Waterproofing is laid, which is suitable for a simple plastic film;
A reinforcing mesh is installed and beacons are set up;
The concrete solution is poured.

The minimum thickness of the floor screed using a reinforcing mesh cannot be less than 4 cm. Due to the presence of the mesh and the low height of the screed, the concrete used for pouring must be made from fine crushed stone. Compliance with this requirement will allow you to fill the solution with 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 height of the fill will depend on many factors: the value is determined separately for each case. In terms of technology, a height of more than 15-17 cm does not make sense; structures with such a height are created only if necessary, since 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 there are heavy loads on the floor. The simplest example of such a room is a garage: the weight of the car and its impact on the floor when moving are large, so the height of the screed of 15 cm is fully justified.

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

Sometimes the height of the concrete pour is increased in order to hide significant surface differences. In practice, significant irregularities in the original surface are quite common, 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 the differences. Fix sharp drops with a powerful jackhammer. If surface defects can be corrected in these ways, then the need for pouring concrete to a great height disappears by itself.

The minimum fill layer in this situation is also not suitable, 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 the payment of the builders' work will add up to a round sum. Most often, high costs will not be justified, so it is worth doing at least partial leveling with a bulk layer of crushed stone.

Pouring a screed of maximum thickness during the installation of warm water floors is also not financially justified. The 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 huge.

How to fill?

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

Concrete pouring is the most popular, but in order to use it, you need to know a few important points. The solution itself is prepared from cement, sand and water. Experts recommend buying cement not lower than the M-300 grade - with a particle fraction of 3-5 mm, such material will ensure high quality of the final coating. The use of not sand, but its screening for the preparation of a solution, will also have a positive effect on the final result: the adhesion of screening particles is much better.

To increase the strength of the future flooring and prevent cracking and destruction of the screed into crumbs, it is necessary to add plasticizers to the cement mortar. At this point, special attention should be paid to those who are going to make a screed for warm water floors. Plasticizers are special additives that increase the strength and plasticity of the concrete layer.

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

Concrete screed takes a long time to dry. The solution must dry itself; it is strictly forbidden to turn on a warm floor for this. Drying of the floor is carried out within a month, and the surface is periodically wetted with water to avoid cracking.

Arrangement of the floor with the help of special semi-dry mixtures has recently gained popularity. Such a screed does not require the addition of a large amount of water, dries faster and has greater strength. The range of special mixtures for the repair of floors today is quite large.

Unlike a concrete solution, a semi-dry screed will take a much shorter amount of time, the main thing is to wait for the period specified by the manufacturer. After its expiration, you can start laying the decorative coating and turn on the heating system if you installed a warm floor. The use of dry mixes for pouring floors looks preferable when the time allotted for repair work is limited.

A semi-dry screed requires less financial costs, but the performance characteristics of the final coating significantly exceed those of a concrete screed. The coating of such mixtures has better noise and heat insulation, is more resistant to cracks and delamination. After the material hardens, a perfectly flat surface is obtained, ready for laying laminate or parquet boards.

The screed is the layer between the concrete base of the floor and its top coat. It is necessary for high-quality leveling of the floor. The durability of the result of the work depends on the screed. Screed installation is needed regardless of the type of coating used: parquet, tile, linoleum, laminate, carpet, etc.

According to the manufacturing method

Wet. It is a cement-sand mixture. A special dry composition is also sold - it is made on a cement basis, or using gypsum. They are poured and the surface is completely leveled. If cement or sand was used for the screed, the surface is reinforced. Dry mixes do not require this procedure. The option is universal, common in construction. 10 cm or less is the optimal layer thickness.
Dry. Also called a screed. Represents a design from sheets of the large size from 15 to 30 mm thick. In the case of strong surface differences in levels, the dryness of the screed will not allow achieving the desired degree of leveling. Then, under the floor covering, a layer of dry screed is placed on top of the wet one.
Semi-dry. It differs from the classic, wet, manufacturing method by a significantly smaller amount of water in the mixture. The advantages of this type of screed are a short period of time between laying the screed and the floor, no leaks. The presence of fiber in the composition of the mixture allows you to minimize the number of shrinkage cracks.

Mechanized semi-dry floor screed provides a minimum amount of construction debris after laying. The mixture is usually kneaded outdoors and fed through a hose. For convenience, you can contact the companies involved in laying semi-dry floor screed. One of these, "EUROSTROY 21 VEK" (the company's website www.prestigehouse.ru), uses modern equipment and German technologies in its work.

By number of layers

Single layer. It is laid for 1 time to the required thickness.
Multilayer. Consists of rough and finish surfaces. For example, to ensure rigidity at the junction of the slabs with the ceiling, a rough concrete version is first laid, and when finishing, an absolutely smooth finishing screed is laid on top. Rough screed in thickness - 20 mm or more, finishing screed - from 3 to 20 mm.

By type of connection

Solid. It is firmly bonded to the base coat layer.
floating. Not linked to anything. It is used when it is necessary to use a film with waterproofing properties, as well as sound or heat insulation. The optimal thickness is 35 mm or more.

Screed materials

Cement is the most common screed binder, as is gypsum. The following fillers improve the properties of the mixture: sand, polymers, mineral-based additives. To obtain the desired consistency, the composition is diluted with water.

. The screed from it is moisture resistant, it is used for any type of floor structure. Cement is mixed with sand, the optimal ratio is 1 part of cement to 3 parts of sand.
There is also sand concrete - a mixture sold in stores. Sand concrete has a drawback - fast shrinkage. Therefore, it is necessary to monitor the uniformity of the composition and the thickness of the poured layer, which must be at least 30 mm, otherwise the screed will crack.
For uniform stress distribution and protection from cracking, the screed is reinforced from the inside or a part of the propylene-based fiber is added to the solution. After laying, the screed is periodically moistened, for about 10-14 days. The screed dries for a long time and for moisture-sensitive coatings - laminate and parquet - it will remain too wet for at least 20 days.
Gypsum. Plastic, easy-to-install screed. Does not shrink, laying it in a thin layer is allowed. Complete drying - in 1-2 days. Recommended for wooden floors. But it is not suitable for rooms with high humidity, as the gypsum will become like dough. If polymers are added to the gypsum, the screed can be used in rooms with moderate humidity.
Concrete. In terms of composition and manufacturing technology, a concrete screed is similar to a cement screed. The main difference is that cellular concrete is added to the mixture. There are types of concrete screed: foam concrete, expanded clay concrete, perlite concrete.
Self-levelling or self-levelling compound. Sold in finished form, designed for various floor coverings. It happens thin-layer, from 2 to 7 mm, and thick-layer, from 5 to 30 mm. If the floor irregularities are large, a rough rough screed is first made, and a self-leveling mixture is placed on top.
. The composition is similar to drywall. Represents the strong construction plates covered with a waterproofing structure. Laying is done on a pre-filled layer of polystyrene. The plates are placed with a slight overlap on each other to close the joints. The main advantage of the screed is that you do not need to wait for drying. The final floor covering can be installed the next day. Often used for mounting screeds in apartments.

materials

1. 1. Concrete mixer.
  2. Hydraulic level.
  3. Rule.
  4. Construction bubble level.
  5. Master OK.
  6. Drill with mixing nozzle.
  7. Stationery knife.
  8. Bucket.
  9. Pencil, marker.
  10. Roulette.
  11. Ruler.

Stages of work

Stage 1. Definition of the horizon

The zero level is measured using a spirit level - this is how the water level is called. Marks are placed in all rooms. The optimal height is from 1.2 to 1.5 m from the floor level. The starting mark is placed anywhere. The second and all subsequent ones are marked by the water level along the horizon line, but not the floor.

All points connect and get a zero level. Throughout all installation work, it will determine the horizontal plane. Check the zero level accuracy several times.

Sometimes expanded clay or gravel is poured under the screed. Then they retreat a few cm from the marked point and make an additional line for pouring the selected pillow material under the screed at this level.

Stage 2. Determine the height differences

This is necessary to calculate the correct level of screed and the required volume of mortar.

In different rooms we measure the distance from the old floor to the zero level point. We write the resulting value at each measurement point. It is better to make more points so that the measurements are more accurate. The minimum value is the maximum level of the old floor, and the largest value indicates its minimum height. The difference in values is the height difference of the old floor.

For example, max = 1.30 m, min = 1.25 m.

1,30 – 1,25 = 0,05.

That is, the height difference is 5 cm.

30 mm - the minimum thickness of the cement screed, where the plasticizer is added. Earlier, we already mentioned that otherwise cracks will go along the screed. Builders sometimes add liquid soap as a plasticizer. And on the packaging of the self-leveling mixture, the manufacturer indicates the optimal layer thickness.

With a multi-level screed - calculation of the difference in heights. Differences in height along the level of the floor at the joints of the coatings are not allowed. The screed is planned differently by levels: the thickness of the coatings is not identical. The difference in it must be compensated for by differences in the levels of the screed.

For example, in the kitchen - ceramic tiles, in the room - parquet. The layer under parquet will be thicker than for tiles and is multi-layered. We sum up the thickness of all layers, including the parquet itself, subtract the sum of the layers of the tile, including itself. We get a screed drop. It is recommended to take a spare 2 mm from the side of the tile if the parquet layer is higher.

Stage 3. Surface preparation

We clean the base coat. Usually a construction vacuum cleaner is used. In its absence, you can simply sweep well, then wash everything with a regular cleaning agent. With the help of a primer, additional dedusting can be done. The use of Betonokontakt means is optimal - it provides good adhesion for the screed and the base, makes the surface rough.

Partitions and walls require temporary waterproofing. For this purpose, you can use roofing material. The height of the roofing tape sticker is 10-15 cm from the level of the screed.

Next, we look at the base. Delaminations are not allowed, they must be cleaned. If there are large cracks, cover them with a thick mortar based on non-shrinking cement. If the floors were “ironized” during construction or smeared with “milk from cement”, then the film is removed so that there is proper adhesion to the base coat.

Stage 4. Setting up beacons

The screed is aligned on them. Rigid elements are usually used as them - metal profiles that can be fixed in a fixed position and not be afraid that they will bend at an unnecessary moment.

The mounting method is different: you can build a hill of cement or simply screw the beacons into the floor. An important requirement is the parallelism of the guides. The distance between adjacent ones should allow putting on the ends of the rail, along which the composition will be leveled.

Beacons with the help of a rack level are aligned in length and ratio with each other. Where height differences are formed, plywood formwork is placed so that the solution cannot flow into another room or area.

Stage 5. Mixing the composition and pouring the screed

Few people do it manually, they often use a concrete mixer - this way the composition is more uniform. Do not increase the proportion of water for the homogeneity of the mixture, otherwise the screed will be fragile. For this purpose, special additives are sold that make the solution plastic and homogeneous.

The filling should resemble a thick dough without lumps, spreading, but not spreading over the surface. It is used for 1-1.5 hours and in one go. It is not allowed to leave it for several days. Also, you can not fill the room in parts for several days. An exception is a screed of different levels or different rooms.

The solution is poured between the beacons and leveled with a rail-rule, which is moved strictly along the beacons, shifting the excess mixture. To level the surface of the screed, the rule additionally makes movements to the right and left.

The process of leveling the concrete mass using the rule

Video - Floor screed

Stage 6. Post-installation care

A simple operation often overlooked by workers. It consists in watering the coating 2 times a day. If this is not done, the screed will crack. Irrigation period - 10 days.

The cement screed needs up to 28 days until it becomes strong enough. The chemical processes that take place require sufficient moisture.

Beacons are pulled out approximately 3 days after the end of the installation of the screed. The recesses are primed and filled with a new portion of the solution. After that, we moisten the coating again and cover it with a polyethylene film for 2 weeks. In some cases, this is not recommended, then moisturizing is also done often - 2 times a day.

Stage 7. Checking work

It is done in several stages.

What else to read

How to remember people? Effective ways. Remembering faces If you want to be remembered How to improve your memory: effectively remembering faces and names I must admit that I myself do not always...

Windows: Automatic logon (autologin) If you're running Windows 7 on your personal computer, you'll often need to confirm your login (by...

Standard photo sizes A photograph is one moment of life that remains in memory for many years. No matter what happens, but when you take...