How to make a cement floor screed in an apartment. Floor screed in an apartment: cement-sand screed technology

Do-it-yourself floor screed is a task that may arise before you if you decide to make major repairs in an apartment or a private house. It can be finished and rough, for wet and dry rooms, rigid and floating, dry, semi-dry and traditional wet. A rough screed is understood as a leveling layer of cement-sand mortar over the floor slab, slight irregularities are allowed, since it implies additional leveling in the next step.

A fine screed is a finishing layer of floor finishing, must be perfectly even and can serve as an independent coating, or as a basis for laying floor coverings (linoleum, laminate, carpet, etc.), as a rule, self-leveling mixtures are used to create it. The main functions of screeds are to level the surface, if necessary, create slopes, impart strength and rigidity to the surface, as well as heat and sound insulating properties. In this article we will tell you how to make a floor screed correctly and what are its features for various premises.

Types of screeds

Screeds are classified depending on the base material that makes up their composition. DIY floor screed can be concrete, magnesite, anhydrite, asphalt, mosaic, based on gypsum and epoxy resins. Currently, the building materials market offers many different types of ready-made dry mixes with which you can make a floor screed with your own hands.

Screed for wet rooms

For wet rooms, the composition of the screed will be slightly different. Let's take a look at how to make a bathroom floor screed. A prerequisite is the creation of waterproofing. It is recommended to use a modern material - euroruberoid as a waterproofing layer. This roll material is laid dry in 2 layers with overlapping joints.

Important! Place the edges of the waterproofing on the wall to a height of 5-7 cm. This will protect the joints of the walls and floor from leaking.

After that, beacons from metal profiles are laid on a concrete solution strictly according to the level. The mortar for wet rooms is made from three components: sand, cement and a dry waterproofing mixture, which is sold in bags. (for example, the manufacturer Ceresit). The video shows in detail the process of making a concrete screed in a bathroom:

Screed for underfloor heating

For the installation of a warm floor, a cable or pipes (in the case of a water-heated floor) are laid on the surface, and then they are poured with a cement-sand mortar 1: 3 with the addition of reinforcing additives.

The video shows how to properly make a floor screed for water heating:

Floating screed

This type takes place if the floor slab needs additional heat and sound insulation. The mortar is placed on top of thermal insulation and sound insulation on a special layer (you can use a polyethylene film with a thickness of 0.1-0.15 mm). The layer performs the function of separating the solution and insulation. For a floating screed, a cement-sand or calcium-sulfate solution is used.

It is recommended to use a damper tape, which is glued at the junction of walls and floors along the entire perimeter of the room, taking into account the protrusions and columns. It protects the surface from cracking during concrete shrinkage, and also increases the sound insulation of the room. The height of the overlap of the tape on the wall is taken in accordance with the total thickness of all layers of the future floor.

Video. Floating floor. Types of solutions, filling methods, nuances, subtleties:

Dry and semi-dry screeds

In the case when it is required to carry out repairs in an accelerated time and there is no time for the full drying of a traditional wet screed, you can perform a rough screed using a semi-dry method. To do this, add a small amount of water to the cement-sand mixture, sufficient to obtain a loose concrete mass after mixing. It is also necessary to perform reinforcement with the addition of fiberglass to the solution. After that, the mixture is applied to the base with alignment with the rule of beacons, and then the surface is polished. This technology is carried out most quickly and efficiently by a mechanized method.

A dry screed is a filling of dry filler - quartz sand or expanded clay, on top of which plywood is mounted, or chipboard, gypsum fiber board. This technology provides good sound insulation, light weight of the structure, no wet work in the room, and therefore no dirt and no risk of fluid leakage from the solution into the ceiling. This type of screed is easy to do with your own hands, because it is easy to manufacture, does not require machine mechanisms, special equipment and special care, however, it is afraid of moisture, and if it gets into the structure, the floor can swell, deformation of the surface and the formation of irregularities.

Video. Dry floor screed technology. This method is suitable if you need to meet a tight deadline and there is no desire to mess around with a liquid solution:

Finishing screeds

For the device of a finishing screed, self-leveling finishing mixtures of factory production are often used. They are cement and polymer based. Self-leveling floors are easy to clean, they form a durable, even and smooth surface that is easy to clean. Self-leveling floors are divided into types depending on the binder used in their composition. There are methyl methacrylic (MMA), polyurethane, polyurethane-cement, acrylic-cement and epoxy compounds.

Advice! The strength grade of the topcoat should not be higher than the grade of the rough screed solution on which it is laid. Otherwise, deformation and delamination will occur over time.

Video. Finishing screed device with self-leveling mixture:

Screed laying technology

Let us consider in more detail the device of a traditional wet screed using the example of a concrete one. Do-it-yourself floor screed is performed using the following tools:

• building level;
• rule;
• beacons (guides);
• drill with a nozzle for mixing the solution;
• putty knife.

Depending on the purpose of the room and the materials used, the technology will vary. Consider the stages of this process:

• preparation of the base, priming;
• thermal insulation (if necessary);
• waterproofing (if necessary);
• reinforcement (if necessary);
• placement of beacons (guides) with leveling;
• mixing the solution;
• fill;
• care of the finished surface.

The first stage is the preparation of the base. It must be dust-free, remove debris, if there is dirt and oil stains, bitumen, they must be removed. If there is an old dilapidated screed, it must be dismantled. After that, you need to treat the surface of the floor slab with a primer using a roller or brush and let it dry for 5 hours. If there are water and sewer pipes in the room, then they need to be routed along the floor.

For thermal insulation of the room, you can use expanded clay or expanded polystyrene, the main thing is that the surface of the insulation is rigid. If the do-it-yourself floor screed is done on a soil base, then first you need to lay a layer of expanded clay, and then a layer of sand, with the obligatory compaction of each layer. For greater effect, it is recommended to wet with water.

Waterproofing is usually carried out in wet areas (where there are plumbing and sewerage connection points). To protect against moisture, waterproofing is also sometimes arranged in the premises of the first floor, basements.

After that, reinforcement is performed. It is used if the surface is planned to be subjected to heavy loads. For this, reinforcing bars are used, the cross-section of which is selected depending on the planned load (the diameter is in the range from 8 to 20 mm), or reinforcing meshes (with a diameter of 6 mm bars). Sometimes plastic reinforcing meshes are used instead of metal ones. Reinforcement meshes will also help to avoid deformation of the concrete layer and cracking in the event of building shrinkage. Concrete is a brittle material and does not work well for bending and tension; reinforcement allows you to eliminate these deficiencies and protect the surface from cracks.

After that, the placement of beacons (guides) is performed. They should be displayed clearly in accordance with the building level, because the subsequent flatness of the surface depends on this.

The next step is to fill the solution. When the screed is ready, it is left for a while until it dries completely. Do not forget to take care of the screed during this time, periodically spraying it with water. Concrete slowly gains its strength (within 27 days), it should harden gradually. It can crack if it dries too quickly. Therefore, as a care, you need to moisten the finished screed with water 2 times a day for a week, and then cover it with plastic wrap and leave it for 2 weeks.

Regardless of the type of finish floor covering, if the floor slabs have unevenness or a strong slope, then they will have to be leveled. Such a pouring of the floor screed with your own hands is performed using cement or gypsum mortar or various board materials (GVL, chipboard, OSB). Making it yourself in an apartment or cottage is not so difficult. The main thing is to follow the building rules and the instructions below, and be ready to work.

Screed types

The floor screed is a rough finish. At the bottom of it there is an interfloor overlap or soil, and on top there is a floor covering in the form of linoleum, parquet, ceramic tiles, etc.
A screed is made for:

• concealment of communications (underfloor heating pipes or water supply, electrical wiring, etc.);
• redistribution of loads from the upper decorative layer down to the base;
• leveling the surface and / or giving it the desired slope;
• strengthening the base for the final floor covering;
• providing sound, hydro and thermal insulation.

You can make a screed yourself in several ways. And the choice of the method largely depends on the requirements for the loads that will then arise on the floor. This is when deciding how to connect the drain of the washing machine to the sewer, you just have to follow the instructions for the plumbing fixture.

In the case of a screed, everything is much more complicated. Each technology for its implementation has its own pros and cons. First, you need to clearly define the existing needs.

There are three main types of floor screeds:

1. Dry team.
2. Wet (classic).
3. Semi-dry.

The first technology involves laying wood and gypsum boards. This method eliminates the use of gypsum or cement mortar and is characterized by a high speed of screed installation. Plus, due to the low weight of materials, it has the smallest load among analogs on the overlap from below. However, in terms of price, this option is the most expensive. And he's afraid of moisture.

Features of expanded clay screed with insulation

The second method is based on pouring liquid concrete from cement and sand. This screed has the greatest strength, durability and moisture resistance. However, due to its large mass, it is not allowed to be used everywhere. If the floor is leveled in an apartment in a new building, then this option is quite acceptable. Only a too thick layer of concrete should not be poured. But for an old house with wooden floors, this technology will not work.

Wet screed

The third method is an improved variation of the second. It also uses a cement-sand mixture. However, the amount of water used for mixing it is several times less than when preparing ordinary concrete. As a result, the curing time of the floor screed and the volumes of construction dirt generated during work are significantly reduced. But you have to pay for this by the need to use the technique for grinding and the rigor of technology compliance.

Semi-dry screed

In addition, screeds are:

• related;
• floating;
• on the separating layer.

The first ones are the most durable and imply a rigid adhesion of the mortar to be poured with the underlying base. The latter have a heat and sound insulating substrate made of mineral wool, expanded polystyrene, wood or cork boards. They do not touch the overlap and are not rigidly adhered to it, like screeds of a related variety.

The third option also has a separating substrate. But in this case, it is thin and performs the functions of exclusively waterproofing. Usually it is oiled or bituminous paper or polyethylene. Unlike a floating analogue, this floor screed in an apartment can be made with a thinner layer. Plus, it turns out to be even more durable.

Screed types

A separate line includes self-leveling mixtures of the "self-leveling floor" type. They are cement and gypsum, but all have polymer plasticizers for quick solidification.

Their main purpose is to create a perfectly flat surface up to 10 mm thick without much effort on the part of the performer. Often this option is used in conjunction with other types of floor screed as an upper leveling layer. Then the general design of the roughing is called a combined two-layer.

What you may need, materials

To make a floor screed, you will need from tools:

• beacons for horizontal alignment;
• building level;
• concrete mixer;
• rule;
• trowel and / or shovel;
• grinder (for semi-dry screed);
• roller (for self-leveling mixture);
• a bucket and a drill with a nozzle for mixing the solution;
• tape measure and pencil.

Screed materials and tools

It is best to take a mixture for making a solution for a floor screed immediately ready with the right proportions of components. So there is less chance of mistakes when mixing cement, sand and other components. But you can also purchase these components separately and do the batch by hand. Only for a self-leveling composition, this is not worth doing, it is extremely difficult to prepare it yourself with the proper ratio of ingredients.

Features of surface preparation

When preparing the surface for the screed, it is necessary to remove the existing skirting boards, old flooring and logs (if used). As a result, a wooden or concrete floor should remain without any extraneous construction debris.

Further, the cleaned base is repaired in case of deep cracks or torn potholes and primed. Sealing of defects is done with concrete mortar after preliminary priming of the repair areas. Leaving flaws without sealing is not worth it. If you make a floor screed over such weak points, they will then continue to collapse. This will inevitably damage the new top layer.

Floor preparation before screed

If there is an old screed on the floor, then it should be carefully checked for integrity and reliability. In most cases, it is recommended to completely remove such concrete. But if it is still strong and does not peel off from the base, then pouring a new leveling layer onto it is quite acceptable.

Step by step instructions - how to make a floor screed

The general step-by-step instructions for the correct durable screed are as follows:

1. Preparation of the base.
2. Laying or filling of underlying materials.
3. Exposing beacons and laying out edge damper tape.
4. Mesh reinforcement (if necessary) and mortar mixing.
5. Pouring and leveling the prepared mixture.

If a dry floor screed is made in an apartment or a private house, then the last two points boil down to laying and fixing wood or gypsum fiber boards. There are no particular difficulties. Dealing with how to connect a toilet is often more problematic than aligning under a floor covering.

The main stages of work on the implementation of the floor screed

Dry

The prefabricated structure of sheets of OSB, chipboard or gypsum fiber board does not differ in particular strength and is prone to delamination during a flood. But on the other hand, these disadvantages are leveled out by the speed of installation, as well as excellent heat and sound insulation.

A floor screed is made using this technology, usually on top of a perlite or expanded clay backfill. Then the waterproofing is spread. Directly adhesion of the laid sheets to each other is made with glue and self-tapping screws. In this case, the latter should be carefully selected in length, so that when screwing in, they do not rest against a dense base and do not raise the covering to be laid.

The backfill is done with a height of 3-5 cm. If more is required (for example, to hide pipes), then the screed should be done with slabs in two overlapping layers. One will not be enough to provide the required strength standards.

How to make a dry floor screed with beacons inside

Wet

When performing a screed with a wet method, the main thing is to fill the entire volume of the solution in one go. It is impossible to allow one layer to solidify and pour another layer on top of it, they will inevitably disperse later.

It takes about one week to harden 1 cm of concrete in a screed. In this case, the screed is usually made 3-5 cm - as a result, until it is fully ready for further work, you will have to wait at least a month. This is the main disadvantage of this technology.

The second important point is lighthouses. The easiest way to make them is from drywall profiles. You can also use tripod pin rappers. The more precisely these horizontal guides are set, the smoother the surface will be.

Today, the requirements for finishing work are much higher than a couple of decades ago. Almost all floor coverings require a base, if not perfectly flat, then with a very small difference - no more than a few millimeters. Therefore, almost every repair means leveling the floor, but they do it with a screed. The process is long and requires considerable financial investments. Everything will be cheaper if you do most of the work yourself. Even if there are no skills, do-it-yourself floor screed is not such a difficult business. Compliance with technology is the key to success.

The screed is an intermediate layer between the base (floor) and floor finishing materials. They can be divided into two groups - leveling and leveling and thermal insulation. The screed with thermal insulation function is used on the ground floor, above the basement or unheated room. It is also made under a warm floor - to reduce heating costs.

There are two screed device technologies:

• Monolithic. For laying a monolithic screed, various grades of concrete are used. Both heavy (DSP, with crushed stone) and lightweight (foam concrete, with polystyrene, expanded clay concrete and with other light fillers). They can be liquid and semi-dry, depending on the amount of water in the solution.
• Prefabricated screed. This is when there are many layers, they can be of different materials. This includes dry screeds, on logs, with insulation, soundproofing.

There are two types of connection with the base:

• Regular. This is if the mortar is poured over a floor slab, for example. What is the disadvantage? The fact is that if the house starts to "lead", the floor will crack along with the base.
• Floating. When the base and the screed are separated by an intermediate layer. For example, if a polyethylene film, thermal insulation (expanded polystyrene plates), waterproofing or any other separator that separates the screed material and the base is laid under the concrete layer.

All requirements and norms are spelled out in regulations. SNiP 3.03.01-87 "Bearing and enclosing structures", SNiP 2.03.13-88 "Floors",. To accurately navigate what and how to do, study these norms. Then do-it-yourself floor screed or control over the work of the team will not be a problem.

How to choose the type of screed and what layers are needed

Making a floor screed with your own hands is not such a problem. The problem is to choose the type, not to be mistaken with layers, mass, choose the right materials and calculate their quantity. And the best screed for each case is different. It is one thing to renovate a new building, and another to overhaul the housing stock. In addition, everyone has their own requirements and ideas about the “best”. But there are technical issues that define the boundaries of your desires. These moments must be monitored.

Weight

When creating a floor and foundation, a certain load is laid, which the floor can carry. It should be looked at in the project or clarified with the operating organization (usually with the chief engineer). The average design load is 300-400 kg / m², but it can be more or less.

If the floor is wooden, it will not withstand a heavy load. The specific value depends on the section of the lag and the step of their installation. But on wooden floors, most often, they make a dry screed along the logs. The gaps between the logs are filled with heat and sound insulating material, and a floorboard or sheet materials are placed on top. To improve sound insulation, sound-absorbing gaskets are used when assembling the screed.

If the load capacity of the floor allows, you can make the screed from cement-bonded particle boards (CBPB), with or without gravel filler. But on top of concrete with gravel, a leveling layer is needed. Although, it is almost always needed. The floor screed rarely comes out perfectly even, you have to pour a layer of roving on top of it.

Don't want to overload the structure? Use lightweight concrete with lightweight aggregate. Anyone you like best. I like wooden floors - do not make a wet screed, put logs, lay the floor from boards. Anything that fits within the limits of load capacity can be done.

Waterproofing

In residential premises from the 2nd floor and above, waterproofing is not needed. This layer is required on the ground floor if there is no basement in the house, as well as in all "wet" areas on any floor. These include shower, toilet, bathroom, kitchen, balcony and loggia. Sometimes, for reliability, they can capture the corridor. Do-it-yourself screed in a bathroom or toilet is a good experience to start with.

There are roll waterproofing materials, there are liquid compositions - mastics, rubber paints, compositions based on copolymers. In basements or on the first floors of houses without a basement, a layer of waterproofing is placed under the screed. In damp rooms - under and over the screed, under the floor covering (regardless of the number of storeys). Most often, waterproofing is placed in two layers - to increase the level of reliability. You can combine different materials, for example, roll + mastic.

Noise isolation

Apartment dwellers know well how poor sound insulation interferes with living. Especially in the presence of violent or inadequate neighbors. And the noise from above interferes no less than from the side. Sometimes even more. To keep your neighbors out of the picture, you have to be quiet. And all because the screed is made ordinary, without sound insulation.

There are two ways to reduce the noise level - absorption and decoupling of the structure. With absorption it is easier - in the screed and not only it is necessary to use low-density porous materials. Carpets made of building materials - polystyrene / expanded polystyrene and low density mineral wool - do the best with this task.

The second way to reduce the level of noise transmitted through the floor is to decouple the structure. In simple terms, in a screed it is the use of layers of different densities, the use of porous gaskets, which exclude direct contact of the screed with rigid structures. In our case, these are walls. That is, if you do not want to walk on tiptoe so as not to disturb your neighbors, it is better to do a floating screed. Under the concrete layer, lay not a polyethylene film (or not only it), but a layer of mineral wool or foam. And lay porous materials around the perimeter, which will separate the concrete from the walls. Density is the minimum allowable for the estimated weight of the concrete to be laid from above.

If you will be doing a dry screed, soundproofing pads are also placed under the logs. They must be placed in the places where they are adjacent to the walls. And the gaps between the lags should be filled with material with good insulating characteristics. Do-it-yourself floor screed is good for what you do for yourself and can take longer to get the best result.

Thermal insulation

Residents of high-rise buildings do not need a layer of thermal insulation in the screed. Is that under the warm floor. In this case, it is better to make thermal insulation - so as not to heat the neighbors from below and to reduce heating costs. The most common materials for this layer are expanded polystyrene foam and mineral wool. Their density depends on the type of screed. More dense ones are laid under the concrete layer (expanded polystyrene with a density of at least 25 kg / m³, mineral wool - 160-190 kg / m³). In floors on logs, the density may be less - everything is decided by the heat-insulating and sound-insulating characteristics.

Expanded clay to use as insulation is ineffective. Compared to the above materials, its thermal insulation characteristics, to put it mildly, are not impressive. They are 3-4 times lower. In practice, this means that 35 cm of expanded clay can replace 10 cm of expanded polystyrene.

Floor screed composition

As you understand, the composition of the floor screed may be different even in two apartments located on the same floor. It all depends on what the owner wants to achieve. Here are some examples.

Either way, the result is a relatively flat concrete base. With different characteristics and properties, but outwardly - the same. On such a base, you can lay tiles, parquet. All flaws will be leveled out when laying the tiles. But here the differences should not be too large. According to the tile laying technology, differences of 2-3 mm are permissible.

Some coatings require a perfectly flat surface. These are laminate, carpet, linoleum, art vinyl and other soft floor coverings. For such materials, one more layer is needed - from a finishing or leveling mixture. It is poured on top of a ready-made floor screed. For this, self-leveling mixtures are usually used. Just don't think that you just need to close them and pour them on the floor, and then they will spread themselves. Not at all. They also need to be spread over the surface, but they just don't need to be so carefully aligned. After distribution, the composition itself “will be on the horizon”.

Stages of work

To make a screed with your own hands, you need to know when and how to do it. In the process of repair, the screed is poured before the start of finishing work. That is, first they align the ceiling, walls, and put windows. Only then the screed is poured. Not earlier. Because all leveling mixtures, plasters, putties weigh a lot. Stepladders and other equipment are needed to work. All of this leaves marks on the floor. And the screed ripens for at least 28 days. During this time, it is gaining design strength (subject to certain conditions). It is unlikely that you will wait so long before leveling the ceiling or walls. So all the hard and dirty work must be completed before pouring the screed.

Painting the ceiling, gluing wallpaper, applying decorative plaster - these works are no longer so dirty, they do not need heavy materials. They can be started when the concrete has reached 50% strength. At a temperature of + 20 ° C and sufficient humidity, this happens a week after pouring.

Floor screed laying technology

It is about the procedure for pouring concrete mortar. It can be any loaf - from heavy to light. Maybe a semi-dry screed - a solution with a minimum amount of water.

This is a step-by-step instruction on how to make a do-it-yourself screed in general form. There are still points that depend on the specific composition of the screed and the selected materials, but in general, the sequence of work is just that.

Care after pouring

Do not think that after pouring and leveling the concrete, the work is already finished. In order for concrete to "ripen" and not dry out, it needs certain conditions. First, you need a temperature not lower than + 17 ° C. Secondly, a certain humidity is required. And these conditions must be created and maintained.

If you have filled the screed in an unheated room in winter, you will either need:

• more time for aging;
• special additives and solution, which make it possible to normally gain strength to the solution at lower temperatures;
• heating.

At low temperatures, but not in frost, it is easiest to add some additives and cover the laid mortar. First with a film, then with something that retains heat.

The screed is covered with a film

If the temperature is above + 25 ° C, care must be taken that the solution does not dry out. To protect against evaporation, it is necessary to curtain the windows - so that there are no zones of local overheating, cover the surface with a film. And, every two to three days, wet the concrete abundantly. Abundant - until puddles appear. In this case, care must be taken that the surface is not washed out. Such hydration is desirable for at least two to three weeks.

What materials are needed for floor screed

The basis of a wet or semi-dry screed is a solution. They use both a simple cement-sand mixture (CPM) and with aggregates. You can add plasticizers, which accelerate the maturation of concrete, make it more plastic. For the screed, they take cement of the M400 or M500 brand. Screed concrete of class M150 or M200 (not to be confused with cement brands).

Higher classes of concrete (with a high cement content) can also be used. The surface will be more durable, but the shrinkage and the likelihood of cracking when drying is too great. A floor screed made of concrete grade M150 for an apartment or house is more than sufficient in strength. You will not drive a car ... Any other load is not terrible for such a floor.

Concrete proportions for screed, batching procedure

To obtain a cement-sand mixture for concrete M150, take 1 part of sand and 3 parts of cement (M400 or M500). Water - 0.48-0.55 liters per kilogram of cement. Medium or fine gravel can be added. The proportions are given in the table.

When mixing, first dry-mix the bulk components until homogeneous, then add water in parts. Its exact amount is difficult to determine - it depends on the moisture content of the sand and gravel. Therefore, it is added in small portions, constantly stirring. It is more convenient for a screed if the solution is low-plastic - it slides off an inclined shovel.

Plasticizers can be added to the composition, which make the solution more plastic. A solution with increased plasticity is easier to dispense. The cheapest additive of this kind is PVA glue, but there are specialized ones. Add to the solution no more than 1% by weight of the additives. Fiber may also be helpful. These are short fibers that prevent the development of cracks during the shrinkage of the screed itself and small deformations during the shrinkage of the foundation. There are other additives that change the properties of the solution, but they increase the cost, and there is no special need for them for pouring the screed in an apartment or house.

How much concrete and cement is needed

How to determine how much concrete is needed? You can roughly calculate. You know the area to be poured, you know the thickness of the layer. We convert all values \u200b\u200binto meters and multiply. We get cubic meters - this will be the required volume of concrete.

Let's count with an example. We will fill an area of \u200b\u200b45 square meters, a layer of 5 cm. We translate 5 cm into meters. This is 0.05 m. Now we multiply 45 m² * 0.05 m \u003d 2.25 m³. You will need approximately 2.2-2.5 cubic meters of cement mortar. Knowing the required volume of mortar and the grade of concrete, you can determine the cement consumption. It can be taken from the table.

Please note that the table shows the cement consumption for DSP, that is, without crushed stone. Having decided on the volume of concrete, you can calculate the mass of sand. It needs 3 times more. Better to take construction sand, not river sand. Quarry sand has sharp edges, and river sand has smooth edges. It seems that the difference is small, but it is not - with quarry sand, concrete is stronger.

Filling the screed with step by step with a photo

Your first DIY screed will give you confidence. The matter is not too difficult, but physically the work is hard, even if there is a concrete mixer. And if you also interfere with your hands, it will be very difficult. Try small volume first. It may well be that you decide then to order the concrete in a mixer.

Look at the example of a floating screed, a thick industrial film serves as a separator. The following tools are required for filling:

The most expensive tool is the laser level. If the floor screed is not the only type of work done on your own, this tool will be very useful to you. So it is better to buy it, and you should choose good quality.

How to calculate the minimum layer, where to make the zero level

If the base were even, the screed would be a very simple matter - the solution was poured in, leveled with an even layer. All. But the fact is that this is extremely rare. Usually there are humps somewhere, depressions somewhere, a few corners can be higher, a little lower. Since the minimum screed layer is 30 mm, it is necessary to find the most protruding part of the base and, relative to it (plus these 3 cm), deduce the zero level.

For work, you will need a laser level with the ability to build planes. Expand the horizontal plane at any distance from the floor. Let it be 10 cm. Next, take a ruler or tape measure and move along the perimeter of the room, measuring at what distance from the floor we "catch" the laser beam. It is displayed as a bright stripe around the perimeter, so you can immediately see how things are with the corners. If in each of the corners there are 10 cm to the beam, you are incredibly lucky. But usually the picture is different.

If the floor screed is being done throughout the apartment, you need to check all the rooms and look for the highest point in the apartment. The zero level should be beaten off throughout the apartment the same, however, taking into account the characteristics of the flooring. For example, floor tiles are thicker than art vinyl, and this must be taken into account when pouring the screed. In rooms intended for laying tiles, the level should be slightly lower - then you will not have any differences in floor level in the apartment.

When we find the point at which the distance to the ray is the smallest, this will be the highest point of the base. She will become decisive in applying the zero level. This is the level at which the screed will end. To this point we add the planned thickness of the screed (but not less than 3 cm). At this level, we unfold the laser plane. Rays are displayed on the walls, which represent the level of the screed. Take a ruler, pencil and transfer the line. Now we determine the average thickness of the screed - we go through the room again, checking how much distance is obtained to the zero level. Now it is already possible to more accurately determine the flow rate of the solution and the required amount of cement.

Not all models of laser levels allow changing the height of the unfolded plane. If you cannot set it at the desired level, you will have to work a little. It is necessary to calculate how much higher the plane passes, postpone this distance from the laser line, draw a straight line.

Foundation preparation

If there are gaps, we close them, we clean off all unnecessary from the walls (we leave the lines). We remove the debris, it is advisable to vacuum it, but when using a film this is not critical, you can just sweep it up. We spread the film. She should go up the walls. The overlap height is 3-5 cm above the zero level. If the width of one sheet is not enough, one piece of film overlaps the other by at least 15 cm. For reliability, the joints can be glued with double-sided tape.

The film can be glued to the walls with adhesive tape, but such an attachment is unreliable - it constantly falls off. It is better to take the bar, press the film with it, nail it to the walls. Yes, they are plastered, but small holes can be repaired.

We expose beacons

The concrete solution will need to be leveled. Beacons serve as a reference point - special strips that are set exactly at the same level with the zero mark. There are such special metal films, which are called lighthouses in hardware stores. These are strips of a special profile, 3 meters long, with a protruding part height from 3 mm to 15 mm. For the floor screed, take 10-12 mm.

As beacons, you can use any even strips of any material. For example, pipes - round or profiled, a profile for drywall, even wooden even planks. The only condition is that the material must be perfectly flat. Any lighthouses can be exposed to mortar, you can - to screws. There are also special adjustable stands for displaying beacons. But they are expensive, they are needed only for a while, since after gaining 50% strength, the beacons are taken out of the concrete, and the stands remain.

The distance between the beacons is determined by the length of the rule - 30-50 cm less than its length. We set the planks along the long side of the room, from one wall to the other. When installing the first lighthouse, we retreat about 30 cm from the wall. That is, the extreme strips should be approximately 30 cm from the walls. We divide the rest of the space into equal parts so that the distance is less than the length of the rule.

For example, the width of the room is 4.3 m, we will work as a rule of 1.5 m. We consider this: 4.3 meters - 0.6 m (twice 30 cm), it will be 3.7 m. You can put two beacons. They will divide the remaining space into three parts - 1.2 m + 1.3 m + 1.2 m. The distance can be equal, you can move the extreme profiles a little closer / further.

For solution

The arrangement of the screed begins with the installation of beacons. The final result will depend on how exactly they are exposed. First, let's look at how to expose the beacons to the solution. Knead the solution from a standard DSP with the addition of one part of gypsum. This will make it more flexible. We knead the thick solution. He should lie in a "bunch" and not swim. We add a minimum of water.

Along the wall, in the right place, at a distance of 50 centimeters, lay out heaps of mortar. In height, they should be above the zero mark. To make it easier, we turn on the laser level, we achieve the coincidence of the plane with the mark applied to the walls. Put the bar on the solution, press it in so that it is in the same plane with the laser.

This is not as easy as it seems. Either higher, now lower than necessary. Even if the profile is filled up in only one place, you have to start all over again. It's a little easier if you press the beacon with the rule - apply it in length and press it smoothly, following the laser beam. So efforts are easier to control and beacons are easier to set up.

We leave the bars set at the level alone for a day. During this time, the solution will set, and you can continue.

For dowel screws

To expose beacons to screws, take fasteners with a rod length greater than the height of the screed. The head is selected so that the selected type of beacon is well supported on it. Draw a line on the floor along which we will set the lighthouse strips. We drill holes at the base, insert dowel plugs. We screw in the screws so that the caps are on the same level. The height is determined taking into account the fact that the lighthouse bar also rests on the screws.

This method seems more time consuming. But believe me, putting a beacon on a solution normally is another task. As a result, it takes more time. Checked. Especially if the do-it-yourself floor screed is done for the first time. In addition, immediately after the beacons are exposed, you can start pouring the screed.

Laying out and leveling the mortar

The solution is spread between two beacons, spreading it slightly. Having laid out a certain amount, they take a rule, they level it and level the solution. He is moved slightly left and right, at the same time being pulled towards him. Beacons are used as a basis. The bottom edge of the rule rests on them. The plank captures the excess solution, pushes them in front of it. Possible voids and holes are filled along the way.

If, after the passage, dips formed as a rule, add the solution with a trowel, level again. So until we get a flat surface. We knead a new batch of solution, level it again.

To work conveniently, the screed is poured from the wall farthest from the entrance. It is more convenient to completely fill one span between the beacons, leave the next empty, then fill in the next. Then - the third. With this technology, the screed can be poured in parts. This option is good for those who make repairs after work, have a couple of hours in stock.

Floor screed - as you know, the basis of everything. Leveling and concreting the floor is necessary primarily to create a base on which the finishing coating will be laid. In this article, you will receive all the necessary information about the do-it-yourself screed device.

Which is better? How to do it right? How to use beacons? You will receive comprehensive answers to all these questions, supplemented by photo and video materials.

The pledge of a perfectly flat screed is the use of special beacons in the work. They serve to ensure that the level of the grout is the same over the entire surface of the room.

That's why, installation of beacons for floor screed is the most important stage of the whole process... Treat it with the utmost care.

So, as you can see in the photo, metal beacons are fixed to the floor using the usual mortar that you will use. But before that, make sure you have all the necessary materials and tools available:

• metal beacons, assuming that the distance between them should be 100-150 centimeters;
• special solution for screed;
• craftsmen for convenience;
• a large basin and access to water (for stirring the solution) as in the video;
• bubble levels of different sizes;
• damper tape around the entire perimeter of the room;
• rULE - to level the screed with your own hands.

First of all, you need to mark the floor in order to understand where and at what distance to mount the beacons and how to do the screed in general. At the walls, the distance to the lighthouses should be 20-30 centimeters, the distance between the lighthouses may be different, depending on the length of your rule, for small spaces, it is most convenient to have small distances of 100-150 centimeters. Lighthouses fit in only one plane.

In advance, it is worth attaching a damper tape to the wall, which will become a "layer" between the screed and the walls.

Putting beacons on the floor

In order to fix the lighthouse on the floor along the entire length of the proposed installation, we make small bumps from the ready-made screed solution. After that, until the solution has frozen, we sink the beacons in the solution and begin to level them using bubble levels.

Important! If the solution remains above the level after leveling the beacon, it must be equalized to the level of the beacon.

Very carefully you need to measure the level of not only a single beacon, but all at once and in different planes. To do this, you can use a thread stretched across, or any available means.

When all the strips of the lighthouses are installed and aligned, you need to wait until the solution that fixes them to the walls hardens.

Preparing the screed solution

Today, hardware stores and markets offer a large variety of ready-made dry mixes for do-it-yourself floor screed. Which one to choose is up to you. The main thing is to carefully read the information on the bags and their areas of application before buying a batch of the mixture.

Ideally, choose well-known brands proven over the years, but in some cases you can use less well-known brands, but with good recommendations from familiar builders.

To prepare the solution, you will need a large container, water and a mixing tool. Usually, you just need to add water to the finished mixture in the proportions indicated on the bag and mix thoroughly.

How to make a screed can be seen in the video below the article.

Note that it is better to measure the amount of water carefully, because lack or excess of moisture in the screed can significantly affect its quality.

Some masters prepare "the old fashioned way" mortar for floor screed from cement-sand mortar... This is also appropriate, but more time consuming, because in this case, it is necessary to take into account the grade of concrete and the amount of sand to comply with the required proportions. Such a solution will ultimately cost a little less than the ready-made mixture, so we give the proportions for the mixture:

In ordinary premises, concrete grade M150 is suitable, in rooms with increased load - M200. Which screed is better? It all depends on your preferences and operating conditions. If you want to do everything yourself, quickly and easily, use ready-made dry mixes.

An important point! The floor screed solution must be prepared gradually, because its curing time is usually only a few hours. Therefore, it is better to knead the mixture in small amounts.

DIY floor screed

When the beacons are installed, and the first portion of the solution is mixed, it is time to start pouring the screed. There are no special rules and tricks in this, anyone can handle it.

So, the whole point is to fill the space between the beacons with a screed solution for the floor with your own hands. Leveling is done using a rule, or in extreme cases, a flat board or bar. You can simply pour the solution onto the floor using a bucket, as shown in the video below.

By the way, if there is a need to strengthen the floor, it is recommended to lay a reinforced mesh in the screed.

So, focusing on the beacons and gradually mixing more and more portions of the solution, all the voids are filled and leveled. The result is a perfectly flat and durable surface.

How the screed should dry

Depending on which dry mix you use, the drying conditions for the screed may differ. In some case, a few days will be enough for complete solidification. Sometimes (in the case of using cement-sand mixtures), you will have to "take care" of the screed with your own hands, pouring plenty of water every day.

Arrangement of a floor screed is a process that, with a good repair and even more construction, no one will be able to avoid. And in this process, a lot of dusty, dirty and wet work is usually done. After them, the screed must be left to "ripen", "helpfully" moistened for several days, without walking 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 proceed in an organized and quick manner, we suggest that you familiarize yourself with this article, which will tell readers how to make the floor screed themselves. Moreover, there is nothing supernatural and prohibitively difficult in this, of which we intend to convince our readers.

A floor screed is an intermediate layer that is organized between any substrate and the floor finish. What is a screed for?

• To give the floor the required rigidity and strength in accordance with the expected loads.
• For leveling the floor horizontally or, conversely, giving the desired slope in some areas, for example, in shower cabins.

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

• For covering and protecting the thermal insulation layer from mechanical stress.

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

In many other cases, screeds make two-layer .

• The first layer aligns the surface horizontally, or gives the desired slopes. Usually it is made of a cement-sand mixture or concrete. It is customary to say that the first layer is rough screed ... Later on, you can lay tiles or porcelain stoneware on it.
• The second layer is called clean screed ... It already makes the surface perfectly flat, under the floor finish, for example, under laminate, parquet, carpet. Very often, the final screed is performed giving a perfect surface when used correctly.

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

• Tied screed , which is characterized by the fact that it is firmly attached to the previous layer. More often it is a concrete screed on a concrete floor slab. The desired adhesion and uniformity of this design also provides excellent mechanical strength. Such screeds can be done only 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 a separating layer ... This design must be in contact between two different materials. For example, when a concrete screed is made on the ground. Or in the case when gypsum or dry screed is laid on concrete. And also the use of a separating layer is mandatory if the moisture content of the underlying layer is above normal. Various rolled materials based on bitumen (roofing felt), polymer films or coating compositions can be used as a separator. Obviously, the screed will already be a separate structure, so it is advisable to reinforce it and make it at least 3-5 cm thick.
• Floating floor screed is a further continuation of the previous one. She is sure to arrange if you want to apply any insulation. The floating screed is separated from the base by a layer of insulation together with waterproofing. It is also necessarily separated from the walls. It can be insulation, but less thick, 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 from temperature exposure. Working in such conditions forces you to use reinforcement and have 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. Aggregate in the form of dry bulk material is poured on a prepared and insulated base of such a screed. Most often, granular is used, which is a good heat and sound insulator. Sheets are laid on top of it gypsum fiber plates fastened together. Such a screed is equipped very quickly and this is its main advantage. However, a dry screed 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 the way they are installed. Let's list them:

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

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

• Continuous floor screed using self-leveling compounds ... This method is also referred to as "wet". As we noted in this way, it is very convenient to make a clean screed. Such screeds are made with a thin layer of 0.5-20 mm, first of all for economic reasons, since dry mixes for preparing solutions are very expensive. But the styling technology and the result observed later are above all praise. The working solution is simply poured in strips over the surface, rolled with a needle roller to remove bubbles, and that's all.
• Dry or prefabricated floor screeds. We have already mentioned them earlier. You can read more about them in our portal.

All floor screeds, with the exception of prefabricated (dry) ones, are made on the basis of two main binders component - cement or gypsum. There are also others - magnesian, bituminous, anhydride - but they are not used for housing construction, therefore they will not be considered. Let's note the strengths and weaknesses of these two main materials.

Cement screed prices

cement strainer

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

Naturally, in addition to the 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 is more correct to speak cement-polymer or gypsum-polymer .

In cement screeds, foam 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 reinforcing layer with more durable fillers is also required.

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

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

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

• Foundation preparation;
• Exposing lighthouses;
• Solution preparation;
• Floor screed device.

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

Preparation of the base for the floor screed

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

Screed base - soil

The best time to equip rough floor screeds on the ground is the foundation stage. Then all excavation 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 mark the main stages of preparation.

• The first thing to do is to select 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 clay or loamy soils, then it is necessary to take care of drainage so that moisture does not "prop up" the floors from below.
• Next, the creation of the so-called filtration or drainage layer begins. For this, sand is poured with a layer of at least 100 mm. More is possible, but note that 100 mm is the lower limit. Thereafter, the sand is tamped by hand tamping or using an electric or gasoline tamping machine.

• It should be noted that the maximum allowable a layer of sand that need to be tamped - this is 200 mm. If a larger layer is planned, then the tamping work is divided into stages, but not more than 200 mm at a time. During the compaction process, it is necessary to periodically water the sand with a hose.
• A layer of crushed stone or coarse gravel is poured onto the sand. The minimum thickness is also 100 mm. This layer is rammed manually or mechanically. Crushed stone or gravel helps to better compact the sand layer and give the filter layer a rigid base.

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

Vibratory plate prices

vibrating plates

• If you still have 150-200 mm at your disposal, then you can lay a layer of concrete with the addition of expanded clay on a gravel-sand cushion. This will be the first step in thermal insulation, but which will still be insufficient 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. Skinny concrete is usually 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 ground floors for screed is the absence of 150-200 mm for the expanded clay concrete layer. Then skinny 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 tamp it so that the solution penetrates into the space between the rubble stones. With the help of a trowel, a rule and a float, it is necessary to form a flat outer surface, which will be the basis for the future floor screed.

The subsequent steps are the same for both cases. After the dry "gasket" of lean concrete, it is imperative to carry out waterproofing measures. For this, bituminous mastics are used, with which the entire surface is coated in at least two layers. Do not forget that the walls must be coated with mastic to a height not less than the height of the floor screed. In regions with a high level of groundwater, after the mastic, it will be in no way out of place to roll on the basis of bitumen or dense polyethylene film laid with an overlap.

Screed base - old screed

Those who got this option should not be envious, since in most cases the old screed will have to be dismantled. Even if it gives the impression of reliability and flawlessness. Even if it does not "bunch" when tapped and has a smooth surface without cracks. Here are the arguments.

the new screed, the "perfection" of the old one can easily be broken. In new conditions, delamination from the base, cracks may occur, which will affect the upper layer.

A new screed on top of the old one is an additional load on the base. This is especially true for floors on the upper floors. A slab with an area of \u200b\u200b1 m² of cement-sand screed with a thickness of 5 cm already weighs 110 kg.

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

Screeds 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 tied concrete screeds stick to each other only due to adhesion and will delaminate quite easily under mechanical stress.

To dismantle the screed, it is best to call a team of workers specializing in this. From experience - it will come out much cheaper. 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 comes with all the necessary slotting and stone cutting equipment, shovels, garbage bags, and a vacuum cleaner. They immediately take away all the garbage collected during slotting work and the owner does not have to worry about calling a separate machine. Work for professionals goes on in a continuous mode: one or two people hammer, another one or two immediately collect garbage in bags, and the rest take it out and load it into a car.

The main task of the owners is to negotiate with everyone who may be uncomfortable with the noise. In panel houses, this is the whole house. And, of course, make sure that after the brigade's departure there are no traces of the “noisy guys” and dust from the old screed on the site and in the entrance.

In private houses, everything is simpler, there is no need 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 hammer drill with a chuck not SDS +, not SDS-Max. Chisels are also needed for the hammer drill. Sometimes they use jackhammers, but this step can only be taken if this tool is in the hands of a professional. Improper use of the heavy-duty jackhammer can easily cause the concrete slab to break.

In addition to a hammer drill, a 230 mm grinder with a stone cutting disc, a construction vacuum cleaner, shovels, brooms, a large number of durable bags can be very useful. Work must be carried out in work clothes made of thick fabric and in a headdress, in gloves, in a mask or glasses. Since there will be a lot of dust, a respirator is required. It is better to protect 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 into one day, so assistants are definitely needed. Let's describe the main stages of dismantling the old screed.

• If in the room under the screed there are electrical wiring routes, heating or water supply pipes, then a diagram that should remain after installation is desirable. If it is not there, then you will have to use a special device - a detector of hidden wiring and metal, which must 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 then move deeper into it. This will make it easier to immediately remove the exfoliated pieces of the old screed. But before starting dismantling, it is necessary to carry out "exploratory drilling". To do this, cuts are made in a small area with a grinder with a stone-cutting disc, and then small pieces of the screed are broken off with a perforator with a shovel or a jackhammer to get to the next "cultural layer". If that layer is the required supporting plate, then you need to measure the thickness of the screed to be removed with a tape measure in order to know the reference point.
• To beat off the old tie, you need to start with low rotations of the perforator engine and break off at first in small pieces. Further, when the degree of adhesion of the screed to the base is already clear, then it is possible to increase the speed and break off in large pieces. Everything will be intuitively clear. When working, you should always take a stable body position and hold the tool with only two hands. It is not necessary to press hard on a perforator or a jackhammer, this does not affect the force from the blow, but the hands will get tired faster.
• It is better to remove the pieces of the breakaway screed immediately with shovels, load them into strong bags and take them out to a certain place for subsequent export. This is another argument for 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 for 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 skill with the instrument.
• If the old screed is reinforced with a wire mesh, then before dismantling the grinder with a stone-cutting disc, it is necessary to make cuts to such a depth that would ensure the cutting of the reinforcing mesh. The work of the grinder must be combined with the work of a vacuum cleaner, since there was 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.
• Where pipes or hidden wiring pass, a large hammer drill or jackhammer should be bypassed. In these areas, then after the "heavy artillery" it is better to let work with a small hammer drill or even a hand chisel and hammer. And you also need to be careful in the corners and near partitions, especially if they are made of drywall or cellular concrete.
• After dismantling and taking out all the debris, the surface of the base is cleaned with a perforator with a wide blade from the remnants of the old screed. Then the room is swept, the floor and air are sprayed with water from a sprayer and 15-20 minutes are given for all the dust to settle. A vacuum cleaner removes the remaining dirt.

Prices for polystyrene concrete

polystyrene concrete

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

Tiles laid during the days of developed socialism in the USSR have two extremes when dismantled. Either she literally "jumps" herself from the base, or "stands to the last." Moreover it happens that in one area the tiles behave differently. And all because before the masters did not have tile adhesives with predictable properties in their arsenal. Therefore, they glued who to what. They used just cement, 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 DIYers mistakenly believe that the harder the hammer blow, the more willingly the tile will lag behind the base. However, practice shows that a small puncher with a sharp blade can handle old tiles better than a "monster", but with a blunt blade. That is, when dismantling an old tile covering, it is not the strength that is more important, but the place of its application.

After dismantling the old screed and thorough cleaning, the preparation of the surface for the new screed will hardly differ from what will be described in the next chapter.

Screed base - concrete slab

It is most pleasant to make a screed on such a surface, when you do not have to do earthwork or dismantle old coatings. But 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 flaws in the surface will be visible.
• All joints of reinforced concrete slabs (if any) are cleaned, processed, and then sealed with a cement-sand mortar of the same recipe that will be used for the future screed. And also with this solution you can seal up the junction of the walls and floor, in which there may be gaps.
• All the dried splashes of solution, lime and others on the surface, as well as everything that lends itself to a spatula and hammer, is beaten off and cleaned.
• If there are large depressions on the upper surface of the slabs, then they can also be covered with the same mortar as the joints between the slabs.
• If there are cracks, then they are cut to a width of at least 5 mm, and then filled with special repair mortars for concrete.

• After all 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 is applied. Priming is required in any case, even if a screed is to be made on the separating layer.
• If the screed is tied, it is recommended to use a special composition - "Betonkontakt", which contains a complex of polymers, cement and quartz sand. After processing with this primer, the surface becomes rough, to which all building materials "stick with pleasure". However, we advise you to apply "Betonkontakt" already after placing 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 plastic film is laid on the floor. The joint of the strips should have an overlap of at least 100 mm, and the approach to the walls - the thickness of the future screed plus 20 mm.
• A damper tape is glued to the walls around the perimeter of the room, which serves to compensate for thermal expansion.

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

Prices for "Betonkontakt"

concrete contact

Exposing beacons for floor screed

The floor surface intended for the screed 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 may 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. An exception is the bathrooms, which should be 15-20 mm lower. Therefore, with proper repair, it cannot be so that in each separate room the screed is made only in his interests. In no case! You can do a screed in a room, but taking into account the entire 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 technique.

• 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 comfortable height for work - about 140-150 cm. Beam position marks are made on the walls of the premises with a marker.

• The level is transferred to some room where there is already a mark and is exposed by her . Further, the position of this mark is transferred to all walls. With the help of a paint cord, a horizontal baseline is struck.
• Similar actions are performed in all rooms. As a result, it should turn out that a horizontal baseline is drawn on all 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 vertical distance from the measurement points to the floor level is measured and recorded with a marker or pencil directly on the wall.

• Finds the minimum and maximum distance from the baseline to the floor surface. In the example shown, the minimum distance is 1420 mm and the maximum is 1445 mm. The height difference is 25 mm.
• Let's say the recommended minimum screed thickness for any grade of sand concrete is 30 mm. This means that 30 mm should be set aside from the highest point and it should be obtained that the zero level will be 1420-30 \u003d 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.

It is very appropriate to put these calculations 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.

Now is the time to learn how to place the beacons correctly. These actions cannot be called hard physical labor, but a lot depends on the correct placement of beacons. It is they who set the surface of the floor and, from the slightest mistake, all further work can lead, in the worst case, to further elimination of shortcomings, and in the best - to banal overspending of dry mix, from which the screed solution will be prepared.

Let's give an example. Let's say you have an apartment with an area of \u200b\u200b100 m² you need. For this, sand concrete M 300 will be used, which has a minimum layer size of 30 mm. When beating the zero level, it turned out that the thickness of the screed can be from 30 mm to 55 mm (we gave this example earlier). This means that the average thickness of the screed will be approximately (30 + 55) / 2 \u003d 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 \u200b\u200b1 m². It turns out that there will be consumption for the whole apartment: 4.25 * 100 * 20 \u003d 8500 kg of dry mixture, which will be 212.5 bags of 40 kg.

Now imagine that when installing the lighthouses, the master instead of the minimum 3 cm at the highest point set 4 cm with the "iron" argument "the pocket does not pull the stock". We recalculate: an extra 1 cm added to the screed over the entire area of \u200b\u200b100 m² will result in 20 * 100 \u003d 2000 kg, which in 40 kg bags will have an additional 50 bags. It turns out that the stock "pulled the pocket". And it's not so much about money, but about the extra load on the floor. The extra 2 tons will lie on the base of the floor. The extra 2 tons will need to be dragged, prepared, and laid.

All readers probably know that the most inconvenient during transportation and especially when lifting to floors is a piano. Movers 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 screed in the considered example is equal in weight to about 8 conventional pianos or one conventional Lexus RX 400 SUV.

There are too many ways to display beacons to describe them all in one article. Each master has his own favorite method, which does not have to be similar to others. In principle, what's the difference if two masters get equally good results with different methods of setting beacons. 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 sections. The ceiling guide profile is very widely used, " borrowed"In plasterboard systems, which we know as PN 28 * 27 or UD 28 * 27. Its shape and sufficient rigidity allow it to be used for lighthouses. For example, how it is done in the picture.

In the described method of placing beacons, we will use the PM-10 beacon profile, originally conceived for plastering, 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 PM-10 are perforated to facilitate its attachment to the leveling surface in different ways.

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

When the beacon profile is pressed into the mortar pad, be sure to make sure that it is pressed against the rule along its entire length. Surplus protruding above the lighthouse is cleaned. When the mortar is dry, you can start 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 glue gypsum solutions or even alabaster. In this case, the lighthouse is fixed almost instantly and work on laying the screed can be started immediately. Everything seems to be fine, but it turns out that in the body of the screed there will be foreign inclusions from other materials. During the operation of the screed, in those places where there are "strangers", cracks are likely to form, since the coefficients of linear thermal expansion differ for different materials. Therefore, beacons should be installed only on the solution with which the screed will be made.

The method of installing beacons on a solution has a main drawback - it is the impossibility of correcting the position in case of an error. Only the dismantling of the lighthouse and re-installation will be able to correct the situation. Therefore, it is better to use a method that will make it easy to mount, dismantle the lighthouse and correct its position. This is easily realized using self-tapping screws with dowels and a special attachment - a plastic clip for attaching beacons.

This clip consists of two parts - the clip itself and the lock that fixes the lighthouse. This type of beacon attachment is good in that the clip itself can be attached to the head of the self-tapping screw after it has been screwed in and adjusted in height. There is a special groove for this. Later, already after the lighthouse is wound into the clip, the final fixation with the lock is in progress The result is a very reliable mount that can still be adjusted in height. The price of such clips is cheap - 100 pieces cost 250-300 rubles.

Consider the process placing beacons with plastic clips... For convenience, we will present it in the form of a table.

Picture	Process description
	On the prepared surface of the floor, marking of the position of the beacons is made, which should be installed in the direction of pouring the screed from the far wall of the room to the entrance door parallel to the side walls (if the room is rectangular). An interval of 200-300 mm should be maintained from the side walls to the guides nearest to them. The distance between adjacent lighthouses is 1-1.5 meters. The rule laid on adjacent beacons must still have a margin of at least 200 mm on both sides.
	On the lines of the position of the beacons with an interval of 500 mm, holes are drilled with a puncher, into which the dowels are immediately driven.
	The room where the beacons are placed is the highest point, according to earlier calculations. A self-tapping screw is screwed in at this point corresponding to this point, but not completely. The laser level is set and set according to the base line previously drawn on the walls.
	On a straight wooden block, a mark is made for 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 level of the screed relative to the baseline. The bar is installed vertically on the screw head and the position of the mark is controlled.
	By screwing or unscrewing the self-tapping screw with a screwdriver, they achieve the coincidence of the mark on the bar and the laser level beam. The self-tapping screw at this point can be considered exposed, 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 higher than the head of the exposed screw. A long bit is clamped into a screwdriver. Then the bit is inserted into the slots of the exposed self-tapping screw vertically and it is controlled that the laser beam is on it.
	A strip of white masking tape is glued onto the bat in a circle, then it is again placed in the self-tapping slots vertically and a marker is made to mark the position of the laser beam.
	Self-tapping screws are added to 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 screws, and the adjacent ones should be oriented opposite to each other.
	The position of the clips is checked by the rule, the level and the laser beam. The rule should lie strictly horizontally on all clips.
	The beacon profiles are inserted into the grooves of the clips. All joints of the profiles should only fall on the clips.
	Clip-on profiles are fixed with snap locks.
	The room is cleaned with a vacuum cleaner.
	The floor surface is primed with a deep penetration compound.
	After the primer has dried, a semi-dry solution of sand concrete is mixed and all lighthouses are strengthened with it. The same solution can be used to fix the position of the damper tape.

The proposed method is also good in that 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 expediency of reinforcing the screed, because by its intended purpose it is often not a power element that carries the main load. And this is partly true. But the lack of reinforcement can only be justified in tied screeds laid on a reliable concrete base, and in all other cases it will not be superfluous. Consider the cases when 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 plates are also necessarily reinforced, since it has a much lower bearing capacity.
• Screeds on the ground should be reinforced with reinforcement, since they are usually laid on a loose foundation. External factors such as seasonal swelling can be another reason for reinforcement.
• If heavy objects are installed in the room or the screed is subjected to any dynamic loads, then reinforcement is required.
• Screeds with a height of more than 5 cm are reinforced to avoid cracking during the drying process.

Various materials can be used for reinforcement. Let's consider which ones.

Reinforcement of the screed with metal meshes

The oldest proven method of screed reinforcement is steel mesh made of 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. Meshes for reinforcing screeds are made of VR-1 wire with a diameter of 2.5 mm to 6 mm. If earlier the frame was formed with the help of thin wire, which was used to twist the laid rods, nowadays, grids connected by spot welding are offered. The cells can be square or rectangular 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. Thin wire nets (up to 3 mm in diameter) can be sold in rolls, and thicker ones in the form of cards of 0.5 * 2, 1 * 2 and 2 * 3 meters.

A very important element in any wire mesh is the presence of notches on the bars, located with a step of 2-3 mm along the entire length. They significantly increase the adhesion area of \u200b\u200bthe frame to the concrete solution, which strengthens the finished screed. When buying a wire mesh, it is necessary to strictly monitor that all wire intersections are welded, since not all manufacturers do this. And it is also worth checking the meshes for the absence of strong foci of corrosion, which in a highly alkaline concrete solution will expand when it solidifies.

There are many sources on the Internet that tell you how to "correctly" reinforce a floating screed with floor heating pipes. A wire mesh is placed on the layer of heat and waterproofing, and only then pipes of the warm floor are attached to it with plastic clamps. The deeds of such "craftsmen" can be seen in the photograph.

This "reinforcement" is possible in its essence - 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 inside the concrete, while they must be spaced 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 ones it is better to place it in the lower third, so it will work better under various arising loads.

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

• The mesh is installed on slides made of cement mortar - exactly the same as the screed will be poured into. 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 stratification. It is unacceptable to use gypsum solutions!
• The reinforcing mesh is installed on supports made of pieces of broken brick, concrete fragments or other materials at hand. This method is also allowed, but it is quite difficult to set the mesh at the same distance from the base. And then, when the screed is laid and moved along the mesh, 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 mesh is to use special reinforcement clamps. They are made of plastic, have calibrated dimensions and are selected for any kind 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-sandy screed structure in the worst way. 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. It is recommended to use at least 8-12 clamps per 1 m². It depends on the diameter of the reinforcement or wire, the mesh spacing and the base material.

Rebar clamps - a modern and best solution for installing reinforcing mesh

The most common reason why screed reinforcement is needed 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 exercise. The effectiveness of such "reinforcement" is close to zero. The most correct thing is to fix the pipes to the thermal insulation, and on top of them place steel nets on the reinforcement clamps.

Let's note the advantages of using steel reinforcing meshes for screeds:

• Such screeds have the highest tensile strength, bending, for stretching and compression.
• Excellent resistance to temperature extremes over a very wide range.
• Steel meshes laid on top of floor heating pipes make it possible to distribute temperature gradients more evenly, since metal has a thermal conductivity many times greater than concrete.
• Correctly installed screeds with steel reinforcements have a long service life.

There are few drawbacks to steel reinforcement - it 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, therefore 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 emerged - reinforcement and mesh made of polymer and composite materials. Let's briefly review them and immediately note the advantages and disadvantages.

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

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

Let's note the disadvantages of composite reinforcement:

• Lower stiffness of composite reinforcement than steel.
• Lack of ductility - high fragility.
• The heat resistance of composite reinforcement is worse. GRP loses its properties at 150 ° C, carbon fiber at 300 ° C, and steel only at 500 ° C.
• When cutting composite rebar, a large amount of harmful dust is generated. This is especially true for fiberglass reinforcement.

They work with composite reinforcement in the same way as with metal ones. When knitting frames, wire or plastic clamps are also used, and for installation - clamps or mortar cushions. The correspondence of the diameters of steel and fiberglass reinforcement can be seen in the following table. At a price, 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 installing the frame and pouring the screed, care must be taken, because composite reinforcement is much easier to break than steel, since it works much worse in bending.

Prices for fiberglass fittings

fiberglass reinforcement

For the reinforcement of screeds located on reliable bases, plastic nets are now widely used. They are made of polypropylene or fiberglass with a special impregnation that prevents the action of an alkaline environment inside the concrete. The meshes 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 often used. The width of the web is from 50 cm to 4 meters, and the length of the net roll is from 10 to 50 meters. It is certainly very convenient. Let's note the advantages of plastic nets for floor screed reinforcement.

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

Reinforcement of screed with fiber

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 and in the thickness of the screed. It is they who reinforce concrete in all planes, since they are located chaotically. Their addition, even in small quantities, significantly increases the grade of concrete, impact resistance and strength. In fiber-reinforced 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 not used in screeds. Its purpose is concrete for massive monolithic structures, mainly prefabricated.

• Fiberglass fiber - significantly improves the quality of concrete, which reduces the amount of cement up to 15% and water up to 20%. It is not used in monolithic structures and screeds, since fibers from special alkali-resistant zirconia glass is very expensive. Therefore, fiberglass fiber found hisapplication 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 4-5 times, abrasion resistance - 2-3 times, tensile strength - 2-3 times, compressive strength - 1.5-2 times, water resistance - 2 times. This type of fiber can partially dissolve in cement slurry, but from this it only gains strength. It turns out that the reinforcement is both chemical and mechanical. Consumption - about 0.8-1.2 kg per 1 m³ of ready-mixed concrete.

• 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 react chemically with concrete solution and does not change its properties during the entire life of the concrete. The consumption of polypropylene fiber is approximately 0.6-1 kg per 1 m³ of the finished solution.

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

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

Conclusions on the reinforcement of the floor screed

The opinion of the authors of the article about reinforcement is unambiguous - 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 reinforcement done correctly makes the screed better.
• Highly loaded screeds, as well as those made on the ground, must be reinforced with a reinforcing cage.
• Composite reinforcement does not offer any advantages over steel at current prices.
• Any reinforcing frame must be inside the screed, and the thickness of the protective layer must be at least 15 mm.
• on a reliable basis, it is enough to use a polypropylene reinforcing mesh.
• Reinforcement with polypropylene or basalt fiber is always best done, since the costs for this are incomparably less than for all other components of the solution, and the result, when 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 at the construction of private houses in the territory of the former USSR, there were no questions with this. Either simply on the surface of the floor, or in homemade troughs, a solution consisting of cement, sand and water was kneaded with shovels, and then it was laid on the floor surface using wooden floats, slats, pieces of edged boards and other improvised means. And many ties made then serve to this day. But this does not mean that we should continue to use these "old-fashioned" methods.

Modern screeds are often made on a layer of insulation, and warm floors are no longer a luxury item either. Accordingly, the requirements for what kind of solution should be prepared also increase. Let's tell the readers right away that mixing with shovels on the floor or in the trough, as some current sources may even say, is an outdated approach. A good screed must have a homogeneous structure, therefore, the preparation of a solution for it is better compared to the craft of a pharmacist, which is from various containers using 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 attitude 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 to prepare the solution yourself. At the same time, the necessary ingredients are purchased in the required volume, which are mixed in certain proportions. It should be borne in mind that with this method, experience or clear instructions are desirable, not to mention the quality of the individual components of the solution.
• The second method is the use of ready-made dry building mixtures, which are specially designed for floor screed. This makes the job easier, but more expensive.

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

Self-preparation of mortar for floor screed

Modern SNiPs do not at all interfere with the independent preparation of the solution, but its grade should in no way be 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 components of the screed - cement and sand, it is also recommended to use a special additive - plasticizer ... What does it do?

• In order for cement to turn into stone, it needs a certain amount of water, approximately equal to a quarter of its mass. For 100 kg of cement, approximately 25 liters of water are needed. But such a ratio will not allow obtaining a plastic and flowable cement solution with fillers, therefore, an additional amount of water is introduced into the mixture, which makes it convenient to lay the solution. Plasticizers allow you to minimize the water-cement ratio, which has a beneficial effect on the rate of solidification 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 screed body. This is especially true in pouring underfloor heating screeds. The air when laying the screed, due to the plasticity of the mortar, freely escapes by itself, and the cement-sand mortar better "grabs" the underfloor heating pipeline.
• The branded strength of the finished solution increases by 20-40% when using a plasticizer.
• Solutions with a plasticizer have a frost resistance 50% higher than without it.
• The "life" of the mortar, at which it can be worked with when laying the screed, increases significantly. This allows you to mix in large quantities and increase productivity.
• The water resistance of screeds with a plasticizer is significantly higher than without it.

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

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

• As a binder, it is necessary to use Portland cement itself 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 there are 25 kg bags for easy transportation. Of course, it is necessary to check that the expiration date of the cement is not exceeded.

• It is recommended to use quarry sand as an aggregate, in which grains of sand have an irregular shape with sharp edges. In a screed, such sand will adhere well itself with you, with cement and the base. River sand, with prolonged exposure to water, takes on a smoother shape, which means it will more readily flake off the screed.
• The water for preparing the solution should be used only clean, free of impurities of oil products, fats and other contaminants. Naturally, the containers for water must also be clean and intended only for it. It should be noted that the required amount of water does not need to be added immediately, since a solution with a very high water content can be obtained. This will have a negative effect on the ease of installation and the strength of the screed. The sand may already contain a certain amount of water and the use of a plasticizer also greatly affects the water-cement ratio.

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

Calculator for calculating the amount of ingredients for floor screed mortar

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