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With a dry screed, it's a little more difficult. Dry screed

Such a screed has significant advantages. It does not require drying. It is possible to lay floor coverings without waiting 45 days, as in the case of using Traditional mixtures, but the very next day. It is also significantly lighter than traditional concrete mixes. Now, with the optimal thickness of the screed from 3 to 7 cm, per 1 sq.m. it is necessary to stack from 70 to 120 kg. mixtures. Agree, this is a very serious load on the ceiling and load-bearing walls of the house: for an apartment with a total area of 100 sq.m., you will need to lay at least 7 tons. concrete mix.

The essence of the prefabricated floor with a dry screed is as follows. A fairly thick layer of dry backfill is applied to the floor slabs. From above it is covered with durable sheet material (dry screed). And already a finishing floor is laid on it. The number of layers and the materials used may vary depending on the characteristics of the floor and the requirements for its quality. A dry backfill floor can be laid not only on slab floors, but also on floors with lags (both stationary and adjustable). In general, the idea of infill prefabricated floors has been known for a long time and was widely used in our mass housing construction 30-40 years ago. In recent years, prefabricated dry floors have received a new life due to the arrival of modern building materials on the market.

Due to the absence of wet processes during the installation of dry floors, labor intensity and the duration of the construction cycle are reduced, it becomes possible to easily lay communication lines in the screed, provide high heat-shielding properties of the floor, and sometimes the required sound insulation.

The main problem with these bases is the fear of moisture, and leaks are simply fatal for them. Therefore, a vapor barrier layer is always laid on the ceiling. Next, a bulk material is applied to it, which serves to create a flat surface for flooring, as well as to provide the required level of thermal insulation and sound absorption.

The vapor-moisture-insulating layer protects the backfill located on it from moisture, which inevitably occurs in direct contact with the ceiling.

Moisture vapors appear from the underlying room or from the concrete of the ceiling, as well as from suction from the walls.

For steam and moisture protection, an ordinary polyethylene film with a thickness of 200-250 microns is most often used. (in the case of a reinforced concrete floor), glassine or bituminized paper (for a wooden floor), or other modern vapor barrier.

For backfilling, specially selected materials are used - screenings from the production of expanded clay, expanded perlite sand, quartz and silica sand, fine-grained slag, etc.

If the surface of the floor slab does not require leveling, instead of backfilling, slabs of extruded polystyrene foam (PSB-35, PSB-50) laid tightly to each other can be used. Also, polystyrene foam boards are used in addition to backfill to provide the required thermal protection and sound insulation.

The thickness of the backfill depends on the quality (the number and size of irregularities, the surface of the floor slab, as well as the presence and characteristics of utilities and other equipment. Usually the layer thickness is 30-50mm. The best materials for a "dry" screed are moisture-resistant slabs (GVLV), moisture resistant plywood or chipboard.

The disadvantage of a "dry" screed is its hydrophobia, i.e. these floors must not be exposed to moisture, otherwise the plates will swell.

Installation of a "dry" screed is carried out, unlike the traditional one, after all plumbing and electrical work has been completed and the operation of engineering networks has been checked.

First, prepare the base - remove the old one, close up the cracks. Then, using a hydraulic or laser level, a backfill level mark is applied to the walls. To ensure vapor and moisture insulation, a polyethylene film is laid with an overlap of strips on top of each other of at least 20 cm. On the wall, the film should rise no lower than the level of the future backfill. That is, the backfill should be "wrapped" with a film.

Along the perimeter of the floor along the walls, a tape of mineral or glass wool grade M75 or M100, polystyrene foam or other similar material is laid. This is necessary for the thermal expansion of the future floor.

After that, the backfill is poured out and leveled with a rail at the marked level.

The laying technology is determined by the type of sheets used. Gypsum-fiber sheets are laid along the backfill in two layers, firmly fastening them together during installation with glue and self-tapping screws. Seams from fasteners puttied and polished.

A floor with a subfloor laid in this way can withstand the same loads as a concrete screed floor. The base has an impact noise reduction index of 18-22dB.

Chipboards, plywood or other sheet materials are laid, depending on the thickness, in one or two layers. The surface of the screed is covered with bituminous waterproofing.

One of the world's leading manufacturers of building materials, KNAUF, has developed special systems for the installation of a "dry" screed based on gypsum fiber sheets. These systems are very easy to use and can be purchased at any hardware store.

The KNAUF system is used in residential, office and administrative premises with a normal load, to form an even base, as well as to improve the heat and sound insulation qualities of the floor. The surface is intended for any subsequent coating, such as parquet, tiling, etc. This system has the following characteristics:

Minimum construction thickness: about 45mm.
Compressive strength of the screed: not less than 10 MPa.
Thermal conductivity of the screed, W / m2., C: 0.22-0.41.
Airborne noise reduction index, dB: by 2-4.
Impact noise reduction index, dB: by 18-22.

The floor element (it is also called the super floor) is two moisture-resistant gypsum-fiber sheets glued to each other with a 50 mm offset at the factory. The size of each sheet is 1500x500x10mm. Thus, the overall dimensions of the superfloor are 1550x550x20mm.

Floor elements are mounted in the above sequence - film, edge tape, backfill. The room temperature during operation should be at least 8 degrees.

Laying floor elements starts from the doorway to the window from right to left. The end fold of the top sheet is cut off with a knife or saw, and the element is placed close to the walls in the right corner farthest from the door. The folds of the laid sheet are made with PVA glue. Then the second and subsequent sheets of the first row are laid. This row is laid out along the cord.

The second row is laid out with the remainder of the last sheet of the first row in such a way that the offset of the joints of the sheets is at least 250 mm. Starting from the second row, the floor elements are fastened together with special self-tapping screws 19 mm long. They have a countersinking head, which allows you to drown the screw to a depth of 1 mm. For this purpose, you can also use special building brackets with a length of 18mm.

In the place of the doorway, under the upper fold of the element, a lining of GVLV with a width of 10 mm is laid.

If the top coating is linoleum or carpet, then the gaps in the joints of the plates must be puttied, sanded and primed.

After that, the protruding edge tape and film are cut off, the joint between the wall and the floor is sealed with sealant. And then you can lay the flooring.

A smooth, even base for the finish coat is a prerequisite for flooring. This is the only way to ensure its reliability and durability. In the view of many apartment owners, construction work of this type is necessarily accompanied by destruction, dust, dirt and other consequences of work related to pouring a cement-sand screed. If we add another long wait of three to four weeks, then the picture that emerges is not at all rosy. Is there a way out?

Perhaps for someone it will be a discovery, but quite often such a picture can be avoided. The solution to all these problems is a dry floor screed. What it is, how to do it, what pros and cons it has - these are an approximate range of questions that we have to deal with.

Dry or wet floor screed

Several methods can be used to form a flat surface. Classical pouring with concrete mixture is labor intensive and has a long final drying time. An alternative to it is a dry floor screed. What it is and what features the coating has should be analyzed even before choosing the arrangement method.

The peculiarity of this method lies in the formation of a flat surface of the base using several types of materials. For this, a special bedding is used, which must have certain properties. First of all, these are good indicators of thermal insulation. Changes in qualities under the influence of external factors are also not allowed. For these purposes, you can use expanded clay, or ready-made compositions from manufacturers. After the final leveling of the surface, gypsum fiber sheets with locking fasteners are mounted.

Before doing a dry floor screed, you should consider the relevance of its use. In this case, certain restrictions should be taken into account:

The performance of the premises. The formed leveling layer must not be exposed to moisture. When it enters the building mixture, a change in properties occurs. Therefore, it is necessary to additionally install a waterproofing layer. Materials for dry screed are not designed for use in "wet" rooms - bathroom, kitchen.
Area. If the size of the room is large enough (from 50 m² or more), the installation of the screed will be difficult due to the mandatory division of the area into sectors.
Load degree. Despite the fact that the floor screed mixture will not experience mechanical stress, it will affect the gypsum fiber boards.
Compatible with underfloor heating. The backfill itself has good thermal insulation properties. Therefore, heating elements cannot be installed in it. Dry floor screed for underfloor heating can only be compatible with film heating.

These are not the only conditions for applying this surface leveling method. First you need to familiarize yourself with the recommendations from the manufacturer and determine the optimal operating rules.

The use of technology for rooms with a slope is unacceptable. This will lead to the formation of voids and a decrease in the thermal insulation index in a certain part of the room.

The main difference between the dry method and the use of cement-sand or dry building mixes for floor screed is the use of liquids. True, dry-type materials do not provide a particularly high density, but these indicators are sufficient for their installation in any residential area.

Advantages and disadvantages

Arrangement by the above method should begin with an analysis of its pros and cons. They depend on the type of materials used and the characteristics of the room. This takes into account the required performance of the coating.

One of the disadvantages is the relatively low mechanical strength of the formed layers. In their structure, they are similar to wooden models, with the exception of the filler of the space between the lags.

What else distinguishes this technology?

Small consumption of material. It differs significantly from the method of concrete pouring.
A small mass reduces the load on the floors. All dry building mixes for this work have a small specific gravity. Therefore, a layer thickness of 20-30 cm will not affect the overall characteristics of the building.
With some skills, a dry screed is laid in just a couple of days. After the final laying of the sheets, the floor may be subjected to loads. When pouring a concrete surface, this will require waiting from 7 to 20 days.
There are no wet processes, so dirt does not spread throughout the living spaces. Not only dirt. There is also no cement dust, a fairly strong allergen.
Labor intensity, including work such as loading and unloading, lifting materials and equipment to the floor , several times less.

The technology of dry floor screed does not involve the use of concrete mixers, special containers or other special equipment. The exception is rooms with a large area, where the speed of work is important. In this case, you need equipment with which you can quickly form an even leveling layer.
Through the bulk layer of the system, it is possible to lay intra-apartment communications.
One of the priorities is for a warm floor. Due to its high thermal insulation characteristics, it significantly increases the energy efficiency of the system. The ideal option is considered to be an IR film, which is placed directly under the finish coating, the presence of a layer of thermally reflective material is a must.
It simultaneously performs the function of additional thermal and sound insulation.
Installation is quite simple. Also suitable for a wooden base, if it is, of course, durable.
Provides stability of the layer to distributed and point loads - up to 1 t/m 2 and 360 kg, respectively.
The top coat can be installed as soon as the screed is completed. Almost any material is chosen for it.

The advantages of this technology also include:

the possibility of carrying out work at any time of the year;
use in old buildings, since the loads are minimal;
work, if necessary, can be performed alone without assistants;
more economical way: the cost of installation work and the price of equipment is less.

It also has disadvantages, although they are few. The main one, perhaps, is increased sensitivity to moisture, therefore it is completely unsuitable for the device in rooms with a high percentage of moisture, for example, a bathroom, and where water leakage is theoretically possible. It is also not recommended to carry out installation work in wet weather.

If you still decide to use this option in the bathroom, then pay special attention to the waterproofing device. At the joints of the walls and the base, it is necessary to lay a waterproofing tape and take care of a special waterproofing layer covering the floor surface.

Now you know the difference between a dry floor screed. The pros and cons of technology make it relevant for the arrangement of residential premises. Most of all, this applies to places where there is a need, if possible, to reduce the load exerted on the floor.

Prefabricated dry screed from OSB boards

First you need to define the terminology. The term OSB gets its name from the abbreviation for oriented strand board. This means that large chips are used for production, located in a special pattern relative to each other.

During the manufacturing process, large chips are located at the edges of the structure, smaller components are placed inside. To increase the mechanical strength, the outer layers have a longitudinal orientation of the wood fibers, and the inner layers have a transverse orientation. Subsequently, plates with a dense and homogeneous structure are formed by hot pressing.

Specifications: thickness, weight

Before choosing the material for making the floor from OSB boards, you should familiarize yourself with the technical specifications. They directly depend on the specific model, its performance. In most cases, the manufacturer indicates these parameters on the packaging. However, difficulties may arise during the piece purchase.

The most important parameter is the water resistance index. It determines the possibility of installing the coating in a particular room - a bedroom, kitchen or bathroom. Depending on the degree of processing, this value can range from 12% to 25%. For the arrangement of floors, it is recommended to use slabs in which the swelling parameter in thickness does not exceed 15%.

When creating a rough surface that will not be subjected to mechanical stress, you can use a material with an elastic modulus of 1100 N/mm². If it is planned to install the plates as the main coating, it is recommended to choose the value of this indicator from 1600 N / mm² and above.

Due to its design, this material has the highest specific gravity. But in order to analyze the total mass of the future coating, it is necessary to know the optimal thickness of the OSB slab on the floor. For a rough surface, it can be equal to 6-9 mm. When arranging the main coating, models with a thickness of 16 to 25 mm should be mounted, depending on the load on the floor.

To optimize cutting, manufacturers have provided several sheet sizes: 1220×2440, 1220×3660, 1250×6000, 1250×2500, 1250×3700. Since polyurethane resins are used for gluing the layers, they have increased fire safety; when the temperature rises, they do not emit harmful components. The latter fact is very important for operation in residential premises.

QSB plates have similar qualities. The difference lies in the manufacturing technology - furniture production waste is used for this. Chips are smaller, and therefore better performance.

Laying technology

One of the key advantages of OSB is the relatively easy installation. For its implementation, requirements are imposed on the quality of the rough surface. An important point is the correct choice of a specific model of floor material.

Before leveling the floor with OSB boards, it is necessary to draw up the actual characteristics of the room. The following factors will influence the laying technology:

The initial material for the manufacture of floors is wood or concrete screed;
Temperature and humidity parameters in the room;
Total coverage area;
The value of the maximum load on the surface.

A laying scheme is preliminarily drawn up. One of the defining conditions is to minimize the number of joints. That is why large sheets are most often used. In general, the installation technology allows you to perform all the work without the involvement of craftsmen. But before that, you should read the general recommendations for installation.

Installation on a concrete floor

Before installation, the cement surface must be treated. After a long period of operation, cracks and chips will inevitably form on it. They need to be carefully sealed. If the level difference exceeds 7 mm per 1 m.p. - Install the adjusters.

In practice, this is required only as a last resort. Most often, installation is carried out on a prepared base. To reduce the influence of moisture, a layer of waterproofing is installed. It can be a film material or mastic.

Then you need to follow these steps:

Cutting according to a previously drawn up scheme.
Cleaning the floor from dust and dirt.
Installation of material, adjustment of its joints.
For fastening, you can use glue. It is important that it does not adversely affect wood and concrete.
Joints should be tightly fitted to each other. It is recommended to use models with side mounting elements.
To compensate for thermal expansion, it is necessary to leave a gap of 5-7 mm between the base and the wall.

During installation, it is important to make the flooring the right side. Most stoves have front and back sides, which are designed for specific operating conditions.

On a note

For better fastening, you can fix the canvas with dowels. If it is planned to install decorative material on top of the OSB, the fixing heads must be recessed into the subfloor.

On the wooden floor

Before laying OSB boards on a wooden floor, check the condition of the lag. They must not be damaged, the surface and structure must not contain fungus and mold.

Often, for the arrangement, it is required to first install a layer of insulation. As a rough base, you can use cheap OSB with a thickness of no more than 8 mm. It must be remembered that during operation it may be exposed to moisture. Therefore, it is necessary to choose moisture resistant models.

After that, a layer of waterproofing is mounted. It should cover the entire surface of the floor and pass under the logs. If it is impossible to dismantle the log, processing can be done with liquid mastics. After that, you can install a layer of thermal insulation.

Rules for the arrangement of wooden floors.

To increase the mechanical strength, it is recommended to install two layers of OSB. The first is located across the lag, and the second - along them.
The boards are fastened with side screws. It is important that the joints are not at the same level.
After installing OSB boards on the floor, the level is checked. If necessary, you can perform partial dismantling and install adjusting pads on top of the log.
A thermal gap is made without fail.

To form the top layer, it is necessary to use models with a thickness of 16 mm or more. If you plan to install one layer, the distance between the lags should be no more than 30 cm. Otherwise, there is a high probability of damage to the material.

When laying ceramic tiles over OSB, use a special adhesive that will not damage the wooden base. It must be remembered that a high-quality OSB floor slab should not have irregularities and obvious defects.

Properties and characteristics of GVL

First you need to consider the properties of this material, its structure and composition. Outwardly, it is similar to standard gypsum boards. But that's where the identity ends.

For the manufacture, a mixture is used, which includes gypsum and cellulose fibers. Their ratio is usually 80/20. Fibers are needed to improve mechanical strength, a similar example is acrylic.

As a result of pressing and adding special fastening compounds, GVL sheets for the floor are obtained with the following properties:

The density index is 1200 kg / m³. This makes it possible to use fixing materials (screws and nails) without damaging the surface;
High degree of sound insulation. The thicker the GVL Knauf sheets, the higher this indicator. For some models, it is 35-40 dB;
Fire safety. The material can be used in rooms with increased requirements for fire safety;
Low thermal conductivity. It is an additional property that does not cancel the use of insulation;
Flexibility. Usually it is 5.5 MPa, which is one of the best indicators for such materials.

For laying on a rough surface, it is recommended to use moisture-resistant models. They are less affected by moisture that can accumulate in cellulose fibers. Therefore, if there is a question, GVL or plywood on the floor, it is better to do everything first.

To obtain a high-quality floor surface, it is necessary to purchase models from well-known manufacturers. One of them is Knauff.

On a note

Despite the fact that the price per meter of GVL is relatively high, it will pay off its cost due to quality and long service life.

Despite all its positive qualities, in practice one may encounter some difficulties in choosing the optimal coverage model. In order to avoid possible complications during the installation process, it is necessary to familiarize yourself with the recommendations of specialists.

Since the GVL slab will be attached to the floor, heat losses through the joints should be avoided. To do this, choose a model with a mounting groove. With its help, you can not lay two layers of material, as is necessary when installing plywood or OSB.

Another important indicator is the flooring material. To ensure sufficient rigidity, the base must be homogeneous. In this case, there will be an even distribution of the load. Therefore, you can choose models up to 0.5 cm thick. But it all depends on the degree of maximum mechanical pressure on the material.

When choosing, you need to pay attention to the following nuances:

The condition of the edges is smooth, without defects;
Package. If the sheets are stored indoors, they may not be packed. But during long-term storage, condensation may accumulate inside;
Cost and dimensions.

The last factor directly affects the cost. Currently, manufacturers make products with a width of 500, 1000 and 1200 mm. The thickness in this case can be 10, 12.5, 15, 18 and 20 mm. The length varies from 500 to 3000 mm. Standard GVL sheets have an affordable cost, which is determined by their dimensions.

On a note

The average price for a sheet measuring 1200 * 2500 * 10 from the manufacturer Knauff is 1625 rubles.

Prefabricated system in section

In fact, this is a system of materials that are laid out on a leveled base in a specific sequence in the form of a “pie”:

a waterproofing layer (film or membrane) laid on floor slabs or the surface to be repaired;
damper tape, which is used to create the required compensation gap;
leveling layer, as a rule, from expanded clay, slag or other backfill material;

If the base is sufficiently level, thermal insulation boards made of EPP (extruded polystyrene foam) or high-density mineral wool are laid at this stage. Thus, on the one hand, the level is finally leveled horizontally, and on the other hand, the necessary sound and thermal insulation is provided.

sheet material as a base for a finishing floor covering, which perceives the load and distributes it to the backfill layer located under it. It can be moisture-resistant plywood, OSB, chipboard, etc. Recently, ready-to-install elements made of moisture-resistant gypsum fiber (GVLV) are predominantly used.

On a note

The optimal thickness of the cake is 35-45 mm, and 20 of them fall on the share of the leaf layer.

With a lower height of the system, it is impossible to provide the required degree of strength and stability, with a higher one, the installation technology has certain nuances.

Repair of floors based on dry screed Knauf

Knauf dry floor screed is essentially special sheet panels laid on loose material, laid out in a thin layer. Soft, finely dispersed backfill, pressed by these sheets, transforms into a solid and durable base, which is able to withstand fairly large loads.

Expanded clay sand used in Knauf technology is fine-grained. According to the standard, the size of its granules should not exceed four millimeters. The backfill is leveled “along the beacons” using the rule.

On a note

Backfilling over large areas is leveled using a special machine.

Gypsum fiber sheets Knauf (GVL) are made of gypsum and cellulose, the fibers of which perform a reinforcing function. They are characterized by high strength and fire resistance. Sheets are eco-friendly and chemically passive. Unlike drywall, they do not have a paper backing.

The structural elements of the Knauf superfloor are panels that are glued together from two gypsum-fiber sheets. They are somewhat offset from one another, due to which folds of about 5 cm are formed along the perimeter of the element. It is due to them that the elements are fastened during installation. Standard panel dimensions in mm are 1200 by 600 by 10.

Instructions for the device

The surface on which the system will be laid is thoroughly cleaned of debris. It is also necessary to remove the protruding ends of all metal elements, say, wires, fittings, etc. The same is done with those on the concrete surface. If the metal is cut, then the concrete is knocked down with a chisel.
A vapor barrier film is spread on the cleaned base with a minimum overlap of 20 cm. At the edges, it is brought onto the walls so that the edge passes above the line of the future floor.
Further along the perimeter of the room, a damper tape is laid vertically, which in the future will compensate for the thermal deformation of the Knauf panels. Due to the presence of a compensation gap, it is possible to exclude swelling of the floor surface during temperature fluctuations.

Further, the beacons are removed and expanded clay is poured into the remaining cavities. It is recommended to lay a few more free ones to the corner from where the GVL sheets will begin to be laid. It will be possible to move freely along this impromptu path, keeping the rest of the backfill intact.
On panels that are adjacent to walls or other vertical surfaces, folds are cut. The initial row is laid out along the wall opposite the front door, and gradually moving towards it. The folds of each previous row are lubricated with adhesive or mastic.
Each subsequent row is laid with an offset of up to 25 cm relative to the previous one, and the possibility of the formation of cruciform joints must be completely excluded. Glued joints are additionally fastened with screws. They are fixed in increments of no more than 30 cm.

You will need a room plan on which markings will be applied. You need to pay attention that their trimming can be done only on one side. Removing mounting locks will affect the degree of waterproofing.

To calculate the dry floor screed Knauf, a calculator is used that will determine the required volume with great accuracy. It takes into account not only the area and volume, but also the degree of level difference.

Suppose the area of the room is 20 square meters. m., and backfilling of expanded clay is carried out with a layer 5 cm thick. Under these assumptions, the volume of the aggregate will be 20 * 0.15 = 1 m 3. As a backfill, we will choose the most popular Knauf Compavit today. Note that the material is supplied to the market in 4-5-layer bags with a volume of 50 liters. This bag weighs 30 kg.

Calculation example

So, for the device of the desired subfloor, 1 m 3 of backfill will be required. Since 1m 3 \u003d 1000 l, we find that the minimum consumption of Knauf expanded clay backfill for floor repair in a standard one-room apartment is 1000: 50 \u003d 20 bags.

Of course, you need to purchase material with a margin, because in practice it takes more, and the larger the area of \u200b\u200bthe room, the greater the error.

One GVL Knauf covers 0.75 m². Thus, to cover an area of 20 square meters. m. it will take about 15 sheets.

Video - do-it-yourself dry floor screed

What is a floor screed, not everyone knows. Meanwhile, this is a very important component of the repair, and like any element of this industry, it is constantly being improved, new materials and more modern technologies for its creation appear. If until recently the most popular was a concrete or cement screed, today the so-called dry screed is in demand. Of course, it has both its pros and cons, but for quick leveling of the floor without the skill of installation work, it is the best option.

What it is?

The word "screed" is quite common and is used in several meanings. However, they are all from the field of repair and mean something that makes any structure, be it a prefabricated closet or a floor in an apartment, more resistant to damage and stress. If we are talking about the floor surface, then the screed is also designed to eliminate height differences.

Simply put, a screed is an intermediate layer between the subfloor and the top coat, which provides a better and more durable floor service, and in some cases additional functions.

Dry screed is a thoughtful alternation of materials that are laid in layers under the floor finish:

A thin polymer film that provides moisture protection. Suitable ordinary polyethylene up to 2 mm thick. A dry screed is afraid of excess water, so it is better to protect it in such ways. The film is laid out over the entire surface of the floor and goes on the wall to the level of the intended finish. Sheets of film are overlapped, and the resulting seams are fixed with mounting tape. Its area should exceed the floor area, taking into account overlaps.

Damper tape (edge or edge). It is placed around the perimeter of the room, along the bottom of the walls, up to the mark of the finish coat. The tape is necessary in order to neutralize the expansion of dry matter from the backfill composition (from 0.5 to 1 mm). When there is pressure on the walls in the room, small cracks form in them, and the tape prevents their occurrence. It is also required for use when arranging a warm floor. The required length of the tape is the sum of the lengths of all walls along the perimeter of the room;
Beacons for installation and regulation of the plane in the process of backfilling the screed;

Leveling layer. This is any loose substance (expanded clay, pumice, slag, sand), most often fine-grained, which forms the surface and thickness of the dry screed. A flat surface is formed from the lighthouse to the lighthouse, taking them out and leveling the trace from them so that the slab coating lies evenly in the future. The volume of the leveling layer depends on the area of the room and the desired thickness of the screed. The minimum allowable is 3 cm;

Sheet material forming a new subfloor surface. It is necessary to evenly distribute the load on a dry screed. Plywood, chipboard, OSB-boards, and abso-cement sheets are often used. Their total area should correspond to the area of \u200b\u200bthe room plus a margin.
PVC film for the top layer. It is designed to protect the screed from moisture and negative influences;
Glue and screws may be required.

Kinds

In total, there are four types of screed: wet, dry, semi-dry and screed based on self-leveling mixtures.

Wet screed is a classic option that includes several varieties based on the use of different materials in the composition of the substance.

Depending on the characteristics and origin of the bulk component, a dry screed can be:

Sand, cement-sand or cement-sand

This is a screed that is made on the basis of sand with the addition of other components. For example, cement. It can be purchased ready-made, or you can make it yourself by solving the issue of drying river sand and getting rid of microorganisms. Ready building mixtures are often made from quarry sand. It is easier to dry out, because it forms far from water and has fewer living organisms that can begin active life under the flooring if they are not disposed of.

Optimal in terms of its performance is alluvial or washed river sand. It goes through a standard processing procedure (washed) necessary to screen out unnecessary components in the composition of the substance.

Alluvial sand has a lot of advantages:

It does not settle over time, which is very important for a screed without the use of water and binders;
It is environmentally friendly, has no impurities and living organisms;

It lacks clay;
Ideal raw material for dry construction work due to not too fine and not too large grains of sand;
Cleaned sand does not enter into chemical reactions when other components are added;
The work is clean and dust free.

slag

A screed based on this material is popular due to its two advantages: high thermal insulation performance and low cost, since slag is a waste product.

For dry screed, one of four types of slag can be used:

Domain. It is a free-flowing material that is shaped into a fine mixture for use in construction. Its composition is harmless, despite the myths, and is in many ways similar to the composition of cement mixtures. Blast-furnace slag is frost-resistant, which allows it to be used both in an apartment and in a private house, where the first floor is much colder.

Metallurgical. This type of slag is not used by itself. Rarely, a product of its production, mineral wool, is used as a heater or substrate when forming a dry screed. By itself, mineral wool is one of the best heaters.

Coal. A large fraction of coal slag is used to form building blocks, and an artificially crushed one can be used both for pouring a wet screed and for a dry one. Mechanized processing of large fragments makes them suitable for various applications in repair. Coal slag has excellent thermal insulation properties due to organic impurities in the composition (clay, ash, sand, etc.) and a very low cost.

Fuel. Dry filling with fuel slag, despite its low popularity, is one of the best options, which is suitable for both houses and apartments. Due to the various impurities in its composition, it not only has high thermal insulation performance, but also copes well with sound insulation. An important nuance: fuel slag should not be fresh. It can be used after at least 3 months of storage in strobes.

Expanded clay

Expanded clay is a material widely used in repair and construction work. These are granules of fusible clay. They undergo a firing procedure and have a hard shell and a porous structure. Expanded clay particles for floor screed differ in different sizes and low weight. Often combined with sandcrete screed to level the surface of the floor with large height differences.

Expanded clay screed has several advantages:

Low cost of materials and works;
Significantly less weight of the screed than when using other materials;
Good insulating qualities;
Organic origin of raw materials;
Fast installation.

Volcanic (perlite)

A material related to expanded clay is perlite. This is sand or gravel of volcanic origin. Does not apply on its own. The screed requires the so-called "expanded" perlite, which undergoes a thermal shock procedure at very high temperatures. This makes its structure porous, like expanded clay, and eliminates excess moisture in the composition. After that, it can be used for a high-quality dry screed with sound and heat insulating properties.

Vermiculite is considered similar in properties to perlite and expanded clay. This layered material of organic origin is also subjected to a thermal shock procedure, which results in the formation of small elongated sticks used as a bulk component when installing a dry screed. Its insulating qualities are also at a very high level.

Cement-bonded

The installation of a DSP screed is very different from the installation of a bulk dry screed, since this material is already pressed into slabs up to 50 mm thick.

This method of leveling the floor surface has several advantages:

Features of the components of the composition and the multi-layered plates make them very durable, withstanding heavy weight loads and resistant to mechanical damage;
The surface of the DSP board is already smooth and even and does not require additional leveling efforts;
The composition of the materials used in the production includes only organic substances, so DSP boards can be used in any type of premises, including a children's room;

With characteristics similar to other sheet materials, they differ in a lower price;
Plates are resistant to temperature extremes and adverse environments and better withstand high humidity;
Possess good indicators of sound insulation and thermal insulation;

They are not subject to rotting and the formation of harmful microorganisms, since, in addition to wood fragments, they contain a mixture of cement and other substances;
Frost-resistant and poorly amenable to combustion.

Concrete

All types of dry screed using concrete (gypsum-concrete, sand-concrete, expanded clay-concrete) are repair tools that can be called eternal classics. No development of technical and scientific progress has yet offered an option better and more reliable than these materials. In addition, compositions based on concrete, cement, gypsum or sand can be used for both wet and dry screeds.

In the first case, the solution for pouring is diluted, and in the second, ready-made slabs are used. Dry concrete screed rarely turns out perfectly flat. As a rule, it requires additional leveling of the surface, and it is important to supplement it with bulk mixtures.

Peculiarities

Dry screed is a fairly new method on the Russian market. Not everyone had time to appreciate it, so there are many different opinions about its quality.

In fact, a dry screed has objective advantages and disadvantages.

Technology advantages:

Can be used for different types of premises: a private house, a summer residence, a cottage, an apartment in an apartment building and on the ground floor, outbuildings;
Loose mixes and sheets for leveling the surface together make up less weight (especially if it is not sand, but porous materials) than a liquid concrete screed. It does not give a strong load on the floors in the structure of the room, prolonging its service life;
The work is clean, free of dust and the use of liquid;

Screed elements are made from substances of organic origin;
Dry screed can be used in combination with floor heating systems, whether it is a water floor or electric. The absence of glue and formaldehydes in the composition in this case gives a big plus, since when the temperature rises, they inevitably begin to be released into the air;
You can make a dry screed alone, without professional skills;

The cost of material and installation work is many times cheaper financially;
Installation of a dry screed does not require operational work. A large area can be covered in stages, which is impossible when working with liquid compositions that quickly harden in air;
The list of necessary tools is much shorter. You will not need, for example, such a thing as a concrete mixer;

Cracks do not appear, there is no risk of leakage of the liquid composition to the neighbors;
Dry screed contributes to the fact that the sound insulation and thermal insulation in the apartment is significantly increased. You can also use tile materials for dry screed under a stretch ceiling to muffle sounds from above;

Using a dry screed, you do not need to postpone subsequent repairs for 30-40 days. It does not use water, so it does not require prolonged drying. You can make a floor covering in a few days, when the screed will settle a little naturally;
Sheets covering the dry backfill make the surface of the subfloor as smooth as possible and suitable for any type of finish;
Long service life, on average - 20 years.

Dry screed also has disadvantages:

The screed is not a monolithic solid formation, therefore, over time, smaller particles settle down, so the height of the screed itself changes;
It is undesirable to use under soft floor coverings such as carpet and laminate due to their lack of a solid base. High point loads on the screed will eventually make it uneven;

Not suitable for use on ground surfaces;
Subject to abrasive wear;
Organic matter is a good breeding ground for bacteria, microorganisms, and even rodents in a private house;

Dry screed from most materials, especially slabs, is afraid of moisture. It cannot be used in rooms with high humidity, as the floor will blister and become uneven;
The fixation is not as rigid as with a concrete screed, there is a risk of air bubbles in the backfill layer and damage to the floor heating pipe system, since they can move slightly under water pressure and when temperatures change.

Comparison with other materials

The advantages and disadvantages of dry screed are important not only in themselves, but also in comparison with other technologies for strengthening the floor and increasing insulation in the house.

There is an opinion that a dry screed is better than a wet mortar. Professionals in the field of repair do not give an unequivocal answer to this, since the optimal type of screed is selected taking into account many aspects. These include the operational state of the premises, especially the supporting structures, and its functional purpose, and the requirements for the screed, and the type of finish, and the repair budget.

The advantages of a dry screed over a wet screed include:

The ability to use this type of screed in old houses and buildings, where it is forbidden to give too much load on the supporting floors. As a rule, in such rooms there are big problems with poor sound and heat insulation, and a light-weight screed made of organic porous materials helps to correct the situation. At the same time, a liquid screed is powerless, since they will not even issue permission for its installation in the appropriate authority;

Dry screed is beneficial to use with small financial opportunities. Many mixtures do not even have to be purchased ready-made, you can make them yourself. At the same time, the cost of the necessary tools, materials and raw materials will be an order of magnitude cheaper than for the installation of a wet screed. And there is no need to hire skilled workers;
Wet screed requires great professionalism. The mixture hardens quickly, so pouring large areas in one go can be very problematic;

Under adverse environmental conditions, a wet screed may crack after drying;
The wet method takes a long time to set;
The cleanest installation work

In some respects, a dry screed still loses to a wet one:

It is worse combined with underfloor heating and soft floor coverings;
Wet screed (cement, concrete, mixed) after drying becomes an even monolithic layer and does not settle, which cannot be said about dry;

All types of materials and mixtures are afraid of moisture, they can not be poured under the floor in the bathroom or toilet. Only cement-bonded particle board is suitable for this purpose;
The service life of a high-quality liquid screed is from 20 to 40 years.
Under it, you must first level the surface of the subfloor with large height differences.

Between these two technologies is the semi-dry screed, which also has competitive advantages.

Comparing it with a dry screed, we can conclude that in many ways they are similar:

Low cost of materials with high quality;
Does not require additional efforts to level the surface;

Saves financial and time resources on installation and cost of tools;
Due to the smaller amount of water in the composition, it hardens and hardens more slowly, so the laying process can be long, like a dry screed;

It is possible to proceed with the installation of the finishing coating already on the 4th day after laying the mixture;
Semi-dry or dry-pressed screed is not done by hand. A machine is needed to compact it, and this increases financial costs and limits the use of technology in small spaces.

In some aspects, a dry screed is inferior to a semi-dry one:

Semi-dry settles less and is more resistant to stress, respectively, and its service life is longer;
Fiberglass improves wear resistance;
The porous structure improves the insulating qualities with less abrasive wear.

Separately, it is worth considering a new technology, which is often called a self-leveling floor or a self-leveling mixture. A self-leveling floor is sometimes used instead of or together with a screed, and this method also has its pros and cons.

In some aspects, dry screed is similar to potting mix. So, the mixture also gives an even and smooth surface without additional effort, dries quickly, allowing you to start finishing the floor earlier, and works well as a soundproofing layer. It is more wear resistant than dry screed. An additional advantage is that the self-leveling floor can simultaneously perform the function of a decorative coating, that is, it is not necessary to finish it on top with other materials.

Despite the positive properties of self-leveling compounds, there are still more arguments in favor of a dry screed:

Leveling the floor with large level differences is best eliminated with a screed, since it is easier to pour a layer of the desired height;
The mixture for pouring the floor is very expensive, and the thicker the layer, the more expensive a square meter is;

A dry screed is less demanding on the condition of the subfloor, while a liquid mixture requires the most even and dry area;
Self-leveling floor - not for use in large areas;
The dry mix weighs much less.

Technology and device

The dry screed structure is a prefabricated system consisting of backfill intended for leveling the floor, gypsum fiber sheets and accessories. The ideal basis for the floor is reinforced concrete floors from 14 to 22 centimeters thick.

Before proceeding with the installation, you must make sure that all recommendations and requirements are met:

If repair work is carried out on the ground floor of an apartment or private house, the structure must additionally provide for a polymer film up to 0.3 mm thick, bitumen-polymer materials and mastic. They are necessary to protect the screed from condensation, freezing, moisture ingress;
At the junction of the floor and walls, a gap of 9-10 millimeters must be left to fill it with a soundproof gasket (you can use damping tape, soft wood fiber, mineral wool and other insulating materials). Also, the walls along the height of the entire screed must be pasted over with an edge tape made of foamed polyurethane foam to avoid cracks on their surface;

Ready-made kits for independent work should be accompanied by documentation and instructions. Dry screed strength - 20-24 MPa (from 200 kilograms per 1 square meter to 240);
Optimum conditions for work occur when all wet, plumbing and electrical work has already been completed. The room must have a minimum level of humidity and a temperature of at least 5 degrees;
Before starting work, all components of the system should spend 1-3 days in the installation room in order to adapt to the particular microclimate of this room.

Work progress:

Work surface preparation. Dry screed is not the most demanding mortar for leveling the floor surface, however, the smoother and drier the floor surface is, the better the screed installation will be. To do this, the draft floor must be dedusted, in some cases lined with a film, sealed the joints between the floor elements and the junction of the walls to the floor.
Determining the level of height (thickness) of the screed. To carry out geodetic work, you will need a laser or water level, as with a wet screed. With its help, it is necessary to mark on each wall at several points the total height (top) of the screed and the height of each leveling layer separately.

Installation of the leveling layer. This step is not always needed. Some of the floors are in a suitable condition, but in some cases the height differences are too large, and the surface of the floors has many flaws. They need to be eliminated with a cement-sand mortar or factory leveling mixtures (for self-leveling floors).

It is important to note that cement mortar with a thickness of less than 3 cm will crack after drying. It can only be used in cases where the overlap allows additional weight to be loaded and a sufficiently large screed thickness is required. The second method will help save its height - a ready-made mixture for pouring the floor. Its thickness can be any, and much less than 30 millimeters.

Installation of vapor barrier and waterproofing. Another optional step. It is needed only in cases where there is a risk of condensation or an increased level of humidity. The choice of insulating materials and the way they are applied to the work surface depends on the type of floor.

If these are concrete slabs, then a film coating is needed, which is overlapped by 15-20 cm and is displayed above the level of the screed along the wall. The edging tape is glued on top.

If the subfloor is wooden, the best remedy is paraffin or bituminous paper with an overlap of 5-10 cm. It is not necessary to display it on the wall.

Installation of thermal insulation and sound insulation. Depending on the type of screed, different manufacturers offer different solutions at this stage. In some cases, additional slab material is responsible for the insulating qualities, which is laid under dry backfill; in some, there is enough porous bulk material, which already absorbs sounds well and prevents heat loss.

Dry backfill has the property of "leaking" beyond the boundaries of the room in the places of doorways and transitions from room to room. It is recommended to install fences in such places that the screed remains flat and tight in all areas of the floor.

To align it, you do not need special equipment, you only need guides (beacons) and a leveling rail. You need to start from the wall, which is opposite the doorway. Installation of beacons and backfilling are done at the same time. There are no recommendations regarding the uniform distribution of the backfill, this is done by eye, with alignment with a rail and orientation to the marks on the wall. The rail moves along the guides and smooths out all surface irregularities.

Installation of sheets of the upper floor. Stack sheets, focusing on the geometry of the room. The gap between them should not exceed 0.9-1 mm. Sheets are applied in two layers. After the first, it is necessary to apply adhesive mastic, lay the top layer of gypsum fiber boards on it. It is important that the joints of the first layer do not coincide with the joints of the second. They need to be shifted by 25-30 cm.

Before the mastic dries (to remove excess glue that will come out at the joints when fastening with screws), it is necessary to fasten 2 layers of sheets together with self-tapping screws, then putty the joints of the sheets. The fixer is attached along the edges of the sheet with steps of 30 cm.

Not all types of screeds provide for such a complex finishing procedure. In some cases, the gypsum fiber already has a double thickness, and then one layer is enough.

After completion of the work, it is necessary to wait 3-4 days before proceeding with the installation of the floor covering.

Thickness

Some installation nuances require more detailed consideration. One of the pressing questions is what is the minimum thickness (height) of a dry floor screed.

If everything is clear with a wet one (from 30 mm to 50 mm according to the standard), then when using a dry screed, everything is a little more complicated. Here it is important to consider the following factors: the condition of the floor, the height of the ceiling, the requirements for heat and sound insulation.

With the height of the ceiling, the situation is also quite obvious. If the repair is carried out in a typical apartment, where the standard height does not exceed 2.5 meters, a fifteen-centimeter screed (and this is without taking into account the finishing of the floor) is not suitable. In this case, you need to choose either the optimal combination of materials for the prefabricated screed, or give preference to a dry-pressed or leveling mixture. With a ceiling height of 2.7 m, the thickness of the screed will not significantly affect the appearance of the room if it raises the floor by 10 or more centimeters.

Information about the condition of the work surface is easy to obtain by a simple inspection. In the presence of large differences between the floor slabs (boards), the presence of dents, irregularities, chips, cracks and cracks, the required height, taking into account the leveling layer, will be from 50 to 100 mm. The difference depends on what material was used as a leveling material. If cement mortar, then its minimum thickness should be 30 mm. If the leveling mixture, here you can get by with much lower rates.

For high-quality thermal insulation and noise protection from below, either increase the thickness of the screed to 150 mm, or use thin insulating materials between the protective layer on the floor and dry backfill. On average, the thickness is from 60 to 100mm.

To improve sound insulation, additional layers of dry matter and gypsum fiber sheets are also used, but the thickness of the structure (vapor barrier + leveling layer + insulation height + dry backfill + first gypsum fiber layer + mastic + second fiber layer) should not exceed 15 centimeters. Also, a thickness of 150 mm is necessary for leveling a heavily damaged floor surface and when working with complex wooden flooring.

It can be concluded that the minimum thickness of a dry screed is 5-6 cm, the recommended one is 9-10 cm, and the maximum allowable is 15 cm.

How to calculate quantity?

One of the most difficult tasks is the calculation of the required amount of materials to perform a dry floor screed.

Manufacturers are trying to facilitate this work by indicating the approximate consumption of materials in the passport for finished kits. In fact, these materials may not be enough, given that non-professionals often take on a dry screed.

Accurate calculations will help to avoid unforeseen situations.

Elements required to complete the work:

vapor barrier film;
Edge tape;
Soft wood fiber or mineral wool;
Dry backfill;

Gypsum boards;
Mastic or glue for gypsum fiber;
Profile for lighthouses;
Self-tapping screws for fixing GVL-layers to each other.

This is not a complete list of the necessary tools and materials, but the rest (a screwdriver, a cutter, a level, a rail made of wood or plastic, and others) are needed in a single copy and do not require preliminary calculations.

The calculation is carried out in stages, in the order in which the materials will be needed during the work:

Vapor barrier and waterproofing. It requires sheet material based on polyethylene, bitumen or fiberglass. The required amount of film is the area of \u200b\u200bthe room plus 15-25% for allowances (overlap and wall). The width of such material is usually from 1 to 2 meters. The length is limited by the length of the roll.
Lighthouses. They require a profile, and if it was not in the factory kit, it must be made manually from wooden slats or polymers. The minimum number of profiles per room area is 1 per meter. That is, if the room is 12 square meters with sides 3 by 4, it is more reasonable to purchase 4 profiles of 3 meters each.

Any sheet material for dry filling(insulation, base, insulation). It is calculated in an intuitive way: the area of the room is divided by the area of \u200b\u200bone sheet. At the same time, it is important to take into account that damage to the sheets during transportation is possible and it will not fit entirely everywhere, fragments will have to be cut out. Taking into account the errors, it is necessary to purchase sheet material with a margin of 1-3 pieces. The same applies to the finish coating of the screed with gypsum fiber panels.
damper tape and material for sealing joints. The length of the tape is taken from the calculation of the perimeter of the room (minus the doorway). The material for sealing gaps and joints is calculated in different ways, depending on its density and type. Sheet - in centimeters, weight - in grams.

Dry backfill. For different types of backfill, the indicators are different, they are indicated on the packaging or in the online calculator. For example, one of the most common and high-quality materials - expanded clay, is required in the amount of 30-50 liters per square meter. The exact figures depend on the desired height of the screed. The larger the area, the greater the run. It is better to purchase the material at the maximum consumption, since in practice it is usually higher than the average.
Glue. Its consumption is quite large. 500 g of glue is needed per 1 m2.
Self-tapping screws for fixing sheets. The exact number of fixer elements for GVL depends on the size of one sheet. Self-tapping screws are screwed in at a distance of about 30 cm from each other. Knowing this, it is easy to carry out the calculation for individual sizes. Having determined how many screws are needed per 1 sheet, their number must be multiplied by the number of sheets. On one sheet you need about 10 pieces plus or minus 2.

How long does it dry?

One of the most problematic moments when pouring a wet screed is a long period of complete drying. The advantage of a dry screed is that practically no liquids are used during its installation, but it needs some time to shrink before the installation of the flooring begins. The question is how long should it take

The exact time depends on the complexity of the screed. So, if the construction used a semi-dry or liquid base as a leveling layer, it will dry for about 28 days. The leveling liquid hardens faster - from 2 to 7 days. If there was no leveling layer, it will take 2-4 days for the evaporation of excess moisture from the dry backfill and its shrinkage

Mastic or glue between GVL sheets dry for a different period of time. Depending on the thickness of the layer and the characteristics of the microclimate of the room (humidity, air circulation), the mastic hardens completely in 12-28 hours.

The drying time of the adhesive depends on the surface area, layer thickness, temperature and humidity in the room, preliminary degreasing of work surfaces. Approximate time is one day.

Scope of application

Dry screed is an almost universal tool for strengthening the floor, leveling the height, improving the insulating qualities.

The scope of its use is very wide:

For laying in a private house (country cottage, dacha, frame or modular, block, brick or wooden), apartment in apartment buildings. Cottages and dachas can be residential or used only as a seasonal vacation spot. In the first case, a dry screed will ensure a comfortable stay in the house, since it will be quiet and warm, and in the second case, it will protect the house and the warm floor, if any, from freezing at sub-zero temperatures. Since a rarely heated house freezes through, and hypothermia of heating systems is undesirable, this is a very important function.

In an apartment building, in addition to the cold floor due to concrete floors between floors, there is another problem - good audibility. A dry screed 10 centimeters thick is able to isolate extraneous sounds from the apartment from the lower floor. This is especially true in new buildings. The problem of a cold floor can also arise in Khrushchev, but in this case it is better to choose a self-leveling floor that does not take more than a couple of centimeters from the height of the rooms.

For laying on different surfaces and ceilings: on wooden floors, bricks, concrete slabs, blocks. Wet screed is not the best solution for leveling the floor, the surface of which is highly absorbent. A lot of moisture will go into the tree, there will be a risk of fungus, and the screed may crack after drying. It is difficult to prevent this, even using numerous layers of primer. The best way out is a dry screed using a thin insulating layer.

Carefully lay the screed on the ground. In order to avoid the greenhouse effect, it is recommended to use high-quality waterproofing with foam for insulation. It also helps to use a sand layer. Dry screed lays much better on sand. But, if possible, combining with soil (soil) is best avoided.

To match with underfloor heating. The problem can occur when falling asleep a water-heated floor. Since the dry screed will not be monolithic, there is a risk of damage to the pipes. The way out is a dry-pressed screed. For a semi-dry screed, protecting the water floor pipe system is a feasible task.
For premises of different functional purposes. Underfloor heating is required in many rooms: in the children's room, bedroom, kitchen, bathroom and toilet, sauna. At the same time, it is not always necessary to combine the screed with the heating system, a sufficiently good layer of backfill and GVL with a total thickness of 15 centimeters.

Problems can arise with high humidity in the bathroom. For such places, a combined screed made of DSP boards, which are not afraid of moisture, is more suitable. They can also be used for screeding on the balcony and loggia, and for wall insulation in rooms close to the street (in the attic, in the attic, in vestibule rooms).

For use under various types of floor coverings. Dry screed can be safely laid under tiles, boards, laminate, parquet, porcelain stoneware. With an additional layer of rigidity - under the carpet and linoleum.

Manufacturers and reviews

An important role in the choice of materials for a dry screed is played by the reputation of the manufacturer and the reviews of the owners of houses and apartments using different products.

According to numerous estimates of those who have tested the technology of dry floor screed, the undisputed leader is the German company Knauf. There are several reasons for this:

Knauf are pioneers in this industry. It is they who own the development of an alternative to wet screed, and it is they who supply the construction market with a complete set of necessary tools and materials. All elements are produced on modern equipment using patented technologies.
Knauf is impeccable quality. It is customary to expect high standards from German firms, and this manufacturer fully lives up to these expectations. Reviews confirm that working with the elements is easy. The performance of the product is also praised. The floor does not sag, there is no smell of dampness, which means good waterproofing and no condensation, the floor surface remains at a comfortable temperature even without an additional heating system, the insulating qualities of the coating are on top.
Knauf is practically the only supplier of all dry screed components in the domestic market. He is a kind of legislator, and if there are other components, they have received the approval of the pioneering company.

There are also negative reviews about this product: mold, dampness, subsidence of the floor, high cost. The cost is mentioned in many reviews, but the rest of the shortcomings arise only when mistakes are made during installation. If you strictly follow the manufacturer's recommendations, the screed is of high quality and lasts for many years.

The manufacturers that received the go-ahead from the Knauf flagship include two firms: Kerafloor and Kompevit. Both production facilities are located in Belarus and specialize in dry filling for screed. With decent quality, this product is marked as cheaper.

Successful examples and options

Dry screed is a good way to save on underfloor heating. It is perfect for apartments and country houses, both in combination with a floor heating system and without it. A well-made dry screed is the key to successful installation of any type of flooring, and a well-made floor is an integral part of a beautiful interior.

For how to lay a dry screed, see the following video.

When building a house, when the main work is completed and it's time to think about installing a floor covering, many begin to think: "Dry floor screed - what is it? Pros and cons of this coating - what are they?" Dry screed is perhaps the easiest way to level a floor and does not require a long drying period, as was previously the case with a cement mixture. The basis turns out ideally equal and suitable for a flooring of any finishing covering. Next, we will consider what a dry floor screed is, the pros and cons, how to make such a coating without outside help. Like any other material, dry screed has its positive and negative sides.

Pros and cons of dry floor screed, laying technology

Dry screed for the floor began to be used in the last century, but was used mainly for rough floors. Over time, the builders came to the conclusion that a dry floor screed, subject to all the laying rules, is ideal not only for rough, but also for finishing floors. In this article, we will consider what a dry floor screed is, the pros and cons, reviews and the technology for its manufacture.

A dry screed consists of two components: a dry mix directly - it can be expanded clay, perlite or vermiculite, and a hard coating - such as waterproof plywood, chipboard, waterproof gypsum-fiber sheets. To date, the Knauf dry floor screed, the pros and cons of which are widely discussed by many builders, is one of the best on the market. Such floors give a feeling of warmth in winter, and in summer, on the contrary, provide coolness. What is a dry floor screed? Pros and cons, the price of the materials used - all these issues will be discussed in detail in the article.

Benefits of using a dry floor screed

Fast installation times. When using a dry screed, you do not need to wait 1.5 months for the coating to dry, as when using a cement mixture.
Work can be performed at any temperature.
During installation, there is practically no weighting of the structure, which is very important for dilapidated houses.
The absence of dampness and dirt during installation, which will allow you to use this method in almost any room, regardless of the existing repair.
The possibility of laying any communications, from water and sewer pipes to underfloor heating systems and even electrical cables.
This coating has good heat and sound insulation properties.
All work can be carried out even by an unprepared person.

Cons of using dry screed

This screed is very sensitive to moisture and needs high-quality waterproofing.
Not intended for rooms with a large number of visitors.
Immediately after installation, rustling sounds may appear, which occur due to the fact that the material has not yet dried. You should not worry about this, because over time the unpleasant sound will disappear.
It is undesirable to use in rooms with high humidity, such as kitchen, bathroom, etc.
The appearance of uninvited guests is possible, since the dry mixture is a comfortable place for rodents and various insects to live.

These are perhaps the most basic pros and cons of a dry floor screed that you need to know before choosing this leveling method.

Reviews of dry floor screed

You can find a lot of reviews about a dry floor screed, but it is quite difficult for an ordinary person to understand them. We examined the pros and cons of a dry floor screed from the position of the manufacturer, and now we will indicate what cons ordinary consumers find in this coating. All negative reviews boil down to the following:

The floor sags a lot over time.
The coating becomes very brittle and subject to deformation.
Installation is too expensive.

In fact, everything is not so deplorable. The leveling layer consists of expanded clay, which by its structure is a fairly hard material, practically not subject to compression. Therefore, there is no need to talk about any drawdown. The same can be said about his fragility. If, when installing a dry screed, you do not deviate from the technology and choose the appropriate materials for the top layer, then you can be sure: such a floor will delight you for many years. And the cost of installing such a floor is comparable to a concrete screed, but, unlike a concrete one, a dry one is completed in a couple of days, while a concrete one will have to be stretched for a whole month.

Materials used for installation

For any construction work, it is necessary to prepare a certain set of materials. Dry floor screed is no exception.

To waterproof the base, you will need a plastic film, as well as adhesive tape. Adhesive tape is necessary to seal the joints of the film, since its width is often not enough.
Leveling layer. You can use anyone, but most often expanded clay sand is used for these purposes.
Metallic profile. For high-quality leveling of the floor, it is necessary to carry out all work strictly according to the lighthouses.
Damper tape - serves for additional sound insulation and is laid along the walls around the entire perimeter of the room.
Gypsum fiber sheets must be moisture resistant.
To fix these sheets, you can use glue or self-tapping screws.

We prepare the base

First of all, it is necessary to remove the existing flooring, and then clean up the remaining construction debris. The pros and cons of a dry floor screed are obvious, so if there are gaps or any defects in the base, they need to be repaired. If necessary, communications are laid and only after that it is possible to start laying waterproofing.

Installation of waterproofing

A dry floor screed does not like moisture, so first of all you need to take care of high-quality waterproofing. For these purposes, it is best to use plastic wrap. Of course, it is possible to use other materials, but the effect will not be the same. If you skip this important step, then moisture will come into direct contact with the material, which will cause it to swell and deteriorate. The floor will become uneven, which can lead to heterogeneous damage to the finish. The waterproofing should be laid in overlapping strips, that is, each strip of film should overlap the previous one by 10-15 centimeters. Joints must be sealed with tape for greater protection.

Damper tape laying

For high-quality laying of a dry screed, a small gap is required between the screed itself and the wall in contact with it. This is necessary to protect against various deformations of the leveling layer, as well as for additional sound insulation. After all, the sound wave is very well transmitted through solid structural elements. In order to get rid of this noise, a damper tape is used. It is made of polyethylene or glass wool and glued along the floor, thereby creating the gap necessary for a dry screed, which becomes an insurmountable barrier to various noises and significantly increases the comfort of people inside the room.

We install lighthouses

Beacons in a dry screed device are an important element, without which high-quality work is almost impossible. In the future, it is to them that the sheets of the top layer of the screed will be attached. Lighthouses can be made from various materials: boards, slats, but a metal profile for drywall is best suited for this purpose. Be extremely careful: the waterproofing layer should not be damaged. The use of self-tapping screws at the stage of installation of beacons is strictly contraindicated. The profile should be fixed to the waterproofing layer using a conventional cement mortar. The first row of lighthouses must be arranged at a distance of thirty centimeters from the wall, and the gap between the rows should be maintained on the order of one meter. After installing the beacons, you can start backfilling the leveling layer.

Alignment of the dry mixture on the beacons

To perform this procedure, it is necessary to pour a leveling layer a couple of centimeters higher than the guides are. After that, with the help of a level or some even object, they are carried out along the beacons, thereby leveling the dry screed. The nuances of a dry floor screed is that the thickness of the leveling layer is calculated individually in each case. It all depends on the degree of unevenness of the floor, as well as on those communications that need to be hidden under the floor. As a rule, with small irregularities, five centimeters are enough.

The best material for dry floor screed is expanded clay. Of all the materials, it boasts the smallest shrinkage, light weight. At the same time, the sound and heat insulation properties of this material remain at a height even with a small coating thickness.

Laying the top layer of the screed

For mounting the top layer, there are also a lot of materials for every taste. It can be moisture-resistant gypsum-fiber sheets, and sheets of waterproof plywood, as well as chipboard. But here, too, there are certain rules and recommendations from which it is undesirable to deviate if you want to get a quality result.

Laying the top layer should start from the door.
In order for your floor to be more durable and resistant to stress, the top layer of the screed must be laid with some offset of the sheets relative to each other, as if you were using brickwork.
When installing the sheets, they should be moved as little as possible, because even a slight displacement can lead to the formation of pits and bumps on the leveling layer, which will subsequently affect the final result.
Sheets should be fastened with self-tapping screws directly to the guides, it is also possible to fasten with glue. If you have chosen self-tapping screws, then it is advisable to maintain the same interval between fasteners of the order of 12-15 centimeters.
After all the sheets are securely fixed, you can proceed to puttying the joints.
If you decide to make a dry screed in the bathroom or in the kitchen, where there is usually a lot of humidity, then you should take care of additional waterproofing of the top layer. As a rule, bituminous coating is used for these purposes. If a dry screed is made in the remaining rooms, then additional waterproofing is not required, and you can proceed to laying the finish coat.

This is all the pros and cons of a dry floor screed associated with laying the top layer.

Finishing coat installation

Subject to technology, in the end you will get a perfectly even coating, completely suitable for finishing. A distinctive feature of a dry screed is the fact that one day is enough to carry out all the work, but many experts advise: before the top coat is applied, let the dry screed rest for one day. This is necessary so that the glue dries well and the tension of the materials goes away. . The technology also allows finishing work immediately after the end of the dry screed installation, without waiting a day. The finish can be anything. You can easily lay laminate, carpet or linoleum. It all depends on your imagination and financial capabilities.

The cost of installation of dry floor screed

The price of a dry floor screed consists of several components - this is the material itself and payment for the work. As mentioned, the installation of a dry screed does not require special qualifications, so it can be done on your own. Now let's talk about the cost of materials:

Waterproofing. As a waterproofing, ordinary polyethylene film is used, so its cost is relatively low and is about 18 rubles per square meter.
Edge tape costs even less - about 6 rubles per meter.
The cost of the top layer of the screed can vary widely, depending on the material and thickness of the coating, and averages 300 rubles per square meter.
The main component of a dry screed is loose material. Its cost is around 180 rubles per pack.

We examined what a dry floor screed is, the pros and cons, installation tips. As you can see, there is nothing complicated here, and anyone can do all the work, even someone who has never done this before. If you want to do everything quickly and without large financial costs, then a dry screed will come in handy for you.

There are many reasons why it is not possible to carry out a conventional cement screed floor. These are the limited time for preparing the base for decorative flooring, the unfavorable climatic conditions of the room for the complete drying of the wet concrete layer, or the need to have constant access to the laid communications. But we must not forget that the opportunity to give the floor perfect evenness with a dry screed at minimal cost and in a short time has its own characteristics.

Features of dry floor screed

There are two types of floor screed: made of wet cement-sand mortar or prefabricated, also called dry. The latter method is considered much more economical and therefore is becoming more common in construction and repair work. Another reason for its popularity was the relative simplicity of the dry floor screed, which does not require complex preparatory operations and high professionalism of the craftsmen.

The leveling of the base occurs with the help of loose materials of a medium-sized fraction.

Typically, expanded clay or perlite expanded sand is used for this purpose. The subsequent tamping allows compacting the backfill, making it perfectly even, and the coating with gypsum-fiber sheets creates a stable and durable rough floor base.

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Disadvantages of dry floor screeding

The disadvantages of using a dry screed are less than the advantages that it has. Despite this fact, the disadvantages of this warp leveling tool are quite serious. Before making a final decision on the application of this method, it is necessary to take into account all the factors that can subsequently affect the quality and durability of the base.

The main disadvantage of a dry screed is the need to avoid any contact with moisture.

In rooms such as the kitchen and bathroom, its device is contraindicated, since the penetration of water into the thickness of the backfill will inevitably lead to the formation of mold and fungus, which can only be eliminated by completely dismantling and replacing the base. For the same reason, it becomes impossible to install a water-heated floor system - the slightest leak will cause irreparable damage to the base. Even the laying of reinforced waterproofing will not protect the backfill layer and GVL from water penetration. It is better to carry out work on the installation of a dry screed in dry and warm weather so that the expanded clay or sand mixture does not absorb moisture. It is impossible to level the floors with a dry screed in rooms with a lack of heating and the presence of high humidity. Basements, basements and other similar places are unsuitable for its use.

Dry screed has a rather soft base and does not tolerate mechanical stress. Plasterboard coating does not withstand constant physical pressure on the surface in crowded places, so a dry screed is more suitable for residential premises. The main criterion for the strength of this method is the good quality of the compaction of the dry mixture. Violation of the technology of this process can lead to low stability of the base. Fine-grained filler - the material is loose and rather unstable. Its uneven shrinkage can lead to surface level differences and the appearance of curves in the decorative flooring. All this will contribute to the violation of its integrity and the rapid wear of the floor.

The surface of the floor, which is based on a dry loose screed, is not recommended to be subjected to any increased physical pressure. This applies to the installation of massive partitions made of slabs, blocks or bricks. They can push through the foundation with their weight, which will serve as a reason for unplanned repairs. The same applies to heavy items of furniture.

In rooms with low ceilings, it should be noted that a large layer of dry backfill will significantly reduce the height of the room.

Before deciding on the choice of floor leveling method, it is worth making the necessary calculations and measurements so as not to subsequently encounter a significant deterioration in the interior and a decrease in the free space of the room.

Another negative point of the dry screed device is the rustling of expanded clay when moving on the floor for the first time after completion of work. This effect will stop after the level of the infill completely shrinks, but for some time you will have to put up with an unpleasant sound. The reproduction of insects and rodents in the dry mix layer is also a weak point of the dry method. Therefore, when using it in private homes, it will be necessary to carry out regular disinfestation and deratization to get rid of dangerous rodents and pests.

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With a dry screed, it's a little more difficult. Dry screed

Dry or wet floor screed

Advantages and disadvantages

Prefabricated dry screed from OSB boards

Specifications: thickness, weight

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Properties and characteristics of GVL

Prefabricated system in section

Repair of floors based on dry screed Knauf

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What it is?

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Sand, cement-sand or cement-sand

slag

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Pros and cons of dry floor screed, laying technology

Benefits of using a dry floor screed

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Reviews of dry floor screed

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We prepare the base

Installation of waterproofing

Damper tape laying

We install lighthouses

Alignment of the dry mixture on the beacons

Laying the top layer of the screed

Finishing coat installation

The cost of installation of dry floor screed

Features of dry floor screed

Disadvantages of dry floor screeding

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