Dry screed disadvantages. Dry floor screed, pros and cons of the KNAUF system. Advantages and disadvantages of this technology

To obtain a flat surface, perform a floor screed: dry or wet. Each of the options has its advantages, but there are also many disadvantages. Traditionally, many craftsmen prefer the "wet" method, which involves pouring with a semi-liquid mixture. Its disadvantages include labor intensity, a large amount of dirt, it will take at least 2-3 weeks to dry. The cement layer creates additional stress on the floor.

An excellent alternative to the wet method is the dry method. It allows you to get the perfect foundation with less time and effort. In the future, it can be used for laying parquet, linoleum, carpet, tiles. This technology is gaining in popularity. Performing a dry floor screed with your own hands will not be difficult.

The name "dry floor screed" means that it does not use water. The classic "wet" version involves the use of a semi-liquid mixture of sand, cement and water. Due to the force of gravity, forcing the liquid to be evenly distributed over the volume it occupies, a perfectly flat surface is provided. It would seem that you can think of better? However, specialists managed to create a fundamentally new technology, the implementation of which is available to an ordinary person.

The floor, made on the basis of a dry screed, is a multi-layer structure. The first layer is dry backfill, then gypsum fiber sheets (GVL). Such a dry-pressed floor screed creates excellent sound insulation and retains heat well. Its creation will take no more than 2 days, depending on the amount of work. The only limitation for doing dry floor screed with your own hands is wet rooms. Absorbing moisture from the air, expanded clay or other filler, it loses its shape and swells. As a result, the floor is no longer even, and the finish is deformed.

Manufacturers offer several options for dry mix for floor screed. They differ in the complexity of preparation and purpose. They are chosen taking into account the characteristics of the base:

Alpha - suitable for flat floors;
Beta - for a flat base covered with a layer of porous or soundproof material;
Vega - placed on a leveling, soundproof layer;
Gamma - intended for laying on a leveling layer of backfill, after laying heat-insulating materials with an interlayer of gypsum plasterboards.

The finished screed is a bit like a puff cake. It can be laid on concrete or even wood. Inside it, you can safely lay communications. It is perfect for installing a warm floor, it has a positive effect on its energy efficiency.

Dry floor screed technology

Before proceeding directly to the work, you will need to prepare materials: waterproofing film, expanded clay, gypsum plasterboard, profiles for beacons. The sheets are fastened with self-tapping screws, additionally fixed with construction glue. The dry floor screed is carried out in stages.

Preparatory stage. The arrangement of the floor begins after the completion of the installation of plumbing, fitting of pipes, power grids, and the completion of other work. Remove old materials before installing new flooring. Then level the base, seal the cracks, protrusions, chips with a cement mixture. When the "dirty" stage is passed, you need to thoroughly sweep the formed debris, collect dust. Mark the height of the screed on the walls.

Stage two - laying the insulation. The dry floor screed technology includes a waterproofing layer made of polyethylene or glassine. Better to use the whole canvas. If the installation is carried out in pieces, they should overlap each other with an overlap of at least 20 cm. The film is brought onto the wall up to the floor mark (at least 6 cm). Insulation is chosen taking into account the characteristics of the overlap:

concrete - take polyethylene with a thickness of 200-250 microns;
wood - it is better to use glassine or moisture-proof paper impregnated with bitumen.

The task of the moisture-proof layer is to protect the backfill from swelling when absorbing water or steam.

Performing a dry floor screed with your own hands, you should not forget about soundproofing. It is made of glass wool, polypropylene foam or mineral wool, gluing tape around the perimeter of the walls. Such a strip will protect against extraneous noise, it prevents the floor from deforming during thermal expansion.

Stage three - placing beacons. Without using devices, it is simply impossible to evenly lay the bulk mixture. It is not worth hoping that then it will be possible to level it with a level: each pass along the viscous base leaves traces of the feet. Complex equipment is not needed, U-shaped profiles are enough. They are turned upward with a sharp edge, set in level, and fixed with self-tapping screws. Between them then expanded clay will fall asleep.

The main stage is the arrangement of the floor. First of all, the mixture is poured, trying to create a uniform layer. It is made from expanded clay, fine-grained slag, quartz sand, or a ready-made mixture is obtained. The amount of backfill is determined by the unevenness of the floor. The layer thickness on average reaches 4 cm, it is not recommended to make it more than 6 cm. Sheets are laid on the prepared floor, they are fixed to each other. The sheet should not be pressed into the sand, nor should it be moved. Laying GVL on the backfilled surface begins from the door. If the sheets run on top of the insulating material, they move from the opposite wall to the door.

The sheet material is laid with an offset (like bricks) to provide the floor with strength and stability.

The sheets are fastened with self-tapping screws along the perimeter, placing them every 15-20 cm. Additionally, the canvases can be fixed with glue. Irregularities are sealed with putty, then sanded. The surface of the sheets is covered with bituminous insulation. Now you can start finishing. Although it is better to give the floor 2-3 days to "lie down".

Pros and cons

The dry floor screed has earned its popularity due to its many inherent advantages. The main one is that it does not need to be dried. After the end of the installation, you do not have to wait 45 days, as is the case with a concrete base. The very next day, you can lay linoleum, lay tiles or lay a parquet board. Another important plus is the low weight of the coating. The additional floor load it creates is minimal. The time that will have to be spent on execution depends only on the area of the premises and the efficiency of the contractor. This layered "cake" improves sound and thermal insulation.

To complete the picture, it is necessary to note the disadvantages of a dry floor screed. There are not many of them, but they are there. This coating is not recommended for unheated rooms, bathrooms, showers. A traditional or semi-dry screed is suitable for them. Having dealt with the pros and cons, you can safely get to work. For residential premises, this option is ideal. Its small shortcomings are more than compensated for by the simplicity and speed of installation. Its implementation is within the power of even one person. Only when laying GVL is it better to use the help of another person, since it is inconvenient to cope with them alone.

How to make a dry floor screed

Starting the repair, each master decides the question: what can be done independently, and what work will require the involvement of specialists? A dry floor screed is quite do-it-yourself. The implementation technology is simple, does not require the use of complex equipment. If you carefully study the order of execution, then there will be no difficulties. Here it is important to adhere to the accepted rules, to use the materials recommended for dry floor screed.

A common mistake of craftsmen is the neglect of the damper tape laying. Its absence will make itself felt immediately after the start of floor operation: squeaks, sounds will not let you enjoy the new renovation. The tape can be glued to PVA, double-sided tape, or fixed directly to the polyethylene with a stapler.

Another important question: what to choose as a backfill? There is no strict requirement - sand, expanded clay or slag. These materials have similar characteristics: they do not burn, keep warm, do not shrink. The thickness of the layer should be at least 3, but not more than 6 cm. If the floor is even, you can do without it at all. Then, instead of backfill, plates of extruded polystyrene foam are used.

When starting the installation of a dry floor screed made of GVL sheets, it is important to avoid direct walking on the backfill. Therefore, the sheets begin to be laid directly from the door. When one sheet is laid, the floor is still "walking" underfoot. There is no need to be upset: each subsequent sheet gives the structure the required stability.

Installation work can be carried out at any time of the year. The main thing is to follow the technology exactly, laying out "layers" of a waterproofing film, a leveling layer, surrounding it with a damper tape, and sheet material as a basis for the topcoat.

Dry or wet floor screed is a mandatory step before laying parquet flooring or laying a roll covering. The choice between wet or dry technology is determined by the surface strength requirements and the operating conditions. A concrete screed is a solution for damp rooms, in other cases, a dry one is a preferable option, since the process of laying it is cleaner, takes less time and is cheaper.

Technology

Laying dry screed "puff pie" is not difficult if you have the skills to work with the level, rule and gypsum fiber panels. The whole process is conventionally divided into three stages:

Preparatory... Beating the floor level, measuring the values of the minimum and maximum, marking the horizon with a pendulum and a laser level.

Basic... Installation of guides, backfilling of expanded clay, leveling the layer along the horizon with the rule.

Finishing... Laying the sub-floor from reinforced gypsum-fiber panels, fastening them together with glue and self-tapping screws.

A few hours after the gypsum panels have been laid, linoleum can be laid on them, plywood can be stuffed on top of which the parquet will lie, or the tiles can be laid on a special hydrophobic glue.

Peculiarities

A dry screed is a multi-layer frame for a finishing floor. Installing it is no more difficult than leveling a layer of concrete or a semi-dry mixture with polymers accelerating hardening and other admixtures as a rule. For household or office repairs, on the timing of which the opening of a business or a move depends, a concrete screed is not suitable - it will take at least three weeks to wait for hardening.

The rough floor of the dry screed is assembled from gypsum fiber boards. The material can withstand a load of up to 300 kg / cm 2, which is enough for installing furniture, including trade chests and heavy safes. And in the filler it is convenient to hide communications: water, wires, heating.

Pros and cons

The main disadvantage of dry screed is hydrophilicity. If a water heating pipe breaks through under the floor, you will have to dismantle the entire structure and do the screed again. In the bathroom and shower, it is advisable to make a concrete screed.

Dry technology has many advantages:

Simple installation. Specialists will assemble such a screed in a room up to 50 square meters in one day.
Lack of wet processes. You can lay the finishing floor immediately after the installation of the gypsum fiber screed boards.
Heat and sound insulation. The expanded clay filler does not allow the floor to cool, it also prevents excessive noise from entering the room.
Environmental Safety. The sandwich construction contains no toxic components.
Ease. The load on the floors is up to three times less than when pouring a concrete screed.

For a warehouse, shower or bathroom, choose a concrete or semi-dry screed, in other cases dry technology is more profitable. It is not necessary to dry such a screed, because the repair of the apartment with it will be reduced by almost a month. The heat and sound insulation qualities will be appreciated by the owners of premises in office buildings and apartments in panel houses, and lightness is a determining factor when choosing a screed for frame and wooden houses.

In any room, achieving the smoothest possible surface is a very important point in construction work. Smooth floor, characterized by strength, is a guarantee of durability and correct installation of the topcoat.

A dry floor screed, the price of which compares favorably with other methods of leveling the base, is of interest to an increasing number of people who want to carry out an extensive range of repair and construction work in a short time.

Do you need repairs? Which screed to choose?

Different technologies are used to level the base. For this, a concrete mixture or a leveling surface is used, filling the entire space at the set level. But as an alternative, there is another alignment option that has advantages and disadvantages. This is a dry screed. You need to know when it is more profitable to use it, and what are its features, what are the pros and cons of a dry floor screed?

Before embarking on the responsible work on leveling the surface, several factors must be taken into account:

features of the base;
the time of the year in which the renovation works are carried out;
deadlines to meet;
financial capabilities of the owner of the premises.

To create a high-quality floor, you need to know all the nuances of the screed and choose the best option that is ideal for a specific surface. Considering all of the above, the technology of creating a "dry floor" is increasingly being used as an alternative.

Dry floor screed - what is it?

In order for the coating to last a long time, it is not at all necessary to level it with a concrete mixture and wait about 28 days to dry. Leveling with dry mixes is a worthy alternative to the "wet" process. If a dry screed is to be completed in record time, not inferior in quality and strength to a coating made using a different technology.

The emergence of this method of leveling the surface came from the 70s of the last century. Then, for the first time, prefabricated dry floors were used in mass construction. Today the principle has remained the same, but the materials have changed. made according to this technique, practically have no drawbacks. Prefabricated coatings of a new type are widely used in construction.

Why is it important to adhere to technology?

To obtain a coating that has all the advantages that differ favorably in terms of the timing of the complex of measures and installation, the exact technology of dry floor screed must be followed. If you ignore the requirements for its arrangement, there is a risk of getting an uneven coating, which threatens in the future to negatively affect the appearance and quality of the finished floor, even with an ideal finish. It is also highly likely that a departure from the requirements will entail deformation and destruction of the building or its foundation. When purchasing a mixture, you should pay attention to the instructions. Careful study of the rules and strict adherence to them will save you from common mistakes.

Stages of work

Features of dry screed in the apartment

When performing work on leveling the surface, one should take into account the characteristics of the room, because different bases require different preparation. So, the dry screed should be at the same level. Bathroom and toilet are not taken into account. You should take care in advance about finishing materials for the floor in each room. To avoid mistakes, it is necessary to accurately calculate the height of the final coating of the finished floor for the correct marking of the thickness of the screed.

Plates placed in one plane guarantee perfect adhesion of the finished floor. To make sure that the work is done correctly, you need to use a bubble level building. If the slabs provide for overlap during installation, then they are fastened to each other.

How to correctly calculate the consumption of materials

If a dry floor screed is being made, the consumption of materials should be done based on some parameters:

dimensions of the repaired premises, its area;
the thickness of the layer that is poured onto the base;
the variability of the materials used.

When answering the question "Dry floor screed - what is it?" it is important to list the list of materials that make up a solid foundation.

The number of GVL-, fiberboard- or particleboard-sheets, or thick plywood is calculated based on the floor area. The length of the room is multiplied by its width, the result is divided by the area of the sheet. If the surface is complex, then it is necessary to divide it into simple squares, after which it is easy to calculate the total area to be covered with slabs.
The waterproofing film is calculated taking into account an overlap of 15 cm and a bend on each wall of 10 cm. The sleeve of the film is 150 cm, if you cut it, it turns out 300 cm. It is important to know how the film spreads - along or across. The exact material consumption is then calculated.
Expanded clay is needed in granules of different sizes, slag is also used, less often sand. Material consumption depends on the thickness of the backfill. Due to differences in the base of the coating, an average value is taken, which is calculated from the minimum and maximum thickness measurements. A small margin will not hurt, since it is difficult to make an accurate measurement.

Variety of materials. How not to make a mistake in your choice?

The technology that was relevant several decades ago, when the surfaces were leveled by the P-71g-2, is a thing of the past. Prefabricated floors based on dry screed are successfully used everywhere today. The dry floor screed "Knauf" from the German manufacturer, famous for its unsurpassed quality, favorably differs in the building materials market.

The use of the technology of this company, where special gypsum-fiber boards "Knauf Superpol" and a waterproofing film with a leveling mixture are used, is very popular. This method saves time, does not require huge labor costs, and the load on the floors is minimal.

The materials used (gypsum fiber board and expanded clay) are the key to successful work and long-term operation of the coating. Evaluating the pros and cons of dry floor screed, masters note only its advantages.

Is a dry screed expensive?

When carrying out work, an important factor is their cost. When compared with concrete pouring, the advantages of free-flowing technology are undeniable. How much does a dry floor screed cost? The price of the issue depends on the quality of the materials used. On average, per square meter of surface, craftsmen take from 400 rubles.

But in any case, it will cost several times cheaper than alternative surface leveling works. And this is an important argument in favor of this technique in construction.

Benefits of dry screed

The indisputable advantages of "dry" works also include:

accuracy of work, excluding splashes, drips and dust (this cannot be avoided in the case of a concrete-sand screed);
it is not required to wait for the surface to dry, but you can use it immediately, covering it with a topcoat;
works are carried out regardless of the season;
minimum loads on the floor of the building, which is especially important in structures of old construction;
the use of a bulk layer for laying communications when organizing a heated floor;
providing sound and heat insulation;
minimal involvement of labor, because, if necessary, the screed is performed without helpers.

Flaws

Considering the pros and cons of dry floor screed, it turns out that its main disadvantage is the fear of moisture. Therefore, during installation work, special attention is paid to the waterproofing layer.

The film must protect against leaks, which have a detrimental effect on the bulk mixture and the material laid on it. After all, a swollen floor will lead to deformation of the finish coating made of laminate, linoleum. For prophylaxis, wooden floors are covered with a special protective compound.

But in the presence of only one minus, a dry screed has such advantages that make it in demand and relevant when carrying out repair and construction work.

A smooth, even base for the topcoat is a prerequisite for flooring. This is the only way to ensure its reliability and durability. In the minds of many apartment owners, construction work of this type is necessarily accompanied by destruction, dust, dirt and other consequences of work associated with pouring a cement-sand screed. If we add another long wait for three to four weeks, then the picture is far from rosy. Is there a way out?

Perhaps it will be a revelation for someone, 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 are the pros and cons - this is an approximate range of issues that we have to deal with.

Dry or wet floor screed

Several methods can be applied to form a flat surface. Classical concrete pouring is characterized by laboriousness and a long final drying period. An alternative 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 base surface 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. Also, changes in qualities under the influence of external factors are 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 making a dry floor screed, you should consider the relevance of its use. In this case, certain restrictions should be taken into account:

The operational qualities of the premises. The formed leveling layer should not be exposed to moisture. When it gets into the building mixture, the properties change. Therefore, it is necessary to additionally install a waterproofing layer. Materials for dry screed are not designed for use in "wet" rooms - bathroom, kitchen.
Square. 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.
The degree of load. Despite the fact that the mixture for the floor screed will not experience mechanical stress - it will affect the gypsum fiber boards.
Underfloor heating compatibility. The backfill itself has good thermal insulation properties. Therefore, heating elements must not be installed in it. A dry floor screed for underfloor heating can only be compatible with film heating.

These are not the only conditions for applying this method of surface leveling. You must first 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 mixtures for floor screed is in the use of liquids. True, materials for a dry type do not provide a particularly high density, however, these indicators are sufficient for their installation in any living room.

Advantages and disadvantages

Arrangement with the above method should start 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 filling the space between the logs.

What else makes this technology different?

Low material consumption. It differs significantly from the concrete casting method.
The low weight reduces the load on the floors. All dry building mixtures for this work have a low specific gravity. Therefore, a layer thickness of 20-30 cm will not affect the general 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 exposed to stresses. When pouring a concrete surface, this will require a wait of 7 to 20 days.
There are no wet processes, so dirt does not spread through the living quarters. Not only is there no dirt. There is also no cement dust, a rather 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, or special containers or other special equipment. The exception is rooms with a large area, where the speed of work is important. In this case, equipment is needed with which you can quickly form an even leveling layer.
Through the bulk layer of the system, intra-apartment communications can be laid.
One of the priorities is for underfloor heating. 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 finishing coating; the presence of a layer of thermo-reflecting material is required.
It simultaneously performs the function of additional thermal and sound insulation.
Installation is simple enough. Also suitable for a wooden base, provided it is of course solid.
Provides layer stability to distributed and point loads - up to 1 t / m2 and 360 kg, respectively.
The topcoat can be installed as soon as the screed is completed. Almost any material is chosen for him.

The advantages of this technology also include:

the ability to carry 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;
a more economical way: the cost of installation work and the price of equipment are less.

It also has disadvantages, however, they are few in number. The main, perhaps, is the 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 nevertheless decide to apply 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 the technology make it relevant for the arrangement of residential premises. Most of all, this applies to places where there is a need to reduce the load on the floor as much as possible.

Prefabricated dry screed from OSB boards

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

In the manufacturing process, large chips are located at the edges of the structure, while smaller components are placed inside. To increase the mechanical strength, the outer layers have a longitudinal orientation of the wood fibers, and the inner ones have a transverse orientation. Subsequently, slabs 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 characteristics. 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 indicator of water resistance. It determines the possibility of installing the coating in a specific room - bedroom, kitchen or bathroom. Depending on the degree of processing, this value can be 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 on which no mechanical forces will be applied, a material with a modulus of elasticity of 1100 N / mm² can be used. If it is planned to install slabs 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 board on the floor. For a rough surface, it can be 6-9 mm. When arranging the main covering, 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 standard sizes of sheets: 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 residential use.

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

Laying technology

One of the key advantages of OSB is its 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 flooring 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 starting material for the manufacture of floors is wood or concrete screed;
Room temperature and humidity parameters;
Total coverage area;
Maximum surface load value.

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 masters. But before that, you should familiarize yourself with the general installation recommendations.

Installation on a concrete floor

Before installation, it is necessary to treat the cement surface. After a long period of operation, cracks and chips inevitably form on it. They must be carefully putty. If the level difference exceeds 7 mm per 1 lm. - install adjusting lags.

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

Then you need to follow these steps:

Cut according to the previously drawn up diagram.
Cleaning the floor from dust and dirt.
Installation of material, fitting of its joints.
You can use glue for fastening. It is important that it does not negatively affect wood and concrete.
The joints must fit tightly together. It is recommended to use models with side mounting elements.
To compensate for thermal expansion, a gap of 5-7 mm must be left between the base and the wall.

During installation, it is important to make the flooring the correct side. Most slabs have a front and a back that are designed for specific operating conditions.

On a note

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

On a wooden floor

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

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

After that, a waterproofing layer is mounted. It should cover the entire surface of the floor and pass under the joists. If it is impossible to dismantle the lag, the treatment can be carried out with liquid mastics. After that, a layer of thermal insulation can be installed.

Rules for arranging a wooden floor.

To increase the mechanical strength, it is recommended to install two layers of OSB. The first is located across the log, and the second along them.
The plates are fastened with side screws. It is important that the joints are not flush.
After installing OSB boards on the floor, the level is checked. If necessary, you can perform a partial dismantling and install adjusting pads over 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 on top of OSB, use a special adhesive that will not damage the wooden base. It must be remembered that a high-quality OSB floor board 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 plasterboards. 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 bonding compounds, sheets of gypsum fiber board are obtained for the floor with the following properties:

Density indicator - 1200 kg / m³. This makes it possible to use fastening materials (screws and nails) without damaging the surface;
High degree of sound insulation. The thicker the sheets of GVL Knauf, the higher this indicator. For some models, it is 35-40 dB;
Fire safety. The material can be used in rooms with high fire safety requirements;
Low thermal conductivity. It is an additional property that does not negate 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 susceptible to moisture, which can accumulate in cellulose fibers. Therefore, if the question is, gypsum fiber board or plywood on the floor, it is better to do everything with the first one.

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 recoup its cost due to the quality and long service life.

Despite all its positive qualities, in practice, you may encounter some difficulties when 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 board 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 material of the floor. To ensure sufficient rigidity, the substrate must be uniform. In this case, an even distribution of the load will occur. 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 with prolonged storage, condensation may accumulate inside;
Cost and size.

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

On a note

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

Sectional prefabricated system

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

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

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

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

On a note

The optimal thickness of the cake is considered to be 35–45 mm, with 20 of them falling on the sheet layer.

With a lower system height, 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 Knauf dry screed

The Knauf dry floor screed is inherently special sheet panels laid on bulk material, laid out in a thin layer. Soft, finely dispersed backfill, pressed by these sheets, is transformed into a hard and durable base, which is able to withstand sufficiently large loads.

The 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

The backfill on large areas is leveled using a special machine.

Knauf gypsum fiber sheets (GVL) are made of gypsum and cellulose, the fibers of which perform a reinforcing function. They are characterized by high strength and fire resistance. The sheets are environmentally friendly and chemically passive. Unlike drywall, there is no paper backing.

Structural elements of Knauf superfloor are panels that are glued from two gypsum fiber sheets. They are somewhat displaced one relative to the other, 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 held together during laying. The standard dimensions of the panels in mm are 1200 x 600 x 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, for example, wire, reinforcement, etc. The same is done with those on the concrete surface. If the metal is cut off, 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. Along 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 will further compensate for the thermal deformation of the Knauf panels. Due to the presence of a compensation gap, it is possible to exclude the 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 sheets 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 filling intact.
On panels that are adjacent to walls or other vertical surfaces, folds are cut off. The initial row is laid out along the wall opposite the front door, and gradually move towards it. The folds of each previous row are lubricated with an adhesive or mastic.
Each subsequent row is laid with an offset of up to 25 cm in relation to the previous one, and the likelihood of the formation of cruciform joints must be completely excluded. The glued joints are additionally fastened with screws. They are fastened in increments of no more than 30 cm.

You will need a room plan on which the markings will be applied. Please note that trimming them can only be done on one side. Removing the mounting locks will affect the degree of waterproofing.

To calculate a dry floor screed Knauf, a calculator is used, which will determine the required volume with great accuracy. Not only area and volume are taken into account, but also the degree of level difference.

Let's assume that the area of the room is 20 square meters. m., and expanded clay backfill 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 demanded today "Knauf Compavit". It should be noted that the material is supplied to the market in 4–5-layer bags with a volume of 50 liters. Such a bag weighs 30 kg.

Calculation example

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

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

One GVL Knauf covers 0.75 m². Thus, to cover an area of 20 sq. m. will require about 15 sheets.

Video - do it yourself dry floor screed

The uncomplicated technology of dry screed for leveling the floor allows you to cheaply and quickly prepare it for the installation of the finishing decorative coating. Its principle has been known for a long time, and improved materials make it even easier to implement.

Attracts dry concrete screed with low weight and versatility. It increases the mass of the structure being erected to a minimum, is relatively inexpensive, besides, it will help to save money that you can work with it yourself without spending money on hired labor.

Why dry?
Pros and cons of dry screed
Materials and tools for dry floor screed
- Consumption of materials for dry screed
Surface preparation
Dry screed laying technology
- Exposing lighthouses
- Backfill of expanded clay
- Laying sheet material
Screed cost and material consumption

Why dry?

For many decades, traditional types of cement screeds have been successfully used in practice. The classic components for such screeds were necessarily:

cement;
sand;
water.

Only their ratio and the quality of individual components changed. But experts from the German company Knauf set about implementing a new project suitable for leveling the floor - it was they who came up with the joint use of materials such as dry screed and gypsum fiber boards (gypsum fiber sheets). The technology turned out to be so simple that it became available to everyone. Here, in addition to GVL, expanded clay will be required as the basis of the screed.

First, a loose material is poured onto the rough floor - expanded clay, which is sprinkled with sand or perlite, and then tile materials are laid on top: gypsum fiber board, fiberboard, chipboard or plywood. The modules of the upper bonding layer are fastened with self-tapping screws and glued.

Pros and cons of dry screed

A dry floor screed is quick and easy to install. But in addition to these two advantages, it has a number of others:

Materials for dry floor screed cost several times less than for concrete, which is always a significant plus.
Greater cleanliness of work - since the cement-sand mixture does not mix with water, dirty streaks and puddles do not appear.
Bulk insulation is most often used as a pillow for a dry screed, which guarantees good thermal insulation of the floor.
The design is much lighter than with a traditional cement screed, because the leveling material and expanded clay weigh much lighter, in addition, their use reduces the consumption of dry mix for the screed, which means that the load on the floor is also reduced. Therefore, this system is advantageous when renovating floors in old wooden houses.
The fill layer can also be used for laying various communications or, for example, a warm electric floor in the form of mats or cables. After arranging the dry screed, you can immediately start laying the topcoat, while after laying the "wet" cement screed, you will have to wait a very long time until the concrete is completely dry.

As you can see, there are many advantages here, and if you list what disadvantages a dry screed has, then perhaps one, but very significant and unusual, will be remembered - the fear of water ingress. One has only to get a small amount of water on the surface of plywood, gypsum fiber board or chipboard, as they swell with bubbles and warp.

Materials and tools for dry floor screed

In order to perform a dry screed, a knowledgeable master will surely invite an assistant. No matter how light the materials are, you will have to drag a lot of them, and besides, it is more convenient to stack large sheets together.

So, here are the materials you need:

GVL with dimensions 60x120 cm. This format of sheets has been specially reduced so that even one worker can handle them when laying. These are two sheets glued to each other with some offset, which are also called "dry floor elements".
Small fraction expanded clay. A dry mix for floor screed can be not only expanded clay, but also a fine-grained fraction of slag, perlite and even crumbs from expanded polystyrene plates.
Polyethylene film as a waterproofing, which is laid on the base before backfilling expanded clay.
Self-tapping screws for fixing GVL.
PVA glue.
Edging tape.

And also tools for work:

roulette;
pencil;
jigsaw or knife that can be used to cut GVL;
screwdriver;
narrow spatula;
rule;
metal profile PN-27/28 (it will serve as beacons).

As an additional tool, you may need a paint brush, which will come in handy when, before applying glue at the joints of the slabs, you need to wipe off expanded clay crumbs from them.

Consumption of materials for dry screed

First of all, you need to take care of the required amount of materials, because when a dry screed is made, their consumption can be significant, so it is important to correctly calculate their amount:

The volume of expanded clay is determined by the layer thickness and the total backfill area. At least 3 centimeters of expanded clay can be filled in, however, the thicker the layer, the better the floor will be thermally insulated. On the other hand, we must not forget that the higher the floor rises, the closer the ceiling will be to it, that is, the room will become lower.
It is cheapest to use ordinary polyethylene film as waterproofing, the thickness of which is not less than 0.2 mm. Its amount should exceed the area of the room, since part of it will go for overlaps and allowances on the walls.
The number of guide metal profiles will also depend on the size of the floor.
The length of the damper tape, which is laid along the perimeter of the walls, is determined by this perimeter.
Slab leveling materials should also, in aggregate, have an area equal to the area of the room, but with some margin.

Surface preparation

If the repair takes place in the apartment, then before making a dry screed, you need to remove the old floor covering and all the layers under it until a reinforced concrete floor appears.

The surface of the slab must be inspected and all defects found on it (grooves, cracks, chips) must be repaired, using a ready-made plaster mixture or cement-sand mortar for this purpose.

The repaired places need to be allowed to dry, after which the repaired sub floor should be thoroughly swept out of dust and dirt, so that then we can put the waterproofing material on it - polyethylene. The film must completely cover the floor surface and "climb" on the walls along the entire perimeter to a height that is determined by the thickness of the dry screed.

The film is usually laid in the form of several parallel stripes, which should overlap each other by 10-15 cm. To make the waterproofing airtight, the edges of the strips must be glued together with construction tape.

The question may arise: if the screed technology is completely dry, then why do we need waterproofing? The thing is that the floor slabs are not monolithic, they have gaps that let moisture through, albeit slowly, from the lower floor or from the subfloor (if we are talking about the first floor). Therefore, only high-quality waterproofing can stop the flow of moisture. These precautions are also justified by the fact that the dry screed does not like water ingress.

Then, along the perimeter of the walls, you need to place a damper tape. This tape is made of foamed PVC, one side of which is self-adhesive, protected by a polyethylene film. The protective film must be removed and the tape must be immediately glued to the wall surface. The purpose of the damper tape is to compensate for the thermal expansion of the dry screed. In addition, it will prevent the leveling sheets from contacting the walls, which will protect them from deformation, and the residents from an unpleasant squeak.

After installing the edge strip around the perimeter of the walls, the entire vapor barrier structure at the base of the floor is considered complete.

Dry screed laying technology

If a dry floor screed is chosen, its technology consists of several successive stages. These stages will be listed below with reference to the fact that expanded clay will serve as a bedding.

The process of installing a dry screed begins with attaching the beacons as guiding elements. It is with their help that the dry screed - expanded clay is leveled in height, they determine the thickness of the bulk layer. Some seasoned craftsmen manage to do without beacons, but beginners are strongly encouraged to use them.

Exposing lighthouses

Most often, special T-shaped lighthouse profiles are used for dry screed, which are attached with self-tapping screws to the base of the floor, but before that they need to be exposed using certain tools, which include:

rule;
laser level;
pencil.

Sequence of work:

The laser level must be installed in the center of the room and switched on.
After that, half a meter from one of the corners of the room, a self-tapping screw should be screwed into the floor, a rule should be installed vertically on it and a trace of the laser beam should be marked on it with a pencil.
After that, along the diagonal of the room, closer to the other corner, also screw another self-tapping screw into the floor, put a rule on it and check the coincidence of the line drawn on it with the laser beam.
If they diverge, then the self-tapping screw should either be screwed in even deeper, or unscrewed a little, ensuring that the mark exactly coincides with the laser marker.
Carry out similar actions with all intermediate self-tapping screws, or it is easier to do: pull a thin and strong thread between the extreme fasteners, and, focusing on its level, screw the self-tapping screws into the floor after 20 cm.
Then you can check the work - put a flat rail on the screws, and a regular water level on it. If everything is done correctly, the level will confirm the horizontal position of the rail.

After that, the lighthouse must be fixed with cement or plaster mortar.
The guide element on both sides of the self-tapping screws should be overlaid with mortar and allowed to dry.
Do the same with all other lighthouses.

Backfill of expanded clay

If not a dry screed with sand is done, but with expanded clay granules, then they should be as small as possible. After all, sheets of leveling material will rest on them, which in the case of large granules will have a point, chaotically located support and from this will deform, and dips will appear.

Expanded clay for a dry floor screed should not be poured onto the entire floor at once, but only its area.

Having reached the level of the beacons in this place, you should immediately put a tile leveling material on top, for example, gypsum fiber board.
The legs of a working person should be on a clean floor, free of expanded clay.
After that, you can proceed to backfilling the next section and laying the next slab on it.

But a number of craftsmen also have an alternative approach - they first cover the entire floor with expanded clay, level it with the rule according to the level of beacons, and then move along the floor, placing pieces of gypsum fiber board or plywood under them.

Laying sheet material

There are a number of points that require special attention:

If gypsum-fiber sheets are used for alignment, then it is advisable to lay them in two layers, which must be fastened with self-tapping screws, and then the joints should be coated with glue. Considering this feature, Knauf began to produce ready-made double sheets with a folded joint - "Knauf superfloor". It makes it easy to create beautiful flooring that meets all modern requirements.
In the case of using plywood or chipboard, they can be laid in one layer, but only if their thickness is at least 12 mm. These materials must also be treated with protective agents - bituminous mastic or hot drying oil.
When stacking, sheets must be pressed tightly against each other. If the gaps still work out, then they should be filled with a putty solution.

If the expanded clay is backfilled in sections, then installation should be started from the corner farthest from the entrance door of the room. If the floor is completely covered with expanded clay beforehand, then the installation, on the contrary, should be started from the front door, so that you can easily move along the previously laid slabs.

In the case of using the "super-floor Knauf", the folds of the slabs must be coated with glue and connected with special self-tapping screws with a length of 19 mm. These self-tapping screws have countersink heads, thanks to which the fasteners are deeply recessed into the GVL. This helps to get rid of unnecessary height differences during the installation process.

When all the installation work is completed, then all the protruding edges of the damper tape and plastic film must be cut off, and the resulting gap between the walls and the dry screed must be filled with sealant.

Screed cost and material consumption

Calculation of a dry screed is quite easy to do. So, for a room with an area of 100 m2, approximately 150 m2 of waterproofing, 100 m of a profile, 5 kg of glue and 1200 self-tapping screws will be required.

The consumption of the dry mix for the screed here will depend on the thickness of the screed: if the average thickness of the backfill is about 3 centimeters, then 4 m3 of bulk material will be required to accommodate such an area.

Well, the answer to the question of how much a dry screed costs is made up of the cost of all the materials necessary for work.

Would you make a dry floor screed in your apartment or house? Or do you already have experience with it? How did you like it, and what shortcomings did you note? Let us know in the comments.