How to make a concrete screed on a wooden floor. Concrete screed on a wooden floor How to pour wooden floors under tiles

Tiled and self-leveling floors on wooden floors cannot be made without a leveling screed.

Leveling a wooden base can be done using a wet cement-sand mortar, a semi-dry mixture with fiberglass, gypsum fiber board, or Knauf floor slabs over a layer of insulation.

Figure 1. Screed on a wooden floor.

Features of the screed device for wooden floors

The cement-sand screed, after drying and gaining strength, turns into monolithic slab, not subject to linear changes. And wood has the ability to expand or shrink under the influence of humidity and temperature changes. Screed connected to the base, under the influence of unstable wooden structures, will become covered with cracks and collapse.

Therefore, the main condition when installing a concrete screed on a wooden base is its isolation from wooden structures. So that the screed solution does not touch the wood of the walls and floor.

In addition, the screed should not put too much stress on the floor.

Preparing the base for the screed

Before deciding to pour a concrete screed over a wooden floor, carefully inspect the base. Check the condition of the joists and floor boards.

The wooden covering must be rigid and durable, without traces of mold or rot.

If the covering does not inspire confidence, you can strengthen it by installing additional joists, or replacing worn flooring boards.

Figure 2. Repairing a wooden floor.

Before installing a leveling screed on a repaired wooden base, we carry out the following preparatory measures:

Large cracks and junctions with walls are sealed with epoxy putty or polyurethane foam.After hardening, cut off the excess sealant and sand down any unevenness.
We clean the floor surface from debris and dust and treat it with an antiseptic and then with a primer twice.
We attach the damper tape to the walls along the perimeter of the room using double-sided tape. It will separate the concrete floor from wooden wall. The tape should be 5-10 centimeters wider than the height of the screed.

You can use foam polystyrene or a wooden board for these purposes.

We lay a dense plastic film, at least 100 microns thick, separating the screed and the floor boards. We lay the film strips overlapping, fastening them together with tape, overlapping the walls by 15-20 centimeters.

Figure 3. Insulation of wood flooring.

We strictly monitor the integrity of the coating to ensure the tightness of the insulation. Moisture should not be allowed to enter the wooden floors both during the installation of the screed and during the operation of the coating.

A wet screed installed on a wooden floor must be reinforced. To do this, place on the insulated surface steel mesh, with a 10x10 cell. When pouring, the mesh should fall into the screed mass, so it is better to lay it on mortar supports.

Important!
A semi-dry screed does not require additional reinforcement, since the reinforcing fiber is contained in the solution.

Using a laser or hydraulic level, we mark the height of the screed. To do this, we transfer the horizon line to the wall. It can be at a height of one meter from the floor. Then, using measurements, we find the highest point of the floor and from there, adding three centimeters of screed thickness, we find the mark of the screed surface. We transfer this line to the wall around the perimeter of the premises.
We place guide beacons along the insulating layer, along which the screeds will be aligned. We make them from a solution, in the form of continuous strips, or steel profile installed on mortar slides. You cannot screw the profile to the base with self-tapping screws so as not to damage the integrity of the insulation.

We adjust the height of the beacons strictly according to the level, pressing the slats into the mixture or adding a solution under them.

We arrange the first row of beacons at a distance of 15-20 centimeters from the wall, and the next row - 1-1.5 meters from each other, but no more than the length of the rule.

Filling the screed can only begin after the beacon solution has dried.

Semi-dry screed device

Semi-dry screed is made from cement, sand, modifying additives and reinforcing fiber. The minimum amount of water necessary only to hydrate the cement is added to the mixture.

Such a screed must be carried out in strict accordance with the manufacturing technology and building regulations. Following a certain sequence.

Preparation of the solution

The solution, in large quantities, is prepared at the construction site, in a pneumatic blower. This device performs the function of a mortar mixer and a concrete pump. With its use, there is no need for lifting mechanisms.

Figure 4. Production and supply of solution using a pneumatic blower.

All components of the solution are loaded into the device’s container in a certain sequence and mixed thoroughly. Under pressure compressed air the mixture is supplied through a hose to the work site.

To ensure uniform distribution of the mixture flowing through the hose, special dampers are used.

The solution can be prepared directly at the installation site in a mortar mixer or in a container using a construction mixer.

It is better to use ready-made dry mixture in bags for such purposes.

If it is not there, take cement and sand in a ratio of one to three and, stirring, gradually add fiber, at the rate of about 700 grams of fiber per cubic meter solution.

At the end of the process, add a little water and mix until smooth.

You can make installation easier by adding plasticizers to the finished mixture.

Important!
We check the correct consistency by squeezing a small amount of the mixture in a fist. Ready solution It should turn into a dense lump that does not release water when squeezed.

Screed device

The semi-dry mixture must be laid strictly according to the installed beacons, starting from the far wall of the room.

We level and compact the solution using a rule and a vibrating screed, carefully filling all the junctions.

Two hours after installation, the beacons can be removed and the resulting cavities can be sealed with a solution.

Figure 5. Grouting a semi-dry screed.

Rub the entire screed with a disk grinder. Grind the corners and junctions with the walls using a trowel. At the same time, it is better to walk on a freshly laid screed using special concrete shoes to avoid pushing it through and damaging it.

If the room is more than 20 square meters, we cut expansion joints along the surface of the screed.

After grouting, the surface becomes perfectly smooth and even.

After a day you can walk on the screed, and after three to four days you can begin finishing.

Semi-dry screed is an ideal base for tiles or other covering on a wooden base.

It has many advantages over wet or dry screed:

the finished coating is highly durable and abrasion resistant;
due to the semi-dry porous structure, it is much lighter than a wet screed, its installation does not significantly load wooden structures;
has high sound insulation and thermal performance indicators;
the use of a minimum amount of water in a mixture with reinforcing fiber fiber eliminates the formation of cracks and shrinkage of the finished screed;
dirty wet processes and the ingress of water from the solution onto the ceiling and lower floors are eliminated;
Modern technology and efficient equipment make it possible to produce large volumes of semi-dry screed in a short time.

The permissible thickness of a semi-dry screed is from three to five centimeters.

It is possible to perform a semi-dry screed using a heated floor system.

In this case, it is necessary to lay polystyrene foam on the wooden base, and then roll insulation with foil layer.

Figure 6. Layout of a heated floor system in a screed over a wooden floor.

Place the heated floor cable system on the insulation.

I recommend!
When installing underfloor heating systems in wooden houses, it is better to give preference to heating mats or infrared heater in the form of a film with heating elements that can be laid on the finished screed in a layer of tile adhesive.

Wet screed

Screed by wet technology It is made from cement and sand, in a ratio of 1:3 with the addition of water, to a plastic, creamy state.

Such a screed requires careful waterproofing of the base, preventing water from the solution from penetrating onto wooden structures.

The solution is prepared directly at the pouring site and laid in an even layer along the beacons.

It is not advisable to install a wet screed on a wooden floor for the following reasons:

due to the severity wet screed requires a rigid and durable foundation;
the wet process increases the humidity in the house, which is not desirable for wooden structures;
for minor damage film waterproofing, water from the screed may get on wooden base and lower floors;
a wet screed requires mandatory reinforcement, which additionally makes the structure heavier;
The drying time and strength gain of the wet screed is 28 days;
During the entire drying period, a wet screed requires care: protection from drafts and moisture.

Figure 7. Wet device cement-sand screed.

Installation of dry screed on a wooden base

A dry screed consists of a layer of insulation and a rigid covering made of gypsum fiber board, gypsum plasterboard or special two-layer floor slabs of the Knauf system.

Expanded clay of different fractions can be used as insulation, hard mineral slabs or Penoplex.

Under the expanded clay we lay a layer of waterproofing made of dense polyethylene, 200 microns thick, so that it is not damaged when filling and compacting the expanded clay.

Important!
We place polyethylene on the walls 10-15 centimeters above the screed mark and secure it with construction tape. We lay the polyethylene strips overlapping and glue them together with tape.

We mark the height of the expanded clay layer using a laser level. We transfer the marks to the walls around the perimeter of the premises.

We install beacons from a metal profile for drywall. We check lighthouses strictly according to building level marks.

Pour a layer of expanded clay, carefully compacting and leveling with a long lath. We fill and compact the junctions with the walls.

Figure 8. Installation of gypsum fiber board screed on expanded clay.

A day later, we lay it over the compacted expanded clay layer. plasterboard sheets or floor slabs of the KNAUF system.

If using sheets, lay out the first layer on the expanded clay surface, leaving deformation gaps between the sheets of 1 millimeter, with offsets at the seams.

We cover the first layer with glue and lay the second layer of sheets on it, also moving the seams by at least 30-40 centimeters. We fasten the layers together with self-tapping screws.

When using ready-made Knauf panels, we lay them on a compacted surface and fasten them together using special locking joints.

Seams, joints and recesses from self-tapping screws are sealed with putty, sanded and coated with two layers of primer.

Advantages of dry screed:

perfectly level base;
excellent sound and heat insulation due to expanded clay;
low weight does not require reinforcement of structures;
the surface is ready for finishing immediately after installation;

Figure 9. Diagram of the installation of a gypsum fiber board screed on a wooden base.

The only drawback of dry screed with insulation is its large thickness, which does not allow its use in rooms with low ceilings.

Which screed to choose

If you have a strong and rigid wooden base, it is better to choose a semi-dry floor screed.

It will not load the floor too much; water from the screed will not get onto the wooden structures, even if the integrity of the waterproofing is damaged. Will create solid foundation for styling any finishing coating floor.

When leveling floors in old and dilapidated wooden houses, preference should be given to a dry coating. Dry screed is suitable if you need to insulate the floor of the first floor or the ceiling above an unheated basement.

If you decide to make a screed on a wooden floor, contact specialists who will help you choose best option leveling your floor and will perform the work efficiently, quickly and professionally.

Screed on a wooden floor is not the best solution for installing a new floor. However, despite this opinion, if all technologies are followed, it is actually feasible. In addition, there are designs wooden floors which, being in good condition, are easier to fill with self-leveling flooring than to redo the entire floor structure.

This article will be useful for those who are building their own Vacation home. Having made a self-leveling floor over a wooden one, it is easy to lay tiles in the bathroom or kitchen at home.

Also for owners country houses information about septic tanks from concrete rings. You can get information about septic tanks and place an order.

Wooden floor structures

Before you start talking about the screed on wooden floor you need to understand the designs of wooden and plank floors.

It hardly makes sense to screed a wooden floor that is laid on joists and a 220 mm thick floor slab. The thickness of such a wooden floor is 70-77 mm and the best solution for such a floor would be to remove the wooden floor along with the joists and make a screed over the concrete floor slab.

Screeding a wooden floor makes sense if the floor joists are high brick pillars. The height of such pillars can reach 30-40 cm (or more) and it is not possible to replace them with a screed. You can see two photos of schemes for such floors below.

It is precisely floors of this design that we can talk about, like possible reason for screed.

Features of screed on wooden floors

Before deciding to screed a wooden floor, pay attention to the following:

A screed on a wooden floor is an unconnected screed, that is, the layer of such a screed will not be connected to the bottom layer of the base and will be an isolated layer of the floor, not connected to anything. This leads to some features of screeds on wooden floors.

Firstly, the wooden base for the screed must be very strong and completely motionless. Depreciation, which is so characteristic of a wooden floor, should be completely eliminated. If the wooden floor possibly vibrates, the screed above it will crack, which is unacceptable.

Secondly, depending on the selected material for the screed, the thickness of the screed can be quite thick. For example, when using a cement-sand mixture for screed, the thickness of the screed should be from 10-12 cm. The weight of such a screed will significantly increase the load on the wooden floor. If we take into account that the wooden floor is laid on joists, and there is a step between the joists (the distance between the joists), then as the load on the wooden floor increases, the distance between the joists must be reduced. IN large rooms the distance between the logs can reach 85 cm. Therefore, having decided to make a cement-sand screed in big room, you have to disassemble the floor, reduce the step between the joists by installing new joists and restore the wooden floor again.

It’s a lot of work, and perhaps you should think a hundred times before making a cement-sand screed on a wooden floor in a large room.

In order not to disassemble the floor and not reduce the distance between the joists, use not a cement-sand mixture, but, for example, anhydrite floor levelers. The thickness of such a screed is from 30 mm, the leveler does not require reinforcement and can be used for unbound screeds.

Third, A cement-sand screed on a wooden floor is made, always with a reinforcing mesh. This is done, again, to increase the strength of the screed. Moreover, fiberglass in the screed will not save you from using reinforcing mesh. That is, for a semi-dry screed, you will also have to make a reinforcing mesh with cells of 100×100 mm.

Conclusion. The use of cement-sand screed for large rooms with wooden floors is not justified by labor-intensive work. However. If the circumstances and conditions are such that it is impossible to avoid screeding a wooden floor, then to install the screed it is better to use a leveler suitable for independent screeding rather than using a cement-sand mixture. And in general, I would not consider a cement-sand screed as a priority for screeding on a wooden floor, although the use of a high-quality leveler will significantly increase the cost of the screed material.

Material for screeding on wooden floors

To make a screed on a wooden floor you will need the following material:

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Polyethylene film with a thickness of 200 microns, for waterproofing the screed layer from wood and walls;
Mixture for screed. Read about choosing a mixture a little higher. If you choose a cement-sand mixture, then prepare a reinforcing mesh, preferably with a stainless steel coating. The mesh should not be in rolls. Why not in rolls?

You have to fix the reinforcing mesh on a wooden base, but you must not disturb the waterproofing, that is, do not tear the film. Think about how you will attach the mesh. At the same time, think about how you will attach the beacons for the DSP screed, because there is nothing to attach the beacons to, the base for attaching the beacons is polyethylene.

Why am I making these notes? In my opinion, it is better not to install a cement-sand screed on a wooden base in large rooms. The amount of work and problems will completely overshadow the result. Replace DSP with “Rovnitel” for isolated bases (unbound screed). For example, an anhydrite floor leveler.

Wood screed technology

The wooden floor must be strong, immovable, dry and not rotten. The same applies not only to the floor boards, but also to the joists and pillars on which it is laid. Rotten boards need to be replaced.

Important! Do not screed on a newly laid wooden floor; it may become deformed. The age of the wooden floor for screed must be more than one year when the floor is used in the range of home temperatures. Although I can’t imagine who needs to screed a new wooden floor.

The heads of the nails with which the boards are nailed need to be recessed a few millimeters so that they do not tear the layer of waterproofing film that needs to be laid on top of the boards.

If your apartment is on the ground floor and there is a basement or ground below you, then the seams between the boards need to be filled with epoxy putty. Epoxy putty is chosen because it does not allow moisture to pass through. The seams are sealed so that evaporation does not form between the film laid under the screed and the boards.

If the joints between the wall and the floor are wide, then seal them construction foam, and on top with epoxy putty and liquid waterproofing.

After the putty has dried, polyethylene 200 microns thick is spread on the wooden base. Polyethylene is spread with an overlap of 10-15 cm on the walls. Two adjacent pieces of polyethylene are laid with an overlap of 20-25 cm. Seal the joint between the pieces of polyethylene with non-wetting mounting tape. Tape the overlaps to the wall with tape.

The polyethylene should lie flat, without folds. Under the polyethylene there should be a clean wooden base free of debris.

Preparation of the solution

Let me remind you that we make a screed from a mixture of leveling agent. We make the screed solution according to the instructions on the package. The leveler mixture is added to the water, not the other way around. Stir the mixture until it becomes thick sour cream. mechanically, mixer at low speed.

How to check the thickness of the mixture

To check that the consistency of the mixture is correct, find a container with a diameter of 70 mm so that it can hold 1 liter of solution. From this cylinder, pour 1 liter of solution onto a 50x50 cm plexiglass plate. The diameter of the spread solution should be 34-38 cm. This means that the density of the solution is correct. The density of the solution must be checked constantly.

Set the screed level

The unbound screed with leveler must be more than 30 mm. For a wooden floor, choose 50 – 60 mm. It is better to measure the level of the screed laser level. If the room is very small, it is enough building level. Using the laser level, draw a screed line along the wall and place benchmark beacons (levels on legs) along the floor surface.

Filling the screed

The finished leveling mixture is poured continuously over the entire surface of the floor from the far corner to the exit. Helpers will be needed for successful pouring. One dilutes the mixture, the second continuously pours the solution, the third levels the solution according to the level of the beacons and marks, using a special metal rod with oscillating movements (raising and lowering the rod) along and across the cast surface.

Caring for a poured screed

In a room with a poured screed there should be no drafts and low temperatures. If you did use a solution from CPS, then cover the screed with polyethylene. The anhydrite self-leveling floor must be protected for 2 days from excessive insolation (direct rays of the sun), too high a temperature, drafts and water. After two days the room needs to be ventilated.

Some conclusions of the article

Before screeding, evaluate the structure of your wooden floor;
Cement-sand screed is very heavy and will put a lot of stress on the wooden floor, so you may have to reinforce the wooden floor;
If possible, replace the DSP with a high-quality leveler for an independent screed;
DSP screed on a wooden floor is cost-effective only for small rooms, kitchens, and bathrooms;
Think a hundred times before using a screed on a wooden floor in houses with wooden floors, remember the load.

And one last thing. If you plan to use tiles as finishing, replace the screed on the wooden floor, if possible in level, by laying cement bonded bonded boards (CBB).

Many experts argue that it makes no sense to make a screed on a wooden floor - it is too cumbersome, and there are a lot of materials available for dry leveling of the base. But in some cases it is necessary to give the floor a certain rigidity and level it in height using concrete mortar. This technology exists and determines the way to make a screed on wooden floor. It has its own characteristics that must be taken into account during the work process.

What you need to know about wooden structures

Despite all my undeniable advantages, wooden structures have a significant drawback, which is their shrinkage. When the humidity regime changes, wood changes its size, increasing or decreasing in volume, shrinking in height, stretching or shortening in length. For this reason, screeding on new boards is strictly prohibited. Leveling the wooden base can only be done after three years of use of the flooring.

The design of a wooden floor involves laying joists on which floorboards are mounted. It is worth noting that it is advisable to make screeds on them only if the logs lie on brick pillars, the height of which is at least 30 cm. If the logs are located directly on the floor slabs, then it would be wiser to dismantle the floor boards and make the screed in the traditional way.

What you need to know about screed

The design features of laying the screed on a wooden floor mean that it is completely isolated from the lower layer of the base and is in no way connected to it. From this follows its name - untied screed.

After the concrete solution has completely hardened, the screed turns into stone slab, not subject to any linear changes, which cannot be said about the wooden base on which it is poured. If the wood and the concrete layer are “connected,” then the instability of wooden structures under conditions of changing humidity conditions will cause cracks to appear on the surface of the concrete, followed by its destruction. In this regard, it was developed special technology, which determines how to make a screed on a wooden floor so that it is not connected to either the base or the walls.

Basic principles of leveling a wooden floor

The technological process of installing a screed on a wooden base consists of creating a waterproof layer between the moving wood and the monolithic concrete layer. To create such a border use:

plastic film separating the screed from the wooden floor;
damper tape that cuts off the concrete layer from the surface of the walls.

This method allows you to get a floating leveling slab that is not connected to wooden structures - neither to log or cobblestone walls, nor to the floor board. The screed, in this case, will not be exposed to “moving” wood, as a result of which it will not crack or crumble.

To avoid the appearance of fungus on the surface of the wood, it is treated with an antiseptic and a primer with a water-repellent effect. Only after this is it possible to lay plastic film on the wooden base.

Contact with polyethylene has bad influence on wood, therefore they are widely used as waterproofing of wooden structures. bitumen mastic or materials impregnated with bitumen. But not in the case of a screed poured onto a wooden floor. Here, polyethylene film is most appropriate for certain reasons:

it does not stick to concrete;
the wooden base underneath can swell and shrink without consequences;
the boundary between the screed and the floor prevents the wood from drawing moisture from the concrete mortar during the setting process, as a result of which depressions are not formed;
concrete does not absorb moisture from wood, and therefore there is no need to worry about cracks appearing.

How to make a screed correctly

Work on the screed installation begins with preparing the base:

remove boards;
check lags - replace those that do not inspire much confidence;
additional logs are installed if the step between them is less than 40 cm;
floor boards are returned to their place and secured to the joists with self-tapping screws, damaged floorboards are turned over or replaced with others;
check the floor for squeaks - if necessary, identify the cause and eliminate it;
the cracks formed between the boards are sealed with sealant and wait for its final setting;
treat the wood with an antiseptic if it does not have paint coating, as well as a water-repellent primer.

Next, determine the level to which the screed will be poured. By using laser device Mark the “horizon” on the wall at a height of approximately 50 cm from the floor, set equal distances down and draw a line defining the level of the top of the screed.

The distance from the drawn line to the surface of the wooden floor should correspond to the average thickness of the future screed (usually 5-7 cm).

The next stage is the installation of insulation, resulting in a waterproof pallet. For this:

A damper tape is laid along the walls along the entire perimeter, a couple of centimeters wider than the thickness of the screed. It is attached with glue or double-sided tape;
a polyethylene film is laid with an overlap of at least 10 cm on adjacent canvases and with an overlap of at least 15 cm on the walls. The laid layer should not have folds or punctures, much less holes. Patches are applied to accidentally torn film, and all joints are taped.

On top of each of the concrete strips lay metallic profile and press it into the solution until it is flush with the line previously marked on the wall.

If installation is necessary reinforcing mesh, the work is carried out in several stages. First, the first layer is poured, after it hardens (about a month) the reinforcement is laid, and only after that the beacons are placed. To speed up the process in concrete mortar fiber is added, which provides strength to screeds whose thickness is more than 5 cm.

On final stage When installing the screed, the mortar is poured and leveled along the beacons, which are removed after a day, and the furrows are filled with concrete. As it hardens, the screed is sprayed with water for a week and covered with polyethylene so that it can evenly part with moisture.

After the screed has completely dried, the process of installing it can be considered complete.

Wooden flooring is distinguished by its environmental friendliness, favorably ahead of similar coatings in many respects.

But what if the wooden floor has become unusable?

The answer is quite simple - screed on a wooden floor.

Removing a wooden floor may not be possible for some reason.

It is in this case that wood covering the screed is poured, while this work directly on top of the wood flooring.

This job is easy to do.

In order to obtain the expected result and in order to complete the floor reliably and efficiently, you will need, first of all, to take care of the materials and tools necessary to complete this work.

The following materials and tools will be needed:

sand and cement;
polyethylene film;
acrylic sealant;
plasticizer;
moisture-resistant soil;
putty made on the basis of epoxy resin;
metal mesh that will be used as reinforcement.

After all the tools and materials necessary for the procedure have been prepared, you can begin to fill the wooden floor with a screed.

Stages of screeding a wooden floor

Work on pouring screed onto a wooden floor covering should begin with careful preparation of the base.

So, you will need to clean the floor from debris and dust that is sure to be on it.

If there are rotten or damaged boards, they will need to be turned over or fixed to the joists in an inverted state.

It is preferable to replace damaged and rotten boards with new ones.

Thus, all the work can go down the drain.

The gaps present between the boards must be mandatory fill epoxy resin(putty).

If the gaps in the floor boards are large enough, you can use polyurethane foam, which can completely fill the existing voids.

The joints should be thoroughly coated with acrylic sealant.

After polymerization of the foam is completed, as well as after the mounting foam and sealant have dried, it is necessary to re-clean the floor surface from dust, and then coat the boards with a moisture-resistant primer.

Preparation of the solution

It is worth immediately noting that this screed on a wooden floor is practically no different from an ordinary one.

So, 1 part of cement is mixed with 3 parts of sifted sand.

The solution should be mixed in a special plastic container of suitable volume, using a special drill attachment called a mixer.

After mixing, the solution must be allowed to sit for 3-5 minutes, then stir it again.

The average material consumption is approximately 15 kilograms per square meter floor area.

The prepared solution must be applied within one and a half hours after mixing.

It is important to know! Part cement-sand mixture It is recommended to add a plasticizer modifier, due to which the properties of the floor become more reliable.

With the addition of a plasticizer, the strength indicator, as well as the degree of water resistance, significantly increases.

However, if a plasticizer admixture is used, the cost of the screed for pouring a wooden floor increases.

As alternative option can be used ready mix, which involves the use of an additional plasticizer, or a dry screed.

The procedure for pouring screed on a wooden floor

This video will show you how to make a concrete screed on a wooden floor.

Let's watch and learn!

After everything necessary materials, the tools are prepared, and the floor surface is cleaned, you can proceed to the priority stage - pouring the solution onto the wooden floor covering.

Work algorithm:

The wooden floor should be covered with a layer of moisture-resistant primer.
The next step is laying it on the floor surface polyethylene film. When laying the insulating layer of film, you will need to make it perfectly flat (in no case should it have holes or other flaws, including folds).
When attaching the film, you will need to make an allowance of 5 centimeters above the edge of the future screed.
Next, you need to set the beacons (beacon slats).
Now a cement-sand mortar is prepared and a screed is applied over the film.
Once it has dried, the edges of the film should be trimmed.
It is worth noting that minimum height The screed should be within five centimeters, however, it is better if the layer exceeds the above-mentioned value.
At the end of the work, the reinforcing mesh is laid.
Now wait for the solution to dry completely.
Two days after the floor has been poured, you will need to remove the beacon strips, then prime the surface, filling the voids, followed by grouting with fresh mortar. After wetting with water, the coating must be covered with plastic film for four weeks.

Performing the screed efficiently and step by step - excellent result, which will serve as a reliable and durable coating.

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It is advisable to apply a heavy layer of screed to a wooden floor.
The use of polyethylene film is mandatory, since this synthetic material plays the role of an insulator, preventing solid wood influence the screed.
It is strongly not recommended to pour the solution on a wooden base that has been recently completed, since fresh boards tend to deform under the influence of weight.
Knead sand-cement mortar It is strongly not recommended several hours before pouring the floor surface. The screed solution should be prepared an hour before pouring.
In order to dry the solution on the floor faster, you cannot use additional heating devices.
To obtain the most durable, reliable coating, it is better to wet the surface with water several times a day after pouring the floor screed or completely cover the screed with polyethylene.
There should be no drafts while the screed is drying. The screed should dry naturally for several days.

Doing the work step by step, listening to useful tips qualified workers, you will be able to avoid poor-quality results.

Particular attention should be paid to the sequence of filling the floor, since failure to complete one item of work can lead to unwanted surprises that jeopardize all your efforts.

In contact with

Wood floors, when installed with the right materials and installed correctly, can remain durable and resilient for decades. Sometimes the question arises of laying concrete screeds directly on such floors. Why does this need arise? People think about a concrete screed in cases where they want to perfectly level the floor in order to lay some kind of covering on it ( ceramic tiles, layer polymer materials). The same method is also used when a complete wooden flooring turns out to be prohibitively expensive.

What you need to know about wooden floors

Wood, which has a lot of technological advantages, is also known for one significant drawback that should be taken into account when working with it. This disadvantage lies in its lack of static properties: even after construction is completed, the wooden elements continue to “live”, guided only by their own laws. Changes in humidity levels and temperature regime call:

increase or decrease in volume wooden parts and elements;
their shrinkage in height;
increase or decrease in their linear dimensions.

This feature of wood has determined the rule that always guides builders involved in the construction of wooden structures: fine finishing log buildings should be carried out no earlier than two years after their construction. In relation to our topic, this rule should be interpreted as follows:

Pouring concrete onto a new concrete floor is strictly prohibited. Concrete screed can only be laid 3-4 years after completion of the floor installation work.

The mobility of wooden floor structures increases when any heating systems are installed underneath them. Each startup and shutdown of such a system will cause them to move slightly.

If we compare the mobility of wooden structures with the mobility concrete slab, which is formed when laying the screed, it should be noted that the geometric dimensions of the latter change only during hydration. When the hardening of the concrete ends, the dimensions of the monolith practically do not change. Such a difference in the behavior of wood and concrete, if they are in close contact, can cause cracks to appear in the screed. Moreover, in such a case it may even crumble completely.

The technology of leveling, carried out without connection with the walls and the wooden floor, which we will discuss below, allows each of the elements - floor boards and concrete screed - to exist, obeying only their own principles and without causing harm to their neighbor.

Materials required to complete the work

If an assessment of the condition of the wooden floor and other related conditions has led you to the conclusion that a concrete screed is really necessary and that it is quite possible to make it, it is necessary to prepare in advance the materials that will be required during the work.

When preparing, it is necessary to remember that the mass of the fill must be sufficient to ensure that the screed adheres tightly to the boards. However, the large weight of the concrete used can cause the floor to sag, bend, and then destroy the laid screed.

If the condition of the floor tells you that such a course of events is quite possible, when preparing concrete mixture You should use a plasticizer, which will give the concrete some mobility while maintaining its integrity. An additional advantage of plasticizers is that these substances can have a positive effect on increasing the water resistance of the screed, which will additional protection for wooden structures.

And so, the list of materials required for laying the screed includes:

cement and required amount plasticizers;
film necessary to separate concrete from the surface of a wooden floor;
sand;
any suitable sealant;
epoxy or other suitable putty;
primer with a water-repellent effect;
metal mesh for reinforcement.

During preparation, you need to make sure that there are no breaks in the purchased film. Since the film should be laid overlapping, and its edges should rise slightly to the plane of the walls, when calculating its quantity, at least 15% should be added to the area of the room.

You should also remember about the tools that will be needed during the work. In particular, you will need:

a spatula with which putty and sealant will be applied to the floor;
hammer and screwdriver for strengthening the floor with nails or screws.

Preparing the surface of wooden floors

Concrete screed can be applied to the floor only if its surface is completely ready for it. When preparing it, you should carefully examine each floorboard to make sure that there are no rot or cracks on them. All boards must be securely fastened, there should be no gaps between them. Boards that are heavily damaged are removed and replaced with new ones. If there is a need to reupholster the floor, the nail heads should be recessed. The resulting depressions must be carefully puttied.

When preparing the floor surface, you must:

fill all the cracks on the floor with putty and, if necessary, foam;
handle wooden elements using sealants;
after all substances applied to the floor have dried, clean it of debris and treat it with a moisture-resistant primer;

when the primer has dried, roll out the film overlapping, so that it extends fifteen centimeters onto the plane of the walls. Excess film must be trimmed. The film must be secured, if necessary, using tape. The use of nails to secure it is unacceptable.. For achievement best result A reinforcing mesh can be laid on top of the film.

In the video below you can see how the film is correctly laid on the surface of a wooden floor:

Having completed all these operations, you should start applying preparatory markings. One of original ways markup is presented in the following video:

Rack beacons are fixed directly onto the film covering the floor using concrete, the distance between which should not be greater than the rules used when leveling the concrete mortar.

Concrete screed and the process of pouring it

Pouring is preceded by the production of a concrete mixture. To prepare it clean sand and cement grade 400 are taken in a ratio of 3:1. The solution is prepared on the basis of water with the addition of special plasticizers or similar substances. Can be used for mixing plastic container big size and a drill with a mixing attachment. After mixing the solution, you need to let it settle and then mix it again.

If the thickness of the screed does not exceed 1 cm, then the consumption of the concrete mixture will be about 15 kg/m2. Pouring the solution should be done while focusing on the beacons. The entire floor must be poured at the same time. Laying in parts is not allowed. During the pouring process, using a needle roller, you need to remove any air bubbles from the cement mortar. Leveling the mixture poured onto the floor so that the concrete screed is level is done using a wide spatula or rule.

Techniques for leveling screeds on wooden and concrete floors are similar, so you can use the following video to learn more about the techniques involved:

The drying time of the laid screed is 28 days. During the first two days after installation, it should be moistened with water three times a day. After this, the beacons are removed, and the surface is primed and rubbed. After a month, the concrete screed is completely ready for full use.

In the video below, although it is not in Russian, you can clearly see all the schematically presented stages of laying a concrete screed on a wooden floor.