Screed on a wooden floor under a tile: how to fill it. Laying a concrete screed on a wooden floor Dry screed on a wooden floor

Quite rarely, plank floors are leveled with. Experts believe that it is not very rational to burden the wooden coating with a heavy concrete slab. In addition, the wood base and the cement layer do not coexist so well, both during pouring and solidification, and during operation. Many professionals prefer to fill other alignment schemes - dry. Nevertheless, there are many who want to make an underground house in a wooden house, or lay it in the kitchen and in the hallway - in such and similar cases, and the arrangement of concrete on a wood base helps. Methods for this exist, and they have some characteristic features.

What does this give us? The wooden component of the structure can move as it pleases, but the screed that lies motionless will not crack and will not begin to crumble from changes in the configuration of the draft base.

Features of the concrete floor device in the house: the use of the film

Scheme of a concrete screed on a wooden floor

A reasonable question arises: why polyethylene film? It is not so favorable for a neighborhood with a rather capricious tree, it contributes. Moreover, in wooden buildings it is successfully replaced with glassine, bituminous mastic or impregnated roll materials. It turns out that concrete does not stick to polyethylene film at all.

Thanks to this feature:

on both sides of the border (film), both the screed and the base can move freely;
wood and cement do not interact with each other, wood will not suck moisture from the hardening concrete, causing the formation of cavities and shells;
the poured layer of cement alignment will not pull polyethylene, will not stretch and tear it;
after hardening, the concrete will not begin to gradually absorb moisture from the wood, contributing to the formation of cracks in the wood.

Important necessary precautions for those who decide to take on the concrete floors in the house with their own hands. You will definitely have to process all the wooden parts of the structure, even before the start of work, and with the Aquastop water-repellent primer. So you can minimize the negative impact of polyethylene on wood, and reliably protect the base.

Floating screed: concrete floor installation in the house

We have considered the principle of technology, now let us dwell on the progress of work and their sequence:

it is necessary to remove the flooring of the boards and conduct a thorough audit;
all unusable lags, unreliable and not inspiring confidence, must be removed and replaced;
if the bearing capacity of all the lags is insufficient for the planned load, then they must be reinforced with an additional beam. The step between the individual components should be no more than 0.3-0.4 meters;
floorboards are returned to their place, damaged ones can be turned over;
we seal the gaps between the individual boards with a sealant.

On the walls we mark the zero level, at a height convenient for you. It is determined with the help of a meter.

Concrete screed - reinforced

The height is chosen arbitrarily, it can be from 0.3 to 0.7 m from the base of the dismantled coating. Equal segments are laid down from the line of the vertical level drawn on the wall, their size depends on the planned thickness of the future screed. It will be quite convenient to immediately mark the width on the wall. In this case, when the height is exceeded, it will be easier to immediately slightly reduce the thickness of the leveling layer.

What should you pay attention to? The standard capacity of a floating cement slab is five centimeters. It should be remembered that a layer already one centimeter thick will put pressure on one square of a wooden covering weighing about 120 kg. Without proper strengthening of the lag, their wooden structure is not able to withstand such a mass. Logs or must be securely reinforced, or (if possible) replaced with a metal channel.

Concrete floor pouring: insulation device

The next steps in the manufacture of the leveling screed are the construction of insulating cut-off barriers that will be between the planned leveling layer of the wooden base of the floor. The result of our actions should be a kind of pallet, the walls of which do not let water through.

Floor insulation scheme

Along the perimeter of the room, along all four walls, a foamed polystyrene fence is being constructed. A tape made of this material is attached with tape or a stapler (the first is better). Its thickness is 1-2 centimeters, and the width should be greater than the power of the future screed. In addition to the role of the barrier, this part will be able to neutralize sound vibrations. Also, with its help, the floating plate will be able to slightly lengthen and expand. When the finish coating is laid, the excess that comes to the surface is cut off, and these places are covered with a baseboard or its substitute.
A layer of polyethylene film is laid with an overlap of 10 cm on each other, and with an approach to the walls of 15-20 cm.

What is extremely important? In waterproofing, the presence of holes, folds, slots and holes is strictly not allowed. Work should be carried out carefully, trying not to pierce or tear the layer of waterproofing material. If holes are nevertheless formed, they should be closed with patches from the same material.

It is best when the polyethylene film interlayer does not have any joints at all. If this does not work out, then all existing joints, with indispensable overlaps, must be securely taped with adhesive tape.

Carefully sealed insulation will ensure the quality and reliability of the leveling layer.

Lighthouses for leveling the concrete floor in a private house

Beacons for concrete screed - for a flat floor

This task requires special care and accuracy. Do not use metal nails and screws. It is most convenient to form special beds over the entire equipped surface. They are made from the same solution, the same consistency and the same composition as the planned screed. A heavy strip of mortar will not allow the film to lift up and wrinkle when the master walks, as it will be tightly pressed to the base.

The distance from the outer bed to the wall should be approximately 20-30 cm. The distance between the individual ridges should be one meter or a little more. This is necessary in order to make it convenient to level the screed, relying on the beacons as a rule. Reinforcing mesh for the floor

The thick cement pad, which is the screed, needs reinforcement. Most often, its role is played by a metal mesh, simply laid on the floor. But above we have already noted the extreme importance of the integrity of the insulating film separating the cement mass and the wooden base. It is not easy enough to move along a rigid, lying on a polyethylene film, and not break the latter.

Let's also pay attention to the fact that the reinforcement is designed to strengthen not only the very bottom of the concrete layer.

It should be deep in the mass of concrete, and in order to ensure such an arrangement, it is advisable to pour the cement not in one step, but at least in two, or more:

initial layer;
mesh laying, placement of beacons, finishing pouring.

Those who are aware of the performance characteristics of concrete are probably well aware of how much each individual layer of such a screed dries. Between these two steps, you will have to wait at least 28 days, which is almost a month, and you will have to wait the same amount after pouring the last layer.

Is there a way to avoid such a long wait? Yes, there is such a method, but then it is better to use fiberglass instead of a metal mesh. In the process of preparing the concrete mixture, they are introduced into its composition, and their randomly placed parts provide good adhesion of the material in all directions. An additional plus - already heavy, the screed will be noticeably lighter, because the fiber weighs several times less than the reinforcement.

Concrete screed in a wooden house: pouring

It is performed according to the usual, traditional scheme.

The progress of work can go in different ways: it depends on the floor area of the room, and on its configuration.

The entire area of \u200b\u200bthe room, work starts from the opposite wall to the entrance.
Each room is separate, while it is separated from the adjacent room at the time of work by a partition from the board (formwork).

What are the rules for caring for a concrete screed in a private house? Approximately 24 hours after the end of the pour, the finished cement pad is well moistened. Then, during the week, it is moistened daily (sprayed). After four days, the coating made is closed with a plastic film so that it parted with moisture evenly. It is also recommended to ensure the uniformity and stability of air humidity and temperature in the room.

Wooden floors are rarely leveled with concrete. Many experienced builders believe that hoisting a heavy monolithic structure onto a wood floor makes no sense. Moreover, the concrete layer is not very “friendly” adjacent to the wooden base, not only during solidification, but also during operation. In this regard, it is more expedient to use dry leveling schemes. But in those cases when it is necessary, for example, to lay tiles in the washing room, you have to look for a way out.

We’ll make a reservation right away that a concrete screed on a wooden floor is a completely feasible task, but here, as in any other business, there are specific moments.

Plank floor - photo

Wood is a special material that has not only a number of technological advantages, but also one significant drawback. It is not static, therefore, even at the end of the installation work, it “behaves” according to its own laws, peculiar only to it. Changes in temperature and humidity cause the lumber to shrink, increase / decrease in volume, stretch or shrink. By the way, it is for this reason that after the construction of the log house, the final finishing is carried out after about 2 years.

But even after a two-year period of shrinkage, wooden structures are still moving, albeit not so intensively. For example, a wooden floor with underfloor heating moves every time the heating system is turned on.

Video - Concrete floors in a wooden house

Unlike wood, a monolithic concrete base only slightly changes its geometric parameters during hydration, and after complete solidification, it almost does not move at all.

And if this base were tightly connected to an unstable wooden surface, then the slightest movement of the latter would lead to the formation of cracks on the concrete surface.

One of the reasons for the appearance of cracks is non-compliance with the technology of pouring concrete on a wooden base.

But the leveling technology described here is intended to ensure that both elements cannot harm each other, and its (technology) distinguishing feature is that during pouring, the base does not contact the walls.

Scheme - an example of arranging a screed on a wooden floor

Design features of plank floors

It is hardly advisable to pour the screed over the floor, equipped with logs and floor slabs. Such floors often have a thickness of about 7-7.8 cm, and the only right decision in this case can only be the dismantling of all wooden elements, followed by pouring over the floor slab. Another thing is if the logs are high and located on brick pillars. Such pillars have a height of over 0.3-0.4 m, so it is impossible to replace them with a concrete screed. Schemes of such floors are presented in the images below.

1 - base; 2 - waterproofing from two layers of roofing material; 3 - lower harness; 4 - top harness; 5 - outer cladding with grooved boards; b - non-ferrous metal plate with holes; 7- outer wall from boards; 8 - plaster; 9 - plinth; 10 - plank floor; 11 - lag; 12 - a column of bricks; 13 - antiseptic wooden lining; 14 - underground
1 - compacted sand; 2 - preparation from concrete; 3 - waterproofing from roll materials; 4 - brick column; 5 - wooden antiseptic lining; c - sheathing from antiseptic boards; 7 - board intermediate flooring: 8 - thermal insulation; 9 - air gap; 10 - floor; 11 - bearing beam

It is these structures that are often filled with a screed.

Pouring technology

The essence of pouring a concrete screed over a plank floor is to create a gap between a monolithic surface and unstable wood elements. For this purpose, the leveling layer is cut off from the walls with a damper tape, and from the plank base - with polyethylene.

Thanks to this, a floating floor is created, without connections to any of the surfaces. As a result, all the lumber elements continue to move in one direction or another, and the screed, which simply lies on top, is not covered with cracks from the permanent change in the position of the boardwalk.

The technical parameters of the concrete screed, as well as the basic requirements, are in SNiP 2.03.13-88 and 3.04.01-87.

SNiP 2.03.13-88. Floors. Download file

SNiP 3.04.01-87. Insulating and finishing coatings. Download file

On the advisability of using polyethylene

Direct contact with polyethylene film is known to adversely affect wood, leading to the growth of fungus and mold.

That is why, instead of a film in wooden structures, roofing material, bitumen-based mastic, glassine, or roll waterproofing with bituminous impregnation are often used. But the cement screed does not stick to the plastic film at all, which is why:

both plates will be able to move freely along the isolating boundary;
the screed will not draw moisture out of the wood, leading to cracks;
the screed when moving will not pull the film, stretch and tear it.

Important information! Before starting work, care should be taken to minimize the negative effects of contact between lumber and polyethylene. To do this, all wooden elements must be treated with an antiseptic and an Aquastop primer mixture, which has moisture-repellent properties.

The filling procedure itself consists of several stages, let's get acquainted with them.

Prices for reinforced polyethylene film

reinforced polyethylene film

Stage one. Calculations

There is one standard calculation scheme: for every 15 kg / m² of dry mix, a thickness of 1 cm comes out. Even if the required amount of materials is known, you still need to buy them with a 10 percent margin.

Table. Dry cement mixes - cost

Manufacturer	Package	Price
"VOS Mixes"	Bag, 50 kg	95 rub.
UMIX	Bag, 50 kg	100 rub.
"Stone Flower"	Bag, 25 kg	75 rub.
"Polymin"	Bag, 25 kg	118 rub.
Kreisel	Bag, 25 kg	132 rub
Manufacturer: "Ceresit"	Bag, 25 kg	160 rub.

Stage two. Foundation preparation

Having dealt with the technology and calculated the required amount of the mixture, you can proceed directly to work. Traditionally, you should start with the preparation of the base.

Step 1. First, the boardwalk is dismantled and a thorough revision of all elements is carried out. Logs are checked. If among them there are unsuitable for further operation, then they must be replaced.

Step 2 If the logs are installed in increments of more than 40 cm, then auxiliary bars are installed between them.

Step 3 Boards - if they are still usable - are nailed back. If slightly damaged floorboards are found, they should be turned over.

Nail heads are recessed by 2-3 mm, otherwise the plastic film laid on top may tear.

Step 4 Skirting boards are removed, thin boards are installed instead (the latter should cover the cracks near the walls). Do not forget that these boards are installed for a certain time, and after pouring the screeds will be dismantled. This will ensure ventilation of the wooden base, prevent it from rotting.

Important information! You also need to close all the cracks. If they are small, then you can fill them with sealant, but it is better to blow out large gaps with mounting foam.

Instead of sealant, you can use parquet putty made on the basis of wood dust, or a home-made putty mixture. To prepare the latter, you need to mix any sawdust with oil paint in a ratio of 4: 1.

Stage three. Padding

When the sealant or putty is completely dry, vacuum the substrate thoroughly to remove dust and debris. Sanding can be done if desired, although this is not required.

Next, a moisture-resistant primer is applied in two or three layers: it will prevent the appearance of air bubbles and the absorption of liquid from the cement mortar by the surface. Also, the primer will serve as additional protection for the wood from mold and fungus.

Concrete floor primer prices

concrete floor primer

Stage four. markup

Using an ordinary or laser level, a zero level is marked along the perimeter of the walls. The latter can be at an arbitrary height, but on average it is 35-70 cm from the base surface. It is necessary to designate several points of the zero horizontal on each of the walls.

Equal distances are laid down from these points, while the thickness of the screed itself must be taken into account.

Important information! The standard thickness of a concrete floating floor is about 5 cm. At the same time, each centimeter of such a floor will create a load on the wooden base of 100-110 kg per square meter. It is for this reason that it is desirable to strengthen the logs, although, if possible, it is generally better to install metal channels instead of them.

Stage five. Waterproofing

Further actions are related to the insulation of wooden structural elements, and the result should be a kind of pallet that does not allow moisture to pass through.

Step 1. A damper tape with a thickness of 10-20 mm and a width slightly exceeding the thickness of the screed is attached to the walls along the entire perimeter. This tape will provide not only damping of sound vibrations, but also the possibility of lengthening / expanding the floating plate. Tape is used for fastening.

Important information! At the end of the finishing of the floor, the excess tape protruding on the surface will be cut off, and the gap formed will be closed with a plinth.

Important information! There should be no wrinkles or damage on the waterproofing layer. The subsequent steps must be performed with extreme caution so as not to tear or puncture the film. If this could not be avoided, the holes must be immediately closed with polyethylene patches.

Step 3. Ideally, the waterproofing layer should be without joints at all. If there are joints, then they are all firmly glued with adhesive tape. Further work of the leveling layer will largely depend on the tightness of the waterproofing.

edging tape prices

edging tape

Stage six. Reinforcement

If the concrete layer is thick enough, then it must be reinforced. There are several methods of reinforcement, only the most common are considered below.

Method number 1. Reinforcing mesh

A very common option, which, however, is not particularly suitable in this case. The fact is that the previous layer is polyethylene, which can be damaged by the mesh. It will be quite difficult to move through the reinforcement without violating the integrity of the insulation. In addition, the film, as noted above, must be in direct contact with concrete, so the mesh must be located in the body of the screed.

For this reason, concrete is poured in two layers:

poured - without beacons - the first layer;
the grid is laid, beacons are installed;
the second layer is poured.

It would seem that nothing complicated, but the concrete layer will dry for a long time - the interval between layers can reach 1 month. Therefore, it is better to resort to the second method.

Method number 2. fiberglass

The next reinforcement method is to add fiberglass directly to the concrete mix at the stage of preparation. The polymer fibers that make up this material are arranged randomly, resulting in maximum bond strength in all directions.

Moreover, the total weight of the screed will noticeably decrease due to the rejection of the metal mesh. Further actions are focused on the use of this particular method.

fiber prices

fiberglass

Stage seven. Installation of leveling

Lighthouses need to be built especially carefully, there can be no talk of any screws and nails. The foundations for future "beds" are made from the same solution that will be used for the screed. "Beds" are formed along the entire length of each of the lighthouses.

Important information! The distance between the "beds" must necessarily be 10-15 cm shorter than the length of the rule (often it is about 120 cm). The distance between the surfaces of the walls and the extreme "beds" should be 25-30 cm.

The metal profile is laid on the tops of the "beds" and heated in the solution in such a way that the height noted earlier (the level of the leveling layer) is reached. The installation of beacons must be done a maximum of an hour after mixing the solution, otherwise it will seize.

Stage eight. Mixing the mortar

A mixture for concrete screed can be purchased ready-made or made independently. Factory dry mixes are sold in bags of 25 kg and 50 kg and diluted with water (6.5 liters per bag or 13 liters, respectively). If necessary, the amount of water can be increased, but not more than 0.5 liters.

All components are mixed with an electric drill with a mixer nozzle, the finished mixture should be used for a maximum of 15 minutes.

For self-preparation of the solution, you need to mix cement (at least “four hundredth”) and sifted sand (preferably river sand) in a ratio of 1: 3. An electric drill is also used for kneading, but the whole procedure is performed in 2 stages. The finished solution must be used no later than 1.5 hours after mixing.

Important information! The strength and water resistance of the solution can be increased by adding special plasticizers (the proportions are indicated on the package). Although there is a cheaper alternative to a plasticizer - ordinary washing powder (a handful for every 100 liters of water).

Prices for cement-sand mixture

cement-sand mixture

Stage nine. fill

The filling procedure is carried out traditionally, i.e. continuously. You should start from the far corner relative to the front door. The surface is leveled using a rule.

24 hours after pouring the screed, the beacons are removed, and the remaining voids are treated with a primer, filled with the same solution and leveled with a trowel.

Video - Screed on a wooden floor

Further care of the screed

Care requirements are the same for a finished dry screed, and for a home-made cement-sand mortar. The next day after pouring, the screed is moistened, the procedure is repeated daily for one week. For the first four days, the concrete must be covered with plastic wrap so that moisture evenly evaporates from the screed.

This completes the procedure for pouring the screed onto the wooden floor.

Wood floors are rarely leveled with concrete. According to the firmly entrenched opinion of builders, it makes no sense to place an overly heavy monolithic slab on a wooden floor. The wooden base and the concrete layer are not very “friendly” with each other, both during the solidification period and during operation, which is why the predominant number of specialists recommend preferring dry leveling schemes. However, those who want to lay tiles in the washing department or arrange underfloor heating are still looking for ways in which a concrete floor screed can be poured over a wooden base. There are methods, and they have specific features.

The nuances of working with a wooden floor

Wood is a special material, which, in addition to a mass of technological advantages, has one significant drawback. It is not static, even after construction, lumber continues to “live” according to their own laws. Fluctuations in the level of humidity, changes in the temperature background cause the scaffold to increase and decrease in volume, shrink in height, stretch and contract in a linear dimension. For this reason, after the construction of the log house, they do not carry out a fine finish for two years.

Attention. Pouring concrete mortar over a new wooden floor is strictly prohibited. Leveling with concrete is possible only after 3-4 years of operation.

Wooden structures continue to move even after the completion of two years of post-construction shrinkage, although without the same agility. Equipped with underfloor heating systems, wooden floors set in motion every switch-on with subsequent shutdown.

Unlike lumber, an artificially created stone slab slightly changes its geometric parameters in a linear direction during the hydration period. After complete solidification, the concrete layer does not show any tendency to move at all. If they were in a tight bundle, the instability of the "frisky" wood would cause crumbling cracks in the concrete. Here, in order to allow each of the structural elements to act according to their characteristic principles, without harming each other, an alignment technology was invented that was not related to the base and walls.

Technological principle of concrete leveling

The essence of the technology, according to which a concrete screed is poured onto a wooden floor, is to create a boundary between the moving components of wood and a monolithic slab. To do this, the leveling layer is cut off from the walls of the room to be equipped with a damper tape, and from the base with a plastic film. The result is a floating deck that is not connected to either the timber or log walls or the base. Thanks to this, the wooden elements of the structure can continue to move in any of the directions, and the screed lying like a tray will not crack and crumble from a continuous change in the position of the rough substrate.

Why use polyethylene film?

After all, contact with it negatively affects the wood, providing conditions for the flourishing of rot and fungus. Usually, in wooden structures, instead of this budgetary waterproofing, glassine, bituminous mastic, roofing felt, or new roll materials with bituminous impregnation are used. The fact is that concrete absolutely does not stick to polyethylene, due to which:

both the base and the screed will be able to “ride” along the insulating boundary;
the concrete leveling layer will not pull polyethylene behind it, tear it and stretch it;
the indestructible limit will remain inviolable, will not allow the wood to suck moisture from the hardening concrete, which is why shells form;
concrete will not absorb moisture from the wood base, causing it to crack.

Note! Those who decide that a concrete floor screed will be laid with their own hands must definitely take care of the foundation itself and minimize the negative from contact with polyethylene. Before laying the waterproofing layer, wooden structural elements will need to be treated with an antiseptic and an Aquastop primer with water-repellent properties.

Floating screed technology

We figured out the principle, it remains to implement it. Traditionally, you need to start with preparation:

we remove the boardwalk and carry out a thorough audit;
we identify lags that do not inspire confidence, we irrevocably change everything that is unreliable;
in case of insufficient bearing capacity of the lag system, we increase their number, that is, we install an additional beam so that the step between the lags becomes approximately 30-40 cm;
we fasten the floorboards back, if they are in a suitable condition, it is better to turn over slightly damaged boards;
We fill the gaps between the boards with sealant.

We have finished with the preparation, we keep the time indicated on the package of the sealed “putty”, and generously cover the wooden floor with waterproof primer, after which we let it hydrolyze.

On the walls we mark at an arbitrary height the zero level found by a conventional level gauge or laser device. This landmark can be located at an arbitrary height, approximately 30-70 cm from the plane of the dismantled coating. From the obtained points of the zero horizontal, we lay down equal distances, taking into account the thickness of the future concrete screed. It will be more convenient to immediately postpone the thickness of the floor covering, so that in case of exceeding the height, you can slightly reduce the thickness of the leveling layer.

Note. The standard thickness of a concrete floating slab is 5 cm. Please note that a layer of 1 cm will "fall" on 1 m² of a wooden floor with a weight of 100-120 kg. Without strengthening the lag system, a wooden structure is not able to withstand such pressure. If possible, builders recommend replacing wooden beams with a metal channel altogether.

Insulation device for concrete leveling

Further steps for the installation of a leveling concrete screed are associated with the construction of cut-off insulating barriers between the wooden parts of the floor and the future leveling layer. The result should be a kind of pallet made of water-resistant material:

First, along the walls, we will create a fence from foamed polystyrene tape, attaching it around the perimeter of the room with a stapler, but better with tape. The width of the strip should be greater than the power of the screed being constructed, the thickness is 1-2 cm. This element, in addition to creating a barrier, will dampen sound vibrations, and also provide the floating slab with the opportunity to slightly expand and lengthen. After laying the final coating, the excess protruding above the surface is cut off, and this technological gap is closed with a plinth or its venerable substitute - a 10 cm board with a galvanized ventilation grill.
Then we lay polyethylene with a 15-20 cm overhang on the walls and with a 10 cm overlap on the previous strips.

Note. Folds, holes, punctures, especially holes in the waterproofing should not be. All further actions on the installation of a concrete screed should also be carried out, trying not to pierce, tear, pierce the insulating layer. On accidentally appeared holes, you need to apply polyethylene patches.

It is desirable that the waterproofing layer has no joints at all, but if this could not be avoided, all joints with obligatory overlaps are firmly glued with adhesive tape. Perfect tightness of the insulation is the key to the excellent work of the leveling layer.

Construction of beacons for leveling

It is necessary to carry out these actions with special care, in no case using screws and nails. The best way is to form beds from a solution with the same composition and consistency as the future screed throughout the area to be equipped. A continuous strip of mortar will firmly press the polyethylene to the base and prevent it from warping and bulging when the master walks on the floor.

Note. Between the wall and the extreme bed, the distance should be 20-30 cm. A meter or 1.2 m should remain between the parallel ridges, so that leaning the rule on the beacons, it is convenient to level the screed.

We lay a metal profile on top of the constructed ridges and drown it in the mixture, reaching the previously marked height, that is, the level of the leveling layer. It is desirable to perform all actions for installing beacons one hour after mixing the mortar, until it begins to set.

The use of microfiber instead of reinforcement

A rather thick concrete layer needs reinforcement. Usually it was a metal mesh, tritely laid on the floor. I hope those who want to learn how to properly and reliably make a concrete screed on a wooden base have not forgotten that it is important to maintain the integrity of the separating insulation layer. Agree, it would be difficult to move on a metal mesh, and even work, without catching and not making a hole in polyethylene.

Recall that the reinforcement generally should not reinforce only the “bottom” of the alignment layer. Its place is in the body of concrete, and in order to achieve the correct location, it would be necessary to pour the screed in at least two steps:

first layer first;
then laying the grid with the installation of beacons and final pouring.

Those who are in the know and know perfectly well how long each layer of concrete screed will dry, this option must have puzzled. Between the first stages and the second it is necessary to withstand almost a month (28 days), and the same amount upon completion of all work.

In order not to turn floor leveling into a long-term epic, it is better to use fiberglass for strengthening. They are introduced into the concrete mixture during the preparation period. The random arrangement of polymer fibers will provide strong bonds in all possible directions. In addition, the mass of a heavy screed will be significantly reduced due to the rejection of traditional heavy fittings.

Direct pouring of concrete

It is carried out according to the traditional technological scheme. Depending on the area of the forthcoming leveling, the mixture is filled with:

or in turn each room, separated from the adjacent room by a kind of formwork - a partition from the board;
or the entire area with the start of work from the wall opposite the front door.

A day after leveling on the lighthouses, these rails must be removed. Treat the furrows remaining from the profiles with soil, fill with mortar and level with a trowel.

The rules for maintaining a concrete screed and cement-sand leveling are similar. A day after pouring, the screed is abundantly moistened, then sprinkled with water daily for another week. For four days, a fresh concrete floor must be covered with polyethylene so that the screed is evenly parted with moisture throughout its entire capacity. It is necessary to ensure the stability and uniformity of the temperature background and the percentage of moisture in the air.

PCI Periplan Ready Leveling Video

It is worth getting acquainted with the technological intricacies both for those who independently take on the difficult task of arranging a screed with concrete mortar, and for those who decide to turn to builders. The result of non-compliance with the rules is the inevitable costly rework.

Many of us know that a dry screed can be laid on a wooden floor. Sometimes even experienced builders do not advise making a wet screed of cement-sand mortar or concrete on a wooden base. But residents of apartments and houses with jogged floors should not give up tiles on the floor or floor heating systems. There are special technologies that allow you to arrange a wet screed on a wooden base.

Wooden base features

Despite the abundance of advantages, wood has one significant drawback - it continues to live its own life even after being used in a certain design. As a result, wooden elements are susceptible to all kinds of changes under the influence of moisture and temperature changes. They can shrink, swell, or warp.

Important: it is precisely because of the non-static nature of wood that the installation of a concrete screed on a freshly laid wooden floor is strictly prohibited.

Even after a few years, the wooden floor elements continue to move, warp and shrink. Underfloor heating systems made of wood cause characteristic structural changes with each temperature difference.

Concrete screed behaves quite differently. It is prone to deformation and shrinkage only during the solidification of the mixture. In the future, no special changes to the leveling layer occur. Rigid adhesion of movable living wood to a stable screed would lead to cracking and damage to the latter. That is why the non-bonded screed technology was invented, allowing each layer to "live by its own laws".

The nuances of the screed device

The essence of the method is that for a screed device on a wooden floor, it is necessary to isolate each layer. To this end, the concrete screed is separated:

from the walls of the room with a damper tape;
from a wooden base with insulating material.

As insulation, you can use polyethylene film, glassine, roofing material, bituminous mastic or modern roll materials. However, preference is given to polyethylene film. Despite the fact that it creates a greenhouse effect for a wooden base, the film has a number of beneficial advantages for a concrete screed:

a smooth surface does not cause adhesion of the insulating layer to concrete;
concrete unattached to the film will not pull it along and tear during shrinkage or deformation;
the integrity of the insulating layer will not give the wooden base the ability to draw moisture from the hardening concrete;
a whole film will prevent the further cured screed from absorbing moisture from the wood, which can lead to cracks in the concrete floor.

Important: in order to negate the negative greenhouse effect of a plastic film on wood, all wooden base elements must be treated with an antiseptic and a water-repellent primer.

Technology

If you decide to make a screed on the floor along the logs with your own hands, then you should thoroughly understand the process of its device, which consists of several stages. A more visual installation guide in the video at the end of the article.

Preparatory stage

At this point, we need to do the following:

All boards must be removed and inspected. Rotten, damaged or cracked elements should be replaced.
We also examine the lags. We replace unreliable beams with new ones.

Tip: pay attention to step lag. If it is more than 40 cm, then it is better to install additional beams to increase the bearing capacity of the floor.

Install the floorboards. Boards with an uneven, damaged surface can be turned upside down.
All gaps between the boards are carefully sealed with sealant.
After the expiration of the curing period indicated on the packaging with the sealant, you can begin to treat the floor with a moisture-resistant primer. Give time for the primer to harden.
Using a laser device, we mark the level of the clean floor on the walls of the room.

Attention: when determining the height of the screed, please note that each centimeter of the thickness of the concrete layer presses on a wooden floor weighing 100-120 kg. Therefore, if it is necessary to perform a high screed, it is worth further strengthening the logs or replacing them with metal beams, for example, from a channel.

Insulation laying

At this stage, you need to make something, like a trough, from waterproof insulating material for pouring concrete. To do this, we do the following:

First of all, we attach a damper tape along the perimeter of the room to the bottom of the walls. You can use a special strip, a regular board or a strip of expanded polystyrene. The tape can be attached with double-sided tape or with a stapler. The optimal thickness of the strip is 1-2 cm, and its height should be a couple of centimeters higher than the height of the screed. This element is needed not only for deformation movements of the screed, but also as a soundproof barrier. After laying the front layer, the protruding parts of the tape can be cut off.
Now it's the turn to lay the plastic film. Adjacent strips of the film should overlap each other by 10 cm. The joints of the film are sealed with adhesive tape. Also, the insulating layer must be wrapped on the walls of the room to a height of 15-20 cm. As a result, you will get a waterproof trough made of insulating material, on which you can safely pour the screed.

Attention: Under no circumstances should there be holes, cuts or punctures in the insulating material. If they appear in the course of the work, they should immediately be sealed with polyethylene patches.

Installation of beacons

It is strictly forbidden to fasten guide beacons with self-tapping screws or nails to the floor. It is best to lay them on cakes or mortar beds. From the walls, extreme beacons are installed at a distance of 20 cm (see video). And the step of the guides relative to each other is 1-1.2 m, but not more than the length of the rule.

As beacons, it is better to use guide profiles for drywall. The arrangement of beacons on the beds from the solution will facilitate their alignment with the level of the clean floor. The lighthouse can be drowned deeper into the solution or raised higher by adding more mixtures, thereby achieving the desired mark (see video).

Tip: if you do everything with your own hands, then keep in mind that after preparing the solution, it is better to lay the beacons within an hour.

Screed reinforcement

The device of a floating screed on a wooden floor along the logs requires additional reinforcement, especially if the layer height is more than 5 cm. Usually, the reinforcement of the screed is done using a metal mesh made of wire or reinforcement. But in the case of floors along the logs, it is better to use a lighter material that will not additionally load the screed. In addition, the metal mesh can easily break the insulating layer during pouring. That is why the ideal reinforcement on a wooden base will be fiber.

The fiber is added to the solution during its mixing. This method of reinforcement is suitable for doing it yourself. Fiber fibers randomly located in the screed ensure the strength of the layer in different directions.

Pouring concrete mixture

Regardless of how the mixture will be poured, with your own hands or with the help of hired workers, leveling is done in one of two ways:

If laying will be carried out over a large area, then it should be divided into separate sections (cards) using formwork and pour the mixture according to the cards. At the same time, it is allowed to take breaks in work when pouring individual sections.
If the room is small, then pouring can be done at a time, starting from the corner of the room farthest from the entrance. In this case, it is not allowed to take breaks in work, so it is better to fill with your own hands with an assistant. While one pours and levels the mixture, the other prepares a new portion.

Laying the solution is carried out as follows:

We spread a portion of the mixture between the beacons just above their level and level it with the rule. To do this, we lay the tool on the guides and pull it from side to side, leveling the mixture.
A day after laying the mixture, the beacons can be removed from the solution, and the recesses from them are treated with a primer and filled with fresh mortar. The top is leveled with a trowel.
The surface of the screed must be sprinkled with water for the first seven days and covered with plastic wrap for the first four days to evenly evaporate moisture. Equally important is the constant humidity and temperature in the room.

Wooden floors, if the right materials are used for their installation and if they are properly installed, can maintain their strength and stability for decades. Sometimes the question arises of laying concrete screeds directly on such floors. Why is there such a need? They think about a concrete screed in cases where they strive to perfectly level the floor in order to lay some kind of coating on it (ceramic tiles, a layer of polymeric materials). The same method is used when a complete wooden floor is too expensive.

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 is that it does not have static nature: even after the construction is completed, the wooden elements continue to “live” guided only by their own laws. Changes in humidity and temperature conditions cause:

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

This feature of the tree determined the rule that builders involved in the construction of wooden structures are always guided by: fine finishing of log cabins should be carried out no earlier than two years after their construction. As applied to our topic, this rule should be interpreted as follows:

It is strictly forbidden to pour concrete mortar on a new concrete floor. Concrete screed can be laid only after 3-4 years after the completion of the floor installation.

The mobility of wooden floor structures increases when any heating systems are laid under them. Each start-up and shutdown of such a system will cause them to move slightly.

If we compare the mobility of wooden structures with the mobility of a 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 concrete ends, the dimensions of the monolith practically do not change. Such a difference in the behavior of wood and concrete in the event of their tight contact can cause cracks in the screed. Moreover, in such a case, it may even crumble completely.

The leveling technology produced without connection with walls and with a wooden floor, which we will discuss below, allows each of the elements - floor boards and screed concrete - to exist, obeying only its own principles and without harming its neighbor.

Materials required for 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 must be remembered that the mass of the fill must be sufficient to guarantee the tightness of the junction of the screed to the boards. However, the large weight of the concrete used can cause subsidence of the floor, bending, and then the destruction of the laid screed.

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

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

cement and the required amount of plasticizers;
the film needed to separate the concrete from the surface of the 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 on 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 amount, at least 15% should be added to the area of the room.

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

spatula with which putty and sealant will be applied to the floor;
hammer and screwdriver to strengthen the floor with nails or self-tapping screws.

Preparing the surface of wooden floors

A concrete screed can be applied to the floor only if its surface is completely ready for this. When preparing it, you should carefully examine each floorboard to make sure that they are free of rot and cracks. All boards must be securely fastened, there should be no gaps between them. Boards with major damage are removed and replaced with new ones. If it becomes necessary to interrupt the floor, then the nail heads should be recessed. The resulting recesses must be carefully puttied.

When preparing the floor surface, you must:

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

when the primer dries, roll out the film with an overlap, so that it goes fifteen centimeters onto the plane of the walls. Excess film must be cut off. Fixing the film, if necessary, should be done with adhesive tape. The use of nails to fix it is unacceptable. To achieve a better result, a reinforcing mesh can be laid on top of the film.

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

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

Rack beacons are fixed directly on the film covering the floor with the help of concrete, the distance between which should not exceed the dimensions of the rules used when leveling the concrete solution.

Concrete screed and the process of pouring it

Pouring is preceded by the manufacture of concrete mix. For its preparation, 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. For mixing, you can use a large plastic container and a drill with a mixing attachment. After mixing the solution, it is necessary 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 / m 2. Pouring the solution should be done, focusing on the beacons. Filling the entire floor must be done at the same time. Partitioning is not allowed. During the pouring process, air bubbles present there must be removed from the cement mortar using a spiked roller. Leveling the mixture poured onto the floor so that the concrete screed is even is carried out using a wide spatula or rule.

The techniques for leveling the screed on wood and concrete floors are similar, so the following video can be used to learn more about the techniques used:

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

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