Replacing wooden floors with screed. Self-leveling floors and wooden base Screed technology for wooden floors

Quite rarely, plank floors are leveled using. Experts believe that it is not very rational to burden a wooden covering with a heavy concrete slab. In addition, the wood base and the cement layer do not coexist very well, both during the process of pouring and hardening, and during operation. Many professionals prefer other leveling schemes over pouring - dry ones. However, there are many who want to make an underground floor in a wooden house, or lay it in the kitchen and hallway - in such and similar cases, arranging a concrete floor on a wood base helps out. 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 lying motionless will not crack or begin to crumble due to changes in the configuration of the rough base.

Features of installing a concrete floor in a house: using film

Scheme of a concrete screed on a wooden floor

A reasonable question arises: why polyethylene film? It is not so favorable for proximity to a rather capricious tree, it contributes. Moreover, in wooden buildings it is successfully replaced with glassine, bitumen 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 sinkholes;
• the cement leveling layer being poured will not pull on the polyethylene, will not stretch or tear it;
• after hardening, the concrete will not gradually begin to absorb moisture from the wood, contributing to the formation of cracks in the wood.

Important necessary precautions for those who decide to tackle concrete floors in their home with their own hands. You will have to treat all wooden parts of the structure, even before starting work, with the water-repellent primer “Aquastop”. This way you can minimize the negative impact of polyethylene on wood and reliably protect the base.

Floating screed: installing a concrete floor in a house

We have examined the principle of the technology; now let us dwell on the progress of work and their order:

• it is necessary to remove the flooring boards and carry out a thorough inspection;
• all unusable logs, unreliable and not inspiring confidence, must be removed and replaced;
• if the load-bearing capacity of all joists turns out to be insufficient for the planned load, then they must be strengthened with additional beams. 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 sealant.

We mark the zero level on the walls, at a height convenient for you. It is determined using a meter.

Concrete screed - reinforced

The height is chosen arbitrarily; it can range 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, if 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 thickness 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 wooden covering weighing about 120 kg. Without proper reinforcement of the joists, their wooden structure is not able to withstand such a mass. The logs must either be securely reinforced or (if possible) replaced with a metal channel.

Pouring a concrete floor: insulation installation

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

Floor insulation diagram

• A fence made of foam polystyrene is constructed along the perimeter of the room, along all four walls. A tape of this material is attached with tape or a stapler (the first is better). Its thickness is 1-2 centimeters, and its width should be greater than the capacity of the future screed. In addition to acting as a barrier, this part can neutralize sound vibrations. Also, with its help, the floating slab will be able to lengthen and expand a little. When the finishing coating is laid, the excess that comes to the surface is cut off, and these places are covered with a plinth or its substitute.
• A layer of polyethylene film is laid with an overlap of 10 cm and overlapping the walls by 15-20 cm.

What is extremely important? The presence of holes, folds, slits and tears is strictly prohibited in waterproofing. Work should be carried out carefully, trying not to pierce or tear the layer of waterproofing material. If any gaps do appear, they should be covered with patches made of the same material.

It is best when the layer of polyethylene film does not have any joints at all. If this does not work, then all existing joints, with inevitable overlaps, must be securely taped.

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

Beacons for leveling concrete floors in a private house

Beacons for concrete screed - for a flat floor

Performing this task requires special care and accuracy. Do not use metal nails or screws. It is most convenient to form special beds over the entire surface to be developed. They are made from the same solution, the same consistency and composition as the planned screed. A heavy strip of mortar will prevent the film from lifting and creasing when the master walks, since it will be pressed tightly to the base.

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

It is placed on the tops of the ridges made, and slightly sunk in the solution to a pre-marked height (leveling level).

It is advisable to carry out all the necessary measures for installing beacons within an hour after the start of preparing the cement mass, since later it will begin to set.

Screed in a wooden house: reinforcement or microfiber?

Reinforcing mesh for floor

A thick cement pad, which is a 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 quite difficult to move on a rigid film lying on a polyethylene film without tearing the latter.

Let us also draw attention to the fact that the reinforcement is intended to strengthen not only the very bottom of the concrete layer.

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

• initial layer;
• laying the mesh, placing beacons, finishing filling.

Those knowledgeable about the performance characteristics of concrete probably have a good idea of ​​how long each individual layer of such a screed takes to dry. Between these two steps you will have to wait at least 28 days, that's 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. During the preparation of 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 is that the already heavy screed will be noticeably lighter, because the fiber weighs several times less than the reinforcement.

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

Let’s say right away that concrete screed on a wooden floor is a completely feasible task, but here, as in any other matter, there are specific issues.

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 after installation work is completed, it “behaves” according to its own laws, peculiar only to it. Changes in temperature and humidity cause lumber to shrink, increase/decrease in volume, stretch or contract. By the way, it is for this reason that after the construction of the log house, finishing is carried out about 2 years later.

But even after a two-year period of shrinkage, wooden structures are still moving, albeit not as intensely. 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 when hydrated, and after complete hardening it hardly moves at all.

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

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) distinctive feature is that during pouring the base is not connected to the walls.

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

Design features of plank floors

It is hardly advisable to pour a screed on a floor equipped with joists and a floor slab. Such floors often have a thickness of approximately 7-7.8 cm, and the only correct solution in this case may be to dismantle all wooden elements and then pour them over the floor slab. It’s another matter 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 made of two layers of roofing material; 3 – lower trim; 4 – top trim; 5 – external cladding with tongue and groove boards; b – plate made of non-ferrous metal with holes; 7- outer wall made of boards; 8 – plaster; 9 – plinth; 10 – plank floor; 11 – logs; 12 – brick column; 13 – antiseptic wooden lining; 14 – underground
1 – compacted sand; 2 – concrete preparation; 3 – waterproofing from roll materials; 4 – brick column; 5 – wooden antiseptic lining; c – cladding made of antiseptic boards; 7 – intermediate plank flooring: 8 – thermal insulation; 9 – air gap; 10 – floor; 11 – load-bearing beam

It is precisely such structures that are often filled with screed.

Pouring technology

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

This creates a floating floor without connections to any surface. As a result, all lumber elements continue to move in one direction or another, and the screed, which simply lies on top, does not become covered with cracks from permanent changes in the position of the boardwalk.

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

SNiP 2.03.13-88. Floors. File for download

SNiP 3.04.01-87. Insulating and finishing coatings. File for download

On the feasibility of using polyethylene

Direct contact with plastic film is known to have a negative effect on wood and leads to the growth of fungus and mold.

That is why, instead of film in wooden structures, roofing felt, bitumen-based mastic, glassine, or roll waterproofing with bitumen 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 insulating boundary;
• the screed will not draw moisture from the wood, leading to cracks;
• When moving, the screed will not pull the film, stretch it or tear it.

Important information! Before starting work, care should be taken to minimize the negative consequences of contact of lumber with polyethylene. To do this, all wooden elements must be treated with an antiseptic and the 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 mixture, a thickness of 1 cm is obtained. Even if the required amount of materials is known, you still need to buy them with a 10% margin.

Table. Dry cement mixtures - cost

Name	Manufacturer	Package	Price
	"VOS Mixtures"	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 RUR
	Manufacturer: Ceresit	Bag, 25 kg	160 rub.

Stage two. Preparing the base

Having understood the technology and calculated the required amount of mixture, you can start working directly. Traditionally, you should start by preparing the base.

Step 1. First, the boardwalk is dismantled and a thorough inspection of all elements is carried out. Lags are checked. If any of them are unsuitable for further use, 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. The boards, if they are still usable, are nailed back together. If slightly damaged floorboards are found, they should be turned over.

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

Step 4. The baseboards are removed and thin boards are installed instead (the latter should cover the cracks in 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 and prevent it from rotting.

Important information! You also need to seal all the cracks. If they are small, you can fill them with sealant, but large cracks are better sealed with foam.

Instead of sealant, you can use parquet putty made from wood dust, or a homemade 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, thoroughly vacuum the substrate to remove dust and debris. Sanding can be done if desired, although this is not necessary.

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. The primer will also serve as additional protection for the wood from mold and mildew.

Prices for primer for concrete floors

primer for concrete floor

Stage four. Marking

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 surface of the base. It is necessary to mark several points of the zero horizontal on each of the walls.

Equal distances are laid down from these points, and 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. Moreover, every centimeter of such a floor will create a load on the plank base of 100-110 kg per square meter. It is for this reason that it is advisable to strengthen the logs, although if possible it is generally better to install metal channels instead of them.

Stage five. Waterproofing

Further actions involve insulating the 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 slab. Scotch tape is used for fastening.

Important information! Upon completion of the finishing of the floor, the excess tape protruding on the surface will be cut off, and the resulting gap will be covered with a plinth.

Important information! There should be no folds or damage to the waterproofing layer. Subsequent steps must be performed with extreme caution so as not to tear or puncture the film. If this cannot be avoided, the holes must be immediately covered with polyethylene patches.

Step 3. Ideally, the waterproofing layer should have no joints at all. If there are joints, then they are all firmly taped with tape. The further operation of the leveling layer will largely depend on the tightness of the waterproofing.

Prices for edge tape

edge tape

Stage six. Reinforcement

If the concrete layer is thick enough, it must be reinforced. There are several methods of reinforcement; only the most common ones are discussed 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 around the fittings without compromising the integrity of the insulation. In addition, the film, as noted above, must be in direct contact with the concrete, so the mesh must be located in the body of the screed.

For this reason, concrete is poured in two layers:

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

It would seem nothing complicated, but the concrete layer will take a long time to dry - the break between layers can be up to 1 month. Therefore, it is better to resort to the second method.

Method No. 2. Fiber fiber

The next reinforcement method involves adding fiberglass directly to the concrete mixture during the preparation stage. 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 be noticeably reduced due to the elimination of metal mesh. Further actions are focused on using this particular method.

Fiber fiber prices

fiber fiber

Stage seven. Installation of leveling

Lighthouses need to be built especially carefully; there can be no talk of any screws or nails. The foundations for future “beds” are made from the same mortar 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 be 10-15 cm shorter than the length of the rule (often about 120 cm). The distance between the wall surfaces and the outer “beds” should be 25-30 cm.

The metal profile is laid on the tops of the “beds” and heated in the solution so that the previously noted height (level of the leveling layer) is reached. The installation of the beacons must be completed a maximum of an hour after mixing the solution, otherwise it will set.

Stage eight. Mixing the solution

The mixture for concrete screed can be purchased ready-made or made independently. Factory-made 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 attachment; the finished mixture should be used for a maximum of 15 minutes.

To prepare the solution yourself, 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 prepared solution should 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 packaging). Although there is a cheaper alternative to 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 using a trowel.

Video - Screed on a wooden floor

Further care of the screed

The care requirements are the same for both ready-made dry screed and homemade cement-sand mortar. The next day after pouring, the screed is moistened, and the procedure is repeated daily for one week. For the first four days, the concrete should be covered with plastic film so that moisture evaporates evenly from the screed.

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

Currently, in repair work, factory-prepared mixtures are increasingly used, which make it possible to quickly and efficiently level floor coverings of any type. Self-leveling flooring on a wooden base is one of the flooring methods that is especially popular.

The main advantages are durability, wear resistance, strength and ease of installation. In addition, materials are available in a wide range, there are even options with 3D images.

What to look for when choosing a material

First of all, you need to carefully examine the packaging. All manufacturers indicate exactly what this or that composition is suitable for. To make a self-leveling floor in a wooden house, you need to choose materials with the appropriate marks; universal compositions are also suitable. But if the packaging indicates that the solution is suitable for concrete or anhydrite screeds, then it cannot be used for wood.

When choosing a composition, you should pay attention to the purpose - only universal or special mixtures are suitable for a wooden base

It is important to remember that self-leveling wood floors are poured with a layer of 3 to 7 centimeters, so it is not advisable to buy expensive gypsum mixtures that are designed for a layer of about 0.2–2.5 cm. It is recommended to use cement or gypsum-cement mortars. To decide on the type, you need to read the composition. The first substance is the one that is contained the most.

In addition to the material, it is necessary to purchase polyethylene film, which will serve as waterproofing. In rare cases, coating waterproofing can be used instead of polyethylene. You will also need damper tape.

Base requirements

It should be noted that self-leveling floors cannot be applied to every surface. The base must meet the following requirements:

1. Floors should not creak.
2. The boards are securely fastened and do not sag while walking.
3. The flooring has a slight sag.
4. There are no serious defects on the surface: large cracks, holes, and so on.
5. Each board must be intact, without traces of fungus and mold.

It is not necessary that the base be smooth, the main thing is good quality of the board, absence of squeaks and solidity

If any of the listed defects are found, part of the floor or the entire surface will have to be replaced.

Preparatory work

Self-leveling floors can be laid on a wooden floor only if the base is properly prepared. The duration of use of the coating, its appearance and performance indicators depend on this stage.

Immediately before starting work, you need to check the air temperature and humidity level. The required parameters are indicated by the manufacturer on the packaging. Compliance with these requirements is the key to successful completion of work.

Preparation of bulk solution

You need to take a clean, dry container and pour water into it at a temperature of +5 to +25 °C. Then add the mixture and mix with a construction mixer or drill with an appropriate attachment for 7 minutes. After this, you need to let the solution sit for about 15 minutes and repeat the procedure. It is better not to prepare the composition in large portions, since it begins to set on average after half an hour.

Attention! It is necessary to strictly follow the proportions specified by the manufacturer. If you add too little water, the mixture will dry out too quickly, possibly even while pouring. Otherwise, the finished coating will be less durable.

Preparation of bulk mixtures is carried out exclusively using a construction mixer or mixing attachment

Pouring technology

The method of pouring floors in a private house or apartment using leveling compounds is practically no different from working with a cement-sand mixture, only self-leveling floors dry out faster.

You need to start from a place that is located lowest in level. The material is poured from the container into the space between the beacons and leveled with a rule, passing it along the beacons. After this, you need to roll the area with a needle roller. Process all stripes in this manner.

When the material begins to set, it is necessary to remove the beacons from it. The resulting grooves should be filled with the same solution and leveled taking into account the finished surface, which will serve as a level. It is recommended to begin further finishing no earlier than a week later.

To ensure that the repair results are not disappointing, you must follow the recommendations:

To install self-leveling floors on wooden bases, you must follow the above rules and recommendations given by manufacturers on the packaging. In addition, it is important to remember that the material dries quite quickly, so it is better to work with a partner.

By choosing a wooden house on stilts, the owner receives a lightweight, inexpensive, environmentally friendly structure, the construction of which is carried out in the shortest possible time. Piles leave empty space under the floor, allowing air to circulate, which prevents wood from rotting and extends the overall life of the structure.

But the design also has a negative feature: during the cold season, the heat loss of the house through the floor increases significantly, which reduces the comfort of residents and increases the cost of maintaining a certain temperature inside. The best way to get rid of the problem would be a “warm water floor” installed in a wooden house on stilts.

Purpose of screed equipment

There is one requirement for buildings of this type: a lightweight structure is not capable of supporting a massive foundation, so the arrangement of the screed should be approached with the utmost responsibility. It consists of three layers, each of which performs a specific function:

• The bottom layer is applied to the “rough” floor, allowing you to level the base. If a level check reveals a slope between two walls exceeding 5 mm, then it is necessary to fill it. This will facilitate the circulation of water in the heating system, reduce the load on the pump, and extend the service life of the mechanism.
• The second layer is needed for thermal insulation so that the house installed on the piles does not freeze, which will significantly reduce its heat loss and reduce the running costs of maintaining a certain temperature in the rooms. The thickness of the insulating material is selected based on the average annual temperature in the region during the cold season.
• The top layer covers the coolant pipes, protecting them from damage, and at the same time plays the role of a stone furnace. When heated, concrete retains the temperature for a long time, transferring it into the room, which reduces the cost of maintaining the temperature in the room.

A properly equipped floor screed in a wooden house under a “warm floor” will extend the life of the building and increase the comfort of the residents.

Existing types of screeds

Currently, three types of screeds are used, which are divided depending on the amount of water in the solution:

• Liquid or wet. They are most widespread due to their ease of installation and high functional and strength characteristics.
• Semi-dry. The percentage of moisture is kept at an average level. By reducing moisture, the time for drying and putting the “warm floor” into operation is reduced.
• Dry. Fine-grained expanded clay, quartz sand or fine-grained slag are used as fillers. A slab of fiberboard, plasterboard or waterproof plywood is laid on the heating pipes. The surface is leveled using putty, and after drying it is filled with a layer of bitumen, which serves for waterproofing.

“Warm water floors” on wooden joists in a private house are laid using one of these technologies. The choice of a particular method depends on the budget, time available and the structural features of the building.

"Floating" screed for private houses

In a house on a pile foundation, two types of screed are used to install a horizontal heating system: a “floating” screed and a wooden deck.

The first option is highly reliable and durable, but its weight will be at least 100 kg per square meter, so before installation you must make sure that the structure of the building can support it.

A layer of waterproofing, usually polyethylene, is laid on the leveled “rough” base. It performs a double function: it protects the wood from moisture and subsequent rotting, and is a separator between the screed and the base on which it is laid. To ensure reliable protection from moisture, the film is taken with a small margin, approximately 15 cm, on each wall, where it is secured with mounting tape, which will ensure tightness. If the polyethylene layer consists of several parts and is laid overlapping, then the joints are also glued.

The insulation is installed next. In this regard, the best options would be rolled, soft materials or polystyrene foam boards, which provide high protection against freezing.

This method of making a “warm floor” screed in a wooden house on stilts involves laying a damper tape around the perimeter of the room where the pouring takes place. Wood is not static, and under the influence of temperature, small movements of the building structure will occur; the tape will level out these fluctuations and protect the screed from destruction. It is important to remember that in a room whose area exceeds 40 m2, several heating circuits are installed; they also need to be separated by a layer of damper tape.

Tip: It is advisable to add a plasticizer to the cement screed mortar. To do this, you can take PVA construction glue at the rate of 1 kg of glue per bag of cement.

To ensure the solidity of the structure and secure utility lines, a reinforcing mesh is laid on the thermal insulation layer. Heating pipes are fixed to it using clamps or special fasteners, maintaining the required distance between turns, so that they do not change their position during the process of pouring concrete.

The last step will be pouring the cement mortar. Its thickness should be within 5-7 cm so that during the heating process the slab does not burst and “cold bridges” do not appear in the cracks formed.

The floating screed does not have a strong adhesion to the base and is separated from the walls by a damper tape, so during natural movements of the structure of a wooden house it will retain its integrity.

Heating system mounted on a wooden base

Let's look at how to lay a water-heated floor on wooden logs. The work is carried out in several stages:

• The subfloor is leveled until the difference between the edges of the site is eliminated.
• The first layer of polyethylene is laid for waterproofing.
• The second layer is foil polystyrene foam. It will provide the required level of insulation, and the foil prevents the spread of heat downwards, concentrating it in the upper part of the “pie”.
• Next, a wooden frame for the heating circuit is assembled. Gutters are cut into it where the pipes will be laid.
• The communications are covered with a layer of galvanized metal or aluminum plates, which will allow the heat to be evenly distributed over the entire surface.
• The last sheets of plywood or OSB are laid on which the final floor covering is mounted.

Another option is to install a “warm floor” in a private house between the joists:

• Skull blocks are attached to the side surface of the logs with self-tapping screws, which will become the load-bearing base.
• Sheets of moisture-resistant plywood are laid on the bars, which are covered with a layer of polyethylene with a slight overlap on the logs.
• A layer of expanded polystyrene is used for thermal insulation. Its thickness should be selected so as to coincide with the top edge of the joists.
• The structure is covered with a layer of vapor barrier film, the area of ​​which should exceed the size of the room by 10-15 cm on each side.
• Next, a reinforcing mesh is placed, which needs to be filled with a thin layer of cement mortar. A layer of foil-covered insulating material is mounted on it, which acts as a heat reflector into the upper part of the structure.
• Heating pipes are laid in increments of 10 or 15 cm.
• A screed 3-5 cm thick is poured and covered with a finishing coating.

We get a water “warm floor” in a wooden house with a screed on a multi-layer “pie” slab, which is lightweight but retains its strength characteristics.

Tip: In low rooms where the thickness of the concrete screed does not exceed 3 cm, it is recommended to use a layer of self-leveling mixture. This will increase the strength of the structure.

Tiles as flooring

The physical characteristics of wood do not allow it to adequately retain the heat received from the heating system, so the best flooring option for horizontal water heating is tiles made of natural or artificial stone.

To obtain an independent screed for “warm floors” for laying tiles on wooden beams in a private house, the following work must be done:

• A “floating” screed is installed using the technology described earlier. The only exception is the thickness of the concrete solution. It should be 3-4 cm.
• After the screed has completely hardened, it is treated with a soil solution.
• Next, the floor covering is installed using tile adhesive.

Despite the possibility of installing tiled flooring on wooden joists, this technique has a significant disadvantage: the service life of wood is lower than that of porcelain stoneware and other tiled materials. To replace wooden blocks that have become unusable, you will have to carry out serious dismantling of the floor covering.

The advantages include:

• Significant cost savings due to lower wood costs.
• The total weight of the floor “pie” and the load on the supporting structure are reduced.
• Installation speed increases.
• The heating system is put into operation faster due to faster drying of the thin layer of concrete.

Despite some limitations, tiling a bathroom, swimming pool and other rooms with high humidity, together with a “warm floor” system, can significantly increase comfort and increase the durability of wooden structural elements.

Screed is an indispensable attribute of underfloor heating. It protects pipes from load and mechanical damage, allows you to obtain a perfectly flat surface of the floor covering, which has a beneficial effect on the comfort of residents. Its only drawback is that installing the screed “raises” the floor level, reducing the total volume of the room. If in rooms with high ceilings this will not have a significant effect, then in low ceilings it may interfere a little.

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 plasterboard, 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 a monolithic slab that is not subject to linear changes. And wood has the ability to expand or dry out under the influence of humidity and temperature changes. The screed connected to the base, under the influence of unstable wooden structures, will become cracked 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:

1. Large cracks and junctions with walls are sealed with epoxy putty or polyurethane foam. After hardening, excess sealant is cut off and unevenness is sanded.
2. We clean the floor surface from debris and dust and treat it with an antiseptic and then with a primer twice.
3. 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 the 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.

1. 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.

1. A wet screed installed on a wooden floor must be reinforced. To do this, we lay a steel mesh with a 10x10 cell on the insulated surface. 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.

1. 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.
2. We place guide beacons along the insulating layer, along which the screeds will be aligned. We make them from mortar, in the form of continuous strips, or a steel profile installed on slides of mortar. 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 screeding must be carried out in strict accordance with 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 compressed air pressure, 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, we 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 of 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. The finished solution 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.

Sand the entire screed with a disc sander. 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 a 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 an 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

The screed using wet technology 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 its heaviness, a wet screed requires a rigid and durable base;
• the wet process increases the humidity in the house, which is not desirable for wooden structures;
• with minor damage to the film waterproofing, water from the screed can get onto the 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. Installation of a wet 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, hard mineral slabs or Penoplex can be used as insulation.

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 plasterboard sheets or floor slabs of the KNAUF system over the compacted expanded clay layer.

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 a reliable basis for laying any finished floor covering.

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 the best option for leveling your floor and will carry out the work efficiently, quickly and professionally.