The thickness of the underfloor heating concrete screed. What should be the thickness of the underfloor heating screed

The period of operation of the heating system largely depends on the thickness of the screed over the water-heated floor. This indicator also affects the efficiency, uniformity of heating and other characteristics.

A frankly thin layer will result in uneven heating. As a result, after a few months, or even weeks, the filling will lose its properties and will be unusable. Too large thickness of the underfloor heating screed will force you to spend additional money on heating, because a significant part of the heat will go to warm it up, and not the room.

general information

The optimum screed thickness is determined by several aspects. In particular, the following indicators are taken into account:

features of the room configuration;
type of mixture;
the purpose of the room.

Indoors complex shape or large area it is difficult to lay pipes for a warm water floor so that they provide uniform heating. Sometimes you have to leave between them long distance, therefore, the thickness of the screed must be increased by 30-60% from the standard.

Mixes intended for underfloor heating have good deformation resistance and thermal conductivity than mortar or self-leveling screeds. The layer of special screed can be 20-40% less.

Premises that are not intended for residential use can be heated unevenly (if there is no risk of damage to the screed due to thermal expansion). In such cases, you can save on the amount of mortar or mixture and lay the screed with a smaller thickness.

Minimum and maximum rates

The maximum diameter of pipes used for this purpose does not exceed 25 mm. Accordingly, a 5 cm thick fill will be enough. But, we must remember that during the operation of the floor, heat is generated and, as a result, the concrete part, along with finishing will begin to expand. That is, the thickness must be such as to prevent the possibility of deformation of the topcoat.

If it comes about an ordinary residential building, the load is calculated at 2 kN per square meter. Accordingly, the minimum permissible thickness screeds above the warm floor - 4.5 cm. The use of a reinforcing structure with a diameter of 0.3 cm and cells of 10 * 10 cm - the ability to reduce this figure to 2.5-3 centimeters.

The use of such a reinforcing mesh allows you to reduce the distance from the pipes to the screed surface.

Be sure to follow the rules

The thickness of the screed for a warm water or electric floor in an apartment is calculated separately for each case, since this value depends on specific conditions. Masters recommend choosing materials responsibly and focusing the attention of beginners: a large layer does not mean that the surface will be of high quality. Experts advise performing a rough fill, but an alternative option would be to have a modern reinforced slab.

Screed thickness over warm floors- an important point in the arrangement engineering communications... To get the most out of heating and to provide optimum strength under external mechanical stress, the parameters of the base must be calculated correctly.

Sanitary standards indicate the thickness of the mortar layer for the formation of a regular floor - it is 40 mm. With low permeability, a decrease in the pouring height is permissible. But when arranging structures with heating, they are in demand modern materials are going complex circuits so the values are calculated individually.

The thin floor screed is easily damaged: too fast heating and abrupt cooling contribute to the formation of a "cobweb". And the load from constant movements, pressure of furniture will accelerate the process of destruction of the coating.

Warming up a thick layer is problematic, therefore, the meaning of operating the system is lost, and the risk of segment failure increases. And non-observance of technologies leads to quick cracking of the surface.

For the equipment of the underfloor heating screed, several preliminary layers are mounted:

Rough screed over the cleaned surface (it can be replaced by a strong floor slab).
Insulation (its approximate thickness is 1 cm).
For hardening, you can use reinforcing mesh up to 10 mm thick.
Further is laid metal-plastic pipe... Or an electrical system is being installed.

The final layer is possible from any suitable material with a thickness of 30 to 70 mm. A decorative finishing coating is laid on top. Determining the required values is difficult for every novice craftsman.

Minimum thickness

There is no officially approved value that unambiguously indicates what should be the minimum thickness of the proposed floor screed. State standards are based on the initial 20 mm, not taking into account the use of metal cement. If reinforcement is not provided, professionals indicate a height of at least 40 mm with a standard pipe diameter. The mesh of the reinforcing mesh is 100x100 mm, 150x150 mm. In such dimensions for a floor screed, the material will be suitable for strengthening the structure.

The minimum is not acceptable in places with heavy load (for example, in technical rooms, common corridors, garages). SNiP 3.04.01-87 (the residential sector is considered) when organizing heating piping of pipes calls the lower threshold the common layer in the range of 500-650 mm.

Since the underfloor heating screed slightly expands with linear heating, an expansion joint will be required - around the perimeter of the rooms, a damper (or edge heat shrinkable) tape is glued around the perimeter of the rooms, taking excessive pressure. The width of such an auxiliary material is 10-15 cm. The tape is additional insulation from the adjacent cooled walls.

Above the heating wiring, the floor should rise by about 3-4 cm - this is the answer of the masters to those who work independently for the first time and find out what is the minimum thickness of the floor screed to be installed. So the heat will be perfectly distributed over the surface, the structure will remain strong, and the room will not shrink.

The smallest thickness of dry floor screed is 40-45 mm. At the rate of one bag of expanded clay mixture (50 l) per square meter... Instructions and a description of the technology are attached to the ready-made formulations.

Maximum thickness

The largest screed for a warm floor is determined by the load, on average, the surface should withstand 200-300 kgf / m 2. Maximum thickness not specified in regulatory documents and is determined by engineering calculations. The more massive the layer, the longer the heating will last; you can wait for heat transfer from the inertial system for a day or more.

For apartments, private cottages - 95-100 mm.
For public spaces - up to 200 mm.
For production - 300 mm.

The floor height should be at least 30 mm for the layer to remain strong, and no more than 100 mm in residential buildings, according to the principle of expediency. The organization of the floor on the ground requires additional insulation.

What is the thickness of the screed for a water-heated floor

The starting design moment to determine the thickness of the screed over a warm water floor may be the diameter of the pipes that make up the structure. The most commonly used material is with an inner diameter of 16 mm and a total of 20 mm.

With the optimal thickness of the water floor heating screed, uniform heating is ensured. According to engineering calculations, with a supply temperature of 45-55 ° C, the bottom will warm up to 30 ° C.

You can take a traditional cement mortar, made by yourself, or purchase ready mix, which are presented in specialized departments. For a screed over a water-heated floor, it is necessary to provide for the presence of expansion joints and cushioning stripes even in tiny spaces. Be sure to align finishing layer, carry out a rough screed. Heating engineers emphasize that it is the concrete flooded array that will serve as a large effective radiator.

Warm water floor from traditional concrete mortar will require a screened out sand fraction and cement not lower than the M-300 grade. The recipe is in compliance with the proportions: part of the cement, 3 - of the sand ingredient and water is added in portions to a viscous state. Thickness concrete screed water floor heating is formed from an elastic "paste": craftsmen successfully add a bit of plasticizers to the mixture (suitable liquid soap or a degreaser for washing dishes at the rate of 0.5 liters per square).

Ready mixtures are used in accordance with the manufacturer's instructions. The thickness of the screed for a water-heated floor in a residential building is more than 100 mm - this is a constant overpayment for energy carriers, inertia and losses in the field of energy saving.

Creative experimenters share their findings: expanded clay, EPS (5-7 cm), mesh are laid on a reinforced concrete slab. Then the pipes are laid. And, wondering: what thickness of the screed for a warm water floor should be in this case, consider a value from 65 to 100 mm.

What is the layer of screed for electric underfloor heating

This innovative heating option is universal: accidents with flooding are excluded, the ergonomic cable has a diameter of up to 7 mm. On a warm floor - the conductor is laid with a snake - a rational concrete pouring... Professionals for wiring recommend laying a reinforcing base, and also do not forget about expansion joints with a step of 4-6 mm, and a depth - up to a third of the coating thickness.

The thickness of the screed for electric underfloor heating is determined simply: up to 450 mm above the mounted cables in rooms with medium and low load. The minimum height of the concrete mix above the cable is 30 mm, which is safe and suitable for ordinary bedroom or home bathroom.

If you are reading this article, then you are probably thinking about installing a water-heated floor in your home. Now you are looking for information about what thickness of a water-heated floor is necessary for a warm floor in your home.

In fact, you are probably interested in one of two questions:

the thickness of all layers of a water-heated floor;
screed thickness of a water-heated floor.

We will analyze each question individually. Let's introduce the concept of not the thickness of the water-heated floor, but.

All layers of warm water, connected together, are called a cake of a water-heated floor. It looks like this:

Floor heating cake or the so-called thickness consists of the following elements:

, which is mounted along the edging of the walls and serves to compensate for the expansion of the concrete screed. Its height is 15-20 cm from the rough screed. Its thickness is not taken into account.
, used more often in the form of polystyrene. It serves to cut off the lower layers from heating with warm floors. Thus, you save on heating agent consumption and warm water floors work as they should. The thickness of polystyrene on the ground floor in cold regions should be 10 cm. In regions with temperate climate 5cm thickness will pass. But it’s still better to go overboard than underdo it. Therefore, take as a basis the thickness of 10 cm.
Polyethylene. Installed on thermal insulation to create an additional greenhouse effect. Its thickness in overall measure we will not take into account.
MAK grid. It is mounted on thermal insulation and serves in a convenient way for laying pipes on it. Ideally, its thickness is 4mm.
... Our main peddler of warmth. The height of the 16th pipe is approximately 2cm.
Concrete screed. Today manufacturers recommend for pouring concrete mix brand M-300. From my practice I recommend the brands M-200, 250, 300. The thickness of the screed of a water-heated floor is 5 cm from the top of the pipe! This is exactly what is needed for competent work water underfloor heating.
Finish coating... Parquet or tiles. The thickness of 2cm is taken as a basis.

Screed thickness of water-heated floor

As mentioned above, the thickness of the underfloor heating screed recommended by the manufacturer is about 5 cm. There are, of course, options when the screed is poured for a water underfloor heating and under a thickness of 10 cm. Here the system begins to work on the principle of heat accumulation.

There is no rigid tie in the height of the screed. As practice shows, it is very rarely possible to achieve the recommended values. Therefore, the main thing is that the minimum thickness of the screed over the pipes of the warm floor should be at least 5 cm. The maximum thickness of the screed should not exceed 10 cm. And then the size of the screed will be ideal for the operation of the warm floor.

The building structure will perform its functions flawlessly if preliminary calculations are made without errors. A precisely selected screed thickness for a water-heated floor will provide sufficient strength and even distribution heat on the surface. To determine all the important parameters of the project, a detailed study of technologies, materials, advice from specialized specialists is necessary.

The picture above shows typical scheme screeds of a water-heated floor, which is used in recommendations for the creation of heating systems built into the floor.

In this example, several practical issues should be noted:

An ideal foundation in domestic construction is a rarity. Therefore, it is necessary to eliminate cracks and other defects in floor slabs. To solve the problem, creating a screed with a thickness of 4-6 cm will help.
Fastening of screed pipes of a water-heated floor can be done different ways... Depending on the option chosen, the cost of the project, the speed of implementation and the complexity of the work will change.
One layer of thermal insulation is sufficient, but modern materials must be used to obtain good results.
Experts recommend maintaining the surface temperature of the water-heated floor screed at a level of + 28 ° C to + 30 ° C. But to fulfill this condition, it is necessary to take into account: the laying step, the type of the main screed, the type of topcoat.

From this information, it can be concluded that the thickness of the screed over a water-heated floor depends on many different factors. It cannot be considered separately. It is necessary to agree with other technical parameters of the heating system project.

If the finish coating of a screed of a water-heated floor does not have sufficient strength (linoleum), it is necessary to install an additional layer of plywood under it.

How to determine the main characteristics

To figure out which screed is better for a warm water floor, you need to make a calculation. The table below shows surface temperature data for different options topcoats.

In all variants, the following initial data are accepted:

Pipe type: cross-linked polyethylene, diameter 20 mm, wall thickness 2 mm.
Supply / return water temperature: + 50 ° C / + 40 ° C.
Bottom on reinforced concrete floor Between the floors of the building, 80 mm thick foamed polystyrene insulation is installed.
The height of the main screed of a water-heated floor is 7 cm.

Surface temperature at different types screeds

Heavy concrete filled with granite aggregates
Distance between lines, mm	100	150	200
Linoleum without insulation, ° С	29	28	27
	26	25	25
Ceramic tile, ° С	33	31	30
A mixture of sand and cement
Distance between lines, mm	100	150	200
Linoleum without insulation, ° С	28	27	26
Laminate on a wooden substrate, ° С	26	25	25
Ceramic tile, ° С	31	30	29
Semi-dry building mixture
Distance between lines, mm	100	150	200
Linoleum without insulation, ° С	25	24	23,8
Laminate on a wooden substrate, ° С	24	23,5	23,2
Ceramic tile, ° С	27,3	26	25,5

From the data obtained, it can be seen that the rather popular "dry" building mixtures are the worst option. They are easy to use. But the created screed coating of a water-heated floor will have a low thermal conductivity.

It should be noted not only the first position in the comparative table, but also the high strength of heavy concrete. Fiber fibers can be used in place of gravel and other traditional fillers.

The data in the table also demonstrates how losses change with the installation of different topcoats. Linoleum, laminate, natural parquet do not conduct heat well. Even at high temperatures in the supply line, it will not be possible to approach the ideal surface warmth. The best way – ceramic tile.

This image was taken with a thermal imager. Areas of a screed of a water-heated floor with more high temperature... You can see what happens if the distance between the lines is too large. A similar result will be in the case when the water temperature is insufficient, or the pipes are installed too close to the surface. By moving them lower, you can get an even heat distribution. But this will increase the inertia of the system. We'll have to increase the layer of concrete, reduce the height of the ceilings.

For residential premises, the main screed of a warm floor is from 6 to 8 cm. If it is planned to install a piano, other heavy products, double reinforcement is installed under the corresponding section.

Project preparation

A high-quality water-heated floor consists of the following layers:

Rough screed 5-6 cm thick. It is poured with preliminary installation of a damper tape around the perimeter of the room.
Insulation of a screed of a water-heated floor. It is better to use factory-made foamed polypropylene with a density of 40 kg or more. cubic meters and higher. The greater the thickness, the less heat loss. It is convenient to work if there are special cutouts on the ends of the products. They facilitate precise mating and ensure tightness of the joints.
Above the insulation plates, install plastic wrap(125-150 microns). It prevents the penetration of moisture from the screed. If high-quality polypropylene slabs with locking joints, glued with adhesive tape are used, additional waterproofing is not needed.
The reinforcement not only reinforces the screed. It is convenient to fix pipes on such a frame. Instead of traditional metal, they are starting to use composite and polymer products... They weigh less, are not destroyed by corrosion processes.
To speed up the work, you need to purchase required amount plastic clamps. Apply 3-4 products for each running meter lines.
Where the screed pipe of the water-heated floor passes through the expansion joints, a protective corrugation is put on it.
When the whole structure is assembled, pour on top cement-sand mixture with fillers.
Next, the topcoat is installed.

The structure of the structure is selected taking into account the characteristics of the installation site, the structure itself. It is easier to mount a water heat-insulated floor on a special substrate with protrusions. Corresponding kits are offered with edge and connecting elements. Some mats have infrared reflective layers embedded in the lower parts to increase the efficiency of the heating system.

When choosing a water-heated floor, you need to check it technical specifications according to the manufacturer's accompanying documentation. The numbers in the names do not necessarily indicate density.

Using the data of the selected project, they make a list of necessary things, Supplies, tools. When determining the thickness of the screed, the load capacity of the load-bearing structures of the property must be taken into account. Layer 1 sq. concrete with a thickness of 6-7 cm weighs from 300 to 340 kg.

Performing work operations

The exact sequence of actions depends on what kind of screed for a certain warm water floor is chosen in the end. Nevertheless, the following expert advice will come in handy when reproducing specific technological processes with your own hands.

Before pouring a rough screed of a water-heated floor, it is necessary to install power cables and other engineering lines. The walls and ceiling are leveled with plaster. If you perform work in reverse order you will have to wait until the screed hardens. Next, it will be necessary to clean it from new contaminants.

In the formation of these building structures control the perpendicularity of the corners to ensure the tightness of the joints with the insulation plates. On a well-created surface, differences of more than 5-6 mm in height are not permissible for one contour. This will prevent air jams from forming.

When choosing boards made of expanded polystyrene with sufficient density, special precautions are not required. With this, the products will withstand the weight of an adult without deformation and damage. However, you should check the cleanliness of the shoes, remove potentially harmful contamination from the sole and from the surface. It is better to install ladders from boards for movement. It should not be forgotten that when pouring building mixtures, heavy loads will have to be moved.

With a large screed area of a water-heated floor, it is necessary to install expansion joints for every 20-25 square meters. area. They will prevent cracking when the temperature rises / falls. A tape made of foamed polymer (polyethylene) 100-130 mm wide, 7 to 12 mm thick is suitable. Such elements are installed only in the main screed.

This step comes in handy quality plaster walls (at least up to 40 cm from the floor). Some types of specialized damper tapes are coated with an adhesive layer on one side. They adhere quickly and firmly to flat surfaces.

At the stage of preparing drawings for a screed of a water-heated floor, it is necessary to accurately establish the points of intersection of pipes with expansion joints. They are located only at the intersection of the supply and return lines. On open areas pipelines (from the screed to the collector and vice versa), a heater is installed.

For creating building mixture concrete grades from 150 to 300 are suitable. Such a range is indicated in reference books in order to provide for a different purpose of surfaces. Stronger screeds (M300) are needed in commercial facilities, warehouses, and production halls. In residential and office premises concrete is created from 1 part of cement M150 / 200 and three parts of sand.

Strengthen the composition of the screed of a water-heated floor with fine granite chips. Since it is supposed to function in a mode with a change in temperature, it is necessary to increase the ductility of the screed. Experimenting with PVA and adhesives of other series is not worth it. The corresponding "free recipes" can be found on the Internet, but their real benefits are difficult to confirm.

In order for a screed for a water-heated floor to be reliable, it is necessary to use specialized additives. They are subject to official guarantees. V detailed descriptions manufacturers provide instructions for correct use.

To fill the main screed of a water-heated floor, the following algorithm is used:

Works are performed at an air temperature in the room not lower than 0 ° C.
First, they check the tightness of the system, eliminate the detected leaks. To do this, raise the pressure (up to 4 atm.) For one day. Further - set the nominal pressure (from 1.5 to 2.5 atm.). Check the values with a pressure gauge.
Markings are applied to the walls, indicating the level of the surface of the future layer. To create an even screed, mounds ("lighthouses") of the desired height are created in the room.
To move a long rule, support guides are installed. The device is moved along them, removing surface irregularities.
Pouring the solution begins from the far site, moving towards the entrance. Gas bubbles are removed from it with a rammer. A simple method, repeated blows with a metal rake, is associated with great labor costs. Faster to execute necessary processing a specialized floor vibrator for building mixes will help.
In the course of performing working operations, the height of the screed is checked according to the marks applied to the walls.
The amount of the solution is created such that a portion of the mixture is laid in a few hours, no more. It is necessary to calculate the technology so that one room is completely flooded in a day. To speed up the processes, mixers and other means of mechanization with electric drives should be used. This technique does not have to be purchased. It can be rented.
No later than 3 days later, the guides (beacons) are removed. The screed recesses of the water-heated floor are leveled with mortar.
So that the hardening of the screed is not accompanied by the formation of defects, it is moistened 2-3 times a day.
After three days, a film is rolled on the surface to prevent moisture from evaporating too quickly.
Under normal temperature conditions, the screed will be ready for finishing. flooring in 25-30 days. The heat carrier should not be heated above + 28 ° C during this period.

Block parquet and some other products made of valuable wood species are mounted at a relative humidity of the screed below 55-65%. If this level is not reached, the drying time is extended.

Video: cement screed for a water-heated floor

Even the minimum thickness of the screed (5-6 cm) is an effective heat accumulator. In the event of an emergency in winter period it will prevent pipes from freezing for 2-3 days. Correct installation systems in the depth of the concrete layer will ensure an even temperature distribution on the surface. This design is well protected from external influences... It remains functional for decades. The listed advantages can be used in full if the above tips are taken into account when implementing the project.

The system of warm water floors involves a screed on top of the heat exchanger pipes, which serves as the basis for laying floor materials. Many are interested in what should be the minimum thickness of the floor screed so that heat transfer occurs as efficiently and quickly as possible, while the strength of the concrete base is sufficient to withstand the expected loads on the surface. To fully understand this issue, it is worth considering different options, both in terms of the characteristics of the heating system itself, and the materials used for the device of the final subfloor. The recommendations set forth in the SNiP, as well as some video materials, will help in this.

Layered construction of a water-heated floor

To do correct system underfloor heating, you need to create several successive layers. From bottom to top, a warm water floor cake should be like this:

rough base;
waterproofing;
thermal insulation;
complex reinforcement plus heating pipes;
finishing screed;
finishing floor material.

Due to the creation of a rough base, an initial leveling occurs, which allows the layer fine casting make it uniform. Moreover, the rough screed should be not only when installing the floor on the ground, but also on the floor slab in the apartments. If basic leveling of the subfloor is not done, the final concrete layer can be very uneven, which will affect the quality of the heating of the floor covering. What a warm floor cake looks like is clearly demonstrated in this video

Functions of the finishing screed underfloor heating

The finishing foundation is created for the following purposes:

reliable protection of pipes from mechanical stress;
heat transfer to the surface and its even distribution.

For the first task, the screed must be thick enough and therefore strong. However, if the finishing base is too high, the second function will not be fully fulfilled. Therefore, it is important to create an optimum layer thickness.

How many centimeters should be upper layer sand concrete depends on several factors, such as:

type of floor material (tiles, laminate, parquet);
underfloor heating pipes diameter;
underfloor heating tasks (main heating or addition to radiators);

At the same time, one should not forget about the requirements for a clean base, which are indicated in the SNiP, and are recommended for mandatory implementation.

Minimum thickness

What can be the most thin screed over floor heating pipes? It depends on several factors. Let's say that the SNiP indicates a thickness of 20 mm, but this is in the case of using a metal-cement composition when installing the base. What to do with other mortars, sand concrete, or semi-dry material, the document does not say anything. However, SNiP spelled out another norm, which determines that the minimum layer of screed over pipe communications laid in the floor (refers to cement mortars, such as classic concrete, or semi-dry sand concrete) must be at least 4 centimeters. If you add the cross-section of the pipe to this, you get 6-7 centimeters. This is exactly what the optimal foundation should be, according to the requirements of SNiP. In practice, it is of this thickness that the finishing screed is made over the pipes. How this happens can be seen in the following video.

When watching the video, you will notice that the screed is of uniform thickness (visually, about 6 cm) over the entire area of the room.

Nowadays, sometimes the upper base of the underfloor heating pie is made with the help of self-leveling solutions with increased strength. When using such materials, the screed is made minimal, that is, so that it slightly covers the pipe communications. Usually this method is used if the floor material is supposed to be tile... Tiles laid on top of a layer of tile adhesive give additional strength to the floor surface.

The thickness of the layer above the electric underfloor heating system is determined in a completely different way. The heating cable is much stronger than pipes used in water circuits, therefore the top layer of the screed in this case bears much less protective function... Moreover, the warm floor, made electric cable or mats, in most cases it is used for subsequent laying of tiles. For these reasons, the thickness of the screed when installing electric floor heating does not exceed 1.5 centimeters.

Important! Whatever the thickness of the finishing base, an expansion gap should be left between it and the wall, where to place the damper tape. At large areas In addition, expansion joints must be made.

Maximum finishing base thickness

The SNiP does not say anything about how many centimeters the maximum layer can be above the underfloor heating system. Strongly exceed optimal thickness screeds in living quarters (house or apartment) make no sense. This will lead to such negative moments:

overspending of materials, therefore, the rise in the cost of activities associated with the installation of warm water floors;
increasing the inertia of the surface heating process;
reduction of useful living space.

Usually, an increase in the layer is associated with the need to level the surface or create a floor on the same level in adjacent rooms. This is best done with a rough screed. Upper base different thickness will lead to uneven heating of the floor. Although this situation will not greatly affect energy costs, since the screed is floating, that is, it is independent of other structures. So she will give off as much heat as she gets from the heating pipes. The unevenness of the thickness will affect only the inertia of the heating of the floating base of the floor.

Important! It is necessary to significantly exceed the layer of the finishing screed over the pipes of water underfloor heating in those rooms where the load on the floor can be significantly increased (garages, other technical buildings). When installing the base in living rooms you should strive to create a uniform layer of optimal thickness.