When installing a warm water floor on top heating elements the screed is poured, used as a basis for the finishing flooring. For private home craftsmen who decide to install a heated floor system themselves, the issue of screed thickness is relevant. What should be the height of the heated floor screed so that the heating elements do not suffer damage from loads during operation, and the heating is as efficient as possible. To answer this question, it is necessary to study the features of the system and the properties of the materials from which the finished floor will be made. In addition, SNiP contains certain recommendations related to this issue.
Installation of a warm water floor
The “warm floor” system involves the presence of several layers laid in a certain sequence. If we consider the system pie from bottom to top, we can see the following order:
- First, a rough foundation is laid out.
- Next comes the waterproofing layer.
- Then a layer of thermal insulation is laid.
- Heating elements.
- Concrete screed.
- Finish floor covering.
The rough base is a necessary part, since it helps level the floor surface. This allows you to get a more even finishing screed. It should be noted that a rough foundation is necessary in all cases, including underfloor heating in a private house or concrete floors. The absence of the first layer can negatively affect the efficiency of the “warm floor” system.
Purpose of the screed
The heated water floor screed is designed to perform the following functions:
- Protection of heating elements from mechanical impact.
- Heat transfer and its uniform distribution over the surface.
To complete the first task, you need to make a sufficiently thick screed, and for effective heating you need minimal screed for water heated floors. In other words, to perform both functions, you need to select the optimal option.
When determining the thickness of the screed over a water-heated floor pipe, several factors should be taken into account:
- What material will be used as the finishing floor covering (laminate, parquet or tiles).
- Diameter of heating tubes.
- For what purpose is a warm floor installed (main or additional heating).
- The magnitude of the expected load on the screed.
In addition, when determining the maximum and minimum thickness of the screed for a water heated floor, you should adhere to the recommended Sanitary Standards and Rules.
Minimum screed thickness
When determining the minimum thickness of the screed over a heated floor pipe, it is best to take the Sanitary Standards and Rules as a basis. It is in this document that it is indicated that when using a metal-cement composition, the thickness of the screed above the heating pipes should not exceed 2 centimeters. Minimum thickness classical cement mortar above the pipe communications, which are located inside the floor, should be at least 4 cm. Adding the diameter of the pipe products to these values, we get a height of 6-7 cm. This value is considered the most optimal and meets the requirements of SNiP. That's why professional craftsmen they make a finishing screed over the water floor pipes of exactly this height.
Modern craftsmen make screeds from self-leveling mortars, which are characterized by increased strength. The use of such materials makes it possible to make a screed of minimal thickness, lightly covering the pipe communications. However, in this case, it is recommended to use tiles as the final floor covering. With this material laid on tile adhesive, the surface acquires special strength, despite the minimum thickness of the underfloor heating screed under the tiles.
As for electric heated floors, completely different calculations are made here. The fact is that the strength of the heating cable is much higher than that of water floor tubes. Consequently, the top layer of the screed has a greater function of heat transfer than protection from mechanical loads and damage. In addition, tiles are most often used as a finishing floor covering for heated floors using electric cables or heating mats. As a result, it turns out that the minimum screed for an electric heated floor is 1.5 cm.
Regardless of the height of the screed, it is necessary to leave a deformation gap between it and the wall, where a damper tape must be laid. If a large area is being poured, then do not forget about expansion joints.
Maximum permissible screed height
There are no instructions in SNiP regarding the maximum thickness of the screed over a water heated floor, but there is no point in exceeding the optimal thickness values when installing a heated floor in a private house. This will be caused by the following factors:
- High consumption building materials, as a result of which the installation of a heated floor will cost much more.
- The inertia of the surface heating process will increase.
- Useful living space will be significantly reduced.
In most cases optimal value thicknesses exceed if it is necessary to make the surface as flat as possible or when installing heated floors on the same level in adjacent rooms. Although it would be more correct to do this at the stage of creating a rough foundation. Because of different thicknesses top screed, the floor surface will warm up unevenly. Due to the fact that the screed is created independently of other structures, energy consumption will not increase due to uneven heating of the floor. But this factor can affect the inertia of heating the floating screed. In general, the screed will transfer the amount of heat that the heating elements will give it.
You should pay attention to one more fact: when installing a screed for a heated water floor in residential premises, it is best to create a uniform layer of optimal thickness. But in places where there is a significant load on the floor surface, to protect the heating tubes of a warm water floor, you can increase the layer of finishing screed. Such premises include a garage or various technical buildings.
When thinking about what the thickness of the floor screed should be, you must take into account many factors. You should not assume that a more impressive thickness will make the structure better. This is the sin of many home craftsmen who do not have the appropriate experience. In practice, it turns out that the final strength of the fill does not in all cases depend on the thickness, because the drying process may go wrong, for example, it will last several months, in which case the screed will never reach required characteristics. In order to achieve the desired result, it is necessary to carry out an accurate calculation.
Optimal thickness
Leveling floors is a fairly important process; it is very rarely neglected. This especially applies to residential premises. An exception may be laying the finishing coating on joists. The thickness of the floor screed for a heated system will differ from the usual 40 mm fill. If you plan to lay water pipes, you will need a 70 mm layer, but the thickness of the screed in this case should not be more than 100 mm. If we're talking about about electrical source heat, then it can be hidden under concrete, the height of which will be 5 cm or less.
After pouring, the solution cannot be heated by starting a heated floor, because this will reduce the strength of the screed. The basis for these figures are the requirements for the strength of the fill. Experts recommend using more precise parameters for the screed. Thus, the thickness of the screed over a water heated floor can be equal to the limit of 7 to 10 cm. As for electrical system for heating, the thickness can be 3-5 cm.
For reference
The hardening time of the largest thickness can reach 140 days. The system must first be checked for integrity and operability. This is especially true for water floor pipes. The system is started again closer to the end of the hardening process, so that the remaining moisture in the depths of the concrete is completely dried.
Minimum screed height
If guided sanitary standards and rules, then in residential premises the solution should be poured in a layer of 40 mm or higher. This figure is minimal. But in some cases, the formation of a thinner layer is allowed. This includes low activity in the use of the premises, as for utility rooms and storage rooms, because they are visited very rarely.
If the thickness of the floor screed is less than 30 mm, then the strength of the material may be insufficient in unforeseen situations. This applies to falls of massive objects. From this it should be concluded that minimum height limited to 35 mm.
It is important to pay attention to exceptions. If there is a goal to increase heat and soundproofing qualities ceilings on an uneven base, a bedding should be formed for a light screed. A solution is poured onto the uneven surfaces of the slab, the thickness of which will be 2 cm. After the material has dried, insulation or sound insulation is laid on top, followed by a thin separating film. On final stage a solution of the calculated thickness is poured to ensure normal strength.
Features of determining the thickness of the screed
Before you determine the thickness of the floor screed, you must decide under what conditions the room will be used. Therefore, to some extent you will be able to determine the operating load on the surface. For example, public rooms such as hallways, corridors, kitchens and living rooms require a significant layer thickness of 70 mm or higher or reinforcement, with which the layer height can be reduced to 40 mm.
If we are talking about a children's room that will combine a play space, it is important to achieve impressive durability of the coating. The thickness of the screed in this case should be 50 mm. If we take into account the above approximate parameters, the question arises as to what is the maximum thickness of the floor screed for the entire apartment. The answer to this question should be unambiguous - the height of the layer should be the same everywhere.
In some cases, the height difference between rooms or within the same space is created artificially, but this option cannot be called the simplest. If you are installing a heated floor system or want to achieve high strength of the base for the finishing coating, then you should choose a thickness in the range from 50 to 60 mm. This will be enough, which is especially important for the reinforcing layer. For calculations, the reference point should be the doorways. After all, if you raise the floor significantly, taking into account the finishing coating, you can reduce their height, which will imply the need to install door leaves of unusual sizes.
Additional information about the minimum screed thickness parameters
Some experts believe that there is no optimal screed thickness. This belief is based on the fact that the mentioned parameter will depend on several factors at once, among them:
- type of overlap;
- soil type;
- purpose of the room.
All these conditions affect not only the final thickness, but also:
- cost of work;
- type of reinforcing mesh used;
- choice of cement brand.
Based on the height of the concrete layer, it can be argued that the screed can have the following thicknesses:
- minimal;
- average;
- maximum.
The minimum thickness sometimes reaches 20 mm. This type of coating can be constructed without the use of reinforcement, but only if self-leveling mixtures are used for the work. The average thickness reaches 70 mm. In this case, you should use fittings or reinforced mesh. The maximum thickness reaches 150 mm. In this case, the screed has the form monolithic design with fittings. This option for a private house can act as a floor and foundation, which are combined into a single system.
The thickness will depend on the materials that you intend to use when arranging the system. For example, a layer of concrete with the addition of crushed stone may have a minimum thickness. For thin screeds the most suitable choice are self-leveling mixtures for finishing floors. At the final stage, such a surface is covered decorative material. Using this technology, it is possible to achieve the formation of a perfectly even, thin layer, after the materials have dried, you can begin installing the decorative coating.
The thickness of the screed over a water-heated floor is also determined taking into account the diameter of the pipes. If the diameter does not exceed 25 mm, then a layer of 50-70 mm will be sufficient. Experts believe that for normal operation of the system and good heating of the room, the thickness of the screed above the heated floor can be 4 cm. If the screed is higher, the thickness will complicate the regulation of the supplied heat, because a huge part of the energy will be spent on heating the concrete.
What needs to be taken into account when arranging a screed with a minimum thickness
After reading the sanitary standards and rules, you can understand that the smallest thickness of the screed can be 20 mm. However, in this case it is necessary to take into account one feature. Depending on what material is used, the layer height may vary. If the screed is formed on the basis of metal cement, then 2 cm will be enough. If you do not plan to use reinforcing mesh, then the minimum thickness cannot be less than 4 cm. This is due to the fact that a lower layer height will not be able to provide wear resistance and sufficient strength of the coating.
If the minimum thickness of the heated floor screed is ensured, then you must meet several conditions, including:
- leveling the surface with a screed;
- Availability ;
- lack of fittings and pipes.
If we are talking about a technical premises, then the thinnest concrete layer cannot be used, because an increased load will be placed on the surface.
Additional information about the screed thickness of a water heated floor system
A water heated floor is a system of heating elements - pipes that are filled with water. They should be located over the entire floor area. Typically such a system is placed in cement screed for protection against mechanical impact. It is important to calculate the thickness of the screed for a water heated floor as correctly as possible. This will ensure the normal functioning of the system.
The thickness of the screed is the key mechanical strength and proper operation of the system, as well as efficient heat transfer and efficiency. If you install a thick screed, it will have a large heat capacity, as a result of which it will be much more difficult to regulate the temperature. Under such conditions, the screed takes much longer to heat up, but it also releases heat over a long period of time.
By laying a screed with a smaller thickness, you will get a floor that heats up in a short time, however, such a structure can overheat and become covered with cracks; heat transfer will occur in stripes, which are limited by the distance between the pipes under the floor. When choosing the thickness of the screed for a water heated floor, you should take into account that this parameter determines the degree of protection of the pipeline and ensures uniform distribution of heat over the surface.
The total thickness of the screed for a residential premises should not be more than 100 mm. If we are talking about pavilions, auto centers and warehouses, then this parameter can be 200 mm or less. The thickness of the screed reaches 300 mm only in aircraft hangars. The minimum thickness when laying a heated floor system is 65 mm. The thickness of the screed on a warm water floor should be equal to the limit from 20 to 50 mm. If the structure is hanging, then a heat and sound insulation layer should be laid between the pipeline and the base, then the thickness of the screed will be 35 mm.
Pouring screed onto a heated floor system
Once you have determined what thickness the underfloor heating screed should be, you should begin work. The base is cleaned, because a dirty coating will not be able to provide the required degree of adhesion. On a clean and dry surface, apply the primer mixture in 2 layers. To calculate the volume of the screed, determine the thickness by multiplying by the area of the room. For residential and domestic rooms, it is recommended to lay the screed in the range from 65 to 70 mm. The layer above the pipes will be 45 mm, while the thickness of the screed under the water-heated floor will be approximately 20 mm. If you use mixtures for self-leveling floors, you can reduce the layer thickness to 45 and 25 mm, respectively. This is due to the fact that such mixtures have a higher density.
Experts do not recommend saving much on thickness, because in this case the floor may react negatively to unexpected loads. If you plan to install large-sized objects indoors, you should consider reinforcing the top layer using metal mesh. It can be used locally or over the entire area. In order to strengthen the screed, you should use solid additives such as fiber or polypropylene shavings. The first allows you to obtain a mixture called fiber-reinforced concrete.
Having chosen an impressive thickness of the heated floor screed, you will expect the layer to harden up to 1.5 months. Before you begin laying the topcoat, you must wait until the base is completely dry. In this case, a self-leveling floor is more convenient, because it is characterized by rapid polymerization.
About the features of screed installation
If you decide to pour a screed for a water-heated floor, the technology for carrying out the work will differ only in the presence of damper joints. If we are talking about a room of 10 m2, then the seams will be located along the enclosing structures. A special cushioning strip must be placed along the bottom of the wall. In the future, this will compensate for the expansion of the material when exposed to temperature.
When the room is more spacious, additional seams will be required. The functions of the damper tape include not only compensation, but also thermal insulation from the walls, because the coating has a heat-repellent foil. In order to achieve a positive result, it is not enough to choose the correct thickness of the screed on a warm water field. It is also important to check the performance and hydraulic tightness of the system. It is necessary to ensure the presence of a heat-reflecting layer under the pipeline to prevent heat loss. The choice of screed materials should be approached as responsibly as possible; this is true for cement, which, if improperly and long-term storage caked.
Conclusion
Before you begin leveling the floor, you must correctly determine the thickness of the heated floor screed. This parameter depends not only on the user’s wishes, but also on design features building, floor properties, floor power, facing materials and other factors.
Although there are no regulatory or regulatory documents, still exist certain rules related to the work.
The installer must take into account the following:
- The thickness of the screed under and above the heating cable.
- Choosing a screed installation method.
- Nuances associated with the preparation of the solution and the pouring process.
A properly made screed for a warm electric floor does not crack, ensures uniform heat distribution throughout the room, and maintains strength over a long service life.
What layer of screed for electric heated floors
A screed under a warm electric floor is not mandatory. It is often poured to level the surface before laying the cable. Manufacturers' recommendations should be taken into account. According to the requirements of most manufacturers of electric floors, a cement mortar screed cannot be thinner than 3 cm. When using special leveling mixtures, the thickness can be reduced to 2 cm.
Optimal thickness Screeds for electric heated floors are selected depending on the following factors:
- Base for pouring. The screed on the ground must be at least 10 cm. The thickness for the screed on the floor slabs depends on the unevenness of the surface. The resulting plane should be perfectly flat.
- Material. The cement-sand mixture is poured with a thickness of at least 3 cm, leveling solutions depending on the manufacturer’s instructions.
Laying the underfloor heating cable in the screed can be done strictly on a perfectly flat surface. Variations affect the uniformity of heating and often cause cable overheating.
What is the thickness of the screed above the electric floor?
Experts' opinions on this matter may vary. Therefore, it is best to refer to the recommendations of underfloor heating manufacturers. According to the instructions given in the operating instructions, the minimum layer of screed should be 4-5 cm.But the thickness may vary depending on several factors:
- Cable thickness.
- Type of floors.
- Screed mortar used.
The larger the volume of the cable, the greater the thickness of the concrete screed. To determine the minimum parameters, you should refer to the operating instructions. The minimum thickness of the screed over a warm electric floor cannot be less than 4 cm for cement mortar and 2 cm for special leveling mixtures.
The total height of the screed for an electric heated floor is from 5 to 8 cm. Provided that the installation is carried out on a flat base, the thickness of the cake can be reduced to 4 cm. Heating mats together with the floor covering reduce the height of the room by no more than 2 cm.
Which screed to choose for pouring
In addition to the traditional sand-cement composition, there are other types of screed recommended for pouring heated floors.Each of existing options has its advantages:
- Wet screed. For preparation, take cement, sand and plasticizer. Be sure to add fiber fiber to avoid the appearance of cracks and deformation during the drying process and during operation. The advantage of the solution is that you can make it yourself. The components are inexpensive, which somewhat reduces the final cost of the work.
The disadvantage of a wet screed is that the floor takes a long time to dry (28 days), there is a high probability of cracks, and the inability to make a perfectly level base. - Semi-dry screed method. A small amount of water is used for production. Popular ready-made mixtures. But if necessary, you can prepare the solution yourself, based on - river sand 120-140l/fiber fiber 130g/cement 1 m/water 14-17 l. /plasticizer 0.5 l.
The advantage of the semi-dry composition is the complete absence of cracks in the screed after drying. There is no need for additional leveling of the floors after drying. - Dry method. The composition of the screed mortar may vary depending on the manufacturer, but most often fine perlite or quartz sand, fine-grained slag, etc. The advantages of the dry method include: quick installation and drying. TO further work You can start after 12 hours.
The screed must be done carefully, preventing possible damage cable. The rupture of protective insulation or conductive conductor during floor pouring is the most common cause of floor failure.
How to reinforce the screed
In order for the installation of the heating cable into the screed to be successful, it is imperative to prevent deformation and cracking of the floor during the drying process. Cracks cause the appearance of cold zones and uneven distribution of heat over the entire surface of the slab.What methods of screed reinforcement exist?
- Additives. When preparing the solution, it is important to use fiberglass. This is a special additive based on polypropylene. After adding fiber fiber to the solution, the strength characteristics increase several times: resistance to mechanical damage, cracking, settling and spreading of the mixture. At the same time, frost resistance and fire resistance increases.
- Reinforcing mesh. Recommendations for pouring screeds for heated floors indicate the need to use a plastic reinforcing layer. The manufacturer additionally provides special stands to raise the mesh above the floor.
In large rooms, cracking of the floor may occur due to the lack of compensation pockets. Therefore, a mandatory measure is to install a compensating damper tape along the walls, as well as between sections of the slab.
How to pour screed correctly
The technology for pouring screeds for electric heated floors is practically no different from that used when installing a conventional cement base. After execution preparatory work and laying out the cable for further installation in the concrete screed, proceed to the following steps:
- Display of beacons. The surface must be extremely flat. In this regard, the step between the beacons is no more than 0.8 m. Although you can find recommendations that the distance between the beacon level should depend on the length of the rule, practice shows that the longer the step, the more irregularities appear during the stretching of the solution.
Initially, we place the beacons along the edges of the room, so that there is 10-15 cm left to the wall running parallel to the plank. The fishing line is stretched, the rest of the guides are positioned under it. If the recommendations are followed, the result is a perfectly flat surface, leveled along the beacons, even when using ordinary cement-sand mortar. - Filling the screed. After the solution used to attach the beacons has dried, you can begin pouring the screed. If the floor thickness exceeds 5 cm, the work is carried out in several stages. First, apply the first layer of 2-3 cm. A day later, the second, finishing layer is pulled along the beacons. It is important to ensure that the rule does not scrape excess solution from the surface and that pits do not form after drying.
- Drying the solution. Care should be taken to ensure that direct Sun rays. The screed is covered with film and watered at regular intervals during the first 5-7 days.
Warm floors built into the screed can be turned on no earlier than 28 days after pouring the solution. According to SNiP, at the same time you can begin laying the flooring.
How to make an electric heated floor without screed
It is possible to lay the underfloor heating cable without a screed. The following two methods are popular:- Grooving screeds for underfloor heating cables. Grooves about 2 cm deep are cut into the slab or concrete screed. To avoid a lot of dust, use special tool with dust bags. The cable is laid in grooves. The top is laid with a solution with the addition of fiberglass or adhesive composition for tiles.
- Laying heating mats- this method is also popular due to its ease of implementation installation work. The design of the mats is quite simple. To connect, you need to spread them over the surface and plug them into a power outlet.
The system of warm water floors involves installing a screed on top of heat exchanger pipes, which serves as the basis for laying floor materials. Many people are interested in what the minimum thickness of the floor screed should be so that heat transfer occurs as efficiently and quickly as possible, while maintaining strength concrete base sufficient to withstand the expected surface loads. To fully understand this issue, it is worth considering various options, both in terms of the characteristics of the heating system itself, and the materials used to construct the finished floor base. The recommendations set out in this regard in SNiP, as well as some video materials, will help with this.
Layer-by-layer design of water heated floor
To make a proper underfloor heating system, you need to create several successive layers. From bottom to top, the pie of a warm water floor should look like this:
- rough base;
- waterproofing;
- thermal insulation;
- complex reinforcement plus heating pipes;
- finishing screed;
- finishing floor material.
By creating a rough base, initial leveling occurs, which allows the finishing fill layer to be made uniform. Moreover, the rough screed should be used not only when laying the floor on the ground, but also on the floor slab in apartments. If basic leveling of the base is not done, finishing layer concrete can be very uneven, which will affect the quality of heating of the floor covering. What a heated floor pie looks like is clearly demonstrated in this video
Functions of finishing screed for heated floors
The finishing base is created for the following purposes:
- reliable protection of pipes from mechanical influences;
- heat transfer to the surface and its uniform distribution.
To accomplish 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 a layer of optimal thickness.
How many centimeters should it be upper layer sand concrete depends on several factors, such as:
- type flooring material(tiles, laminate, parquet);
- diameter of underfloor heating pipes;
- underfloor heating tasks (main heating or addition to radiators);
At the same time, we should not forget about the requirements for the finishing base, which are indicated in SNiP and are recommended for mandatory implementation.
Minimum allowable thickness
What is the thinnest screed over underfloor heating pipes? It depends on some factors. Let’s say that SNiP indicates a thickness of 20 mm, but this is in the case of using a metal-cement composition when constructing the base. The document does not say anything about what to do with other solutions, sand concrete, or semi-dry material. However, SNiP contains 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) should be at least 4 centimeters. If you add the cross-section of the pipe to this, you get 6-7 centimeters. This is exactly how it should be optimal base, according to the requirements of SNiP. In practice, it is precisely this thickness that is used to make the finishing screed over the pipes. You can see how this happens 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 a heated floor pie is made using self-leveling mortars that have increased strength. When using such materials, the screed is made minimal, that is, so that it slightly covers the pipe communications. Typically, this method is used if the flooring material is intended to be tile. Tile laid on a layer of tile adhesive gives additional strength to the floor surface.
The thickness of the layer over an electric heated floor system is determined in a completely different way. The heating cable is much stronger than the pipes used in water circuits, therefore the top layer of the screed in this case carries much less protective function. Moreover, the heated 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 finished base, a deformation gap should be left between it and the wall, where the damper tape should be placed. At large areas In addition, expansion joints must be made when filling.
Maximum thickness of finishing base
SNiP says nothing about how many centimeters the maximum layer above a heated floor system can be. There is no point in greatly exceeding the optimal screed thickness in residential premises (house or apartment). This will lead to the following negative points:
- excessive consumption of materials, therefore, increased costs of measures associated with the installation of warm water floors;
- increasing the inertia of the surface heating process;
- reduction of useful living space.
Typically, an increase in the layer is associated with the need to level the surface or create a floor at the same level in adjacent rooms. It is better to do this using a rough screed. A top base of different thickness will result in uneven heating of the floor. Although this situation will not greatly affect energy costs, since the screed is floating, that is, independent of other structures. So it will give off as much heat as it receives from the heating pipes. The uneven thickness will only affect the inertia of heating of the floating subfloor.
Important! It is necessary to greatly exceed the layer of finishing screed over water underfloor heating pipes 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.
The thickness of the screed over the water heated floor is tied to the diameter of the pipes that are laid when installing the heated floor system. As a rule, when laying MV 12 pipes, the screed thickness is 60 mm, when laying MV 17 pipes - 65 mm.
Along with this, the optimal thickness of the screed for a water-heated floor is determined by SNiP 3.04.01 - 87, which states that the distribution of thermal energy when laying a water-based cement screed is most favorable with a layer thickness of 65 mm.
Recently, the use of water-heated floors has become quite common. But this technology is used only in private houses and cottages, since multi-storey buildings With central heating installation of warm water floors is prohibited due to additional loads on common system heat supply.
Sequence of work when pouring concrete screed
The screed under the warm water floor is poured after laying the waterproofing, insulation layer and water-bearing pipes. Reinforcement using metal mesh with a rod diameter of at least 3 mm is required. Typically, pipes are attached to the fittings and placed below the underfloor heating system. However, many experts believe that in order to properly distribute the mechanical load over the entire surface of the screed, it is more advisable to place the fittings above the water pipes. This arrangement of the reinforcement also contributes to the optimal release of thermal energy from the thickness of the concrete.
The waterproofing layer is made over a rough screed using roll or liquid coating waterproofing.
Next, a layer of insulation is installed. As a rule, high-density polystyrene (over 35 kg/m3) is used. Polystyrene slabs are produced with locking devices along the edges, which allows them to be laid as compactly as possible.
Compound cement mixture must comply with concreting standards and contain cement of the appropriate grade, sand or crushed stone and plasticizers. In order for the screed for a warm water floor to have additional strength, it is advisable to add fiber to the solution. This is an additional type of reinforcement consisting of synthetic fibrous materials.
Screed under a warm water floor must be done at the same time. You cannot flood one area with breaks for several days. This may lead to the appearance of cracks during further operation. For large areas of pouring screed under a water-heated floor, it is permissible to divide the production into certain stages. For example, fill room by room, limiting the area of the screed doorways, under which a thermal compensation gap is subsequently arranged.
Before pouring, the water-bearing pipes must be in full working order, since after the concrete hardens there will no longer be access to them. In this regard, the underfloor heating system is being tested. Connect to pipes operating pressure water and check for leaks throughout the day. If leaks occur, they must be eliminated and only then can the concrete screed be poured.
Compliance with the rules
An important point is compliance with the rules for installing screeds for water heated floors associated with thermal expansion processes.
Along the perimeter of the room at the junction of the screed with the walls and in doorway An edge strip with a thickness of at least 5 mm must be installed. It is attached to the walls with a stapler and metal staples. If the walls are concrete and the metal bracket will not hold in it, you can attach the edge tape to the walls with glue.
After the cement mixture has hardened, excess edge tape made of foamed polyethylene is cut off with a sharp paint knife to the level of the finishing coating.
The second condition, which is often neglected, is the installation of a deformation break at every 8 linear meters poured screed onto a water-heated floor. Only the presence of a deformation gap is guaranteed to protect the floor from cracking resulting from thermal expansion and contraction.
The depth of the compensation gap must coincide with the depth of the screed, equal to the distance between the waterproofing layer to the top point of the finishing coating. Width - at least 10 mm.
If the surface of the screed is covered with ceramic tiles, then the deformation gap should be transferred to the tile. To give it an aesthetic appearance the edges are framed with metal or plastic moldings. Elastic acrylic or silicone sealant. Thanks to this, debris, dust or water will not accumulate inside the seam.
If the final floor covering is a floating floor type (parquet), carpet covering or linoleum, the deformation gap remains hidden under the outer surface. To prevent chipping, the seam boundaries are reinforced with galvanized paint corners.
Complete drying of the screed lasts 28-30 days from the moment of pouring.
Warm water floors without cement screed
Recently, the technology of installing a water floor heating system without screed has become widely used. It is used in cases where floor loads are undesirable ( concrete screed on average weighs about 150 kg/m2) or when raising the floor height by 10-15 cm is impractical.
Water-based heated floors without screed quickly won the sympathy of consumers, since they can be installed much faster and without a long wait for drying. concrete compositions. And the result is almost the same. Thanks to special technological developments, flooring can be laid in any conditions and on any rough surface.
The sequence of work is the same as when installing water floor heating under a screed.
A layer of waterproofing is applied to rough basis, then insulated with polystyrene blocks, flexible pipelines are laid. For more efficient heat distribution, the pipes are laid in special metal trays made of galvanized sheet or aluminum.
After checking the heating system, you can immediately begin installing the final floor covering: laminate or parquet. If the project provides for the installation ceramic tiles, it is necessary to additionally cover it with a solid base: plywood, particle board or moisture-resistant gypsum fiber material. The minimum thickness of such a coating must be at least 10 mm.