The building structure will perform its functions flawlessly if the preliminary calculations are carried out without errors. An accurately selected screed thickness for a water-heated floor will ensure sufficient strength and uniform heat distribution on the surface. To define everything important parameters project, a detailed study of technologies, materials, and advice from specialized experts is necessary.
The picture above shows typical scheme water heated floor screed, which is used in recommendations for creating heating systems built into the floor.
There are a few practical issues to note from this example:
- An ideal foundation is a rarity in domestic construction. Therefore, it is necessary to eliminate cracks and other defects in floor slabs. Creating a screed 4-6 cm thick will help solve the problem.
- The pipes of the water heated floor screed can be secured different ways. Depending on the chosen option, the cost of the project, the speed of completion and the complexity of the work will change.
- One layer of thermal insulation is sufficient, but to obtain good results modern materials must be used.
- Experts recommend maintaining the surface temperature of the water heated floor screed at a level from +28°C to +30°C. But to fulfill this condition, it is necessary to take into account: laying step, type of main screed, type of finishing coating.
From this information we can conclude that the thickness of the screed over a water-heated floor depends on a variety of various factors. It cannot be considered separately. Coordination with other technical parameters of the heating system design is necessary.
If the finishing coating of the water heated floor screed does not have sufficient strength (linoleum), it is necessary to install an additional layer of plywood underneath 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 finishing coatings.
In all options, the following initial data are accepted:
- Pipe type: cross-linked polyethylene, diameter 20 mm, wall thickness 2 mm.
- Water temperature in the supply/return line: +50°C/ +40°C.
- From below on reinforced concrete floor Between the floors of the building there is thermal insulation made of foamed polystyrene foam 80 mm thick.
- 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 chips | |||
| Distance between lines, mm | 100 | 150 | 200 |
| Linoleum without insulation, °C | 29 | 28 | 27 |
| 26 | 25 | 25 | |
| Ceramic tiles, °C | 33 | 31 | 30 |
| Mix of sand and cement | |||
| Distance between lines, mm | 100 | 150 | 200 |
| Linoleum without insulation, °C | 28 | 27 | 26 |
| Laminate on a wooden base, °C | 26 | 25 | 25 |
| Ceramic tiles, °C | 31 | 30 | 29 |
| Semi-dry mortar | |||
| Distance between lines, mm | 100 | 150 | 200 |
| Linoleum without insulation, °C | 25 | 24 | 23,8 |
| Laminate on a wooden base, °C | 24 | 23,5 | 23,2 |
| Ceramic tiles, °C | 27,3 | 26 | 25,5 |
From the data obtained it is clear that the fairly popular “dry” building mixtures are the worst option. They are easy to use. But the created covering of the water heated floor screed will have 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 instead of gravel and other traditional fillers.
The data from the table also shows how losses change when installing different finishing coatings. Linoleum, laminate, and natural parquet conduct heat poorly. Even with high supply line temperatures, it will not be possible to approach the ideal surface heat. The best option- ceramic tile.
This image was taken using a thermal imager. Areas of water heated floor screed with a higher temperature are highlighted in red. You can see what happens if the distance between the lines is too large. A similar result will occur when the water temperature is insufficient, or the pipes are installed too close to the surface. By moving them lower, you can achieve even heat distribution. But this will increase the inertia of the system. We will have to increase the layer of concrete and reduce the height of the ceilings.
For residential premises, the main screed for a heated floor is from 6 to 8 cm. If it is planned to install a piano or other heavy products, double reinforcement is installed under the corresponding area.
Project preparation
A high-quality water heated floor consists of the following layers:
- The rough screed is 5-6 cm thick. It is poured with the preliminary installation of a damper tape around the perimeter of the room.
- Insulation of water heated floor screed. It is better to use factory-produced polypropylene foam with a density of 40 kg or more. m cubic and higher. The greater the thickness, the less heat losses. It is convenient to work if there are special cutouts at the ends of the products. They simplify precise joining and ensure tight connections.
- A polyethylene film (125-150 microns) is installed over the insulation boards. It prevents the penetration of moisture from the screed. If applicable quality slabs made of polypropylene with locking connections, taped with tape, no additional waterproofing is needed.
- The reinforcement not only strengthens the screed. It is convenient to fix pipes on such a frame. Instead of traditional metal ones, they are beginning to use composite and polymer products in construction. They weigh less and are not destroyed by corrosion processes.
- To speed up the work you need to purchase required amount plastic clamps. Use 3-4 products for each linear meter lines.
- Where the water-heated floor screed pipe passes through the expansion joints, a protective corrugation is put on it.
- When the entire structure is assembled, pour it on top cement-sand mixture with fillers.
- Next, the finishing coating is installed.
The structure of the structure is selected taking into account the characteristics of the installation site and the structure itself. It is easier to install a heated water floor on a special substrate with protrusions. Corresponding sets are offered with edge and connecting elements. Some mats have IR reflective layers built into the bottom of them to improve 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. m. concrete 6-7 cm thick weighs from 300 to 340 kg.
Execution of work operations
The exact sequence of actions depends on which screed for a particular warm water floor is ultimately chosen. However, the following expert advice will be useful when reproducing specific technological processes with your own hands.
Before pouring the rough screed for a water heated floor, it is necessary to install power cables and other utility lines. Walls and ceiling are leveled plaster mortar. If you do the work in reverse order, you will have to wait until the screed hardens. Next, you will need to clean it of new contaminants.
When forming these building structures control the perpendicularity of the corners to ensure the tightness of the joints with the insulation boards. On a well-created surface, differences of more than 5-6 mm in height for one contour are not allowed. This will prevent the formation of “plugs” of air.
When choosing polystyrene foam boards with sufficient density, no special precautions are needed. This product will withstand the weight of an adult without deformation or damage. However, you should check the cleanliness of your shoes and remove potentially dangerous contaminants from the soles and surfaces. It is better to install ladders from boards for movement. It should be remembered that when pouring construction mixtures you will have to move heavy loads.
If the screed area of a water heated floor is large, it is necessary to install expansion joints every 20-25 square meters. area. They will prevent cracks from appearing when the temperature increases/decreases. A tape made of foamed polymer (polyethylene) with a width of 100-130 mm and a thickness of 7 to 12 mm is suitable. Such elements are installed only in the main screed.
At this stage, high-quality wall plaster will be useful (at least to a level of up to 40 cm from the floor). Some types of specialized damper tapes are coated with an adhesive layer on one side. They attach to smooth surfaces quickly and firmly.
At the stage of preparing drawings for a water-heated floor screed, it is necessary to accurately establish the places where the pipes intersect 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 back) install insulation.
Concrete grades from 150 to 300 are suitable for creating a building mixture. This range is indicated in reference books to provide for different purposes of surfaces. More strong ties(M300) are needed in commercial facilities, warehouses, and production workshops. In residential and office premises, concrete is created from 1 part M150/200 cement and three parts sand.
The composition of the water heated floor screed is strengthened using fine granite chips. Since it is expected to operate in a temperature changing mode, it is necessary to increase the ductility of the screed. There is no point in experimenting with PVA and adhesives from other series. The corresponding “free recipes” can be found on the Internet, but their actual benefits are difficult to confirm.
In order for the screed for water heated floors to be reliable, it is necessary to use specialized additives. They are subject to official guarantees. IN detailed descriptions Manufacturers provide instructions for proper use.
To fill the main screed of a water heated floor, the following algorithm is used:
- Work is carried out at room temperature not lower than 0°C.
- First, check the tightness of the system and eliminate any identified leaks. To do this, raise the pressure (up to 4 atm.) for one day. Next, set the nominal pressure (from 1.5 to 2.5 atm.). Monitor the values using a pressure gauge.
- Markings are applied to the walls indicating the surface level of the future layer. To create smooth screed, mounds (“beacons”) of the required 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 section, moving towards the entrance. Gas bubbles are removed from it using a tamper. The simple method, repeated blows with a metal rake, is labor intensive. Faster execution necessary processing A specialized floor vibrator for building mixtures will help.
- During work operations, check the height of the screed using the marks applied to the walls.
- The amount of solution is created such that a portion of the mixture can be 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 processes, mixers and other means of mechanization should be used electric drives. You don't have to buy this equipment. It can be rented.
- No later than 3 days later, the guides (beacons) are removed. The recesses of the water heated floor screed are leveled with mortar.
- To prevent the hardening of the screed from being accompanied by the formation of defects, it is moistened 2-3 times a day.
- After three days, a film is rolled out on the surface to prevent moisture from evaporating too quickly.
- In normal temperature conditions The screed will be ready for laying the final floor covering in 25-30 days. The coolant should not be heated above +28°C during this period.
Piece parquet and some other products made from valuable wood species are installed at a relative humidity of the screed below 55-65%. If this level is not achieved, extend the drying period.
Video: cement screed for water heated floors
Even the minimum thickness of the screed (5-6 cm) is an effective heat accumulator. Whenever emergency situation V winter period it will prevent pipes from freezing within 2-3 days. Correct installation systems deep in the concrete layer will ensure uniform temperature distribution on the surface. This design is well protected from external influences. It remains operational for decades. The listed benefits can be fully enjoyed if you take into account the above tips when implementing the project.
The desire to create in the house maximum comfort leads to non-standard solutions in heating installation. Traditional radiators are giving way to underfloor heating systems. The most economical and efficient in operation is the design of a water floor, consisting of a closed loop of pipes with hot water. Uniform temperature distribution, more free space in the room, safety - these are some of the advantages of the new product. The duration and reliability of the system's operation are influenced by several factors: quality pipe material, compliance with installation technology and the thickness of the screed made for water heated floors. Ceramic tiles are often used as a finishing coating. , characterized by strength and ability to retain heat.
Before starting installation, it is worth figuring out what thickness of the screed is considered optimal. This indicator depends on:
- heat capacity of the floor;
- uniform heating;
- lifetime.
The thin layer heats up quickly, starting to warm the room, but soon high temperature The concrete surface begins to crack. This is especially noticeable in the locations of pipes. Heating above normal levels deteriorates the finishing floor covering. Extra centimeters above the water circuit will require more energy for heating. There will also be difficulties in adjusting the system. The advantage of a volumetric screed is significant heat transfer, which lasts for a long time comfortable temperature in the room.
In addition to the accumulation and distribution of heat, the screed performs protective function in relation to hot water pipes. Insufficient circuit coverage will result in high loads and shorten its service life. Protecting the water system is especially important if you plan to install heavy furniture in the room.
Minimum thickness The screed should exceed 6.5 cm; it is recommended for tiles that are not afraid of overheating. The optimal pipe filling size is 10 cm. This parameter is provided for underfloor heating systems in residential premises. For industrial buildings or warehouses, the maximum concrete thickness can reach 20 cm.
The size of the layer depends on the diameter of the pipes; if you calculate from the surface of the contour, then the figure without taking into account the thermal insulation cake will be 2-5 cm. The installation technology allows for the exclusion of the metal mesh from the cake under the contour and its replacement with fiber in the solution. In this case, the thickness of the screed above the water heated floor pipes increases, the minimum mark is 4.5 cm. Compliance with the recommended values will ensure uniform heating and safe use of the heated floor.
Thermal insulation of the base
Before installing the heating system, it is necessary to insulate the base. The thermal insulation layer will protect the water circuit from heat loss going into the basement or foundation of the house. The following is used as insulation:
- Styrofoam;
- extruded polystyrene foam;
- foil-coated backing.
The listed materials are characterized by high strength to mechanical load, resistance to moisture and temperature changes. The thickness of the insulation is 30-50 mm, it is laid on a layer of waterproofing polyethylene film. The canvas is laid overlapping on a clean, dry base; it will protect the insulation from getting wet. Thermal insulation boards are laid end to end, the joints are coated with glue or blown in with foam, the excess of which is cut off.
Penofol or a similar sheet of reflective insulation is placed on top. A layer of aluminum foil is directed upward, this will reflect the bulk of the heat back towards the room. The joints of the foil insulation are taped with special tape. Penofol will protect the insulation from the aggressive effects of concrete. A metal reinforcing mesh is laid over the thermal insulation. This element evenly distributes the high load from the water circuit system and the concrete structure.
Methods and materials for filling the floor
Pipes and elements of the water circuit are filled with screed. There are two ways to prepare it:
- mortar based on cement and sand;
- special dry mixture of factory production.
Which fill is better, each consumer decides for himself, based on the characteristics of the room and his own preferences. The main advantage of the special mixture is the short drying period. Using this composition, it becomes possible to glue ceramic tiles faster and start using water-heated floors .
Damper tape, purpose and installation
A damper tape is installed around the perimeter of the room in which the water-heated floor is installed. This element will ensure the safe expansion of the concrete base.
The elastic strip compresses under load and then restores its shape. If you neglect the damper tape, when the temperature changes, the screed can damage the heating system pipes or the floor covering (tiles, laminate). This will result in complex, expensive repairs with replacement of material.
Concrete screed technology
A mixture of cement, sand and water is the most common pouring option. To create a reliable foundation, M300 cement and screened sand are used. The addition of a plasticizer will improve the physical characteristics of the concrete screed under the tiles. Its use is especially important for filling small thicknesses (up to 3 cm). The plasticizer makes concrete more elastic and prevents cracks from appearing after drying. The addition of fiber helps increase the strength of the solution. It serves as a worthy replacement reinforcing mesh and helps to distribute the screed evenly, without voids, over the entire area of the room.
The preparatory stage includes removing debris from the base and waterproofing it. Suitable as a material bitumen mastic, roofing felt or thick polyethylene film.
The next step is thermal insulation, its technology is described above. Laying the mortar begins from the corner of the room. The mixture is distributed according to the rule according to the level of pre-set beacons. The surface is carefully leveled to create a smooth base for the flooring: tiles, laminate, linoleum.
The final finishing of the floor begins after 1-1.5 months, this period is necessary for the concrete to dry. During this time, the surface of the base remains under a plastic film, preventing rapid loss of water. If necessary, the concrete is periodically moistened.
An indicator such as heat capacity perfectly combines tiles and a warm water floor system. Durable, beautiful and easy to care for, the material is able to maintain a comfortable temperature for a long time. Ceramic tiles Temperature fluctuations and humidity will not spoil it; with high-quality gluing, it will last a long time.
Advantages and features of “semi-dry” screed
The special mixture is diluted with water, the volume of which is indicated in the instructions. When choosing a material, preference is given to a composition with modifiers that ensure the strength and ductility of the screed. The solution is considered ready for use when no liquid is released when compressed, and the composition forms a lump. The “semi-dry” mixture is laid on a clean base covered with waterproofing made of polyethylene or roofing felt. The moisture-resistant canvas should extend about 15 cm onto the walls. Next, beacons made of aluminum strips secured concrete mortar. Reinforcement must be provided for the special mixture.
The solution is sequentially laid across the floor areas and leveled according to the rule. After 1-2 hours, the surface is sanded using a machine with trowel discs. This process simultaneously levels and compacts the solution. It is easier to lay tiles on a smooth base . The minimum amount of water in the composition allows you to start finishing the floor in 4-5 days. Among the advantages of the dry mixture:
- the strength of the created foundation;
- quick drying - after 12 hours you can walk on the screed;
- ease of preparation and filling according to the manufacturer’s instructions;
- the dried mixture does not shrink and cracks do not appear on its surface;
- the special consistency of the composition forms a structure with best performance thermal insulation than concrete.
- Do not neglect thermal insulation when creating a cake for the base; a layer of insulation will protect against energy loss.
- Before pouring the concrete screed, a test run of the water heated floor system is carried out. You need to be sure of high-quality installation systems.
- For the production of concrete screed, only high-quality cement is used, without any signs of long storage. The durability and strength of the prepared solution depends on this.
- The recommended pouring thickness is 10 cm, but changes are allowed in individual cases due to the diameter of the pipes and the characteristics of the base.
If installing a water-heated floor circuit requires knowledge and skill, then screeding under tiles is accessible to everyone. By taking on the work yourself, you can save money, the main thing is not to disrupt the technological sequence of the process.
Are you interested in what type of screed for a water heated floor should be?
Water floor – popular look heating country cottages. Effective, economical, relatively simple device. Most often it is installed on the ground floor - on the ground or above the basement. This is the coldest place in the house.
And for fixation, a tie is placed on top. What thickness of screed over a water heated floor is optimal so that the coating is durable and at the same time does not reduce the efficiency of the heated floor?
There are two types of screeds: concrete ( cement-sand mortar) and dry (using ready-made mixtures). Their composition is different. The height of the screed above the warm water floor is also different.
Features of installation of concrete screed
What thickness of screed is optimal for a warm water floor depends on the composition of the working mixture, the type of floor covering and the diameter of the pipes.
To make the working solution, cement of at least M-300 is used, the size of sand granules is up to nine millimeters. It is better to use the screened fraction. Approximate proportions: for one part of cement, take three parts of sand and less than one part of water: the composition should not be liquid, but viscous.
Plasticizers are added to the solution in proportions from 0.5 liters to liters per square. Plasticity increases the strength of the screed, prevents cracking, and makes the mortar easier to lay. This is especially important for thin screeds. The minimum thickness of the screed for a warm water floor when using a plasticizer is three centimeters, the optimal is five centimeters.
This allows you to warm the floor up to thirty degrees at a coolant temperature of 50 degrees. The cross-section of the pipes is 1.6 cm. If it is larger (2-3 centimeters), the thickness of the concrete screed of the water-heated floor is increased to 7-10 cm.
Attention: the thickness of the screed for water heated floors under tiles can be 5 centimeters or more, since the tiles have high thermal conductivity. If laminate is used as a topcoat, the layer should be thinner, because thermal conductivity wood materials low.
If the treated area is more than forty square meters, in addition to the plasticizer, add fiber (polypropylene fiber) of approximately one cubic decimeter. The fiber performs a reinforcing function - it strengthens the screed and promotes uniform installation.
The maximum thickness of the screed over a water-heated floor when using a cement-sand composition is 8-10 centimeters. This coating has high strength, sufficient thermal conductivity and is not afraid of water.
Before starting installation, a damper tape must be laid along the entire wall at the junction with the floor: it will compensate for the thermal expansion of concrete and prevent the screed from opening. If the wall length is eight meters or more, an additional damping seam is made in the middle of the room.
The screed for water heated floors is laid in an even layer, leveled as a rule, and laid out along the beacons. It is necessary to ensure that there are no voids in the thickness of the concrete.
An important aspect of installation is drying. The screed must dry naturally within a month. During this time, you cannot turn on the heated floor, and also use devices for drying from above - construction hair dryers, heat guns.
A couple of days after installing the screed, it should be moistened with water and covered with plastic film on top. The moisturizing procedure is repeated every three days.
Features of self-leveling mixtures
The finished self-leveling mixture contains gypsum, due to which the screed sets much faster, from seven to ten days. The strength is higher, the thickness of the screed for water heated floors is smaller: 3 cm above the pipes, up to 6 cm in total. The preparation process is simple: the finished mixture is diluted with water in the proportion specified by the manufacturer.
But gypsum-based mixtures have significant drawback: The main component is sensitive to water. It is generally impossible to lay such a screed in damp rooms.
In combination with a water floor - with extreme caution. Most often, mixtures are used for screeds with electric floors. Before buying this material for a water floor, you need to carefully study the characteristics and recommendations of the mixture manufacturer.
After laying the semi-dry screed, grouting and sanding of the base is necessary. This is done 20 minutes after installation (not earlier). You should not delay surface treatment for more than six hours.
conclusions
AND The ideal thickness of a water heated floor screed varies from three to ten centimeters and depends on:
- from the cross-section of pipes;
- from the screed material;
- from the finishing coat.
If the thickness is smaller, the floor will not be strong enough; if it is thicker, its thermal efficiency will suffer.
When making cement-sand mortar, plasticizers and fiber should be added.
Self-leveling mixtures cannot be used in damp rooms.
Video of making a screed for a heated water floor.
Warm floor is complex design, each element of which must be assembled with very high quality. This requirement also applies to cement screed, poured over laid pipes. The service life of such a floor will directly depend on the durability of the poured screed. What are its main parameters? What is important is the composition of the mixture and quality preparatory work. These indicators are relevant for both water heated floors and its electric counterpart.
Fundamental Points
What determines the quality of the screed being poured and its service life? There are four main parameters.
It is important to place it correctly thermal insulation material. Its task is to direct heat into the room. Thermal insulation acts as a special barrier that does not allow heat to escape down into the floor slabs. The insulating layer is usually made up of two complementary materials: foam and reflective material are suitable for this purpose. Polystyrene foam protects with a layer of 3 cm heating elements from the cold of the floor slabs, and the reflective material works to transfer heat into the room.
Surface reinforcement work also plays an important role. For this they use metal mesh, to which the pipes themselves are then attached. Sometimes a second layer of mesh is attached to them, which helps strengthen the future structure.
Why is reinforcement required? Under the screed there is a soft material that is easily deformed. If you skip reinforcement work, the screed will quickly crack during deformation processes in the lower layers.
An obligatory component of the preparatory work is the laying of a damper tape, the purpose of which is to resist deformation of the screed caused by temperature conditions. Due to deformation of the cement coating, heating elements may be damaged. Since their repair seems to be a very complex and time-consuming process, it is not recommended to neglect the work of laying the damper tape.
Installation of damper tape. The composition of the mixture for pouring the screed is more important. The solution must be prepared in strict accordance with the instructions: all components must be added in certain proportions. Depends on the thickness of the screed mechanical strength the entire floor heating system, as well as the main parameters of its performance. The height of the cement layer should be optimal for a particular room: here it is important to take into account the required level of heat transfer, efficiency and ability to respond to temperature changes. The thicker the screed, the greater the heat capacity it has - this is logical. But there is one drawback here, which is that when the screed is too thick, it becomes problematic to regulate the temperature.
You can make a cement screed yourself, but if you make it too high, it will take a very long time to heat up. Such a floor will also give off heat longer, but in everything you need to look for the “golden mean”.
A thin screed will heat up quickly. But this ability is not its advantage. The thinner the cement layer, the higher the likelihood of overheating. And if the screed overheats, the coating will simply crack and all your work will be in vain.
Defects in thin screed due to overheating. The thickness of the screed also performs a protective function in relation to the pipes laid below, and therefore must completely cover them. If the size of the cement layer is selected correctly, the heated floor will warm up evenly and serve you for many years.
The recommended thickness of the heated floor in the apartment should not be more than 10 cm. non-residential premises it may be more: the norm for warehouses, shopping pavilions and other similar rooms is 20 cm. The total thickness of the screed should hide all heating elements; its height may vary depending on the diameter of the pipes used. Experts call the figure 6.5 cm as a minimum guideline.
The thickness of the screed in a residential area should be between 6.5 and 10 cm. If we consider the thickness of the screed directly from the pipeline, then this value can be within 2-5 cm. Provided that thermal insulation was previously laid between the base of the floor and the pipes, and a reinforcing mesh was used, you should aim for a minimum of 3.5 cm.
If you haven't used metal structures, then the thickness of the top layer of the screed should be increased by 1-1.5 cm. Minimum height screed over pipes automatically increases to 4.5 cm. A screed of this thickness is the best option, since it will warm up evenly over the entire surface of the floor.
Pouring the solution
The solution that is poured over the heated floor pipes can be prepared in two ways. The first option is a ready-made special mixture purchased at a building materials store. It is not difficult to prepare a solution for pouring from it, and installation also does not cause any particular difficulties. The mixture is not recommended for use in rooms with high humidity, since the gypsum included in its composition is not resistant to such conditions.
Ready-made self-leveling mixtures can be used for water heated floors. What layer is the mixture laid out? The thickness of the ready-mixed screed is determined according to the instructions included with the building material. It is most often used for electric heated floors, not water ones.
For a water floor, a cement-sand mortar is best suited, which includes: M-300 cement, sand, water, fiber (if there is no reinforcement stack) and a plasticizer. A plasticizer is a special additive necessary to improve the quality and plasticity of the mixture. 
The volume of solution required for pouring is calculated by multiplying the estimated height of the screed and the area of the room where the water-heated floor is installed. It makes no sense to save on such a parameter as the thickness of the screed. If you are installing a heated floor, this should be done according to all the rules. Having saved on screed mortar, you will then have to incur additional costs for a new floor.
The optimal height of the cement layer ensures that the new heated floor will withstand unexpected loads of various types.
If you initially plan to place heavy furniture in the room, then when installing the floor, be sure to install a metal mesh. Fiber is added to the mixture when preparing the solution for the same reason: it helps strengthen the screed.
The screed is usually poured from the corner, and then the solution is leveled using a rule. Here you should also take into account the future floor covering. Almost everything decorative materials are laid on an exceptionally flat surface, so leveling the solution must be taken as responsibly as possible. When laying the screed, it is important to prevent the formation of voids, as they will subsequently affect the heat transfer performance of the floor.
When installing the screed, it is important to follow the technology. After pouring, the screed is left to dry. This requires 1-1.5 months depending on the thickness of the layer. All further Finishing work can only be carried out after the solution has completely dried. The finished self-leveling mortar will dry less, but even here you will need to wait the time specified in the manufacturer's instructions.
What other rules should not be ignored? Before pouring the solution heating system pipes are checked under operating pressure conditions. There should be no defects. All defects must be eliminated before pouring cement: repairing a finished floor will be very difficult. The rules for laying the insulating layer must not be violated, otherwise all the heat from the pipes will go into the floors between the floors of the house, and not into the apartment.
The screed for a warm water floor should be made from quality materials. If the cement is caked, then you should not add it to the solution. The quality of cement as the main element of the screed should be at high level. The durability and performance of a warm water floor directly depends on the quality of the materials used in its installation.
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 electric floor manufacturers, a screed made of cement mortar cannot be thinner than 3 cm. When using special leveling mixtures, the thickness can be reduced to 2 cm.
The optimal thickness of the screed for electric heated floors is 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 minimum parameters, please 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.
Disadvantage wet screed is the long drying time of the floor (28 days), 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 completing the 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. In the stove or concrete screed cut out grooves about 2 cm deep. 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.