Types of pouring level
There are minimum and maximum height of the screed of a warm floor in the room. They will all have their own characteristics and subtleties in conducting the installation. By type, we can distinguish the following options for screeding:
- Thin-layer filling. Here it is best to use self-leveling mixes, allowing you to create a screed layer of up to 20 mm. In any case, the distance should be measured from the pipeline level. As a result, the surface will be able to withstand sufficient load, including from placed bulky furniture. The composition of the mixture is such that it does not require the use of a layer of reinforcement. The strength and reliability of the screed is obtained as required.
- Medium-layer. This also refers to the optimal layer of casting, when approximately 50-70 mm from the top of the contour of the pipeline. In addition, a metal mesh is used to create a strong structure, included in the overall thickness.
- Thick layer. No specialist will recommend to perform the filling to a height of more than 15 cm. Yes, and these figures are among the most recent, above which the layer will not carry any effectiveness. In addition to the fact that it will be a screed, as such, often in private construction such a layer performs the role of the foundation of the future structure.
It is worth noting that much will depend on the composition of the solution of the warm floor, all components. When adding crushed stone, there is a minimum threshold of 50-70 mm above the level of the pipeline. But plasticizers, on the contrary, allow you to reduce the layer of filling to 30 mm.
What can be a screed?
Pipes with water or other heat carrier, used for the arrangement of heating, hidden inside the floor construction. The water underfloor heating is assembled, like a pie, from several layers, among which there is a screed designed to protect the main line from mechanical damage and ensure uniform heating of the entire surface.
Types according to the method of application
Depending on the consistency of the substance used for the arrangement, there are wet, dry and semi-dry screed. The first option is performed from available materials. most often it is sand and cement. over, you can try to implement it yourself. you need a little training and effort.
The peculiarity lies in the correct preparation of the mixture and its even distribution. The consistency will be liquid, which facilitates application and leveling.
The dry method is quite simple to install and can be implemented by your own forces. All components can be purchased. manufacturers offer dry backfill of composite materials and ready-made gypsum boards. The filler is to be placed over the entire surface and top it with GFB, which is fixed with self-tapping screws.
To perform the third type of screed will need additional equipment. We are talking about pneumatic blower and other automatic devices. In order to evenly distribute the semi-dry mixture, you need experience in doing such work.
Equipment can be rented. construction organizations provide it for rent. True, without the skills to cope with the work will be difficult. The mix is better to buy ready-made: making it yourself will be difficult due to the unavailability of certain ingredients. Yes, and the correct recipe manufacturers are in no hurry to share.
The choice of arrangement depends on the characteristics of the room, skills and budget. In any case, having made up your mind to make the floors warm, you can’t save on quality. Even the best material can be spoiled by crooked hands.
over, the system is not made for one decade. the costs are justified and will pay for themselves in the coming years. If you invite cheap shabashnikov and not control every process carried out by them, you can end up paying double the price.
Difference in the material of manufacture
To perform screed can be used a variety of mixes and materials. The solution can be prepared independently, buy the dry mixture and mix it, using the manufacturer’s recommendations, or order the finished material, which will be delivered at a specified time.
- Concrete. it can be ordered or made;
- mortar of sand, cement and additional additives to improve the properties of the future coating;
- Ready mix of cement with mineral fillers, such as Ceresit CN 85 and others.
When choosing ready-made materials for screeding, you should be careful to ensure that they are designed for warm floors and strictly follow the recommendations of manufacturers.
For screeding over floor heating in the bathroom, concrete or sand-cement mixture made in appropriate proportions is more suitable. Especially since its recipe can be improved, creating a more plastic mixture, which is most suitable for the arrangement of floating screed.
For this purpose, it is necessary to buy a special liquid. a plasticizer for concrete. This substance is added in the proportions indicated by the manufacturer on the label. It allows you to get a plastic solution, resistant to damage after drying.
You will also need polypropylene fiber. a filler used to reinforce the mixture. With it, you can create a composition that is as resistant to cracking as possible.
It is important to remember that any mixture, except for dry, must be used immediately. Its storage is unacceptable. will begin the curing process. And this can happen after 2-4 hours, if not otherwise stated in the manufacturer’s recommendations.
Peculiarities of layer thickness selection
One of the key points. to choose the thickness of the screed for the arrangement of water heated floor. It is not good if the value is too low, or vice versa. In the first case, the coating will quickly crack all over the surface and simply fail. Yes, and you can not get even heating.
In the second case, too high a layer over the coolant pipe will take a long time to heat up.
In addition, the user will additionally get the following disadvantages:
- uneven heating. strips of heat alternate with cold, especially if the bottom of the pipe with a diameter of 16 mm;
- High material consumption, which results in unnecessary costs;
- a long time for arrangement. a thick layer will dry more than 1.5 months, which is not always acceptable;
- A significant increase in the floor level will reduce the overall height of the room.
It turns out that the choice of the optimal thickness should be approached responsibly. over, if you look at the recommendations of manufacturers of equipment and materials for arrangement of a warm floor system, they advise to make a screed layer of 40-45 mm on average above the pipe level.
The choice of thickness is directly influenced by such factors:
- laying spacing;
- The diameter of the pipe itself heated floor;
- The type of mixture, which is to fill the surface;
- the height of the ceilings in the room;
- floor strength.
With the peculiarities of calculations of water underfloor heating and determining the optimal step of installation will introduce the following article, reading which we strongly recommend.
Given the raw data to determine the parameters of the future layer. And less than 30-35 mm can not be taken, and the maximum limit is 100-120 mm. These are the recommended limits for living rooms.
In the case of industrial premises approach will be radically different. it all depends on their purpose and loads to be withstood. whether visitors will dance, if it’s a cafe, or ride forklifts when it comes to the warehouse at the supermarket. It is already a question of a thickness of 200 mm or more.
popular material for the arrangement of screed is concrete or cement-sand mortar, applied by wet method. Here it is important not to forget about the need to perform expansion joints, which will ensure a quality integral layer over the water pipes.
For this procedure, a gasket of polystyrene foam width of 10 mm. damper. It allows you to get a floating floor, not connected with the walls of the room, so the impact on them has no heating or cooling.
Rules for making expansion joints depend on the characteristics of the room. The most basic requirement. to lay the damper tape of elastic material around the perimeter of the room. It is important to do this before starting the installation of the screed.
Pouring screed technology for a warm electric floor
Screed for electric underfloor heating is done without regulatory or normative documents. But, nevertheless, there are certain rules associated with the work.
The master performing the installation, has to take into account the following:
- Screed thickness under and over the heating cable.
- Choosing the screed installation method.
- The nuances associated with the preparation of mortar and the pouring process.
Properly made screed for a warm electric floor does not crack, provides an even distribution of heat throughout the room, retains its strength for a long period of operation.
The figure above shows a typical screed diagram of water underfloor heating, which is used in recommendations for the creation of in-floor heating systems.
There are several practical issues to note from this example:
- The perfect base in the domestic construction. a rarity. Therefore it is necessary to eliminate gaps and other defects in the floor slabs. To solve the problem will help to create a screed with a thickness of 4-6 cm.
- Fixing the screed pipes of a water heated floor can be done in different ways. Depending on the option chosen, will change the cost of the project, the speed of execution and complexity of work.
- One layer of insulation is quite enough, but to get good results it is necessary to use modern materials.
- Experts recommend keeping the surface temperature of the screed water heated floor at 28 ° C to 30 ° C. But to meet this condition it is necessary to take into account: the step of laying the pipeline, the type of the main screed, the type of finish coating.
From this information we can conclude 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 coordinate with other technical parameters of the heating system project.
If the final coating of the screed water heated floor does not have sufficient strength (linoleum), it is necessary to install an additional layer of plywood under it.
How to Build a Floor. Insulation and Screed
Above the pipes
The thickness when installing a warm floor depends directly on the diameter of the pipes used.
Thin will help to save fuel, but can not provide an even coverage. This will lead to a reduction in the comfort of the use of the warm field and the rapid degradation of the. Too thick reduces the efficiency of the floor heating, which will lead to higher fuel costs.
Many factors influence the choice of the optimal thickness:
- The thickness of the pipes used;
- the quality of the floor base;
- The required temperature in the room;
- the height of the ceilings;
- type of screed.
The minimum thickness of the screed over a warm water floor of 2 cm can only be obtained by using 1.6 cm pipes. This will require the use of special mixtures and cover the floor with ceramic tiles. Otherwise the floor will quickly fall into disrepair.
Cement mortars can not be poured so thin. The minimum allowable thickness of 4 cm. Achieve it is possible with the use of thin tubes and flat surface. Surface irregularities can increase the thickness of the screed up to 7 cm.
In the case of semi-dry screed, the minimum thickness, using the thinnest pipes, reaches 5 cm.
In some cases, it is possible to lay pipes without first making a screed. This occurs when:
- wooden base, which will not be able to withstand the concrete load;
- in the case of low ceilings;
- In the absence of experience in pouring screed;
- in the absence of time for curing coating (screed qualitatively dries about 1 month).
Installing a water floor without screed has the following advantages:
- rather simplifies the installation process;
- Reduces the load on the floor;
- The height of the room is reduced significantly less;
- even without noise insulation, it reduces the penetration of noise into the room;
- Speeding up the installation process by eliminating certain steps (rough casting and drying);
- Significantly reduces the cost of installing underfloor heating.
However, this option has disadvantages:
- rapid cooling of the room when turning off the system;
- in the absence of quality waterproofing is possible slight deformation due to the impact of moisture.
Sometimes the screed is replaced by covering with polystyrene boards.
There are no restrictions on the thickness (maximum) of the screed. This is where it makes sense to be guided by common sense.
Most often the thickest screed is used:
In the first case, you want to perfectly level the floor rough screed, and then mount the heating pipes and pour screed.
It is believed that for a warm floor screed thickness greater than 17 cm is not rational.
The most optimal overall thickness of the screed 4.5-7 cm creates a good coverage of the pipes and is able to withstand heavy loads. The thickness of the screed over the pipes in this case is 2.5-3 cm.
The process of installation of underfloor heating is quite simple and does not require any experience. It is quite possible to install it yourself.
You can perform wet, semi-dry and dry screed. In some cases, the installation of water pipes without screed directly to the floor or polystyrene boards is used. Nevertheless, the most effective is considered the installation of pipes for water floor screed. This method allows maximum expenditure of generated heat on heating the room, heating uniformity and a smooth decrease in temperature in case of turn off the heating system.
Before laying the floor coverings it is necessary to check the quality of the screed. 2 weeks after the filling it is necessary to dry the screed with a film, for maximum moisture absorption. In about a month the mortar, which covered the pipes, will completely harden. The finished surface should be even, the color should be uniform, chips and cracks are not allowed. When tapping the surface with a wooden bar there should be the same ringing sound.
It is important to properly perform the pouring of the concrete mixture of the required height before and above the installation of pipes, so that the result is pleasing for many years.
The difference from the usual screed
Conventional screed is somewhat different from the screed for a warm waterborne floor. The fact that in the latter form of it must necessarily be arranged expansion joints. Even in rooms with a small area up to 10 m 2 must be present. In addition, a cushioning strip must be installed along the bottom of the wall. This is all necessary to compensate for the thermal expansion of the concrete screed during the operation of the underfloor heating system.
For large areas of the premises, additional joints are also made. Here the function of compensation is performed in addition to the tape and thermal insulation for the walls. In this case the thermal insulation must have a thermo-repellent foil.
Installing underfloor heating
How best to lay an electric underfloor heating depends on the type of heating elements. For any underfloor heating, it is important to ensure that the heating elements do not touch the thermal insulation. To do this, they are separated from it with reinforcement mesh.
Installing the cable
Choose the location of the thermal controller. It is mounted at a height of more than 30 cm from the floor. If the device is a hidden type, you have to make a hole in the wall for it, as well as for the power supply and temperature sensor wires. In areas with high humidity thermostats are not installed. They are carried into the adjacent rooms.
A mounting tape is attached to the foundation at intervals of 50-100 cm, with an indentation from the walls of 30 cm. A marking is made on the floor, taking into account the indentation from the furniture. The distance from the walls is 10 cm, and from pipes and radiators. 15 cm. Then the heating cable is connected to the power cable with a sleeve, and then. mounted on the mounting tape.
The power cable is led through the groove prepared in the wall to the thermoregulator, and the heating cable is laid according to the scheme. Thus the radius in places of a bend shouldn’t be less than 5 cm. Curves are made smoothly, without unnecessary tensioning. Fixation is performed with clips or masking tape. No touching or crossing of coils is allowed. The overlap must not be less than 8 cm. All the distances are strictly followed in accordance with the scheme that is developed in advance.
Installing the cable underfloor heating with an indentation
The temperature sensor is freely placed inside the corrugated pipe along with the supply wires. Seal the heating cable at one end with a stopper to prevent cement slurry from getting inside. A pipe with a temperature sensor is placed between the coils of the cable at a distance of at least 50 cm from the wall and is laid in a prepared hole, and then the wires are connected to the thermostat.
After installation and wiring, check the electrical resistance of the heating cable and the sensor. Values should differ from the passport values by less than 10%.
Mortar or filler is plugged in the gaps, and after curing, you check the functionality of the underfloor heating system.
Installing the heating mat
Heating mats are easier to install as the cable is already fixed to a mesh backing that only needs to be spread out on the base. In places of turn the grid is carefully cut without violating the integrity of the cable. In areas where there are obstacles, the grid is removed and the cable is laid with the observance of the distance from the neighboring coils within 6-8 cm.
Heating mat pivoting when laying
An important advantage of heating mats is their thin thickness, which makes it possible to fill a thin screed or to install the heating elements in a layer of tile adhesive. Then the thickness of the fill will be only 8-10 cm, which will not take up unnecessary space in the room.
Installing a rod floor
Infra-red core heaters look like a rope ladder. They contain transverse heaters and 2 longitudinal connecting wires that supply power.
The core roll is rolled out across the floor, starting from the thermal controller. At the points of turning, the connecting wire is cut, and then the ends must be rejoined with a piece of wire. This reduces the reliability of the underfloor heating. It is reasonable to choose rolls of a suitable length. Then there will be no need to cut anything.
After laying in the insulation the windows are cut out in a staggered manner for better adhesion of the screed to the base. All joints must be carefully insulated.
The main points
On what depends the quality of the filled screed and its lifetime? There are four main parameters.
When installing underfloor heating it is important to properly put insulation material. Its task is to guide the heat into the room. Thermal insulation acts as a special barrier that does not allow the heat to go down. in the floor slabs. The insulation layer is usually made of two complementary materials: foam plastic and reflective material are suitable for this purpose. A 3 cm layer of foam shields the heating elements from the cold of the floor slabs, and the reflective material works to transfer the heat into the room.
An important role is also played by work on the surface reinforcement. For this purpose, a metal mesh, which is then attached to the pipes themselves. Sometimes a second layer of mesh is also attached to them, which allows to strengthen the future construction.
Why do we need to reinforce?? Under the screed is a soft material that is easily deformable. If you miss work on the reinforcement, then the deformation processes of the lower layers of the screed will quickly crack.
A mandatory part of the preparatory work is the laying of damper tape, the purpose of which is to resist deformations of the screed caused by temperature conditions. Because of the deformation of the cement coating can damage heating elements. Since their repair appears to be a very complex and time-consuming process, it is not recommended to neglect the work on laying the dampener tape.
Installation of damping tape.
important is the composition of the mixture for filling the screed. The solution must be prepared in strict accordance with the instructions: all components must be added in certain proportions. The mechanical strength of the entire floor heating system depends on the thickness of the screed, as well as the main parameters of its performance. The height of the cement layer should be optimal for the specific room: here it is important to consider the necessary level of heat transfer, efficiency and responsiveness to temperature changes. The thicker the screed, the greater heat capacity it has. this is logical. But there is a disadvantage here, which is that when the screed is too thick, it becomes problematic to regulate the temperature.
Cement screed can be made by your own hands, but if you make it too high, it will take a very long time to heat up. Give out heat such a floor will also be longer, but in all 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 layer of cement, the greater the likelihood of overheating. And if the screed overheats, the coating will simply crack and all your hard work will be wasted.
Defects in a thin screed from overheating.
Screed thickness also performs a protective function in relation to the pipes laid below, so it must fully cover them. If the size of the cement layer will be selected competently, the warm floor will warm evenly and serve you for many years.
The recommended thickness of the warm floor in the apartment should not be more than 10 cm. in non-residential facilities may be greater: the norm for warehouses, retail pavilions and other similar facilities is 20 cm. The total thickness of the screed must hide all the heating elements, its height may vary depending on the diameter of the pipes used. As a minimum benchmark specialists call the figure of 6.5 cm.
Screed thickness in the living space should be in the range of 6.5 cm 10 cm.
If you consider the thickness of the screed directly from the pipeline, then this value can be in the range of 2-5 cm. Provided that between the floor base and the pipes before laying thermal insulation, as well as using reinforcing mesh, you should be guided by a minimum of 3.5 cm.
If you did not use a metal mesh to reinforce the structure, the thickness of the top layer of screed should be increased by 1-1.5 cm. The minimum height of the screed above the pipes is automatically increased to 4.5 cm. Screed of this thickness is the best option, as it will warm evenly across the entire surface of the floor.
The device of a cement screed on a warm floor
A underfloor heating is made up of several layers. Each performs its own function, but together they work as a single system. The screed for underfloor heating is an important part of the system. In order to fill it correctly, you need to know the technological features of installation and the layer-by-layer composition of all types of underfloor heating.
A visual structure of underfloor heating