Minimum thickness of screed for electric underfloor heating. Installation of a water heated floor in a concrete screed

The article was prepared with the participation of specialists from LafargeHolcim

The “warm floor” heating system is popular among both city residents and owners country houses. This is due to the fact that, thanks to the optimal vertical temperature distribution (from floor to ceiling), it helps to create comfortable conditions in the house. One of the options for a heated floor can be an electric one, with a heating cable laid in a sand concrete screed. Many users have questions about how to properly make such a system, avoid installation errors and pour a reliable and durable sand-concrete screed. In this article, with the help of a specialist from LafargeHolcim, we will tell you:

• How to choose the right “pie” of an electric heated floor with a heating cable.
• What should be the thickness of a sand concrete screed when using a heating cable.
• How to choose high-quality sand concrete and cement.
• How to make your own mortar from sand and cement.
• Why is fiber added to sand concrete?
• The main stages of work on pouring sand concrete onto a heated floor screed with a heating cable.

Features of electric underfloor heating with heating cable

Maria A Member of FORUMHOUSE

I have a house with an unheated basement. Overlap - concrete plates. I want to make an electric heated floor on the first floor in the kitchen and hallway under the tiles. I thought: what kind of warm floor should I choose, what layers does the correct “pie” consist of? Is it necessary to install insulation under a warm floor and what kind? How to properly make and fill a screed.

To answer these questions, you first need to understand the types of electric heated floors.

1. Film heated floor. It is laid directly (“dry”) under the final finishing floor covering - laminate, carpet or linoleum. Among the advantages, we note: the minimum thickness of the system and high installation speed. Disadvantages - such a warm floor cannot be placed under tiles in “wet rooms”, because the film is afraid of moisture and aggressive alkaline solutions - tile adhesive or sand concrete-based screed.

The finished floor covering (for example, laminate) must be certified for use with a heated floor system and allow heating.

2. Heating mats (thermomats). This ready product with a certain, calculated cable pitch, in durable insulation, laid in a mesh. This simplifies the calculation of the power of the heated floor and reduces the time for installing the entire system. Most often, heating mats are chosen when it is not possible to increase the height of the floor and pour a full screed, and the mats are mounted directly into the layer of tile adhesive.

Heating mats are produced with a certain width and multiplicity of heating area 0.5 m², 1 m², 2 m², etc.

For example, for dry, insulated rooms and as a heating system additional to the radiator, the power of thermomats is selected at the rate of 120 - 140 W/m². For the main heating system - at least 150 W/m². For rooms with high humidity and non-thermally insulated rooms - 180 - 200 W/m².

The power of the heating system is calculated based on the heat loss of the house, which it must compensate.

3. Warm floor based on a heating (single-core or two-core) cable in a shielding braid, which minimizes the level of electromagnetic radiation.

A heating cable is usually cheaper than a thermomat. Using a cable, you can vary the power of the floor heating system by one square meter, adjusting the cable laying pitch on the mounting tape. Unlike heating mats laid in thin layer(about 5 mm) of tile adhesive, the heating cable is embedded in a screed made of cement-based mortar (sand concrete) 3-6 cm thick, which accumulates heat well (the inertia of the system increases).

The thicker the screed, the longer it takes to cool, but also the longer it heats up, because... a heating cable laid in a sand concrete screed needs much more time to completely warm up the room and the floor covering itself. When using heating mats located directly in the adhesive layer under the tile, heating of the coating (the system reaches operating mode) occurs much faster.

Important: When choosing a heated floor system between thermomats and a heating cable, you should remember that the height of the floor (the thickness of the entire structure when using a cable) will be raised by at least 4.5 cm, taking into account the thickness of the screed (about 3 cm), tiles (1 cm) and tile adhesive (0.5 cm). You can turn on a warm floor made from heating mats within 10-14 days after laying the tile adhesive. Using heating cable and sand concrete screed, this period increases to 21-28 days, because The sand concrete screed must gain the necessary strength.

Correct structure of the system (“pie”) of a heated floor with a heating cable in a sand concrete screed

The “pie” of an electric heated floor with a heating cable depends on the characteristics of the heated room and the magnitude of its heat loss. To reduce heat loss, the base on which the heated floor is mounted must be well insulated. Otherwise, the low-temperature heating system will heat the owner’s room, and at the same time the neighbor’s ceiling (in a city apartment) or, through an uninsulated ceiling, an unheated basement or loggia.

At the stage of choosing the optimal “pie” for electric heated floors, users have a lot of questions.

Maria A

I'm wondering how to properly insulate a heated floor. Is it necessary to roll out the insulation from foamed foil polyethylene over the screed, and is it necessary to lay the insulation under the screed?

beard1965 User FORUMHOUSE

I was planning to make a warm floor. I’m thinking of insulating it with extruded polystyrene foam, rolling out penofol on top, and then laying a heated floor and laying porcelain tiles on a solution with the addition of a plasticizer.

Practice shows that the use of foamed thermal insulation with a foil layer in a heated floor system is one of the most common mistakes. Using this material, users believe that the foil layer will become reflective thermal energy up. In fact The reflective effect of the foil does not work in solids, i.e. V concrete screed . The effect of heat flux reflection appears only in the presence of an air gap between the foil layer and finishing. Classic example- insulation of the sauna, when lining is mounted on the walls on the sheathing, and a gap of 2-3 cm is maintained between the foil and the wood.

Besides this, the usual foil is destroyed (dissolved) in the alkaline environment of concrete mortar or glue, and the foamed (soft) insulation shrinks (compacts) over time under the weight of the screed, which leads to the appearance of cracks.

In a heated floor system, you need to use the so-called. multifoil - special material, in which the foil layer is protected from negative impact alkaline environment of concrete with a layer of polyethylene.

Such a substrate for heating cable prevents direct contact of the heating element with the insulation(does not allow the cable to be pressed into the thermal insulation, which will cause its local overheating) and does not reflect, but distributes heat evenly in the screed. And, thereby, minimizes the so-called. “zebra” effect (uneven heating of the surface of a heated floor, when warm areas alternate with colder ones).

Hence, the optimal “pie” for a warm floor with a heating cable is as follows:

• Insulation is laid on a flat base, free of dirt and dust. Optimally - EPS (extruded polystyrene foam) with a thickness of at least 2 to, optimally, 3-5 cm.
• A damper is installed along the perimeter of the walls. edge tape, which compensates for the thermal expansion of sand concrete screed with heated floors.

• Multifoil (if used) or metal mesh is placed on the insulation, which also prevents contact of the cable with the insulation. Cell size: 25x25 mm or 50x50 mm. Rod diameter 1.6-3 mm.

• A mounting tape is rolled out from above and attached to the mesh. plastic clamps. On the mounting tape, maintaining a laying step (on average 10-12 cm), it is easier and faster to attach the heating cable, fixing it in locks, but you can do without it, in this case the cable is attached to the mesh with plastic clamps.

The heating cable laying pitch (heated floor power per 1 sq. m.) is calculated based on the area of ​​the room and the length of the cable.

In order for the metal mesh to work (reinforce the screed while being in the thickness of the sand concrete, and not under it), you need to lift it above the thermal insulation layer, using stands or small pieces of EPS. Or, as an option, lay a second layer of mesh on the cable for greater reinforcement.

• After laying the heating cable and the temperature sensor, which should be located in the “body” of the screed, the system is checked for the absence of visible damage to the cable and the functionality of the electrical part is tested. Next, the beacons are placed and a screed with a thickness of 3 to 6 cm is poured.

Anna Ruzhitskaya

The screed is poured from the wall opposite the entrance to the room. It should be remembered that when leveling high-friction or molded ties, do not use needle rollers, which can damage the cables.

The nuances of choosing high-quality sand concrete and cement in bags and the features of pouring screed

To the stage of pouring the screed so-called. “wet type”, some developers do not treat it responsibly enough, making mistakes when choosing a ready-made sand concrete mixture M300 or violating the proportions when self-cooking solution. For example, they use a lot of water to give the mixture greater mobility and increase its life time during the laying process, which leads to a decrease in the strength of the screed and an increase in the likelihood of cracks.

Maria A

I want to make my own mixture for pouring sand concrete screed. Questions: how to choose the components of the mixture and what additives are best to use?

Another common question from users of the portal: what is better - to use ready-made sand concrete or prepare a mixture of high-quality cement in bags yourself.

Anna Ruzhitskaya

In terms of convenience, reliability and stability of the result, it is better to use ready-made dry mixtures (sand concrete). For these mixtures it is regulated maximum size sand grains, i.e. In production, seeded sand is used, the cement-sand proportions are strictly maintained, and the crack resistance parameters of the hardened mortar are checked.

Please note that mixtures from trusted manufacturers undergo thorough quality control at all stages of production and meet all GOST requirements. The mixture, precisely measured by weight, is delivered to the site in secure packaging- bags 40 kg.

For a screed device according to warm floor It is better to use a “wet” screed.

A semi-dry screed differs from a wet screed in that it uses a small amount of water necessary to mix the cement-sand mixture.

Therefore, it is difficult to distribute and compact the semi-dry screed efficiently, taking into account the installed underfloor heating system - mounting tape and thermal cable. When the density of the cement stone decreases, due to the formation of air cavities, the heating efficiency decreases, because The thermal conductivity of the screed decreases.

When preparing sand concrete for screed yourself, special attention should be paid to the quality of the ingredients. The sand should be coarse, sifted, without clay and other harmful impurities (shells, plant remains, contamination with petroleum products, etc.). When choosing the proportions of the mixture, you should remember that sand can have different humidity levels, which affects required amount mixing water.

When working with ready-made dry mixtures, pay attention to the availability of information with recommendations on basic recipes and exact proportions for preparing the main types of solutions. This simplifies the work of builders.

Promote quality characteristics sand concrete and screed can be done using plasticizers and fiberglass.

Recommendations for the use of plasticizers and fiber when pouring sand concrete screed

When using a plasticizer, which is added based on the mass of cement, and not the weight of the finished solution, the required amount of mixing water is reduced, because the additive has water-reducing properties. The workability and plasticity of sand concrete also increases. The composition stretches well along the beacons, compacts and smoothes out.

1. Pour the dry mixture into a concrete mixer or working container if the work is done with a mixer.
2. Add a small amount of water (1/3 of the recommended amount) and mix thoroughly.
3. Lightly moisten the fiber and carefully insert it into the mixture. Mix thoroughly until the fiber is evenly distributed throughout the solution. When mixing, no “hedgehogs” should form from the fibers.
4. Measure out the amount of chemical plasticizer recommended by the manufacturer and mix it with the second third of the mixing water. Add to the solution with constant stirring.
5. After 1.5-2 minutes of mixing, add additional water to achieve the required mobility. Stir for another 30 seconds.

The use of fiberglass reduces the labor costs associated with screed reinforcement metal mesh, the quality of the screed increases and the likelihood of cracking decreases.

Before using polypropylene fiber and plasticizer additives, you should familiarize yourself with the manufacturers' recommendations, which are indicated on product packaging, regarding dosages and precautions when working with these components.

Also required proper care behind the freshly laid screed. To retain moisture and prevent its rapid evaporation from the surface, the freshly laid screed must be covered with plastic film or drafts must be eliminated, and periodic moistening must be provided (2-3 times a day during the first week after installing the screed). This ensures uniform strength gain of the screed without causing internal stresses leading to the formation of cracks. Before laying the finishing coating, the surface of the screed must be dust free and cleaned of dirt.

There is a discussion on various topics on the portal.

The video shows the nuances of building a house from warm ceramics and the features of installing a heated floor.

This work requires responsibility from the master, since the quality of the work determines how the floor will look externally, as well as how well the system will cope with its main heating functions.

Screed functions

The underfloor heating system is constructed of several layers, each of which has its own purpose. The screed for warm electric and water floors is an integral, connecting link of the entire system, on which the efficiency of heating will depend. Therefore, you need to know how to properly pour screed under a heated floor.

The screed performs a number of functions:

1. Firstly, it acts as protection against any mechanical damage, and if we are talking about electrical heat field, then here it also does not allow air to penetrate into the system;
2. Secondly, the screed acts as a kind of floor radiator, quite large in area, it is responsible for evenly distributing heat not only over the surface of the floor, but throughout the entire room;
3. Thirdly, it is a flat surface, so the main coating will lie on it well, without any protrusions or dents.

Screed for heated floors

By by and large, a screed under a warm floor is a layer of concrete that is applied on top of the rough floor covering. A standard screed involves its repeated installation, with each layer having its own purpose:

1. The first layer is applied to the rough surface ( rough screed). It is necessary to level the floor. This point cannot be skipped; leveling is carried out on any surface.
2. The second layer is done on thermal insulation. It is necessary to create a base on which the floor heating cable will be installed in the future.
3. Last layer covers the heated floor and ensures heat distribution over the surface. Plus, the top coat is the basis for the final coat.

The screed under the heated floor plays a big role. True, it makes the coating thicker and the height of the room smaller, which often becomes the reason for failure to install a water system. The electric floor does not reduce the already usable space so much.

Mixture composition

Opinions differ as to what type of screed for heated floors is best to use, so there is no definite answer. Some prefer, it contains dry materials. You don't have to wait for the solution to dry. Others choose wet screed, and such users are the majority.

To install a heated floor, you can choose one of the proposed mixtures:

1. A solution of sand and cement is mixed in a ratio of 1:3, respectively. This solution can be used for screeding water and electric floors.
2. A concrete solution containing fine-grained filler. Experts say that such a screed is the most suitable option for water structures, the surface will not crack.
3. Self-leveling mixtures have found their active use in pouring electric heated floors; they are very easy to work with when screeding a heated floor with your own hands.
4. There are also special mixtures that are suitable only for heated floors and no other heating systems. They vary in composition; in specialized stores you will find many different mixtures. Tile adhesive is used during installation.

There are other proportions; they are used depending on the type of floor that is planned to be made. When, after the screed has hardened, the laying of parquet, tiles or laminate begins, then for one share of cement it is necessary to add five shares of sand, as well as water (0.7 shares).

If you plan to use soft materials as a floor covering, for example, carpet or linoleum, then the composition of concrete for screeding a warm water floor can correspond to the following values: cement 1 part, sand - four and water - 0.7 parts.

The addition of crushed stone implies the following proportions: cement - 1 part, sand - 3 parts, crushed stone - 5 parts. As a rule, water is added to half the cement weight.

To reduce time costs, ready-made mixtures are used. How to use them is written in the instructions included.

To make your flooring as durable as possible, use reinforcing mesh, and to make the compositions more resistant, microfiber can be added to them.

Whatever mixture you choose, in any case, when screeding a heated floor, strictly observe all proportions.

Thickness

During the work process, many users ask the question: what should be the thickness of the screed for a heated floor?

And this parameter is very important; there are clearly described rules in this regard, the observance of which is beyond doubt:

1. The thickness of the screed over the entire area of ​​the room should be identical. Only in this way will uniform heating and high heat transfer be achieved. Under no circumstances should screed be poured under a heated floor until all bulges, pits and folds have been eliminated. rough floor.
2. It is important that the coating is not too thin. Insufficient thickness will affect the uneven heating of the floor, the amount of accumulated heat will be negligible and the surface will cool down very quickly. Also, a thin layer can cause the material to crack.
3. It is also unacceptable to use too much thick layer, since in such a situation heat, on the contrary, will be retained inside the structure.

Only maintaining balance and precise proportions will allow you to achieve high heating efficiency.

What is the optimal screed thickness for a warm water floor? Fill at least 5 cm from the thermal insulation layer. Otherwise, cracks will appear in the first operating season. For electric cable system this is 2.5 cm, for - 1 cm.

How to make a screed under a warm floor with your own hands

In order for the procedure to be successful, just adhering to the styling technology is not enough. Worthy of special attention are organizational stages, so initially you need to prepare the base well.

This can be done in several ways:

1. The base is made of floor slabs. Initially, it is necessary to dispose of all unnecessary items from the surface and clean it thoroughly. After this, you need to lay soil on the surface of the slab. deep penetration or concrete contact. For processing, use a regular paint roller.
2. Base from and heating elements. Here you also need to clear the surface of everything unnecessary and get rid of any contaminants.
3. The base is made of earth. The first thing to do is cover the ground with sand, 100-150 mm thick. Next you need to spread waterproofing material, most often preference is given plastic film. Already on the film you need to place a reinforcing mesh. And the finish line is pouring the concrete mixture.

Many users do not know which mesh to use for underfloor heating. Everything is simple here - for a water heated floor you need to choose a special metal one (reinforced) with a cell size from 50x50 to 100x100 mm. For electric, you need a polymer mesh (cell size - 20x20 mm).

Next we move on to the stage of installing beacons. You need to pay special attention to this process and be extremely careful, since the evenness of the floor in the horizontal plane will depend on your care and accuracy in installation.

But it is not necessary to install beacons.

Laying technology without using beacons is popular in situations where pouring is carried out cement-sand screed in small rooms.

It is simply aligned by the insertion rule. Laying the screed starts from far corner. The finished mixture must be poured onto the floor and leveled. Once it is hard, a thin layer of self-leveling flooring is poured. They spread over the surface, and as a result you get an even and durable final coating.

Beacons are installed for pouring floors in big houses or apartments where it is very difficult to determine the horizon level by eye. The beacons are a profile with an edge size of 10 mm. During the installation process, a step of 500-700 mm should be maintained.

It is fixed on the solution. Initially, you need to mark out the room; you need to place it along the long wall. laser level, and only then mark the installation horizon line on it.

After all the above steps have been completed, the first beacon profile is placed on the solution.

It is aligned along the line on the wall. The remaining beacons are installed according to the specified step. The horizon from the first profile is transferred using a building level. At the end, you need to make sure that all the beacons are present and let them stand for a day, during which time the solution will harden.

Next stage- filling the screed.

At this stage, we begin to frame the room around the perimeter. To do this you need to get one. This is a special polymer; you need to glue the walls at floor level. The tape forms a buffer section between the screed and the enclosing structures.

Damper tape is a very important component; it does not allow heat to escape through the walls, and also acts as protection for the screed from cracking in the event of a drop temperature conditions.

After the reinforcing mesh is laid, you need to make sure that the entire system is functioning. Especially when it comes to a water field. If there are leaks in it, then the floor covering urgently needs to be redone.

Next, you can pour the cement-sand composition onto the heated floor. It is important that at this moment the room temperature is between +5-25°C. The mixture must be poured from the far corner. Once the solution is on the surface, you need to level it well.

Once the filling is finished, you need to wait several weeks until the screed is completely dry. You can cover the floor with film.

Another important stage is the device expansion joints. They are needed to level out changes in screed size due to temperature fluctuations. They should be cut a day after pouring the screed in increments of 1500-2000 mm or for a room area of ​​no more than 25 m². After this, the seams need to be filled with sealant and sealed with mortar.

A day after the main work is completed, you need to remove the beacons and seal the seams using cement-sand mixture.

The screed is ready and already on such a strong and reliable base you can lay any finishing coating.

By observing all the requirements and laying the screed accurately and without errors, you will receive an effective source of heating. If you are not sure that you are able to cope with this process yourself, you can always use the services of professionals who will quickly and efficiently complete the work.

When planning to build a house or renovate an apartment, anyone modern man think about how to make your home warm. Warm screed floors have long ceased to be an attribute of luxury and have become commonplace, firmly entrenched in the construction market and have proven themselves to be the best. Despite the fact that they all seem to have the same goal - to bring heat into homes, the heating systems are still different. How to do right choice, if you are not an expert?

To begin with, it is worth deciding on the heating system. In a global sense, all systems can be divided into two types: electric and water.

Electric heated floors carry out heating due to the heated cable laid in the screed. The use of such systems is effective, but limited, mainly for local heating. As a rule, these are mats or cables. We should also consider infrared heated floor systems. They can be represented by film models or structures made of carbon rods. However, all heated floors electric type have the same properties:

• Thermostat required
• Grounding and thermal insulation required
• Place only on a dry base.
• Reliable and durable

Such systems are usually used in apartments. They are mounted under the tiles and serve perfectly as additional heating. IN country houses and cottages give preference to water heated floors. A properly installed water system can completely heat your home, which will help you save significantly on energy bills. Heating of the living space will occur due to circulation hot water through pipes. This is one of the comfortable and economical options heating the house. The price of components and installation is slightly higher than when choosing a radiator heating scheme, but these costs will more than pay off during operation.

What is a water heated floor?

If with electrical systems Everything is more or less clear, what is a water heated floor? Everything is quite simple here too. This is a heating system consisting of pipes embedded in the floor screed through which water circulates. Heating a room with such a system will require much less energy consumption than an electric floor.

Types of water heated floors

The design of the water floor is divided into two types: concrete and flooring. Concrete system involves filling the screed. The flooring system is used without pouring and can be installed in wooden houses. Key element– a plate made of aluminum or galvanized with a recess in the middle. The pipe fits securely into the groove, and the side wings dissipate heat instead of a screed.

In general it will be multi-layered:

• Subfloor, concrete or wood.
• Waterproofing. This includes the installation of a damper tape, which will protect the joints of the walls with the base and provide a technological gap.
• A layer of thermal insulation.
• Water floor design.
• Concrete screed, if necessary.
• Clean floor covering.

Steps for laying heated floors

So, let's consider installing a water floor in a screed. This process is labor-intensive, but fascinating, and you can cope with it either independently or with the involvement of specialists.

Design

It's always worth starting any construction work With the project, the floor is by no means an exception. It is important to calculate the required heat transfer, laying pitch, and pipe length. In short, choose the right layers of the pie and calculate the financial costs. It is at this stage that you need to decide on the final floor covering, whether it will be tiles or laminate. Some calculations depend on this, for example, pipe pitch.

Preparing the subfloor

When the design is completed and all calculations have been made, you can begin preparing the rough surface. Professionals advise starting from the end. That is, first prepare the manifold cabinet, install it in the proper place, and connect the main pipelines. To groove the walls for laying wires in the case of automation. The rough surface must be clean and smooth. Floor level differences should not exceed 5mm. Otherwise, unevenness will lead to the formation of air pockets, which in turn is fraught with fluctuations in hydraulic resistance.

Waterproofing

Waterproofing is a simple and inexpensive procedure. However, it should not be neglected. Thermal insulation properties insulation directly depend on operating conditions. Even a small amount of moisture will not affect it better side. The market is replete with various waterproofing materials, and anyone, even the most demanding builder, will certainly find something to suit their taste and budget. Even regular film will do. At the junction of the floor and the wall, it is necessary to stick a damper tape with a thickness of 6 to 12 mm. It will provide the necessary gap and protect the junction of the floor and wall.

Insulation

Polystyrene foam with a density of at least 30 kg/m3 can be used as insulation for installing a heated floor in a screed. The thickness is calculated at the design stage. The question is serious and important. If the insulation thickness is insufficient, heat loss will occur and you will have to overpay for electricity. And overpaying for unnecessary thickness is not at all professional. From practice, a minimum of 5 cm thick insulation should be used. On the ground floor, even thicker is better.

Laying heated floor pipes

Methods for laying out floor heating pipes

Only now, after careful preparation, can you begin installing the pipes. They can be fastened in any way, laid on a mesh, polystyrene foam, or secured with anchor brackets. It is worth sticking to the snail styling method. Maximum length loops 80 meters. In places where pipes accumulate, it is worth using a casing or insulation. Connect to the manifold in the cabinet and make sure nothing is mixed up. It is better to label each outlet indicating the pipe diameter.

Trial

After laying and connecting pipes to the collector outlets and before pouring screed or installing heated floors, it is necessary to check the system.

Important!!! do not confuse supply with return

After turning off all the taps, a pressure of 6 atmospheres is injected and a visual check is made to see if there are any leaks or pressure drops.

Filling the screed

Cement-sand mortar or a semi-dry mixture is perfect as a floor, which cannot be said about concrete-crushed stone or gravel mixtures. Minimum thickness The screed should be at least three centimeters from the top edge of the heated floor pipe. The pressure in the pipes must be at least 6 bar. After three days it can be reduced to working value.

Important!! The screed should dry naturally.

It will be possible to supply water to the system no earlier than 28 days after pouring the screed. If you do not allow the screed to dry on its own, cracks may appear. It will be unpleasant to understand that colossal work is spoiled by banal impatience.

Equipment setup

Distribution manifold for underfloor heating with mixing unit

After the screed has hardened, it is necessary to install the heated floor equipment. An indicator that everything is working correctly is the data from the flow meters. If the numbers on all return pipes are the same, then everything is functioning correctly and the system is normal. In the case of system automation, installation of thermostats, connection of servos and controllers occurs precisely at this stage. Before the finished floor is laid.

Finish floor

After all of the above, you can proceed to the last, final stage - laying the finished floor. What it will be like is decided at the time of design. Change anything to last stage undesirable. It is important to observe all the points involved in the design. Only then will it work out in the end correct system, which can warm your home for years.

Warm floor under tiles and under screed. Who cares?

They often ask: “is it possible to install a heated floor under tiles, and not in a screed?” It is important to understand that under the tiles they are most often installed different kinds electric heated floor. They create nice effect heated floor, which is pleasant to walk on. But such floors cannot replace the main heating system and will only be a pleasant addition.

If you want to use a heated floor as the main heating system, you will have to hide the cables or pipes completely in the screed. The screed will act as a battery and heat distributor.

Let's summarize some results. A water floor is ideal as the main heating system for a home. It is economical and unpretentious in operation. Built into the screed, solid and reliable, it will bring warmth to your home. You can handle the process of installing and setting up equipment yourself, without the expensive help of professionals.

An electric heating system is more appropriate in apartments, directly as floor heating. She can't heat a whole house. In addition, the costs of paying electricity bills are unlikely to please you. Make your home better, and we will show you how to do it right.

The installation of a heated floor screed has its own characteristics. When performing work, you should take into account that the quality of the screed determines durability, attractiveness, operational properties floor covering. The material will not wear out quickly on a flat surface, but if the base under the coating has bumps and potholes, the floor will quickly become unusable. The base must be perfectly smooth, without any defects.

Work on forming the screed will take place quickly and in an organized manner if workers are provided with a set necessary tools. You need to take care in advance of purchasing everything you need to create a screed. During the work you will need the following tools:

• as a rule,
• building level,
• wire cutters,
• chop cord,
• sharp knife,
• the wire that will be needed to fix the beacons,
• electric hammer drill,
• Master OK,
• solution tank,
• screwdriver,
• grater,
• shovel.

Materials for screed

The screed will meet the requirements and perform its functions well if mixed correctly cement mortar. But you must first purchase the required materials for it. You can also purchase ready-made dry mixtures and dilute them with water in accordance with the instructions that come with them from the manufacturer. But a screed made from dry mixtures costs more than concrete.

If you make cement mortar yourself you will need:

• 50 kg of cement from M400 and above;
• 200 kg of sand, fraction 0.8 mm;
• water 5 buckets of 10 liters each, you can add a little less so that the solution does not turn out to be very liquid, and if necessary, add more required quantity liquids;
• plasticizer ( liquid soap) for the elasticity of the screed, it is recommended to add 150 grams of plasticizer;
• polystyrene foam boards to create a thermal insulation layer;
• metallic profile 20x40 are used as beacons.

When we make a classic cement-sand mortar, first pour water into the concrete mixer. Its quantity is calculated based on the amount of cement. If 3 buckets of cement are used, then add 3 buckets of water. To prevent the solution from turning out liquid, leave a little water. Pour out the rest of the water after pouring all the ingredients into the concrete mixer.

Drawing the horizon

We measure 1.5 m on the walls and draw a horizontal line around the perimeter. For accurate measurements, we use a building level. We find the lowest place and the highest on the floor in this way: we weigh the distance to the base from a horizontal line and draw a line that will indicate the upper level of the screed.

The main stages of creating a screed for a heated floor system

Concrete screed does not require significant costs, therefore it is popular among both professionals and individuals. But when working, you need to take into account some nuances. The solution must be used within 1.5 hours. You cannot fill half the room and leave the solution for another day to fill the second half of the base. The entire floor must be poured at once. Work on forming the screed should be carried out at a room temperature of +5 to +25 degrees.

We form the screed in the following sequence.

1. Prepare the base. We clean the premises thoroughly. We place a waterproofing film on the surface of the base. You can purchase a special solution for waterproofing. We lay polystyrene foam boards for thermal insulation. We place a reinforcing mesh on the heat-insulating layer. According to the diagram, we place the pipes of the underfloor heating system.

2. On the walls we fix the dowels along the line.

5. Damping tape is laid around the perimeter. It prevents thermal deformation of the screed.

6. Mix the solution. The last component is liquid soap. We add the plasticizer extremely carefully to prevent its excess, otherwise it will lead to slow hardening of the concrete mass.

7. Pour the solution onto the base. We start laying it from the far corner, evenly distributing it between the beacons. The solution should have the consistency of semi-liquid dough or thick sour cream, but should not spread on the base.

8. The solution is leveled with a shovel. As a rule, we shift the excess. We begin to work from the far wall towards ourselves, leveling the screed in this way.

9. Special attention should be given to the voids. Air cavities form in the solution, which reduce the quality of the screed. To get rid of them, you need to tug on the reinforcing layer. This should be done before leveling the screed.

10. Level the screed after it has hardened. Once the screed has been laid over the entire base, it is left to harden for two weeks. All this time it is moistened with water. The hardened screed is leveled, removing with a scraper upper layer until the surfaces of the beacons appear.

11. We remove beacons from concrete. This is done this way:

• layer cement screed cut with a spatula. This must be done carefully so as not to damage the heating pipes;
• Lightly tap the metal profile with a hammer and carefully remove the beacons;
• We moisten the resulting cavities with water, fill them with solution, and level them. Using the rule, we remove excess solution.

Removing the beacon from the screed

12. When all excess mortar has been removed from the hardened surface, treat the concrete with a trowel.

13. Damper tape over the screed, removed with a knife.

The thickness of the screed for a satisfactory foundation without significant defects is made 5-10 cm. For a foundation in a dilapidated state, the screed is made more than 10 cm thick, and sometimes even up to 20 cm. For reinforcement, a metal mesh or durable fiberglass with polypropylene fibers is used. For thin screeds, fiber is an ideal option for reinforcement.

Insulation boards are laid along the entire base, and a welt tape is fixed at the bottom of the walls to compensate for thermal expansion. The reinforcing mesh for the screed is used with a cross-section of 3 mm and with cells of 10x10 cm. The reinforcing layer (mesh or fiberglass) is laid on the thermal insulation and a mounting plastic strip with grooves is fixed on it. Heating pipes are placed and fixed in the grooves. Elastic material is laid along the breakdown lines into expansion joints. After this, the underfloor heating system is tested and concrete work begins.

You can check the operation of the heating system after the solution has completely hardened; it will take a month for the screed to completely harden. The temperature in the underfloor heating system is increased gradually so that the concrete does not crack.

What floor coverings require a screed?

For a heated floor system, use any floor coverings that have good thermal conductivity. Ideal option Porcelain stoneware or ceramic tiles are considered to have the highest heat transfer. Besides this material has high performance characteristics, has wear resistance and durability. With all these undeniable advantages, ceramic, porcelain tile flooring will be comfortable for feet only in heating season. In summer the floor will be cold. It is not recommended to lay on a screed plastic tiles, since it will crack when heated.

Most often, in residential premises, laminate flooring is laid on the screed. Now many manufacturers, for example, Parador, Wineo, Tarkett, produce laminate categories designed specifically for heated floors.

Linoleum can be laid on a heated floor if it is made from natural raw materials. If the floor covering has a non-woven base, when heated, such linoleum will release carcinogens.

Natural coverings such as cork and parquet can be combined with water-based floors if these are certified products and the manufacturer allows the installation of these coverings on a heated floor screed.

“Semi-dry” screed using building mixtures

Now there are dry mixtures for screed, which are used with the addition of a small amount of water. "Semi-dry" screed has best properties than ordinary cement.

The advantages of screed made from ready-mixes include:

• porous screed structure with high heat and sound insulation properties;
• no shrinkage, no peeling or cracks form when drying,
• greater strength;
• less drying time.

“Semi-dry” screeds with modifiers and a reinforcing layer are used.

The base is prepared as follows.

1. The base is cleared of debris and loose fragments. Dust is removed with special care using a vacuum cleaner.
2. The cracks are sealed with cement mortar.
3. A layer of waterproofing is laid on the floor (thick polyethylene film), which will protect the screed from moisture. In addition, waterproofing improves sound insulation and thermal insulation properties.
4. The bottom of the walls is covered with damping film. The edges of the waterproofing should extend 15 cm onto the walls.
5. The height difference is measured.
6. The solution is prepared and laid according to the instructions.

It is not difficult to prepare a solution from a dry mixture. The manufacturer encloses with its products precise instructions explaining how to prepare a solution for “semi-dry screed”. The degree of readiness is checked as follows: take a handful in your hand and squeeze tightly; if water seeps out, it means there is excess moisture in the solution. A properly prepared mixture, after compression, turns into a dense lump.

Before laying the “semi-dry” screed, the floor is divided into zones. The semi-dry solution is placed in parts in these zones and is equal to the rule. The thickness of the screed made from semi-dry mortar should not exceed 40 mm. After the mortar is laid, the screed is allowed to dry for 20 minutes and they begin to grout and sand it using a trowel. This technique not only makes the surface of the screed even, but also compacts the mixture. The coating is of high quality and durable.

Video - Screed of a warm water floor

Warm floor - great technology, which is implemented in daily life more and more people. Industries that produce parts for such floors are actively developing, presenting customers with a huge selection of products in their field.

For those who have never faced the choice of this method of heating an apartment, it will be difficult to choose necessary elements without any help, however, having picked it up, it’s waiting for you new problem associated with the installation of heated floors. This article will tell you the technology of laying heated floors under a screed.

Multilayer structure

A warm floor under a concrete screed is installed in several layers:

1. Rough concrete screed. It serves to level the floor, so if the base is already level, for example, it is made of a floor slab, then this step is often skipped.
2. Next is laid heat insulating material, for example, penofol, which will also save you from unnecessary noise. This layer is one of the most important, because thanks to its heat-reflecting properties, you only heat your apartment.
3. Heating elements are laid on top of the insulation. These elements may be water pipe, heating mats, cables and everything that you will find on the heating technology market.
4. The final layer is a clean concrete screed on which the final floor covering, for example laminate, will be laid. This layer experiences heavy loads due to weights and also heat, so it is worth talking about its construction in more detail.

Final concrete screed

As mentioned above, the concrete screed covering the floor must be durable. If the floor cannot withstand the loads and cracks appear on it, this can lead to overheating of individual heating elements, and you will have to redo the floor, so it is important to decide what kind of screed to make for the heated floor.

To avoid such a situation, you must carefully choose the mixture for the concrete screed. There is a wide selection of ready-made mixtures for heated floors on the market, but you can also prepare the solution yourself by mixing cement-sand mortar with glue, where one liter of PVA glue is used for one bag of cement.

If you are building a heated floor using water pipes, then it is better to use a solution based on screenings - a mixture of sand and crushed stone. In this way, you will achieve greater floor strength, as well as better heat transfer, than in the case of a cement-sand mixture.

Screening-cement screed for heated floors mixing technology:

1. Mix 4 parts crushed stone and 3.5 parts sand.
2. Add 1 part dry cement and mix.
3. Make the concrete flexible by gradually adding a small amount of water.

It is very important to follow this technology, because excess crushed stone or lack of sand is a big problem, which will not allow you to properly align the screed.

Special attention should also be paid to the thickness of the concrete screed. For most heating elements, a screed with a thickness of 3-7 cm is suitable, but if you are installing such a floor in production, it is better to increase the thickness of the screed to 10 cm. A screed based on water pipes should also be thicker and amount to 4.5-7 cm deep.

These dimensions allow the floor to be heated evenly, immediately after switching on heating system. The specified thickness of the screed also withstands all physical stress.

It is important to note that for apartments with low ceilings There are special self-leveling mixtures. According to manufacturers, 2.5 cm of thickness of such a screed will be enough to make a high-quality floor. In addition, you can make a different solution yourself by mixing dry cement and plasticizers in the following proportions: 1 liter of plasticizer per 100 kg of cement.

How to lay a heated floor

Having talked about all the intricacies of the concrete screed, you can begin laying the heated floor:

Preparing the rough screed and laying the insulation

The rough screed should be cleaned of all irregularities and dirt. Sharp edges should also be removed with a spatula, however, this is not critical. You can remove all dust with a vacuum cleaner.

Having prepared the surface, we begin to lay the heat insulator. To reflect heat you can use various materials: cork backing, penofol or polystyrene. They can be attached to the concrete screed with dowels or glue, and the joints of the sheets of insulating material should be taped. It is worth noting that for water heated floors it is better to use polystyrene foam, and for electric ones use foil materials, for example, penofol.

Damper tape

This tape is designed to protect the floor from temperature changes. It is made of polyethylene foam and works on the following principle: when concrete expands under the influence of heat, the tape contracts, and when the concrete cools and contracts, the tape expands, closing the cracks.

The tape should be glued between the contours of heated floors, as well as at the junctions of walls and floors along the entire perimeter of the room.

Installation of heating elements

If you are installing a water-heated floor, then attach its pipes at a distance of 10 to 30 cm from each other. Be careful not to bend the pipes too sharply, otherwise it may cause the pipe to burst. Pipes can be secured to the floor with dowels using fastening profiles.

Installation of an electric floor begins with laying the cable on the mounting tape, after which the tape itself is placed on the floor at a distance of approximately 50 cm from each other. Be especially careful when installation work ah in a bathhouse or bathroom, because there the electric heated floor must be grounded, and an RCD module must be installed.

Metal grid

Metal mesh is used in different ways in the construction of heated floors. Some people put it only under heating pipes, some only in the finishing screed, reinforcing it, and some use both at the same time. By placing the mesh under the pipes, you will not have to chisel the base of your floor, because the pipes can be fixed directly to the mesh, and by placing it above the pipes or electrical elements you will make the concrete screed monolithic.

When installing an electric heated floor in a screed with an iron mesh in the bathroom, metal carcass You will also have to ground it.

Finishing screed

Before you start pouring concrete, check the heated floor for functionality. Apply liquid to the water floor and wait a day; if you do not find any leaks and the floor heats well, then you can conclude that it is working properly. Electric floors are checked much faster. All elements should heat well, but not overheat. If your floor is in order, then feel free to start mixing the solution.

Concrete can only be poured at above-zero temperatures. The floor should be poured entirely in one go, but in a multi-level room you can do one go to each individual level.

Before concreting, you can also make special beacons from an iron profile or wooden blocks. Fix them half a meter from the wall, and follow them as you fill the floor.

Start pouring the solution from the corner of the room located opposite the door. Make sure that the concrete level does not exceed the level of the lighthouse. When pouring concrete, pierce it with an iron rod, which will rid the screed of air voids.

Conclusion

Laying a heated floor in a screed is not an easy task, but following the rules and technology, even a beginner can cope with it.