What is the minimum screed thickness for a water heated floor - rules and regulations

“The doctor hides his mistakes in the cemetery, the cook in the sauce, and the builder in the foundation.” (French proverb)

Good day, dear reader!

Many residents of private houses use a warm water floor as their main or additional heating. Even the bathhouse is no exception, for example, here. It has a lot of advantages, the main ones:

— balanced, that is, optimal temperature distribution across the height of the room;

— tactile comfort (this is when it’s pleasant to walk barefoot, but you can also sit and even lie down);

And here is one of the important questions for you - what is the thickness of the screed for a warm water floor. Let's talk exactly about this. Go…

Installation process

The entire installation of a water heated floor in a private house consists of several basic processes.
By doing each one correctly, craftsmen are rewarded with warm water floors in a private home that work reliably for up to 50 years. All work consists of:

• design;
• insulation;
• pipe laying;
• finished floor screeds.

Each part has its pitfalls. You need to get to know them better.

Creating a Project

When installing a water heated floor with your own hands, you should correctly calculate the boiler power. If there is a lack of power, the water will not warm up enough, which will affect the quality of heating. Power is usually taken 15-20% more of the total power consumption.

Each water pipeline is made as a single pipe. To calculate the length, you must first draw all the contours on paper. Their laying diagram and the place of attachment of the collector are indicated.

A correctly drawn up diagram will help with the installation and calculation of equipment and components

Insulation of water heating

In order for the heat to warm the house, and not the ground or ceilings in the neighboring apartment, various insulation is used for underfloor heating, which is laid on a prepared, level base. Differences in height cannot be higher than 5 mm. The system will heat incorrectly and not for long.

Insulation for water heated floors comes from various materials. Application must be justified by location, ambient temperature and type of substrate.

The most popular insulation materials are:

Expanded polystyrene. It is used when insulating the first floors on the ground or in a cold basement. This insulation for underfloor heating has a high density. Available in various thicknesses. The more thermal insulation is needed, the thicker the slabs are used.

Expanded polystyrene is a dense and heat-resistant material. Mineral wool is used in conjunction with wooden coverings.

Profile thermal insulation is the most modern insulation for warm water floors. It is extruded polystyrene foam with a laminated coating and grooves or bosses that help subsequent pipe laying. The only disadvantage of the heat insulator is its price.

Thermal insulation for water heated floors is available in the form of slabs. Their installation usually does not take much effort or time. All seams or joints must be taped with foil tape to prevent moisture from getting into them and reduce heat loss.

Each component of the underfloor heating pie is important

A waterproofing layer is placed on top of the insulation to protect it from moisture or aggressive environments (concrete, cement). It is also recommended to cover the insulation with a foil layer for better reflection and distribution of heat. In practice, this only works for wooden floors. When pouring concrete, it's just a waste of money. When using profile plates, all these steps are omitted.

Pipe laying

Might be interesting

For installation of water heating, copper, metal-plastic and polypropylene pipes with a diameter of 15-20 mm are used. The diameter of the pipe depends on the size of the room and the weather in the region.

For installation, two schemes for laying water heating pipes are used:

• Snake diagram. This is when the pipe is laid out in a uniform snake over the entire surface of the room. With this layout, hot water is first obtained, then it gradually cools, and the cooled water is returned to the return line. Recommended for use in sanitary areas (bath, toilet), corridors and small rooms where the length of the circuit is small.
• Snail diagram. For large rooms, it is recommended to lay out the pipes in a spiral, starting from the middle. The result is an alternation of pipes of different temperatures. Heat is distributed evenly. The hottest pipe is located along the outer wall to compensate for the outside cold.

Heated water floors in the form of a pipeline laying diagram

Each circuit is laid using a single pipe. All bends are made smooth. The distance between the underfloor heating pipes is 7-20 cm. The distance from the wall is 5-7 cm.

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.

Brief description of the “pie” and the tasks assigned to the screed

Screed for heated floors

Why do you need a screed:

Firstly, to protect water pipes from damage;

Secondly, for uniform heat transfer on the floor surface;

Thirdly, for heat and sound insulation from the lower levels of floors.

First, let’s list all the “classic pie ingredients.”

So - materials for a warm water floor

Down up:

1. On the base of the floor there is a concrete screed;
2. Waterproofing (if necessary based on the proximity of groundwater);
3. Insulation. It is needed to prevent (reduce) heat loss into the ground, unheated subfloor or ceiling of the neighbor below. Usually this is expanded polystyrene with a density of 40 kg/m³ and higher or a basalt slab of special “floor” grades. Insulation thickness – requires calculation based on a number of conditions;
4. Thick polyethylene film, two layers;
5. A water pipe laid on a reinforcing mesh and secured to it with clamps. In those places of pipes where expansion joints pass, corrugation is put on;
6. Concrete screed, for example, is an excellent and affordable option;
7. Substrate. Its material depends on what the finishing coating will be (under tiles, laminate, parquet, etc.);
8. Finish coating.

This is a "classic pie". Depending on the specific situation, the “filling” and technology change.

What does the thickness of the screed depend on: On the design features of the room and the customer’s intentions, of which the main ones are:

• a) characteristics of the floor (soil, floor slab, etc.);
• b) finishing (floor) coating materials;
• c) expected surface loads;
• d) coolant temperature and required air temperature in the room.

Total thickness of finished subfloor

Recommended thickness of each of the layers that make up the warm water floor cake. The order of arrangement of each of the layers is shown in the diagram below:

The subfloor must be smooth and durable. The thickness of each layer placed on top of the subfloor, in order from bottom to top, will be as follows.

A layer of insulation 30-90 mm thick made of fibrous polystyrene rigid boards. They must be strong enough to withstand the high load of subsequent layers, and therefore the material density is chosen to be at least 35 kg/m³. The thickness varies depending on how cold the crawl space is. If there is a heated room below the floor, then a layer of 30 mm will be sufficient, and if the floor is laid on the basement floor of a private house, then it is better to place a layer of insulation with a thickness of at least 90 mm.

Multifoil 3 mm thick is laid on top of the thermal insulation. Its main function is to waterproof the next layers of the floor. If the waterproofing layer has already been laid on the rough concrete floor, laying multifoil is not required.

Reinforcing mesh 100x100x4 mm or 150x150x4 mm serves to increase the strength of the screed, which, when reinforced, becomes more resistant to tensile loads. For the convenience of laying pipes according to the diagram, they can be fixed at the desired points on this grid.

The pipe is laid according to one of the diagrams shown below. These circuits are called "coil" and "helix". The first is classic and suitable for any room, while the second is not recommended for use on wooden floors and is most effective for rooms that require particularly intense heating. The permissible distance between pipes is from 10 to 30 cm. The presence of joints inside the floor is unacceptable; the pipe is laid in one piece, the ends of which go into the collector. The average layer thickness is 20 mm.

Before moving on to the screed, we need to talk about the damper tape. It is pre-laid around the perimeter of the walls in order to avoid creating unnecessary stress on the walls. The fact is that the concrete screed, when heated from the heat of the pipe, will expand and create pressure on the walls, and to prevent this, it must be fenced around the perimeter with a special “spring” material. The minimum thickness of such a tape is 5 mm, the optimal is 10 mm.

As a result, taking into account all the described requirements for the arrangement of a water-heated floor screed, the thickness of all layers and a separate concrete screed will be as follows:

1. The entire floor is 80-135 mm, taking into account the thermal insulation layer and the thickness of the concrete layer
2. The thickness of the screed is 50-65 mm, depending on the selected layer height above the surface of the pipes.

general information

In the process of making semi-dry screeds, dry ready-made mixtures have become more often used, which make the work easier and more convenient. A mesh made of steel material or fiberglass is selected as a reinforcing substance. To reduce the load on the floor and improve the strength characteristics, purchase fiberglass.

The concrete mixture dries much faster due to the small amount of water. The average period is 5-6 days. These figures are approximately 5 times faster than pouring a “wet” screed.

The semi-dry version of the subfloor installation can be done both on concrete floor slabs and on a wooden base. The room where the installation is carried out, as well as the subsequent floor covering, will not play a role. The main thing is that the technology is followed at all stages.

It is worth noting that the thickness of the semi-dry screed is determined very carefully. The height of the finished cake is influenced by certain factors.

Composition of the solution

The purpose of the room where the heated floor is installed will affect the components of the fill. For residential premises, the M200 grade of cement, which is added to the solution, will be sufficient, but for industrial facilities - no lower than M400. It's all about the final strength of the structure.

It would not be amiss to add various additives in the form of plasticizers to the composition, which allow you to create a smaller layer of screed, and also will not contribute to the formation of cracks and other defects on the surface.

Old folk remedies indicate the possibility of replacing plasticizers with other materials - PVA glue. True, it no longer justifies itself due to the emergence of more modern technologies that allow one to obtain the best results.

Pouring technology

Preparing for work

Before you start pouring it yourself, you need to prepare the room. Please note that the air temperature in the apartment during work should range from + 5 to + 25 degrees Celsius. Naturally, the base must be cleaned of debris and dust. Otherwise, the solution may lie unevenly and have poor adhesion to the surface. Try to eliminate all gaps in the base. If necessary, perform a rough curl of the base.

The solution should be poured only after all the contours of the heated floor have been laid and its performance has been checked.

During preparation, it is necessary to take into account the possibility of expansion of the concrete mixture under the influence of temperature changes. To avoid cracking of the solution after drying, it is necessary to arrange expansion joints. To do this, you can use a special damper tape or rigid insulation, the thickness of which is at least 1 cm. Such an expansion joint should be made to the entire depth of the screed.

The photo shows the installation of damper tape in front of the screed. Expansion joints are also installed in the passages between rooms

Pouring a heated floor should only be done after careful preparation of the base. Before using the composition, do not forget to check the system for operability and absence of defects.

What is needed to arrange a screed?

For work you will need the following materials:

• Cement mortar or dry mixture.
• Reinforcing mesh or reinforcing compound.
• Waterproofing.
• Insulation.
• Fastening elements.
• Container for stirring the solution.
• Construction mixer or drill with a special attachment.
• Spatula for leveling the mixture.
• Tiles or other finishing material for finishing the surface.

The reinforcing mesh should not have too small cells. Tiles under warm floors are used most often. Naturally, it is also necessary to choose this material correctly. You can lay it with your own hands, following the work technology.

Filling Features

A warm screed is installed in several stages:

1. Laying a waterproofing film, the thickness of which is usually 250 microns. The canvases are laid with an overlap (20 cm) on each other, as well as with an allowance for the wall. Secure all joints with reinforcing tape.
2. Installation of insulation. This is also done with your own hands. It is better to use a special material with an aluminum reflector that will direct the heat upward.
3. Attaching the damper tape. It is fixed at the edges and also divides a large area into parts.
4. Laying the mounting grid. It is on it that the heated floor elements are mounted.
5. Installation of level beacons. They will allow you to pour the solution correctly and evenly.

1. Preparing and pouring the mixture. The composition must be diluted as indicated in the instructions on the package. Otherwise, it may turn out too liquid or too thick.
2. If necessary, the layer can be reinforced with reinforcing mesh. It prevents damage to the screed after drying. A mesh is required if the layer is thick.
3. After a day, the dried composition will need to be covered with polyethylene and left for 7 days.

If you are pouring a water heated floor, then there should be pressure in the pipes at this moment.

Within a couple of weeks after pouring the mortar, you will be able to lay the tiles.

Useful tips

In order for the dimensions to bring the desired result, it is necessary to correctly perform the screed and know the consumption of the central heating system per 1 m2. After all, flaws in such work can lead to significant heat loss, leakage and other troubles.

Here are a few simple rules that you can follow to create the ideal top layer of water heating in a building:

• The screed should be applied at a temperature of 15 degrees Celsius. This indicator is considered optimal, at which cement exhibits all its best properties;
• Before pouring concrete, it is necessary to turn on the pressure in the heating pipes. It should not be more than 5 atmospheres. But it will be possible to use such a heating system no earlier than after 3.5 weeks, because it is during this time that the concrete hardens completely;
• to avoid heat loss, it is necessary to place a heat-reflecting coating under the pipeline;
• The cement you use should be purchased shortly before the work is carried out, because old material often loses its properties.

With the correct choice of concrete screed thickness and scrupulous adherence to the above rules, equipping any building with a water insulation system will be successful. You will quickly experience all the benefits of this type of heating!

Water heated floor screed:

The underfloor heating system connected to heating pipes is a structure made of metal-plastic pipes, laid and fixed on a metal reinforcing mesh and filled with concrete mixture, no less than 30 mm above the top edge of the pipes. This thickness of the screed reliably protects the pipes from mechanical damage and allows you to lay any finishing material on it, including porcelain stoneware, laminate, parquet, linoleum and other materials, except floorboards. To lay a floorboard covering, a warm floor is installed using a different technology.

Excessively thick screed and flooring made of slab stone, porcelain stoneware, mosaic tiles have a high heat capacity, heat spreads evenly throughout the floor, retains and releases heat for a longer time. But the main disadvantage of a thick screed is that it takes more time to warm up and costs more fuel. How then to install a warm floor under tiles and a thick screed, you ask? You will find the answer to this question in the article - heating cable for heated floors under tiles, in which we examined step by step the entire process of installing a heated floor system under tiles with a thick layer of screed.

A screed that is too thin is economical in terms of consumption of materials, it heats up faster, but it can overheat, and the heating will occur in stripes according to the configuration of the laid pipes, and the temperature difference will most likely lead to cracking of the screed itself and the floor covering. To avoid this in the future, you can initially arrange a semi-dry screed with a minimal amount of liquid. Once we already discussed the pros and cons of this type of screed - dry and semi-dry floor screed - the pros and cons of both types, I advise you to read.

Therefore, when calculating the thickness of the screed, it is necessary to take into account the diameter of the pipes, the pitch of their installation, the temperature of the heating water, the type and material of the finishing coating. This can best be done by specialists based on their own experience and knowledge, but still, for residential premises, the thickness of the screed cannot be higher than 100 mm, as this takes away important centimeters from the ceiling height. In this case, the height of the screed above the pipes ranges from 20 to 50 millimeters.

Heating pipes in a screed

Good day to all! the miracle builder poured the screed for me in a new building. good, I didn’t immediately put the floor covering on - the area was worn out and I saw that in one place the pipes (rehau insulated) were lying almost on the surface of the screed. I plan to use Lenolium as a floor covering. What to do?

1. let it be as it is
2. pour in more leveling coating (probably 5 millimeters)
3. unscrew the screed and remove the pipes below (but this is the worst option, I wouldn’t want to)

RAV4, there must be at least 20 mm of screed above the pipes. So leave everything as it is

Mazayac wrote: RAV4, there should be at least 20mm of screed above the pipes. So leave everything as it is

Mazayac, in this place now it is at most 3-5 mm. (

RAV4 wrote: I am planning to use Lenolium as a floor covering. What to do?

1) leave everything as is 2) pour in more leveling coating (5 millimeters, probably)

The third option, of course, is unsuitable, so either 1), but 2) is better. The second option is better. because, judging by the photo, you still need to level the screed anyway. Yours is too clumsy, but you need a smoother one under the linoleum.

Mazayac wrote: there should be at least 20mm of screed above the pipes. So leave everything as it is

Sorry, but we're probably talking about different things. Or we generally look from the point of view of different Galaxies.

If you want specifics, the thickness of the screed, not interrupted by underfloor heating pipes, should have a minimum thickness of 55 mm with a soft finishing coating or 50 mm with a hard finishing covering.

With mandatory CORRECT reinforcement with steel mesh with 50503.5 mm cards with mandatory knitting of cards with knitting wire. Also, with additional insurance against cracking of the screed - using microfiber.

P.S. It turns out that the screed above the TP pipes should have a thickness of at least 50 mm, provided that the screed is reinforced with high-quality reinforcement.

Therefore, it is not clear what hypothetical 20mm you were talking about.

Hydraulic calculation of heating systems. Heat calculation (calculation of insulation) of houses and apartments. Contacts in profile.

RAV4, you need to leave it as is, for the screed the working thickness is at least 35-40 mm. Therefore, hiding it under a smaller layer will not help; there will still be a crack along the pipe

Inch1964, yes, confused with the minimum thickness of the floor screed.

Above pipelines - at least 45mm, without reservations about reinforcement. SP 29.13330 clause 8.2. The answer really hasn’t changed - leave everything as it is.

Mazayac wrote: Above pipelines - at least 45mm, without reservations about reinforcement. SP 29.13330 clause 8.2.

quote: clause 8.2. ". . The thickness of the screed for covering pipelines (including in heated floors) must be at least 45 mm greater than the diameter of the pipelines.” Without reservations about reinforcement and the fact that this is the thickness of the Mazayac pipes, I’m shocked! - It must have been said somewhere that this is the thickness ABOVE the pipes! -and where? ..However, the answer to the TS question is the same - leave it as is

master.msk wrote: Therefore, hiding it under a smaller layer will do nothing, there will still be a crack in the pipe

How can this not work? The author wants linoleum on top - the madam in stiletto heels will pierce both the linoleum and the corrugation at once! And the crack - to hell with it. The pipe must be carefully removed and placed in a layer of mixture with a strength of at least 20 MPa. And the screed must be checked for this condition; if it is weaker, a layer of pouring material with a strength of 20 MPa must be checked. Not even if - since the screed is rough and has flaws - the linoleum will show all the jambs 100%. Therefore, there are no options, first 3, then 2.

BV wrote: no options, first 3, then 2.

Why didn’t anyone ask how thick the shank is? There's probably nowhere to drown there.

Gray, Maybe there is an overlap over the wiring cables, plus I see it near the leg. Beacons made of a 27x28 guided profile, not pulled out. This quality of screed will definitely not work under linoleum.

BV wrote: no options, first 3, then 2.

Why didn’t anyone ask how thick the shank is? There's probably nowhere to drown there.

Gray, 6 centimeters there

Hitgher wrote: Gray, Maybe there is an overlap over the wiring cables, plus I see it near the leg. Beacons made of a 27x28 guided profile, not pulled out. This quality of screed will definitely not work under linoleum.

Hitgher, the overlap is unlikely, this place is about half a meter from the wall and only a madman would pull wiring through it. although anything is possible)

The previous speaker seemed to have received answers. I thought that maybe I could ask my own questions right away, also about the heating pipes in the screed.

1. It seemed to me that the best candidates were a normal PP or Rehau Staff. Or something else?
2. If we talk about Rehau, then with a collector system you can do it sort of without connections in the screed. But won’t these metal corners of 90 degrees of the lower supply to the radiators be in the screed? And again, why not make different systems in the apartment, which means the water supply is also rebuilt, and these are also fittings in the wall?
3. Polypropylene will be cheaper, but there will definitely be fittings in the screed and walls, which means then the collector system is not so needed, which is even cheaper, but the same question remains - how reliable are the connections? One friend says that if the PP is soldered, then well crimped and does not lose pressure or leak, then nothing will happen to the soldering, but with any fitting and for crimping, the connection may lose reliability over time. Is this true or is this only typical for metal-plastic, and this does not happen with Rihau?
4. Is 20 pipes enough for batteries?

And most importantly, suddenly we have experience, we have a heating manifold and there are meters, and the heating pipes will be under the screed, so there is a very strong desire to do, if not heated floors, then at least draw a route, with slight deviations, so that some of them are heated then separate places, such as the floor in front of the sofa and tiles in front of the kitchen work area. But it seems that PP can be simply screeded, but for rehau it is assumed that the pipe should be corrugated and thermally insulated. But then it won’t heat at all? Or will it only fit in a corrugated version? Or can a Rihau stack be used for heated floors and can it be placed in a screed without corrugation or thermal insulation? Also the question is, given that this is a heating pipe and not a full-fledged heated floor, will it be too hot? And if you turn the tap down slightly so that it’s not so hot, then there won’t be enough for the battery? Or maybe the direct line to the battery is insulated, but the return line is not? Or maybe it’s just that insulation comes in different thicknesses and degrees of insulation, and you just need to choose one so that the impact isn’t so great? But then how can we at least estimate this?

In general, it’s clear that the topic is either not interesting, or people who would have something to say about it don’t come into it

Road Runner, if you even google the device of a water heated floor, the complete failure of this idea will immediately become clear.

Road Runner wrote: we have heating in the manifold and there are meters, and the heating pipes will be under the screed, so there is a very strong desire to do, if not warm floors, then at least draw a route, with slight deviations, so that some individual places are heated, such as the floor in front of the sofa and tiles in front of the kitchen work area.

There are many reasons why you should not try to make a warm floor from transit lines to radiators. More precisely, physically it is possible. But it will be bad and there may be bad consequences. It is not possible to explain all these reasons with text in a forum topic.

So, it is correct to do either transits to radiators or water heated floors. Or both, but with separate pipeline systems.

Features of installing a rod infrared floor

This type of heated floor consists of rods that are connected to each other by flexible wires. When current is passed through the rods, they generate heat. This type of heating can self-regulate the temperature, so it can be used without a thermostat.

Installation sequence of the rod infrared floor:

• creating a laying scheme;
• preparation of the base;
• laying thermal insulation;
• preparing the location for the sensor;
• laying out the strips and connecting the cable according to the drawn up diagram;
• fixing the strips to the base using mounting tape;
• installation of a thermostat;
• connecting the sensor and cable to the thermostat;
• connecting the thermostat to the network;
• system testing;
• pouring screed;
• laying tiles.

For such a floor, the best finishing coating is ceramic tiles; it is laid in a screed, the thickness of which should be more than 2-3 centimeters.

Purpose of damper tape and expansion joints

To prevent the concrete from destroying the walls when heated, damper tape is laid along the edges of the room.
Insulation around the perimeter of the room (damper tape) is needed to compensate for the thermal expansion of the concrete mass and reduce heat loss through the walls. According to the standards, the thickness of the protective layer in this place is at least 5 mm and corresponds to the height of the screed pouring. The latter is made of non-hygroscopic polyurethane foam, along the perimeter of which protection is made in the form of expansion joints. The use of insulation on the walls of the house is considered mandatory, while an expansion joint is used only in the following cases:

• the total area of ​​the room exceeds 35-40 m2;
• the length of its sides is more than 8 meters;
• the geometric dimensions of the room satisfy the ratio a/b > 1/2, where “a” and “b” are the lengths of adjacent walls.

The room is divided into small sections, after which additional expansion joints are made on each of them. The layout of the heating circuit pipes is calculated so that their number per seam is minimal. The optimal option is when only two threads pass through it (direct and reverse). It is also important that the pipe is laid through the seam with a slight bend and placed inside a corrugation at least 30 centimeters long.

Acceptable dimensions for different types of screed

Based on the thickness of the screed, rough coatings are conventionally divided into:

1. Thin - from 2 to 7 cm.
2. Thick – from 7 to 15 cm.

Layers less than 2 centimeters are usually made from self-leveling compounds and are not classified as screeds, but as self-leveling floors. And a thickness of more than 15 centimeters is more of a concrete floor with reinforcement.

Design features of screeds for heated floors

Features of arranging a thin floor screed

Thin screeds are used in rooms where there will not be strong point loads when using the floor. Usually these are kitchens, living rooms, bedrooms and other living rooms. Here a layer of 20–50 mm will be sufficient. For corridors and bathrooms, 50–70 mm are already recommended.

Such screeds are poured and leveled literally in one day. Then you still have to wait several days for the concrete to set. But the work itself of preparing the base and mixing the solution, as well as pouring the mixture, is carried out as quickly as possible.

Consumption of sand concrete per m2 of area

Features of arranging a thick screed

Thick screeds are used in areas with higher mechanical loads on the floor covering. Often they are poured not so much to level the floor, but to provide a reliable foundation for this or that equipment. And in fact, it is always a concrete mixture reinforced with steel rods. Gypsum solutions are of little use here.

Thick-layer floor screeds are installed in:

• utility rooms;
• in-house boiler rooms;
• garages;
• baths, etc.

In this case, the time required for pouring the concrete solution and the wait until the floor is ready will increase. A thick layer of concrete takes longer to gain hardness than a thin layer. At the same time, you still have to spend time carefully strengthening the concrete layer with reinforcement. Without it, such a screed will certainly crack when it hardens and will quickly become unusable.

How to calculate the amount of material for different types of screed

conclusions

The article discusses several options for screeding heated floors:

• TP screed in a high-load room. It is made with B22.5 concrete, possibly on soil with a thickness of 85 mm or more, with obligatory mesh reinforcement. Concrete underfloor heating system.
• TP screed in a house (apartment) is made with a cement-sand mixture reinforced with mesh or plastic fiber on a 2-3 cm insulating substrate with the obligatory addition of a plasticizer.
• The semi-dry screed technology is NOT recommended for independent use , excluding small rooms (bathroom, toilet) due to the complexity of the technological processes in the production of the solution and its installation.

Limit layers

There is a maximum height of the screed above the water-heated floor, above which there is no longer any need or usefulness. A large amount of time will be spent pouring, but the efficiency of the underfloor heating system will suffer to a large extent. After all, the entire resulting “pie” will have to be heated constantly.

The greatest thickness can reach 150 mm. Much will depend on the purpose of the room where the work is being carried out. Moreover, in this case, the device is mainly made of a monolithic structure. The height of the screed for a water-heated floor also serves as a foundation. Greater thickness should be provided for certain types of premises, such as garages, parking areas, etc.

It comes to the maximum thickness of the fill in a situation where the soil at the base is very problematic. After all, warm water floors are most often installed in private buildings. Otherwise, the entire structure will be destroyed. A lot of money will be spent, but there will be no results. In the process of preparing the solution, only high-quality materials should be used, since the entire structure is created for a long time. It’s better to spend money once than to spend money later on labor-intensive repairs.

To somewhat reduce costs in this case, it is best to knock down the protrusions on the base as much as possible, and additionally arrange backfill for leveling. But this must be done before installing a warm water floor. In the future, it will be much easier to carry out all stages of installing a water heated floor.

If the pipeline circuit is located in a thick screed, operational problems may arise due to prolonged heating of the subfloor. A lot of resources will be spent on this. There will be no benefit from using the system. This suggests that you must first properly arrange the subfloor in order to lay the pipes without consequences for their integrity.

Maximum

Covering with a thick layer of fill makes the pipes well protected. This layer retains heat for a long time and distributes heat well. But at the same time, its device is more expensive, and its operation may require unjustified energy costs. It is important not to overdo it and make a layer of moderate height.

For ordinary apartments and houses above a heated floor, a maximum height of the protective layer of screed covering the pipe is allowed to be 60 mm. This thickness is justified if a regular, not very strong mixture of cement and sand is used. This will make the surface sufficiently durable and maintain the possibility of acceptable heat transfer.

Attention

A thick floor has high thermal inertia and heating it requires a long time and possibly an increased temperature of the coolant.

Optimal screed thickness

How thick the floor screed should be, its type, and the required mixture composition depend on the following factors:

• the presence of unevenness and differences in height of the base base;
• what exactly the mixture is poured onto (on the floor slab, on the insulation layer or on the pipes - in the case of a heated floor);
• what kind of coating the surface is being prepared for;
• characteristics of the room (floor load, humidity, temperature, etc.).

Basic base

The more significant the unevenness and height difference, the thicker the layer of mortar is needed. For minor defects, the minimum thickness of the floor screed will be 20 mm. If you have to deal with large differences (more than 60 mm), then there is no need to talk about the minimum thickness. In this case, it makes sense to make a solution from a mixture of coarse sand, cement and water; its height will vary from 100 to 150 mm.

Advice! If you want to save on concrete mix, use expanded clay or crushed stone as a partial leveling.

If you think that you can determine the unevenness of the floor “by eye,” then do not be fooled: your eyesight may let you down. It is better to use a special level for this.

Classification

There are 3 types of screed depending on its thickness.

The first type is a thin subfloor. To fill it, self-leveling mixtures are used, which allow you to create a layer of up to 20 mm. In this case there is no need to use reinforcement.

The second type is a screed up to 70 mm high. In this case, reinforcement from metal mesh or reinforcement bars is necessary.

The third type is a layer of maximum thickness up to 150 mm, which is a monolith with internal reinforcement.

Composition of the screed mixture

For unevenness and height differences of less than 20 mm, it is better to use self-leveling mixtures, with which you can achieve an even and thin layer. After drying, you can immediately lay the floor covering on it. Self-leveling mixtures spread over the floor independently, without human intervention. They include:

• gypsum or cement;
• fine sand;
• plasticizers that improve quality indicators;
• glue;
• pigments.

Attention! The minimum and maximum thickness of the screed of a certain composition are indicated on the packaging by the manufacturer. Self-leveling floor is a type of self-leveling mixture that is applied to a concrete base or cement-sand fill.

This composition is used as a topcoat or as a thin layer of screed from 2 to 20 mm

Self-leveling floor is a type of self-leveling mixture that is applied to a concrete base or cement-sand fill. This composition is used as a finishing coating or as a thin layer of screed from 2 to 20 mm.

Advice! For a self-leveling floor, the recommended thickness is no more than 20-30 mm: otherwise, it may crack over time.

Concrete remains an indispensable material for rough pouring due to its relative cheapness. SNiP recommends the following mixture composition:

• sifted sand;
• cement;
• gravel or crushed stone (fraction size from 5 to 15 mm);
• water.

Today, very often, instead of crushed stone, lighter fillers are used, which also have thermal insulation properties. The most common of them are expanded clay and expanded polystyrene (pellets). The first is used only as a component for pouring the subfloor, and the second is used for finishing. The height of laying the mortar is in the range from 30 to 50 mm and is used in cases where there is a need to remove irregularities whose size is more than 20 mm.

For significant differences (more than 60 mm), sand concrete is used, which contains coarse sand instead of ordinary sand. The height of such a layer ranges from 100 to 150 mm.

In order to speed up the process of repairing the floor and in the presence of significant damage to the base, a dry screed is very often produced, which includes materials that do not require drying for a long time. It includes a layer of backfill material, for example, expanded clay, and on top of it there is sheet material (chipboard, plywood, GVLV). If necessary, hydro-, heat- and noise insulation is carried out. The thickness of such a “pie” can be 35-60 mm.

Semi-dry coating

Today, many people prefer dry mixture for laying screed. It is less problematic to pour than a cement-sand mixture. This installation method has its own characteristics. The semi-dry mixture is considered stronger than ordinary cement. After pouring, the drying period is much shorter, which makes it possible to finish laying heated floors faster.

Experts say that the material does not crumble or collapse under the influence of heat emanating from the pipes. It is easier and more convenient to work with this type of mixture.

Before laying the semi-dry mixture, you should carefully prepare the base. All debris is removed, the base is laid with a vapor barrier material. If there are deep cracks or depressions, it is recommended to fill them with a viscous cement solution. Rolled materials are laid with an overlap, and it must also overlap the walls. The seams are treated with special tape. The semi-dry mixture is poured onto the finished base.

The mixing proportions that should be used are indicated on the packages of the semi-dry mixture. The consistency of the material should not contain a lot of water. If you squeeze it in your hand, you get a dense lump. Moisture should not flow down your hand. In this way, they check that the ingredients of the mixture are mixed correctly. Very often, fiber fiber is added to the dry mixture to make the coating even more stable. The fiber is well distributed throughout the structure in all directions.

The minimum thickness of the screed will be 4 cm. Its height also depends on the method of laying the pipes themselves and what material they are laid on. The floor and its maximum height can reach 20 cm. If the base for pouring has significant unevenness, the height must be raised significantly. In general, the thickness will be at least 4 cm and no more than 20 cm.

The coating may be destroyed by improper drying methods. Just because you can walk on the floor does not mean the grout is truly dry. A liquid cement-sand mixture 4 cm high takes at least a month to dry. The mixture prepared from dry materials dries within several days, depending on the height of the coating. In order for the material to harden correctly and without cracking, the surface should be moistened with water and covered with film. As a result, the base will not sag, will dry well and will not crack.

The size of the water coating depends on the type of fill and the characteristics of the base. The more significant irregularities on the surface, the higher the structure will be. This happens due to the application of several layers - this is a necessity to achieve the zero level.

Based on experience, experts say that the relative total height of the warm water coating is 10-15 cm, taking into account absolutely all materials used, including the floor covering.

The influence of screed height on system operation

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 the high temperature causes the concrete coating to begin 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 to heat. 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 at a comfortable temperature in the room.

In addition to the accumulation and distribution of heat, the screed performs a 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.

The minimum thickness of 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.

Manufacturers' recommendations

HENCO

German manufacturer. It is worth paying attention to the demands of such pedantic Germans. Preferring a clear calculation and specific numbers, we recommend a screed thickness of 45 mm. This coincides with the majority opinion. Detailed recommendations here.

KAN

German manufacturer. The recommended thickness of the screed is 45 mm above the heating pipe, but not less than 65 mm from the thermal insulation material. Using especially durable materials when pouring the screed, the thickness can be reduced to 25 mm. You can read more on the manufacturer's website.

REHAU

Builders' favorite material. The manufacturer has developed its own standards for quality and work performance. According to the regulations 45 mm. – this is the thickness of the minimum screed. Do not neglect the maximum figure - in residential premises it is 61 mm, for industrial floors 92 mm.

What should it be: requirements

According to building codes and regulations (SNiP), the minimum thickness of the floor screed is 20 mm. In everyday life, such a minimum is rarely installed. It increases significantly if you need to hide equipment located on the subfloor. Thus, the thickness of the screed when installing a warm water floor should be determined taking into account the basic parameters of the pipes.

It is well known that the layer of mortar above the heating system should not exceed 40 mm. With a greater thickness, the installation of a heated floor is ineffective, since the bulk of the heat received simply will not reach the consumer. The internal layers of the screed will heat up, and the floor covering will receive virtually no thermal energy. The simplest calculations show that the thickness of the screed for a pipe diameter of 25 mm should be in the range of 50-70 mm. A standard screed consists of several components or layers.

The order of installation from bottom to top is as follows:

• waterproofing;
• thermal insulation;
• fittings;
• warm floor;
• screed

Different heated floor designs require different screed layers.

In some cases, the subfloor is first leveled with a thin screed; sometimes the solution is laid directly on the insulation. Its thickness should not be less than 2 cm. The layer is given 1 month to dry, and only after it has completely dried can you begin installing the heated floor, subsequently covering the installed communications with another screed.

An electric heated floor requires a low screed, especially if film heating was chosen. Infrared film is ideal for installation under laminate, carpet and linoleum.

If you plan to cover the floor with tiles, you should use a heating cable. In this case, you will need a less thick screed than when creating a water floor.

Under the pipes

Before laying water heating pipes, be sure to perform a rough pour. It is important that it is made with high quality and can last a long time, since replacing it will require destroying all subsequent layers. There is a significant load on the rough screed. It needs to withstand not only physical stress, but also possible significant temperature changes (for example, when the system is suddenly turned on or off). A poorly executed screed at this stage leads to destruction of the main screed, heat loss and pipe breakage. To eliminate the problems in the latter case, you will need to completely dismantle the floor covering, which will require significant material and time costs.

The mixture for rough pouring is made independently from sand, cement and plasticizer or purchased. The recommended amount of plasticizer is 1 liter per 100 kg of cement. Sometimes, in the absence of a plasticizer, it is replaced with the same amount of PVA glue. According to experts, the thickness of the screed for warm water floors

optimal within 2.5-3 cm.

Filling the floor contour with mortar

In principle, the screed is poured over a warm floor, like any other. If problems arise, it is when installing beacons, since the base underneath them “plays”, and without a certain skill it is quite difficult to bring them to the same level. The distance between them should be such that the rule by which the alignment will be carried out protrudes beyond the boundaries of the parallel beacons by 25 cm. If the tool is 2 m long, the step between the beacons should be 1.5 m.

Screed thickness for heated water floors

Table. We explain all the installation details.

Steps, photo Description Step 1 - drilling holes for dowels You start by drilling holes for fasteners along pre-designated lines. If, as in this case, you have foam plastic under the pipes as insulation, take dowel-nails measuring 8*120 mm. That is, their length should be selected in such a way that, having passed through all the layers, the fastener can enter the rough base. Step 2 - Installing Dowels Before inserting the dowel into the hole, you need to put a washer on it. It will not allow the dowel head to fall into the foam. Step 3 – driving nails into the dowels. Using light blows of a hammer, hammer in the dowels, but not completely. The height to which they should be hammered still needs to be determined. Step 4 - determining the level of driving the dowels. The easiest way to do this is using a laser level. Make a horizontal mark on the walls, and then transfer the mark to any available tool: a chisel, a screwdriver, or, as in this case, a hammer

If you put masking tape on it, you can mark it with a pencil, and then use the tool as a template. Step 5 - determining the mark of the top of the beacon installed on the dowel. Now you need to determine the mark of the top of the beacon when installing it on the dowel. Note! It would seem, why do this if the profile size is already known? This is due to the configuration of its cross-section. As you can see, the head of the screw falls into the recess, and the height of the beacon is no longer 10, but 8 mm. Step 6 - Determining the difference between the finished height of the screed and the height of the beacon Move the previously made floor mark to these 8 mm below, and drive the dowels along it. Step 7 – final driving of the dowel Hit the nail until the mark on the template matches the laser line. Step 8 – installing the beacon on the dowels Next, place the beacon on the dowels and check the mark again. Step 9 - laying out the mortar under the lighthouse Having made sure that the marks match, you can lay out the mortar along the row of dowels, removing its excess so that the heads of the screws are visible. Step 10 - installing the beacon profile on the solution Install the profiles by adding the solution so that the beacons are recessed in it. Step 11 - removing excess mortar Remove excess mortar with a trowel. Step 12 - pouring the screed After the solution on the beacons has hardened, you can begin pouring the main screed

First, fill the space between the beacons with a trowel. Step 13 - leveling with the rule And then, installing the rule (with the wide side) on two parallel beacons, remove the excess mortar, achieving a perfectly flat surface. Note! The next day, when the screed has hardened, it is necessary to thoroughly clean it of deposits. If the finishing coating is rolled (linoleum, carpet), the surface will have to be wetted and ground. As an option, you can make a thin layer (1-2 mm) of self-leveling floor.

Prices for self-leveling floors "Starateli"

Self-leveling floors "Starateli"

As you can see, it is not enough just to know what the thickness of the heated floor screed should be - you also need to try to ensure that it is uniform over the entire area of ​​the room. We hope that our instructions helped you understand this issue and make the heated floor perfectly flat.

What does thickness depend on?

The screed is a layer of cement and sand mortar that is laid on the base of the floor. The floor covering is subsequently installed on this surface. Standard - consists of a mixture of sand, cement and water. Sometimes a special plasticizer is added.

• leveling the coating;
• increasing floor waterproofing;
• laying communications;
• improving thermal insulation;
• increasing the floor height;
• installation of heated floors.

It is impossible to make the floor level without using a screed.

The thickness may vary and is affected by:

• use of the premises;
• planned flooring;
• type of soil (when laying on the ground);
• purpose of the floor.

The thickness may depend on the conditions under which the water floor is installed:

1. Minimum thickness - for ceilings up to 2 cm. Reinforced mesh is not used in this case. The floor is filled with a self-leveling mixture that hardens quickly.
2. Average thickness - 2-7 cm. In addition to concrete mortar, reinforcement or reinforced mesh is laid.
3. The maximum
   thickness is 7-15 cm. Most often it is made simultaneously for the entire house from concrete and reinforcement, while acting in parallel as a foundation.

The classic screed is made of concrete and crushed stone. However, this option cannot be used for thin filling.

When pouring onto a water-heated floor, you must remember its expansion factor. To eliminate it, a damper tape is fixed along the entire contour of the room. It contracts to compensate for the expansion of concrete when heated. Without it, concrete cracks, but with its use it remains intact.

To install heated floors, any of the existing types can be used:

Wet is poured from a solution of cement, sand and water. This option is the simplest and does not require experience in performing such work or special tools.

If you don’t want to deal with the correct proportions of cement and sand to prepare the mixture, you can buy a ready-made one. This option is the thinnest.

Semi-dry consists of the same components as wet, but much less water is used to prepare the solution and a special plasticizer is added to the mixture. It is quite difficult to lay it without experience. In addition, you will need a concrete mixer, without which high-quality preparation of the solution is impossible and vibrating plates.

Dry is made from bulk materials, which are leveled and covered with plywood or chipboard. It is very easy to do this type of screed yourself. However, it has disadvantages:

• large thickness;
• low heat conductivity.

To fill the infrared heated floor, a minimum thickness is used. Under an electric heated floor, you need to pour about 4 cm. Of all types of heated floors, the thickest is necessary for a water one.

The large thickness significantly reduces the height of the ceilings, so it is advisable not to use it in low rooms.

The thickness must be calculated individually to ensure the required strength in specific conditions.

Too small a thickness can be damaged by sudden changes in temperature and pressure on the furniture. If the layer is too thick, you will have to face the difficulty of regulating the temperature in the room and large heat losses for heating. In addition, violation of technology can lead to cracking.

Types of screeds

1. Wet. It is made on the basis of cement mortar.
2. Semi-dry.
3. Dry heated floor. This option has become used very often, as it eliminates the appearance of dirt and problems with the contacts of the electric version of the heated floor. In addition, this option allows you to lay tiles or other finishing material the very next day. Naturally, such a screed must be properly arranged.

These options have their advantages and disadvantages.
However, you need to choose a screed taking into account the characteristics of the room, the design of the heated floor, as well as the time allotted for repairs. Which one is best suited in your case is up to you to decide. Date: September 25, 2021

Determining the minimum

Other layers are also needed while filling:

• rough filling (a floor slab is often used instead);
• insulation;
• reinforced mesh (if necessary);
• layer of pipes (for water heated floors) or cables (for electric heated floors).

After this, the floor is poured and covered with the selected type of coating.

Minimum fill thickness

not regulated by building codes.

It is proposed to make the thickness at least 2 cm, and when using reinforced mesh, at least 4 cm, if pipes of standard diameter are used.

Even the minimum height screed copes well with its functions. Minimum – not acceptable in places with heavy load. Its use is not recommended in rooms where the load is increased (corridors, garage, technical rooms).

Consequently, with proper arrangement, you can save money and minimize the height of the ceilings.

Optimal floor thickness with water heating

are considered 7-10 cm. In this case, the most acceptable screed under pipes is considered 4.5-7 cm, and above pipes about 2.5-3 cm. If reinforced mesh is used, then a total height of 6-7 cm is sufficient.

On the ground

The filling technology will be the same regardless of the type of land and where exactly the groundwater is located. To work, you will need concrete grade M300 (or higher) and reinforcing mesh.

Before pouring the screed, the earthen flooring is leveled and compacted. Medium-fraction crushed stone or gravel can be used as the first layer of backfill. A second layer of sand is laid on top.

Each layer of bedding is compacted using a vibrating plate or manually.

Then the base for the rough screed is covered with waterproofing. These can be specialized materials or thick polyethylene film.

A subfloor 5-10 centimeters thick can be poured onto the finished base.

Sequence of work

Before the screed, waterproofing, insulation and water-bearing pipes are laid. Be sure to reinforce the surface with metal mesh

It is important that each twig is at least 3 mm. The fittings should be at the bottom, and pipes are attached to it

But there are experts who prefer to place the mesh above the water pipes for optimal load distribution. This will allow enough heat to escape from the concrete layer.

The waterproofing layer is applied over the rough screed using roll or liquid waterproofing. Next, they begin to install the insulation layer. Typically, dense polystyrene is chosen. The slabs are stacked compactly due to the presence of locking devices on the sides. The screed for heated floors is poured with concrete of such a consistency that it is easier to level. The solution is mixed by hand or with a concrete mixer. It uses 1 part cement and 4 parts sand, which is pre-sifted. Also add enough water to knead the dough-like mixture and a plasticizer for elasticity.

To make the screed strong, it is recommended to add fiber to the solution, which consists of synthetic fibrous materials.

Pouring the floor with mortar Source couo.ru

It is important to install it at the same time. You can’t fill one area and then do the rest a few days later.

If you do this, cracks will appear in the future.

You should check the condition of the pipes; when the concrete hardens, there will be no access to them. Test the system by connecting the operating water pressure and check for leaks during the day. If smudges appear, they must be eliminated and only then proceed with filling.

Laying heating pipes on wooden structures

Wooden systems are used mainly in houses where a subfloor is installed. Can be modular or rack-mounted. The modules can be purchased at hardware stores and assembled at home according to the instructions included with the kit. The rack system can be made independently from chipboard or MDF 20 mm thick. The technology includes the following work:

• Slats are cut 13 cm wide;
• The subfloor is swept and then vacuumed;

• Covered with polyethylene film overlapping and extending onto the walls. The seams are sealed with tape;
• The route along which the pipes will pass is drawn with chalk;
• The slats are laid out across the joists and secured with self-tapping screws. Where the pipes turn, they are rounded;
• Metal support plates are placed on the slats, which simultaneously serve as heat distributors - when heated, they remove heat from the pipes and transfer it to the floor more evenly. The plates are attached to the slats with self-tapping screws;
• The pipes are laid (there is no need to fix them);
• The entire system is covered with foamed polystyrene or polyethylene film.

The final work is carried out according to the same algorithm as when laying pipes on polystyrene slabs.

How to increase the sound and heat insulation properties of a floor using a screed

When constructing a floating screed, various materials are used as a base, which is filled with mortar, to improve the characteristics of the room - increasing thermal insulation and reducing noise.

Diagram of a floating floor structure using hydro-soundproofing materials

The role of the cement-sand layer, in addition to creating a strong, even base for the finishing material, is also the ability of the structure to dampen low-frequency noise that occurs during vibration. To improve the performance of the room, the screed is laid on the following materials:

1. Foamed polyurethane foam in sheets or polystyrene foam, which can dampen noise and increase thermal insulation in a room.
2. For insulation in the form of mineral wool and other coatings similar in level of rigidity.
3. On dense basalt insulation.

Soundproofing structures

All of the listed materials have the ability to simultaneously provide thermal and sound protection in a room.