The Most Popular Options For How To Fill A Lightweight And Warm Floor

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Video: The Most Popular Options For How To Fill A Lightweight And Warm Floor

Video: The Most Popular Options For How To Fill A Lightweight And Warm Floor
Video: How to Insulate a floor to prevent Cold from below with EcoTec FloorFoam 2023, September
The Most Popular Options For How To Fill A Lightweight And Warm Floor
The Most Popular Options For How To Fill A Lightweight And Warm Floor
  • Floor screed insulation options
  • Preparatory work
  • Solution preparation
  • Pouring the mixture
  • Dry screed using GVL

The use of cement-sand screeds to level the floor slab can increase the pressure on the floor slabs. In order to avoid overloading, it is worth using a lightweight material - monolithic expanded polystyrene concrete. It is made with cement and polystyrene. A mixture of these components makes it possible to obtain a floor screed made of polystyrene concrete, which is sufficiently warm, lightweight, resistant to cracks and shrinkage. Such properties are provided due to the characteristics of expanded polystyrene granules. Moreover, both the density and the weight of the resulting warm screeds can be changed depending on the conditions of use by changing the proportions of the materials included in their composition.

And in order to make the base faster, use the ready-made mixture Knauf UBO. It is a dry construction mixture based on special cement and expanded polystyrene granules as a filler. The permissible layer thickness is from 3 - 30cm.

Knauf light floor ubo
Knauf light floor ubo

Expanded polystyrene coatings are currently considered one of the most popular. And the main reasons for this are the following advantages of a warm screed made of monolithic expanded polystyrene concrete:

  • increased service life compared to most other polymeric materials;
  • good thermal parameters, allowing you to get a comfortable microclimate in the room even without using additional heaters;
  • environmental safety obtained due to the use of only food grade polystyrene in the manufacture of material, poured into cement.

In addition, among the advantages of the expanded polystyrene base is the simplicity of its manufacture. Pouring a lightweight floor screed can be carried out directly on site and in virtually any conditions. Moreover, the dimensions of the mixing plant do not exceed 0.8 m in width and the weight is 100 kg.


The disadvantages of the resulting flooring include only two characteristics of the material - its relatively high price. If you buy a ready-made mixture, then a bag of UBO weighing 25 kg (a rather large bag) will cost about 450 rubles. At a dry mix consumption per 1 square meter with a layer thickness of 30 mm -17.6 kg.

In any case, when using light fillings, you will have to make an additional reinforcing cement floor screed.

Floor screed insulation options

Despite the fact that expanded polystyrene can delay heat loss even without the use of additional insulation, it is recommended to increase the thermal insulation by insulating the floor screed. For this, various materials are used, including expanded clay, polyurethane foam and polystyrene foam. In addition, it is allowed to use a water heating system together with a polystyrene foam floor - especially in private houses, where the heat supply is autonomous.

Expanded clay is considered the most popular insulation under the floor screed and has a high degree of environmental friendliness and fire resistance. The material is quite mobile and requires careful handling when screed floors with expanded clay. Although, to create sufficiently effective thermal insulation, its thickness should be at least 150 mm, which reduces the height of the room. Therefore, do not use expanded clay in rooms with low ceilings.

The materials for the floor screed that are suitable for insulating the screed include foam plates or granules. In the first case, the foam is placed under the screed. When using granules, they are added directly to the screed in a 1: 1 ratio with the base material.

A good option for insulation can also be called, which also has good soundproofing properties. Although, due to its high hygroscopicity, it should be isolated from direct contacts with water, and its relatively low strength requires the obligatory use of a reinforcing mesh, it is not used in a cement floor.


The floor can be insulated under the screed and with the help of foam - a polymer material, the structure of which is made of closed cells. The insulation is distinguished by high moisture resistance and compressive strength, as well as good fire resistance. A waterproofing film and a reinforcing mesh must be installed on foam boards. And the thickness of the screed applied from above must be at least 40 mm.

penoplex in the floor under the screed
penoplex in the floor under the screed

Another insulation under the underfloor heating screed is sprayed onto the surface and does not require additional vapor and waterproofing. Low thermal conductivity ensures a minimum spray thickness, so the height of the room is practically not reduced. And the process of applying the material to the surface itself takes a minimum of time - after 3 hours after that you can start applying the screed.

liquid polyurethane foam pa floor
liquid polyurethane foam pa floor

Performing a warm floor screed with your own hands, you can use a piping system powered by autonomous or centralized heating to improve the thermal characteristics of the coating. In this case, it is imperative to arrange waterproofing and lay aluminum foil over the pipes to reflect heat energy. And only then arrange the screed.

The table shows the characteristics of various types of warm screeds.

CPU (40mm)

CPU (40 mm)

Polyfoam (40 mm) +

CPU (40 mm)

Mineral wool (50 mm) +

CPU (40 mm)

Polystyrene concrete (50 mm) +

CPU (30 mm)

Primer +


Hydro-barrier + +
Insulation + + +
Insulation works + + + +
Reinforcing mesh + +
Solution + + + + +
Work on the main screed + + + + +
Total weight 1 sq. 115 kg 82 kg 64 kg 72 kg 48 kg
Pie thickness 110 mm 100 mm 80 mm

90 mm

80 mm
The average price, RUR / m 2






Preparatory work

Before making a warm floor screed, you need to choose suitable materials and prepare the base. To do this, the remnants of the old finish are removed from the floor covering so that only concrete remains after cleaning. After that, channels for communications are laid at the base - electrical wiring and pipelines (if necessary, cable channels are used for this).

The next stage is the treatment of the concrete slab with a waterproofing mastic or the flooring of a special waterproof membrane. Now you can stick a damper tape on the lower part of the wall, which can protect the screed from cracking and increase the sound insulation parameters of the floor.

At the time of the preparatory work, a suitable polystyrene foam and all the necessary components for the preparation of the screed must have already been selected and purchased. The main material is usually sold in bags of 170 or 420 liters, and the special air-entraining additive SDO (saponified wood resin) is in the form of a powder or solution. The presence of the LMS allows to make the insulated floor screed even warmer and easier to use.

Solution preparation

To prepare the solution from which the screed will be made, not only the main components (cement and expanded polystyrene) can be used, but also several additional components. For example, adding sand increases the durability of the floor covering. Although this reduces the thermal characteristics of the material and, conversely, increases the density. Natural stone, which increases the abrasion resistance of the material, and gravel or pebbles can be used as fillers for underfloor heating screed. It is not recommended to add concrete chips, slag and ash to the solution, which reduce the strength of the floor covering.

Another composition is possible using sand, which can be made by hand. It is important to observe the proportions of cement correctly; it is possible to prepare it without using sand. To save money, start the next one; we take 1 part of cement, 2 parts of sand and 5 polystyrene foam granules and mix. Such a composition can be used in the construction of walls.

One of the most popular ways to make a do-it-yourself underfloor heating screed involves the use of grade 300 polystyrene concrete, which requires 240 kg of cement per 1 cubic meter of polystyrene granules, 0.65% by volume of LMS and up to 120 liters of water.

The ratio of the components required to obtain a material of a different strength can be taken from the table.

Volume of polystyrene, cubic meters m Cement weight, t

Water volume, cub. m

Percentage of additive SDO,%
200 1 0.16 0.1 0.8
300 1 0.24 0.12 0.65
350 1 0.29 0.13 0.62
400 1 0.33 0.15 0.6
500 1 0.41 0.17 0.45

The process of preparing the solution is quite simple - solving the issue for a warm screed, how to make the right mixture, perform the following actions:

  1. The required amount of water is added to the container;
  2. Cement is poured;
  3. The mixture is stirred with a drill until its consistency becomes similar to yogurt;
  4. Polystyrene is poured into the resulting solution.

At the final stage of preparation, the mixer is set to press the polystyrene granules into the solution and is used until most of them are covered with cement. After that, the direction of rotation is reversed and additional mixing is carried out for several minutes. The result should be a material resembling coarse-grained caviar, with virtually no fluidity.


Pouring the mixture

The method of pouring a polystyrene concrete floor involves the installation of beacons that need to be aligned in the same plane. To obtain a sufficiently warm surface and, at the same time, not too much reduction in the height of the room, the upper part of such guides is set at a level of 5 cm from the base. Then they begin to perform the screed, moving from one of the far corners of the room to the wall and leveling the material using a rule soaked in water. To speed up the process, it is advisable to fill not alone, but with an assistant - while one performer pours the material, the second aligns.

In the process of work, you should pay attention to the walls, from which you need to remove the remnants of the solution in time. And, having finished pouring a lightweight floor screed, it is recommended to immediately provide the right conditions for drying it - from 15 to 25 degrees, low humidity and a complete absence of drafts. Failure to comply with the permissible microclimate can lead to cracks on the surface. A day after the end of the work, it is necessary to remove the guides and seal the holes remaining from them with the same mixture.

Dry screed using GVL

Due to the fact that it is impossible to obtain a perfectly flat surface with the help of polystyrene concrete in a short time, other methods of creating a floor covering are also used. One of them is a warm floor on a dry Knauf screed, a feature of which is not pouring a liquid mixture, but filling a special expanded clay backfill. The main steps in this process are:

  1. Foundation preparation;
  2. Laying waterproofing and soundproofing;
  3. Backfilling of the main material. In this case, the thickness of the dry Knauf screed should be no more than 3-5 cm.

The advantages of such a floor include an increase in the speed of its laying, high thermal and sound insulation characteristics, as well as a minimum loss of height in the room. It is worth noting such an advantage as the absence of the need to wait 2-3 weeks until the surface is completely dry. And the disadvantages of a dry warm floor screed Knauf include only the relatively high cost of the material and an increased level of dustiness. Because of this, work is required only with the use of special personal protective equipment - suits and respirators. Although all the money spent on creating a warm floor with such a lightweight screed pays off by a noticeable approach to the completion of the repair.


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