Laying penoplex on the floor under the screed. Choosing the best floor insulation for a concrete screed What is better to put under a floor screed

Depending on the design features of the building and its location, heat losses through an uninsulated floor reach up to 20%. A cold floor often causes increased humidity in the room and, as a result, the appearance of fungus, which will quickly destroy the expensive floor covering. Regular walking on icy surfaces will lead to colds and diseases of the leg joints. You can reduce heat loss and protect yourself from health problems by insulating the floor with Penoplex. The technical characteristics of the material allow it to be laid under a floor screed.

Which penoplex to choose for floor screed

Any insulation, saturated with moisture, loses its thermal insulation characteristics. Penoplex is a slab thermal insulation material made from polystyrene granules using the extrusion method. Thanks to this technology, the structure of penoplex consists of many closed cells that practically do not absorb moisture.

Penoplex slabs are widely used for insulation of civil and industrial buildings, when laying highways and even runways at airfields. The range of products made from extruded polystyrene foam is quite large, but not all types of penoplex are suitable for insulating floors under screed:

Penoplex Comfort- a universal material suitable for insulating walls and floors in private houses and apartments. The density of Comfort penoplex is 31 kg/m³, which is quite enough for a domestic space. Available in thicknesses from 20 mm to 100 mm.
Penoplex Foundation- has increased strength, which does not decrease throughout the entire service life. Insulation density - 35 kg/m³. The thickness of the Penoplex Foundation slabs is 50 mm and 80 mm.
Penoplex 45 is the most durable of all types, used for insulating surfaces subject to heavy loads - airfield runways and highways. The density of penoplex is 45 - 40-41 kg/m³. The thickness of the insulation is from 40 mm to 100 mm.

All of the listed varieties of penoplex are able to maintain their technical characteristics at temperatures from -100°C to +75°C, have zero water absorption and do not contain harmful chemicals.

The technology of penoplex insulation under screed has several options, the choice of which depends on the condition of the base surface.

Penoplex insulation on a concrete base

Insulation of floors with penoplex under screed in an apartment building may differ slightly. Rooms located above the basement have colder floors and, accordingly, require an increased number of layers to prevent dampness and cooling the apartment.

Before starting the main work on floor insulation with Penoplex, it is necessary to prepare the floor surface. This process, regardless of the location of the apartment, is always performed the same way:

After completing the preparatory activities, you can begin laying the penoplex. If waterproofing material is laid on the base, then the slabs can be laid directly on it. If insulation is carried out on a concrete base, penoplex is laid on a bedding of sifted sand. Screeding can be done either semi-dry or wet. Regardless of the chosen method, the minimum thickness of the screed in the apartment should be 40 mm. As an example, consider a semi-dry screed on Penoplex laid on a concrete base:

For several days, the floor surface must be sprinkled with water to strengthen the screed. The drying process lasts approximately 15 days; if ceramic tiles are planned to be laid in the room, then work should begin no earlier than 20 days later. Materials such as laminate or parquet boards can be laid only after the screed has completely dried, having previously laid a waterproofing film.

Penoplex insulated ground screed

Penoplex insulation over the ground is carried out in private houses built on a strip foundation without a basement. There are several ways to install such a floor:

Method 1 - a cushion is made of a gravel-crushed stone mixture on the ground, and sand is poured on top of it, on which the penoplex is laid. A cement-sand screed is poured on top of the insulation.
Method 2 - involves the installation of two layers of screed, one of which will be between the sand and the Penoplex slabs, and the second on top of the insulation. A heated floor system can be installed in the top screed.
Method 3 - medium-fraction crushed stone is used as a cushion on the ground. A layer of sand is poured on top of it and Penoplex slabs are laid. The insulation is covered with waterproofing material and reinforced screed.

Sequence of work on floor insulation on the ground:

Now you need to take a technical break so that the screed gains strength and dries. It is recommended to regularly moisten the screed to prevent premature drying. When the floor reaches brand strength, you can give it a perfectly flat surface by filling it with a leveling mixture. This is especially recommended if you plan to lay laminate or parquet boards in the room. After the finishing layer of screed has dried, the protruding edges of the damper tape are trimmed at the level of the finished floor. The floor insulated with Penoplex on the ground is completely ready for installation of decorative covering.

In conclusion, it is worth noting that the biggest mistake when insulating the floor with Penoplex slabs is the absence of a damper tape between the screed and the walls of the room. Any mortar, even the most elastic, tends to expand and shift, and the absence of a gap will inevitably lead to deformation of the screed and the appearance of cracks.

When insulating a house, it is very important to pay attention to the floor. Walking barefoot on a warm floor is very pleasant. In addition, it is worth considering both at the initial stage of construction and during the renovation of old buildings that condensation, which forms during temperature changes on the floor surface, as well as near the floor and walls, leads to the general destruction of the building. Therefore, it is necessary to insulate by any means. You can insulate a cold floor with polystyrene foam under a concrete screed, you can use logs, you can foam it with polyurethane foam. So there are many ways and they all depend on the selection of material.

Penoplex insulation

Thermal insulation material penoplex is extruded polystyrene foam, which has a structure consisting of closed cells. Because of this, it does not absorb moisture and has greater compressive strength, making it attractive as floor insulation.

Insulation of a cold floor with penoplex under a concrete or other screed occurs as follows:

Compact the soil well.
A layer of crushed stone is poured.
A sand cushion is made.
Penoplex, laid smoothly without gaps, all joints are taped.
A waterproofing layer is laid.
A reinforced screed based on sand and cement, 4 centimeters thick, is made.
Any floor covering. This could be laminate, linoleum, tile.

Before pouring, it is necessary to install an expansion joint around the perimeter of the walls. This is a 2-centimeter wide tape made of foam polystyrene. A gap of 1 centimeter is also made between the wall and the screed to allow for expansion as the temperature increases.

Warm floor

If you install a “warm floor” system, you also use Penoplex. Here is the sequence of layers:

Concrete base.
Penoplex.
Polyethylene.
Warm floor system.
The finishing fill is done using a special mixture with your own hands. Or the filling is done with cement-sand mortar.

Insulation of the first floor

If we insulate the floor of the first floor with penoplex, then we follow the following installation sequence with our own hands:

Reinforced concrete floor slab.
Penoplex.
Waterproofing - polyethylene.
Filling the screed.
Flooring.

Insulation under a concrete screed in a private house

Insulation with mineral wool

What other insulation materials can you choose?

Mineral wool is one of the most popular materials; it can provide not only good insulation, but also achieve a high-quality soundproofing effect.

Insulate a cold floor in an old house on the 1st floor as follows:

All old floor coverings are removed and the floor is cleaned down to the very foundation.
Mineral wool insulation is installed in the form of rigid slabs. For example, Floor Butts - 50 mm.
A vapor barrier layer, for example glassine, is laid.
A mesh of 3 mm wire is placed on the clamps so that there is an air gap of 1 or 2 centimeters.
A concrete screed of sand and cement is made on top. To make it easier, you can add expanded clay.

Foam insulation

You can insulate floors with polystyrene foam granules. For screed, cement and foam granules are mixed in a 1:1 ratio and the floor is poured with this mixture.

If you just use slabs, then insulating the floor with foam plastic under any screed is as follows:

Thoroughly clean the base and seal all cracks and cracks in the base with cement mortar. We waterproof the base with our own hands. To do this, we use roofing felt mastic, or any other material. If it is roofing felt, then we lay it with our own hands, overlapping it with the obligatory approach to the walls. Liquid mastic can be applied simply with a brush or brush. The foam is laid tightly. Attached to the floor using disc dowels. Be sure to reinforce the foam. This technique will protect the material from destruction and give the concrete rigidity. Beacons are installed, and laying of the screed begins. Concrete is scattered over the surface and leveled with a rule or lath. Then everything is smoothed out with a spatula.

Floor waterproofing

Foam and glass screed

There is a special filler made of foam and glass used for filling. This screed has good fire protection characteristics. It does not burn at all and has very good durability. The insulation method is as follows:

High-quality floor leveling.
Surface primer.
Installation of damper temperature tape.
A thick layer of screed is applied along the beacons.
Leveled with a long block.
The beacons are removed, the voids are filled with the same material.

When insulating the floor, so that voids and cracks do not form under it, you need to lay the screed correctly. Any violation of the screed will reduce all your efforts to zero. The insulation is damaged. Everything will have to be redone. Here are some recommendations for pouring screed.

The time for complete drying of the screed is 28 days and this time period must be maintained.

If you prepare the solution yourself, then you cannot violate the proportions. This causes cracks to form in the screed. Some people pour a lot of water to make the process easier. This is also unacceptable.

All soft insulation must be covered with reinforcing mesh.

The thickness of the screed for more durable insulation is 40 mm, for fragile ones – 50 mm.

Do not force-dry the screed. It is also unacceptable to have drafts in the room where the poured floor is drying.

The screed must be constantly moistened

The beacons on which the floor is poured are fixed to the same material so that there is no difference in drying time with the original material.

Be sure to follow the technological process. This is to install a damper tape and apply a vapor barrier layer.

It's no secret that the concrete floor on the first floor becomes hellishly cold in winter, and if you don't take care of proper thermal insulation, then over time dampness and microbes will simply destroy expensive parquet or laminate flooring. But it’s not even a matter of the floor covering; an icy floor in a house is the shortest route to disease in the joints of the legs, so before finishing finishing, it’s imperative to insulate the floor with penoplex under a concrete mortar screed.

Why is penoplex used?

For specialists, the answer is obvious - laying penoplex under a screed on a concrete floor is no more difficult than any other material, the technique is proven and reliable. In addition, the technology of installing an insulated floor by laying penoplex is technically within the capabilities of even people with minimal experience working with this kind of material.

In fact, penoplex is the only material that simultaneously combines several unique qualities:

High strength of penoplex to bending and contact pressure. You can safely step on a sheet of penoplex in shoes, with virtually no consequences for the material;
Extruded polystyrene foam, from which the insulation is made, does not emit dust, does not emit gases or volatile substances, it can be worked with practically without PPA, in this sense, penoplex compares favorably with mineral wool or basalt mats;
Penoplex can be laid under a screed even on a floor slab above a wet basement; the laid layer of thermal insulation will not absorb moisture and will not lose its insulating properties even after 30 years of operation.

If we compare penoplex with its closest relative - polystyrene foam, we can note that with almost equal thermal insulation characteristics, EPPS differs favorably in that it does not crumble or collapse under uneven load. Extrusion technology makes it possible to obtain closed pores in penoplex that are inaccessible to moisture and water vapor.

Important! The only significant drawback of penoplex is its sensitivity to ultraviolet radiation and various types of organic solvents.

The first drawback is compensated by a protective layer of concrete floor screed on penoplex. The second one just needs to be remembered. If you decide to paint the insulation layer with some paint based on an organic solvent, or treat a concrete screed on polystyrene foam with a primer, then instead of a thick layer of insulation you will end up with a thin layer of molten polystyrene.

Sellers of mineral thermal insulation materials like to scare developers with the flammability of polystyrene foam, but at the same time they forget that foam flooring is laid under a concrete screed, which means that in the absence of atmospheric oxygen, in order for polystyrene foam to begin to decompose with the release of carbon monoxide, it is necessary to heat the concrete floor at least than up to 200 o C.

Technology for arranging insulation from EPS

Theoretically, penoplex under a floor screed can be laid on almost any surface, without even removing the remaining debris and gravel. In many cases, penoplex is laid on a soil floor or a gravel cushion, but in such conditions, the polystyrene foam layer is pressed to the floor and fixed by a thick concrete screed or reinforced foundation slab. In our case, the thickness of the screed does not exceed 4-5 cm of reinforced concrete, and whether cracks will appear in the screed due to vibrations of the insulation depends on how carefully the foam layer is fixed to the floor.

Preparing the base for laying penoplex under the screed

At the preparation stage you need to do the following:

Measure the floor area and calculate the required amount of penoplex in square meters. For installation, we purchase insulation 10% more than the received footage for cutting and scrap;
Using a chisel and an angle grinder, we level the concrete floor, knock down and remove all bumps, humps and growths more than 7 mm high;
Carefully remove dust and dirt from the surface of the concrete;
Any traces of oil, kerosene, organic solvents, which are always in abundance on the floor in garages and utility rooms, are neutralized with a solution of caustic soda and washed with plenty of water;
We carefully prime the cement floor with a deep penetration primer, no matter what brand, as long as it is high quality, and let it dry for at least another day.

For your information! All procedures performed were aimed at ensuring that no air pockets were formed between the concrete floor and the foam layer, in which, as a rule, condensation accumulates under the thermal insulation, and cracks often form in the screed.

We prime the floor, then mark the laying of foam sheets. The main condition when adjusting the material is that the seams between the sheets must be identical along the entire length of the joint.

Laying penoplex on the floor under the screed

To stick penoplex to a concrete floor, it is best to use a special adhesive for installing foam and mineral-based insulation. Apply the adhesive mass to the floor and to the working surface of the sheet around the perimeter and in the center of the slab. When laying under the screed, it is important to tightly roll the insulation to the floor and secure the laid layer with mushroom-shaped dowels. After a day, the seams between the plates are cleaned of glue residues and foamed with regular polyurethane foam.

Experts recommend making an expansion gap of 4-5 mm thick along the perimeter of the laid polystyrene foam field along the walls. The gap is filled with foamed polyethylene tape. After pouring concrete under load, the insulation layer will settle and expand in width.

The seams and joints between the foam boards are sealed with construction tape so that the concrete milk from the screed material does not seep inside and form a bridge of cold and moisture on the floor.

Pouring penoplex concrete

Before pouring the screed, the surface of the laid penoplex is covered with a vapor barrier membrane, the panel is glued around the perimeter of the laid insulation, and the edges are laid out on the walls. The membrane must be aligned without folds or weaknesses across the entire floor plane.

If you intend to reinforce the screed with fiberglass or steel mesh, then you must first lay the mesh on “cups” of scrap wire so that the plane of the reinforcement is at a height of at least 2 cm from the membrane. In this case, the concrete screed works to deflect, so we deliberately shift the reinforcement plane closer to the floor, into the area of tensile stresses.

At the next stage, we set up the beacons; for home screeds, you can use wooden, aluminum or galvanized profiles. Because of the laid mesh, the beacons must be installed on supports, screw stands, resting on a layer of insulation. After pouring the concrete, such supports are usually unscrewed from the floor screed.

The width between the slats should not exceed ¾ of the length of the rule. We check the position of each slats with a one and a half meter building level.

To prepare the concrete mass, you can make your own batch from M400 cement, washed sand and a small amount of fine 1-3 mm gravel. To obtain the smoothest possible surface, the plane of the poured concrete screed, after leveling, is usually smoothed with a plaster float moistened with aqueous PVA emulsion.

The room with the polystyrene foam screed must be closed from sunlight and the ventilation should be opened to the smallest amount of air. If the room is hot enough, then the floor can be sprayed with water once a day for 5 days. After two weeks, you can begin stripping the floor, but further operations are recommended to be carried out no earlier than after three weeks of screed curing.

Concrete floors are the most practical option for a private home, due to their strength, durability and low manufacturing costs. But concrete is a cold material, and without high-quality thermal insulation in the winter it is not very comfortable in the house. In addition to high heat loss, condensation, which forms due to the large temperature difference on the inside and outside of the concrete base, also creates problems. There are several ways to insulate a concrete floor in a private house, and even a novice master can do all of them.

Concrete floors can be insulated in three different ways:

simplest - lay the insulation on the concrete surface in a continuous layer. To do this, the base is cleaned of dust, unevenness is eliminated, and, if necessary, filled with leveling mixtures. The insulation can be attached with glue, dowels, or a combined method, after which the finishing coating is installed. Individual insulation materials themselves act as finished floor coverings, which reduces installation time and saves a little money;
frame method - logs are first installed on a concrete base, then the space between them is filled with insulation, and a finished floor is laid. The method is more labor-intensive, but allows the use of materials with a lower density that cannot withstand high loads;
laying insulation under the screed - install a layer of thermal insulation on the concrete floor and pour cement-sand mortar on top, resulting in the formation of a monolithic, solid base. The method is the most labor-intensive and time-consuming, but this base is perfect for any floor covering - from linoleum to tiles. In addition, this option is used when installing electric and water heated floors, which ensures uniform heat transfer over the entire area of the room.

When choosing, the determining criterion is the type of flooring and the method of its installation. For example, soft and rolled materials are not suitable for laying in a screed, since they are not intended for high loads. The same applies to insulation materials laid directly under the finishing coating: they must have good density and rigidity so as not to be pressed through during operation. It is also worth considering that logs and insulated screed take up to 15 cm in height, so for rooms with low ceilings the first installation method is preferable.

Selection of insulation materials for concrete

The insulation market now provides a wide selection of materials, both domestic and foreign. For thermal insulation of concrete floors, particle boards, fiber materials, and foam polymer boards are most often used. Sprayed insulation, which is applied using special equipment, is also gaining popularity. Among the inexpensive options for a private home, it is worth noting expanded clay - a natural, environmentally friendly material with excellent heat-insulating properties.

The key characteristics of insulation are:

density– the higher this indicator, the greater the amount of heat will be retained;
strength– determined by bending and compression. The higher the expected loads, the stronger the insulation should be;
thermal conductivity– the efficiency of heat conservation in the room depends on this indicator. Preference should be given to materials with the lowest thermal conductivity coefficient;
moisture permeability– the higher the indicator, the faster the thermal insulation properties of the material deteriorate. Insulation saturated with water is not able to retain heat, so it will have to be replaced;
durability– in order to save money, it is worth choosing a material with the longest service life, because frequent replacement of insulation and accompanying repairs are expensive;
environmental friendliness– in residential premises it is necessary to use only environmentally friendly insulation, since the floor covering is not a good protection against toxic fumes.

The weight of the material does not play a big role, because, unlike a city apartment, there is no need to worry about increased loads on the floors between floors.

So, let's look at popular insulation materials, their properties, pros and cons.

Material	Main characteristics
	It has low thermal conductivity and perfectly muffles sounds. Available in rolls and slabs, differing in density. It does not burn, but has high moisture permeability, and therefore requires high-quality waterproofing during installation. The service life, subject to installation technology, is 25-30 years. Insulation with mineral wool is carried out only along logs, since the material cannot withstand high loads
	They have good strength and heat capacity, have soundproofing characteristics, and can be laid directly on concrete or on logs. For floor insulation, slabs with a thickness of at least 20 mm are suitable. Moisture resistance is average, so waterproofing is required on damp substrates. In dry rooms, the material can be laid directly on concrete, pre-treated with a primer
	This group includes polystyrene foam and EPS. They are lightweight, easy to install, and have very low thermal conductivity. They can be laid under a screed or between joists, and EPS can also be laid on the concrete floor itself. Polystyrene foam is cheaper, but less durable, so if there are increased requirements for floor construction, it is better to use extruded polystyrene foam. Foam insulation is resistant to moisture and lasts on average from 20 to 30 years
	They form a seamless durable coating with low thermal conductivity and moisture resistance. They are used for insulating concrete along joists. Such thermal insulation is one of the most reliable and durable, but it is also much more expensive than other materials. This is due to the need to use a special installation, with the help of which spraying is carried out
	The most environmentally friendly insulation at an affordable price. Used for insulation along joists and under screeds. To ensure maximum thermal insulation, the material must be covered in a thick layer - from 10 to 20 cm. Expanded clay does not burn, has a long service life, but is very fragile and loses its thermal insulation properties due to damage to the structure
	Lightweight, environmentally friendly insulation with water-repellent properties. Cork has a very low thermal conductivity, it is always warm to the touch, so it is ideal not only as a substrate, but also as an independent floor covering. It can be laid directly on a concrete floor, painted or varnished. The only disadvantage of insulation is the high price

There is another type of insulation that appeared not so long ago and has not yet gained widespread popularity. This is liquid thermal insulation - a new generation material with unique properties. It looks like thick white paint, and is applied in the same way, forming an elastic, durable coating. A 1 mm layer can replace 50 mm thick rolled thermal insulation; moreover, such a coating is impervious to moisture, chemical attack, does not burn and does not emit toxic substances. This paint is used not only for insulating concrete floors, but also for walls, slopes, pipelines, facades, and various containers. The coating lasts for about 15 years if applied correctly.

Liquid thermal insulation coating "Astratek"

We insulate a concrete floor with our own hands

Before insulation, the concrete surface must be inspected and all defects eliminated. This applies to potholes, cracks, and crumbled areas. Small differences in height are leveled with leveling mixtures. This preparation is a mandatory step and ensures the reliability and durability of the floor. Now let’s look separately at the most popular methods of insulating a concrete floor in a private house.

Insulation with polystyrene foam

To work you should prepare:

Eps boards;
waterproofing film;
damper tape;
vapor barrier membrane;
construction tape;
gypsum fiber sheets;
GVL glue;
tools and fasteners.

The surface of the concrete floor must be clean, absolutely dry and not have differences in height of more than 5 mm.

Step 1. The floor is covered with a waterproofing film, the sheets of which are overlapped by 10-15 cm, and the joints are secured with tape. To increase sound insulation, you can lay a second layer of geotextile fabric with a density of 300 g/m2.

Advice. Waterproofing is mandatory for bathrooms, kitchens and other rooms with high humidity; in other rooms, insulation can be laid directly on a concrete base.

Step 2. A damper tape is laid around the perimeter of the room so that its bend falls exactly at the junction between the wall and the floor.

Step 3. The first row of polystyrene foam is laid. The slabs fit tightly together using grooves and ridges on the side edges. The last slab in the row is trimmed if necessary.

Step 4. The insulation must be laid with offset seams, staggered, so the second row begins with a cut slab. Everything else is exactly the same: EPPS is laid joint-to-joint, leveled, making sure that all the slabs are located in the same plane.

Step 5. A vapor barrier membrane is laid on top of the polystyrene foam. Its canvases are also overlapped, the edges are placed on the wall to a height of 10 cm, all joints are sealed with tape.

Step 6. A prefabricated screed is installed. Gypsum sheets are laid on the floor joint to joint in a checkerboard pattern. Next, glue is applied along the seams between the rows in continuous wavy strips and a second layer of gypsum fiber board is laid so that the seams are completely covered by the sheets.

Step 7 When the glue hardens, both layers are mechanically fixed to each other. Self-tapping screws are screwed into each sheet in the corners and in the center, slightly recessing the fastener heads into the material.

After this, you can lay any finishing coating and even install a warm floor under the tiles. Heating elements can be located both in the screed layer and in the tile adhesive layer.

Insulation with mineral wool on joists

To work you will need:

mineral wool in slabs or rolls;
waterproofing film;
wooden beam for logs;
plywood or chipboard for flooring with a thickness of 18 mm;
dowels and screws;
tape measure, level and mounting knife;
drill and hammer drill.

Step 1. The concrete base is covered with a layer of waterproofing film. Adjacent canvases should be overlapped by 15-200 cm, the joints taped.

Step 2. Logs with a cross-section of at least 110x60 mm are installed on top of the film. The distance between the logs depends on the thickness of the floor covering; in this case, it is recommended to take a step of about 300 cm. The timber is placed on an edge, be sure to control the plane with a level, and also make sure that the logs are positioned strictly parallel to each other.

Step 3. Screw the logs to the base. To do this, drill them through and go deep into the base by 50-60 mm. Next, insert the dowels and screw in the screws. The fastening pitch is 40-50 cm.

Advice. To fix the joists to the floor, experienced craftsmen recommend using screws whose threads do not reach the head. Such fasteners allow you to tighten the beam more tightly to the base.

Step 4. Install insulation. A roll of mineral wool is rolled out over the joists, after which the insulation is cut into strips so that each of them tightly fills the space between the beams. If slab insulation is used, the slabs are inserted one at a time between the joists and, if necessary, cut to width. The joists should protrude above the insulation by approximately 20 mm.

Step 5. The next stage is laying the subfloor. The plywood is cut out and the sheets are laid end to end in a continuous layer. You can use tongue and groove slabs with a protective moisture-resistant coating. The material is laid with its long side perpendicular to the joists and attached to the frame with self-tapping screws at 20 cm intervals. The rows of slabs are laid with offset seams, and the joining of the seams in the row is carried out along the longitudinal axis of the joists.

Before laying the slabs, the adhesive is applied to the ends with a brush, which ensures a high degree of moisture resistance.

To provide greater protection to the insulation from moisture, before installing the flooring, it is recommended to lay a vapor barrier membrane with an overlap of strips of at least 10 cm. You can also glue the joints of the slabs during installation, ensuring complete tightness of the subfloor. After this, all that remains is to lay the finishing coating and secure the baseboards.

Prices for Rockwool mineral wool

rockwool mineral wool

Prepare everything you need in advance:

polystyrene foam boards;
reinforcing mesh;
profile for beacons;
rule;
glue;
damper tape;
cement and sand for mortar.

Step 1. The concrete floor is thoroughly cleaned of dust and debris. Damper tape is glued around the perimeter of the room.

Step 2. Take the first insulation board, apply glue with a spatula in the center and in the corners, lay it on the floor and press it with your hands over the entire surface. The next plate is fastened end-to-end with the first, pressing tightly along the seam. In the same way, lay the whole thing to the end, if necessary, trimming the outer slab.

Step 3. The first slab of the second row is cut to create an offset joint installation. Further installation is carried out in the manner described above. If a second layer of insulation is required, the top slabs are placed so that they completely overlap the seams in the bottom layer.

Step 4. A reinforcing mesh of metal rods is laid on top of the insulation. There should be a distance of 20-30 mm between the edges of the mesh and the walls.

Advice. Before laying the mesh, it is recommended to cover the insulation with thick polyethylene film, gluing the joints of the strips with tape. This is necessary not to protect the insulation from moisture (expanded polystyrene is a moisture-resistant material), but to avoid the solution from seeping into the joints between the plates and the formation of air voids in the screed.

Step 5. Profile beacons are laid on the reinforcing mesh and fixed with a small amount of solution. Here it is very important to set the beacons at the level, because the evenness of the floor depends on this. All beacons must be strictly horizontal and in the same plane.

Step 6. Mix the solution and pour it between the beacons. Next, using the rule, the mixture is stretched along the beacons and leveled. If grooves form, more mortar must be added. The thickness of the screed is made within 4-6 cm.

After leveling the surface, the screed is left to dry. When the solution has set well, you should carefully remove the beacons and seal the grooves with fresh cement mixture.

While the floor is drying, it must be protected from direct sunlight and drafts, and periodically moistened for the first 10 days to prevent the screed from cracking.

Insulating a floor by laying insulation on a concrete floor slab, followed by pouring a cement composition is a rather complicated process. In order to carry it out with guaranteed quality of the final result, you must first decide on choosing the thermal insulation material itself. There are a considerable number of types of floor insulation for concrete under screed, and each has its own pros and cons. Let's look into them thoroughly.

What do manufacturers offer today? It is necessary to indicate that all heat insulators are divided into several groups depending on their structural composition:

roll and slab,
bulk,
sprayed

The first include mineral wool in rolls and mats, glass wool, polystyrene foam boards, foil penofol(foamed polyethylene). To the second group - expanded clay, perlite, polystyrene chips. To the third - polyurethane foam.

Let’s immediately make a reservation that although the latter is the best, it is very expensive, and the method of applying it requires special equipment.

The rest are often used for thermal insulation of concrete floors, so let's look at them.

Expanded clay

If we talk about insulation under the screed specifically for a concrete base, then This is what expanded clay was originally created for. These are granules of foamed clay, which are simply scattered on the floor, leveled in thickness (usually within 7-20 cm) and covered with a semi-liquid concrete composition.

It is not necessary to cover the material with waterproofing. Concrete penetrates into the top layer, forming expanded clay concrete, which in its thermal properties is not inferior to any insulation.

The thermal conductivity of expanded clay is 0.16 W/m K.

Foamed polyethylene

It is also called penofol. This is a thin layer of polyethylene foam, which is covered on one or both sides with aluminum foil. The latter performs two functions:

waterproofing,
reflector of thermal energy.

Thermal conductivity – 0.037-0.051 W/m K depending on the thickness.

If you lay it on a concrete floor, then it is better to use a model covered with foil on both sides.

Polyethylene foam itself does not absorb moisture very much. But after its penetration it sharply loses its qualities. Therefore, it must be protected on both sides.

Moisture from the screed mortar will begin to penetrate into all the cracks, which can negatively affect the technical condition of the penofol.

Penofol should be laid on the floor in strips, joint to joint. The connection boundaries are covered with self-adhesive foil tape.

Using Penoplex

The name Penoplex itself is a brand. And the material itself is a high-density polystyrene board. For screed floors this is the best option.

It has low thermal conductivity - 0.031 W/m K.
It has a high density - 45 kg/m³, which affects the compressive strength. And for genders this is one of the important indicators.
Does not absorb moisture.
Does not allow steam to pass through.
Chemically inert.
Absolutely environmentally friendly.
Easy to process.

Today, manufacturers produce foam boards with a tongue-and-groove connecting lock, which makes it possible to assemble seamless coating.

The process of insulation with penoplex is simple. It is necessary to lay the slabs over the entire surface of the concrete floor, connecting them together with a lock, then stretch the reinforcing synthetic mesh over the top, and only then you can pour the solution.

Mineral wool

It should be noted that of all the insulation offered under the screed, this is the most inconvenient. The thing is that mineral wool is a hygroscopic material. It quickly absorbs moisture, becoming practically unnecessary. Therefore, it must be covered on both sides: on the side of the concrete floor with a vapor barrier film, on the side of the screed with a waterproofing membrane. Therefore, the pouring process itself begins with the installation and laying of the lower protection.

Typically, the film is laid in strips with edges overlapping within 10-15 cm, which must be secured with construction tape along the joint. Be sure to lay it over the walls, taking into account the thickness of the entire insulated pie plus the screed.
Next, the thermal insulation material itself is laid out. It is better to use mats for the floor. They should be laid tightly to each other so that there are no gaps left, which can later become cold bridges.
The top film is laid, like the bottom one, in strips with overlap and installation of tape.
A reinforcing frame in the form of a metal or synthetic mesh must be applied to such a heat-insulating cake.

note, if mineral wool is laid in two layers, then the mats should be offset by half the panel. The seams between the thermal insulation elements must not coincide vertically.

The process of laying insulation under the screed

Insulating the floor under the screed with your own hands is not difficult, if you take into account the nuances of installing each heat-insulating material. For example, polystyrene boards do not need to be covered with waterproofing. And without this, mineral wool, after a while, will become just a layer that has nothing to do with the category of heat insulators.

In this regard, expanded clay is a dual material. That is, it can be used in its pure form without covering it with a waterproofing layer . But often craftsmen also use membranes, covering them with insulating flooring.

In principle, the technology itself is the same, regardless of the chosen thermal insulation material.

Correctly lay the thermal insulation taking into account the complete and dense coverage of the concrete floor.
Do not leave gaps and cracks that can become cold bridges.
Pouring the concrete solution is carried out using standard technology, taking into account the thickness.

More and more often, craftsmen are talking about the fact that any screed, even when poured over an insulated floor, it must be carried out with a reinforcing element. The costs are small, labor intensity does not increase, but the strength characteristics of the layer increase. And this increases the service life.

Estimation of the cost of screed with insulation

The only thing that will affect the cost of a poured floor screed with insulation is the price of the latter. Here are the prices for insulation materials that are used for thermal insulation of floor bases.

Mistakes when insulating under a screed

The insulation of the screed must be approached from the position of correctly laying all the layers used. As mentioned above, if waterproofing is used, then the film must be placed on the wall. If this is not done, the liquid solution will find a way to penetrate under the protective layer and into the insulation itself.

If penoplex slabs without a locking connection are used for insulation, they must be laid tightly pressed against each other. Many people recommend filling the gaps between the slabs, as well as between them and the walls, with polyurethane foam. You can't do this. Foam easily absorbs moisture, decomposing under its influence. If you have already used it, then cover the insulation completely with waterproofing film.

The reinforcing frame must be laid in the body of the screed, and not on the insulation. Therefore, the mesh is laid with a slight rise from the surface of the heat-insulating layer. This can be done using special plastic stands, which are sold today in hardware stores.

Before insulating the floors with screed, the last must be cleared of debris. Pebbles, small debris may damage the waterproofing film or the insulation itself.