How to insulate a slab foundation near an operated house. What is the insulation of the slab foundation? Advantages of slab insulation

When choosing a foundation, they are guided, firstly, by reliability, and secondly by cost. It would be nice if both qualities were combined, but this is not always possible. One of the most reliable bases for building a house is a monolithic slab foundation. In some cases - on normal soils for light houses, it is relatively inexpensive, in difficult cases it can be expensive.

Scope and types

A monolithic slab for a house belongs to floating unburied foundations, there are also shallow foundations. It got its name due to the fact that the reinforced concrete base is poured under the entire area of \u200b\u200bthe house, forming a large slab.

A prerequisite is the presence of a sand and gravel cushion, which redistributes the load from the house to the ground, and serves as a damper in case of frost heaving. Often this foundation is the only possible solution. For example, on unstable, loose soils or on clays with a large freezing depth.

The construction of the monolithic slab foundation is simple and reliable, but its production requires a large amount of reinforcement and large volumes of high-grade concrete (at least B30), because the entire area occupied by the building is reinforced and concreted, and even with a margin - for greater stability. Therefore, such a foundation is considered expensive. In principle, this is so, but it must be considered. In some cases, its cost is lower than that of a deep belt - due to less land work and less concrete.

Depth of laying monolithic slab determined depending on the mass of the house and the type of soil. With a shallow depth on heaving soils in winter, the house, together with the base, can rise and fall. With the correct calculation of the reinforcement and plate thickness, this does not affect the integrity of the building. The slab compensates for all changes due to the elastic force. In the spring, after the soil has melted, the house "sits down" in place.

There are four types of slab foundations:

• Classical. A reinforced concrete slab is placed on a sand and gravel cushion with or without insulation. The thickness of the concrete layer is 20-50 cm, depending on the soil and the mass of the building. The thickness of the layers of the pillow depends on the depth of the fertile layer - it must be completely removed. The resulting foundation pit can be filled with sand and gravel by 2/3.

  

• Insulated Swedish plate (USHP) with built-in underfloor heating. Firstly, it differs in that the slab formwork is non-removable - from L-shaped polystyrene foam blocks. This significantly reduces heating costs - heat loss is minimal. Also, underfloor heating pipes are laid on top of the insulation, reinforcement is laid on them (sometimes under them) and everything is poured with concrete, the thickness of the concrete layer is 10 cm. All communications, including water supply and sewerage, are laid even at the stage of foundation preparation - in a sand cushion. That is, after the foundation is made, the heating system is ready and the engineering systems are installed. This approach allows you to speed up construction, but the foundation itself is expensive. This type of foundation requires a competent engineering calculation and the same execution: when calculating and laying communications, you cannot make mistakes, since alterations are impossible. Also, questions arise regarding the repair of systems embedded in the foundation. It is impossible, therefore expensive materials are laid with a long warranty.

  

  USHP - insulated Swedish plate with built-in warm floor

• Russian - plate with stiffeners. To strengthen the structure for heavy houses and in difficult operating conditions (strong frost heaving), Russian scientists came up with the idea of \u200b\u200bmaking more massive stiffeners. They are usually arranged under load-bearing walls. At the same time, the complexity of the work increases - stiffening ribs are separately arranged, separately - a slab. But the bearing capacity of such a foundation is much higher, which makes it possible to reduce the thickness of the slab - up to 10-15 cm.

  

  

  Insulated slab construction technology

  Saving energy is becoming a really relevant topic, so few people build a foundation without insulation. Any slab foundation is a multi-layer structure, and in the case of insulation of layers, even more. To achieve the desired quality level, each level must be met carefully. Let's dwell on each in more detail.

  

  Foundation preparation

  The dimensions of the pit for a monolithic slab should be larger than the building itself, at least by 1 meter. In this area, fertile soil is completely removed. Its thickness is different in different regions - from 20-30 cm to 50 cm and more. In any case, they remove everything.

  

  Drainage pipes are laid along the edge of the pit, just below the general level of the bottom, to drain surface water into drainage wells. This measure is necessary so that the walls and the foundation itself do not get wet.

  

  The bottom is leveled, the pits are filled up, the humps are removed, everything is carefully leveled to the level of the horizon and compacted. Rolls out onto the leveled bottom. It should cover not only the bottom, but also the walls. The canvases are spread overlapping, the edges are glued together with reinforced tape. Geotextile prevents plant roots from germinating, and also prevents the sand washout, which serves as a damper cushion.

  

  Clean sand of medium grain size is poured onto the laid geotextile. Sand layer - 20-30 cm. It is poured in thin layers, evenly distributed and tamped in layers. A layer of sand, which can be efficiently tamped with a manual vibrating plate - 8-10 cm. These are the layers that sand is laid. It must also be laid in a level, in the same layer throughout the excavation.

  

  The thickness of the layer can be controlled with the stretched cords. They are tied to hammered stakes, specially made supports - benches, to the formwork installed in the level (see the photo below). All cords must be in a horizontal plane. Knowing the initial distance from the bottom of the pit to the stretched threads, you can determine the height of the poured layer.

  Crushed stone is poured onto the compacted sand. The entire volume is poured at once, evenly distributing it over the site. The leveled crushed stone is rammed to a high density.

  

  At this stage, sewer and water pipes are laid. In the already rammed rubble, ditches of the required depth are dug. They should be such that there is some space around the embedded elements. Pipes are laid in the ditches, filled with sand, leveled, sand is compacted with a shovel or board. More severe compaction can lead to cracks. Therefore, pipes are laid after ramming.

  Concrete preparation

  Formwork is placed around the perimeter of the pit. It is usually assembled from a 40 mm thick board or 18-21 mm plywood. The height of the formwork for a monolithic slab is the total thickness of the remaining layers. Along its edge, it is convenient to control the level of concrete when pouring, therefore the board must be edged. To save material, you can set the formwork only for preparation. After the concrete has set, it is dismantled and set higher, using it again to pour the main slab. But the loss of time with this approach is significant, so this is not always done.

  In any case, the formwork is supported from the outside with stops and jibs. The structure must be rigid to support the weight of the concrete.

  A 100 mm layer of concrete is poured onto the tamped gravel. It can be concrete of low grades - B7.5 - B10. Concrete preparation will be a reliable basis for laying waterproofing and insulation, and also serves to distribute the load from the house more evenly.

  

  Waterproofing

  Since the monolithic foundation slab is completely in the ground, it needs careful waterproofing. Therefore, two types of materials are usually used: coating and roll. The base is first thoroughly dedusted, then impregnated with a diluted kerosene or solvent primer (and the sides of the concrete preparation are also coated). It is sold very thick and does not adhere well to concrete. As a result, rolled waterproofing does not adhere well and the foundation will get wet. When diluted, it becomes more fluid and penetrates deeper into the concrete. At the same time, it almost does not lose its properties.

  When laying out roll waterproofing, it is released outside the foundation by 10-15 cm. The sheets are rolled out with an overlap, the connecting edges must be coated with bituminous mastic and pressed well. When laying out, you must ensure that there are no creases and waves.

  If the water table is high, you may need two layers of roll-up waterproofing. It is then rolled across, and glued to the primer too ( bituminous waterproofing), but you can no longer breed.

  

  Waterproofing of a monolithic foundation slab is double - coating and roll

  Of rolled waterproofing materials, Gidroizol, TechnoNIKOL Technoelast EPP-4 on high density polystyrene proved to be the best. Technolynicol of this brand has a high tensile strength of about 60 kg, which increases the chances that it will not be damaged during further work. You should not use roofing material, no matter how much you want to save money. IN modern design it is too thin and brittle, quickly loses its properties. You cannot replace the waterproofing in the slab, therefore, lay the best material.

  It is also possible to reduce the capillary intake of moisture through the slab with the help of liquid impregnations such as Betonit. It significantly reduces moisture absorption. It penetrates to a depth of 50-60 cm, so that it will saturate the concrete preparation through and through. The disadvantage of this material is its high price, but the material has excellent properties.

  Warming

  For insulation of the slab foundation, extruded high-density polystyrene foam is used. The thickness of the insulation layer is 10-15 cm, depending on the region (10 cm is enough for the Middle Strip). Laying is carried out in at least two layers, overlapping the seams, which form cold bridges. It takes more time, but heating costs will be lower. If the slabs have an L-shaped lock, they can be laid in one layer.

  

  Since expanded polystyrene is "not friendly" with oil products, a dense polyethylene film is spread on it, and then heat-insulating material is laid.

  Reinforcement

  For the reinforcing frame, ribbed reinforcement of class AIII with a diameter of 12-14 mm is used. It is laid up and down, with a step of 15-30 cm, it may have one or two layers. It all depends on the type of soil and the mass of the building. All reinforcement parameters are counted separately.

  The reinforcement should be at a distance of at least 5 cm from the edge of the slab. Therefore, it is placed on special supports that provide the required gap.

  

  When reinforcing, a cage is obtained; at each intersection, the rods are tied together with a special soft steel wire. There are also connection techniques - using plastic clamps or welding. Tying with plastic clamps is quick, but not everyone trusts them. Welding is not recommended, because the weld is the most vulnerable place for rust, and the connection is too rigid. When using wire and clamps, the whole structure can play a little without breaking the bond, and when welding, such movements lead to the fact that the seam bursts. As a result, the reliability of such reinforcement is low.

  Pouring the foundation slab with concrete

  The thickness of the slab is calculated for each specific case and can be from 20 cm to 50 cm. When pouring, concrete is used not lower than the B30 grade. The entire perimeter must be filled in one day, avoiding the appearance of vertical seams. Therefore, for concreting a slab foundation, most often ready-made concrete is brought: large volumes are required at a certain time.

  

  The schedule for the arrival of the machines should be calculated so that you have time to distribute the first portion and compact it. Construction vibrators are used for compaction, which create high-frequency vibrations. As a result, all air is removed, the concrete mixes better, becomes more fluid and plastic. The result of this treatment is not only a flat concrete surface, but also a higher hygroscopicity class.

  As a last resort, you can fill the slab with horizontal layers. Vertical division in this case is unacceptable, since cracks are likely to go at the joints.

  Curing

  For the normal process of concrete hardening, a sufficient humidity level of 90-100% and temperatures above + 5 ° C are required. It is advisable to fill the stove in warm weather with a temperature of about + 20 ° C. This temperature regime optimal for the hardening process. Caring for the concrete of a monolithic slab consists in preventing mechanical damage and maintaining moisture.

  Immediately after laying, the concrete is covered with a diaper or tarp. This prevents it from heating up from the sun, it is not affected by the wind. The film is glued into large panels. The strips are laid with an approach of 10-15 cm, glued with tape. It is advisable that there are as few unscrewed joints as possible, that is, the shelter should consist of one or two pieces, if one is too inconvenient. In this case, individual pieces of film overlap one another at least half a meter.

  

  The dimensions of the film are such that the side surface of the formwork is also closed, and a load could be placed on the edges of the film, which will not allow the wind to lift it. Also, with a load - boards - they press the place of the overlap of two panels in order to reduce the windage, they can be spread over the surface.

  If the air temperature is above + 5 ° C, approximately 8 hours after pouring, the concrete is poured with water for the first time. Irrigation should be drip, not jet. In order not to damage the surface with drops, you can lay burlap on it or sprinkle a layer of sawdust on it, and cover it with a film on top. The covering material is watered, and it maintains the moisture content of the concrete. In any case, watering is carried out only at temperatures above + 5 ° C.

  

  If there is a threat of frost, the slab and formwork are additionally insulated. You can use any heat-insulating materials, both prepared for building a house, as well as sawdust, straw and other improvised means.

  When to remove the formwork

  

  Differences between insulated monolithic Swedish slab and video about its construction

  As mentioned earlier, the insulated slab under the house developed by Swedish builders is energy-saving. During its construction, a permanent formwork made of extruded polystyrene foam is used. As a result, heat leakage into the ground is minimal. The second fundamental difference is the underfloor heating system built into the slab.

  Since engineering systems are poured into the thickness of concrete, it requires an accurate and competent calculation. High demands are also placed on execution. Even small mistakes are critical. You can do UWB yourself, but it is better to order the project. For an approximate cost breakdown, see the next photo. The amounts are no longer relevant, but the percentages are fair. The cost of the foundation project is about 1%.

  

  In the following videos, you will see the stages of making a Swedish slab for a specific house. Many useful devices are described that will facilitate the work, explanations are given on some of the features.

  And also look at how the Germans are pouring such a plate. There are also many useful nuances.
  

Underfloor heating pipes must be resistant to damage, since they are exposed to mechanical stress during installation. The best option is products made of cross-linked polyethylene PE-Xа. Photo: StoneHut (2)

How to calculate slab thickness and reinforcement section?

In this case, one should be guided by the standards (SP 50.101.2004 and SP 63.13330.2012). An easier way involves the use of ready-made projects that are available from all large construction companies. To check the calculations and compare options, it is worth using special computer programs, for example, Foundation, GIPRO or WINBASE.

On the "classic" Swedish slab, you can immediately erect walls by placing two layers of rolled waterproofing under the first crown (or a row of masonry). Photo: StoneHut

Is drainage required around and under the foundation slab?

On swampy and flooded areas, it is highly desirable. In this case, the function of the drainage layer is performed by the addition of coarse gravel (20–70 mm). The system will be more effective if tubular drains are laid in the thickness of the bedding (they optimal step is 1.5–2 m). Drainage is also required around the perimeter of the slab or blind area. The water should be discharged into a drainage well or downward relief; if the groundwater level is less than 1 m from the surface, it is advisable to use an automatic system. The presence of drainage will reduce the risk of freezing of the soil under the house, extend the life of the foundation and reduce the risk of cracking in the blind area.

The slab is poured under the entire house, including the porch and terrace (veranda). If you attach these elements later, there is a high probability of distortions and cracks at the junction of the walls.

How to build communications?

Water supply and sewer pipes, as well as an electric cable (if its underground input is provided), are laid when installing a pillow. They are protected from possible damage with an EPSP layer or wrapped in several layers of waterproofing material. In principle, it is possible to connect to communications even after the end of construction - through a wall insulated box.

But sometimes they first build a monolithic or masonry base. Photo: "Foundation 47"

Is it possible to build a slab foundation during the cold season?

This is possible, but it comes with increased costs and the risk of reduced structural reliability.

Concrete with winter modifying additives is 25-40% more expensive than usual, and the construction of a heated dome, which is indispensable in severe frost, will cost 30-100 thousand rubles. In winter, earthworks are very difficult, and all other tasks are complicated by the cold and lack of daylight.

The blind area is poured over a drainage pad and reinforced with a road mesh. Photo: IZBA De Luxe

Is it possible to build a slab foundation from homemade concrete?

Only for a small household building. If we are talking about a house, then this method is excluded, because when pouring concrete in small portions, numerous “cold” joints cannot be avoided, which will dramatically reduce the stiffness of the slab and its resistance to cracking. When delivering ready-mixed concrete, the break between the arrivals of the auto mixers should be 3-4 hours.

It is advisable to make an uninsulated blind area in fragments 1–1.5 m long in order to avoid the appearance of cracks. Photo: IZBA De Luxe

Can the flooring be laid directly on the Swedish board surface?

Yes, as a rule, you can do without. In extreme cases, add a thin layer of self-leveling mixture. Note that it is advisable to lay coatings on the Swedish slab that conduct heat well, for example, porcelain stoneware or stone tiles, a special laminate.

On open terraces, a weather-resistant coating with an anti-slip surface is laid on top of the slab, for example, porcelain stoneware or clinker tiles, larch or composite decking. Photo: ShutterStock / Fotodom.ru

3 myths about reinforcement

1. The reinforcement should be knitted, not welded, as welding negatively affects the strength of the metal. In reality, this only applies to alloyed fittings, which are practically not used in individual construction. It is easier and cheaper to knit fittings, which explains the popularity of this installation method.
2. You can knit reinforcement with anything and not necessarily tightly, since the connections are only needed for mounting positioning of the frame elements. Meanwhile, according to building regulations, when knitting overlapping and cruciform connections, the rods must be pulled together without a gap. Overlaps (their length is equal to 40 diameters of reinforcement) should be tied with steel wire in several places.
3. The diameter of the reinforcement is not important as long as the required reinforcement ratio (the ratio of the cross-sectional area of \u200b\u200bthe reinforcement to the cross-sectional area of \u200b\u200bthe concrete structure) is met. In fact, the use of thin reinforcement (8 mm) increases the labor intensity of installation and complicates the quality control of the work performed.

In private construction, it is advisable to increase the reinforcement ratio by at least 20%, compared with the recommended standards, and use high-quality concrete.

A variant of the design of the insulated slab foundation

1 - sand gravel pillow; 2 - insulation (EPS boards); 3 - drainage pipe; 4 - reinforcing cage; 5 - pipes of the underfloor heating system; 6 - flooring (tile); 7 - drainage membrane; 8 - ; 9 - gravel backfill; 10 - moisture resistant finish. Photo: TechnoNICOL

The underfloor heating system is tested in two stages. After installing the pipeline and before pouring the concrete slab, the integrity of the pipes is checked with a fluid pressure that exceeds the working pressure by 1.5 times. The test duration is 3 hours. As an exception, if a hydraulic test is impossible (for example, due to frost), a compressed air test is allowed. When pouring concrete, pipes must be filled with cold heat carrier and under pressure (working or test). After the concrete has set the required strength, a thermal test is carried out, which lasts seven days. First, for three days, a heat carrier heated to 20–25 ° C should circulate in the system. Then the maximum operating temperature is set, which is maintained for four days. During this period, the uniformity of heating of all circuits is checked using a contact thermometer.

Sergey Bulkin

Expert of the REHAU company

Aggregated calculation of the cost of building an insulated slab foundation with an area of \u200b\u200b80 m2

Name of works	amount	Cost, rub.
Geodetic stakeout		12 000
Excavation, pillow device		16 800
Drainage devices		18 000
Plumbing and sewerage pipes		14 500
Installation of formwork, insulation, reinforcing cage		32 000
Installation of underfloor heating pipes		34 200
Concreting, vibration concreting		26 000
Total
Applied materials by section
		14 500
Granite crushed stone	8 m3	16 000
Edged board		3500
Pipes (PVC and polypropylene)	Set	22 000
Reinforcement (12 mm bar and 8 mm mesh)	1.1 t	32 000
EPS sheets CARBON ECO SP 1180 × 580 × 100	235 pcs.	79 900
Gasket and fastening materials		7 500
M300 concrete	13 m3	44 200
Total
Total

It is difficult to build a solid foundation on unstable ground. In such cases, a slab base is used. It acts as a foundation of shallow depth, drifting along the site, while moving soil masses. Since the entire structure is moving, no destructive stresses arise.

For the correct operation of this type of foundation, it must be protected from freezing. Insulation of a monolithic foundation slab:

• prevents the destruction of concrete from temperature differences;
• contributes to the warm floor of the first floor;
• makes it possible to save on heating the building;
• reduces heaving of the soil under the building.

The choice of insulation

Not everyone, even the most effective material, is suitable for working in or near the ground. When choosing a material, you need to be guided by:

• moisture resistance. Being saturated with water from the soil, the product loses its insulating properties. Expanding when freezing, moisture violates the integrity of the coating, nullifying all work;
• strength. Seasonal movements of soil masses create perceptible pressure on the material. It is especially noticeable in rocky soils. Sharp edges can push through the product, leaving cracks or breaks in it;
• resistance to aggressive environments. Soils are often chemically and biologically active. The groundwater may contain an increased concentration of salts. All these factors lead to the premature destruction of the insulation.

When installing insulation inside the building, the material must be non-combustible. If there is a possibility of fire, the harmful substanceswhich can cause suffocation.

With all this, the service life of the insulation should be no less than the service life of the finishing material. In this case, you do not have to change it before the coating becomes outdated. Otherwise, it will be necessary to dismantle the finishing cloth that still meets the standards.

Extruded polystyrene foam is often used for zero cycle work. Insulation of the basement slab with expanded polystyrene, made in accordance with all the rules, allows you not to worry about the safety of concrete and saving heat.

Characteristics of expanded polystyrene

Expanded polystyrene is used for thermal insulation of the foundation slab:

• outside;
• from the inside;
• in the body of concrete

Outdoor insulation technology

The height of the slab can be from half a meter. Freezing around the perimeter is the most dangerous for the foundation. Therefore, in general, the insulation is attached precisely along the side surfaces.

Before covering the foundation with a layer of insulation, it must be waterproofed. Despite the fact that polystyrene foam is waterproof, the coating is not seamless. Moisture penetrates the seams between the slabs, which can destroy the slab.

Waterproofing is done by applying bituminous mastic or melting paraffin wax along the surface and edges of the slab. The second method is more economical and reliable. With the help of a gas burner, lumps of paraffin are melted. The material is evenly distributed over the surface, absorbing into it.

Waxing closes the pores of the concrete, creating a moisture barrier. Full adhesion helps to prevent flaking of the insulation. This means that you can easily attach insulation to it.

Expanded polystyrene plates are mounted on glue or on a cement-sand mortar. The first option allows insulation at subzero temperatures. The underground part is fixed only by gluing. This is necessary to avoid disturbing the hydro-barrier.

The basement part of the insulation of the slab foundation with expanded polystyrene is additionally fixed with plastic dowels. For this, holes are drilled through the glued plates. They go through all the insulation and part of the foundation.

The adhesive is applied around the perimeter of the board and in several stripes in the center. It is kept for 1 minute and the plate is pressed to the surface for a couple of minutes. After gluing, the bottom plates are sprinkled with a layer of sand. This helps to fix them in the mounting position.

The second row of insulation is mounted with offset seams. It is advisable to make bandaging and horizontal joints. This helps to avoid cold bridges.

If the thickness of the plates is not enough, the insulation is carried out in two layers. Products with maximum thicknesses are taken to avoid the installation of several layers. The plates of the upper layer must overlap the seams of the lower ones.

Fixation with umbrellas is carried out at five points of the slab. The dowels are mounted after the plates are completely glued, but no later than three days later.

After installation, the seams are sealed with polyurethane foam. Excess foam is trimmed and the surface is plastered over the mesh. The mesh is necessary for better adhesion of polystyrene foam and plaster.

Internal insulation technology

When insulating a monolithic foundation slab from the inside, the material is laid in two ways:

• Over the plate;
• In the body of concrete.

In the first method, the sequence of work is as follows:

• waterproofing is arranged along the foundation slab, with an approach to the wall;
• lags are screwed on top of the waterproofing layer;
• a layer of insulation is arranged between the lag;
• over the insulation, a waterproofing film is attached to the logs;
• a plank base, plywood or OSB boards are mounted on the film;
• over the subfloor, a cork, expanded polyethylene or pine needles backing is laid. A finishing floor is mounted on it.

You can do without lag. In this case, there is a complete insulation of the slab foundation with expanded polystyrene. The material is laid in a continuous layer. Immediately on top of it, the underlay and the final floor covering are laid.

When installing in concrete, the following work is performed:

• the base plate is waterproofed;
• a layer of insulation with a thickness of at least 100 mm is arranged. It is better to use products with a locking system;
• pVC film with a density of at least 1.42 g / cm3 is laid on the insulation;
• reinforcing mesh is laid. Its role can be played by a masonry mesh with a cell of 100 * 100 mm;
• the surface is filled with a screed not thinner than 5 cm;
• the finishing coating is laid on the screed.

When internal insulation it is worth using only self-extinguishing polystyrene foam. For installation under a screed, products of the G4 flammability class can be used.

Insulation of the body of the foundation slab

Warm concrete is used in many areas of construction. It can be purchased in the form of a ready-made mixture or manufactured in a construction site. For preparation, granular polystyrene foam is added to the initial mixture to form the foundation slab.

For device structural elements polystyrene concrete with density D1200 is used. When preparing 1 cube, the composition includes:

• 300 kg of cement M400;
• 1.1 m3 of expanded polystyrene granules. It is better to use granular rather than crushed material. It has the shape of a ball, which leads to a better enveloping with a cement mixture;
• 800 kg of sand;
• PAD. Saponified resin is often added. Its presence in the composition provides better adhesion and increases heat-shielding properties.

When creating such concrete, you need to remember about shrinkage. It is 1mm per 1m of surface. The plate needs to stand for some time after curing. It is necessary to arrange a leveling screed over the surface.

The flammability class of such a product is G1. The concrete itself does not burn, but the insulation granules are exposed to fire. As a result, pores are created in the body of the foundation slab. They reduce the density of the structure and increase its moisture absorption.

The thermal conductivity of such a plate will be approximately 0.105 W / (m * C). The product requires additional insulation of the slab foundation from below. The thickness of the insulating material will be less than that of plain concrete.

The choice of the type and technology of insulation of the foundation slab depends on design features buildings and construction sites. To choose optimal solution is based on the data of the heat engineering calculation and comparison of the estimated cost.

The slab base can withstand significant external influences and is suitable for construction in areas with complex, unstable soils, prone to frost heaving, with a high level of groundwater. Insulation of the foundation slab will help to significantly reduce heat loss through the base and reduce the effect of frost heaving of the soil. When the soil moves, the structure rises and falls along with the foundation, which protects the structure of the house from cracking.

general information

The slab base structure consists of layers:

• geotextiles are covered with overlapping stripes on the sand layer, the joints are glued with tape;
• crushed stone is poured in a layer of 15-20 cm;
• fill in the leveling layer cement mortar, 5-10 cm thick;
• be sure to isolate the structure from moisture using roll or coating materials;
• arrange a heat-saving layer;
• cover the plastic wrap with 20 cm overlap strips;
• lay the reinforcement mesh;
• poured with concrete.

Installation and insulation of a slab monolithic foundation is expensive due to high consumption building materials... When the soil freezes to a great depth and a significant deepening of the strip foundation is required, the device of the slab will be cheaper, and less land work will be required.

Advantages of a slab foundation

The slab base has advantages:

• the concrete slab serves as the floor of the first floor, which further reduces the cost of its installation;
• is an excellent option for the foundation of a house, the construction of which is carried out on floating soils, the slab and the whole house with it move simultaneously with the soil;
• the slab can be mounted on any type of soil, even on peat bogs and swampy areas;
• the slab is erected above the level of soil freezing, thanks to the sand cushion, frost heaving practically does not affect the structure;
• reinforced concrete slab is not subject to shrinkage;
• suitable for the construction of buildings up to 3 floors.

Insulation of the foundation slab reliably protects it from deformation during seasonal heaving of the soil and extends the life of the structure.

Advantages of slab insulation

Polystyrene foam, polystyrene foam, polyurethane foam are used as heat-insulating material. Mineral wool is not suitable due to its low strength and high moisture absorption.

There is a technology for mounting a Swedish plate. The main difference is that the concrete structure is erected on a layer of heat-saving material, thanks to which the soil under the house does not freeze or heave.

The main advantages of the Swedish plate are:

• the construction of the foundation and the laying of communications are carried out in one technological cycle;
• the heat-saving layer improves the efficiency of the warm floor;
• installation of the foundation is carried out without the involvement of a large amount of construction equipment.

Around the building, a drainage system is provided, consisting of pipes for the removal of rain and melt water.

The design of the slab contributes to the transfer of all loads from the building to the layer of heat-saving material, therefore, increased requirements are imposed on the materials used.

Disadvantages of slab foundation

The slab foundation is not always the best option... You always need to carry out all the necessary calculations in advance and select the most suitable type of base for the house.

Disadvantages of the stove:

• not suitable for construction on areas with a slope;
• to build a house with a basement on a slab, you need to deepen to a great depth, this will be very expensive;
• it is difficult to repair communications under the foundation slab;
• during construction in winter, additional costs will be required for heating concrete and maintaining the desired temperature on the site.

A slab foundation is erected only when it is impossible to arrange a strip base.

Insulation materials

The table shows the materials used to insulate the foundation slab and their characteristics:

№	Thermal insulation material	Characteristics
1	Styrofoam	Consists of air-filled cells. It is produced in the form of sheets, has insufficient density, so its surface needs additional protection.
2	Extruded polystyrene foam	Able to withstand significant compressive loads without changing its size and structure. It is produced in the form of rectangular sheets with small cells filled with air. Lay the sheets in 1 or 2 layers. The second layer must be spread out so that the seams of the sheets of the first and second rows do not intersect. During installation, provide for holes for moisture drainage.
3	Polyurethane foam	It is a type of foamed plastic with many pores filled with air bubbles. The composition is prepared directly at the construction site. The two components are mixed, the result is a dense solid foam that is applied to the surface. The plate insulated with polyurethane foam has high performance in heat and sound insulation, withstands the effects of moisture. Refers to low-combustible materials, and some brands are hardly combustible.

Most often, extruded polystyrene foam is used as insulation under the foundation slab.

Insulated plate installation

The construction of a monolithic slab foundation requires all calculations taking into account geological, climatic conditions and the mass of housing construction.

Insulation of the slab foundation allows you to save significant money on heating the room during operation.

Site preparation

At the stage of creating the project, it must be borne in mind that the site for the foundation slab must be wider than the house building by at least 1 m on each side.

Instructions for performing preparatory work:

1. They clean the construction site from debris, the root system of trees and shrubs.
2. Mark the position of the slab according to the project.
3. They clean and remove the fertile soil layer. The extent to which the slab is buried depends on geological and climatic conditions. Most often, the thickness of the slab varies from 20 to 30 cm, less often the base is deepened by 50 cm.
4. They dig a pit, manually level its bottom and side walls.
5. Pipes are installed around the perimeter to drain rain and melt water.
6. Spread the geotextile in overlapping strips. The material should cover the bottom and extend onto the walls along its entire height.
7. Wooden stakes or metal rods are driven in. Pull the cord strictly horizontally. It will serve as a guide for uniform filling of sand and gravel.
8. Sand is poured, 20-30 cm thick. Sand is evenly distributed over the entire area, moistened with water and compacted well.
9. Spread out geotextiles.
10. Crushed stone is poured, evenly distributed around the perimeter, carefully tamped.
11. They carry out all the necessary communications. They dig trenches for them in the rubble a little wider than the cross-section of the pipes. The pipeline is laid, a layer of sand is poured on top.
12. The sandy surface is leveled.

If the pipeline is laid prior to the compaction stage, the pipes may crack.

Insulation of the slab

Step-by-step instructions for insulating a slab of a monolithic foundation:

1. A removable formwork from boards is mounted, props are installed so that the structure does not fall apart under the weight of concrete.
2. Pour a layer of concrete 50 mm thick.
3. After the cement mortar has completely solidified, sheets of foam are laid on it end-to-end and glued. The adhesive composition is applied in dots along the perimeter of the sheet and in the center. A layer thickness of 10-20 cm is enough. The joints of the row are placed in a checkerboard pattern, with an offset of 1/3. When laying in two rows, the joints must not cross.
4. Spread the dense polyethylene in overlapping strips. The joints are sealed with tape.
5. The reinforcement cage is laid, the formwork is poured with concrete.

After the slab has dried, the formwork is disassembled, the side walls are insulated with the same material that was used for laying under the slab.

The insulated base / plinth helps to increase heat saving inside the building.

When installing insulation on bitumen insulation, you need to wait until it dries completely. If laid on a wet layer, the materials may be damaged and the effect of thermal insulation and waterproofing will decrease.

Heating pipes installation rules

Heating pipes are used during the installation of the UWB. There are such rules for laying them:

• Tighter pipe laying allows for more high temperatures heating the room.
• The distance between external walls and pipes must not exceed 150 mm. Closer to the center, the laying pitch can be increased up to 250 mm.
• To minimize hydraulic losses, the length of one loop should not exceed 100 m.
• Do not lay pipes closer than 100 mm from each other.

Heating pipes must not be installed at the joints of monolithic plates. In this case, it is better to lay two contours. The pipeline crossing the joint is insulated with steel sleeves 30 cm long.

You can watch the video how to make an insulated Swedish stove with your own hands:

The insulated base plate allows you to reduce heating costs during operation and helps to reduce the level of frost heaving of the soil. Thanks to this, the life of the foundation is extended, and living in the house becomes more comfortable.

When choosing a foundation structure for a future building, each developer is guided primarily by its cost, reliability and durability. The ideal foundation that combines all of these qualities is the monolithic foundation slabs, which can be built on various types of soil. But concrete has a high thermal conductivity, so developers need to take care of the insulation of load-bearing structures even in the process of performing construction work.

Warming methods

Insulation of the slab foundation must be carried out in the part that is located in the zone of soil freezing. The developer should lay insulation under the foundation slab, as well as under the outer blind area, which is necessarily created around the building. And also the base of the building and the upper part of the foundation wall should be covered with a special material. Timely warming of a monolithic foundation slab will protect the soil adjacent to the building and its walls from freezing, thereby preventing frost heaving of the soil and minimizing heat loss at home.

When planning the insulation of a slab foundation, the developer must take into account the type of supporting structure:

1. Tape (in-depth). Various materials are used for insulation, which are laid on the vertical surfaces of the supporting structure, above the ground surface.
2. Shallow strip foundation. For insulation, tile materials are used, which are placed on the sole and vertical surfaces of the supporting structure.
3. Pile. Only the lateral surfaces of piles deepened into the soil are insulated.
4. Monolithic tiled construction. The base plate is insulated not only from below, but also on the sides.

Benefits of timely insulation

The insulated slab foundation has a lot of advantages that every developer needs to know about:

1. Developers will be able to save concrete mortar, which is used in large volumes when pouring slab foundation structures.
2. The insulated foundation allows you to minimize heat loss. This has a positive effect on indoor climate as well as on utility bills, which are rapidly increasing in winter time of the year.
3. The timing of construction work is accelerating.
4. The useful life of the supporting structure is maximized, since it ceases to be adversely affected by moisture and low temperatures.
5. The insulated base plate prevents condensation on interior wallsah premises.
6. The service life of waterproofing materials that are used in the construction of slab foundation structures is maximized.

What materials can be used to insulate a slab foundation?

Currently, a huge range of materials is presented on the domestic construction market that developers can use when carrying out insulation measures:

1. Polyurethane foam. This material is made of foamed plastic, which has a porous structure filled with air bubbles. This insulating mixture is created directly at the construction site and applied to the foundation structures using special equipment. The components that have entered into a chemical reaction already on concrete surfaces form a strong foam that hardens almost instantly. This material helps to minimize heat loss, prevents extraneous noise from the street from entering the premises, does not undergo putrefactive changes in constant contact with a humid environment, and is highly resistant to fire.
2. Styrofoam. This material has been used for decades in the construction industry as insulation. Its main disadvantage is its low mechanical strength, which requires additional cladding.
3. Extruded expanded polystyrene. This material has a fine-mesh structure and is supplied to the construction market in the form of rectangular sheets. It has excellent technical properties, is able to withstand high loads, without changing either the internal structure or the geometric shape. IN last years when insulating slab foundation structures, developers use extruded polystyrene foam, since it does not need additional protection and can perform the functions assigned to it for decades.

Why do experts recommend using Penoplex for insulation?

In recent years, many developers prefer to insulate the basement with penoplex. The choice of this material is due to the fact that it has a high resistance to moisture, and also has the lowest thermal conductivity. Due to the fact that the slab supporting structure will have to be in contact with a humid environment for many decades, the insulation of the foundation with penoplex will protect the building from its harmful effects.

Extruded polystyrene foam is ideal for thermal insulation of monolithic foundation structures, as it is able to withstand compressive loads. Polyurethane foam boards and polystyrene foam are cellular materials with a closed structure, so that moisture is not able to penetrate into their cavities. That is why they are used when carrying out insulation measures.

Warming rules for slab foundation structures

Before insulating the slab foundation, the developer must learn about all the features and nuances, as well as about the most effective technologies. If the foundation is insulated with foam from the outside, this will protect not only the slabs, but also the walls from freezing. In the case when the expanded polystyrene panels are laid on the inner sides of the walls, the developer will be able to significantly improve the indoor microclimate, but at the same time, the slabs and walls of the building will not be protected from freezing. From this it follows that the external insulation of the foundation with penoplex will ideal option for any construction site.

External insulation of the foundation with expanded polystyrene or expanded polystyrene is possible only at the initial stages of construction. If the developers miss this moment, then in the future they will only be able to carry out internal insulation of the foundation with penoplex or polyurethane foam.

Carrying out insulation measures during construction

The procedure for warming the foundation with expanded polystyrene must be carried out at the initial stage of construction work. Developers should strictly follow the technology:

1. First of all, a pit is dug, in which a monolithic slab of concrete will be created. Its depth should be 1 meter. Depressions are made at the bottom, into which drainage pipes are laid, the functions of which are to divert surface water into specially created wells. Such measures will protect not only the foundation, but also the walls of the building from getting wet.
2. After laying the drainage pipes, the bottom of the trench is leveled and a special material is rolled out on its surface - geotextile. It will prevent the germination of rhizomes of trees and shrubs, which can disrupt the integrity of the supporting structure.
3. A layer of sand and gravel is laid on top of the geotextile. Thus, at the bottom of the pit, a sand-crushed stone cushion is created (approximately 30-40 cm thick).
4. Utilities are being laid, for example, water and sewer pipes. After laying them, the surface is sprinkled with sand and leveled.
5. Formwork is being built around the perimeter of the prepared pit. For these purposes, it is customary to use boards or sheets of moisture-resistant plywood. From the outside, the formwork must be supported with jibs or stops in order to wooden structure was able to withstand the load that the concrete solution will exert on it.
6. A small amount of concrete is poured onto the bottom of the pit, which will create the first foundation layer. After it has solidified, the developer must proceed with waterproofing and thermal insulation measures.
7. Due to the fact that a monolithic concrete slab will constantly be in the ground and in contact with a humid environment, the developer must perform its high-quality waterproofing. For these purposes, in the construction industry, it is customary to use roll material or coating. The concrete base must be thoroughly cleaned of debris and then dedusted. To increase its adhesive properties, it is recommended to treat with diluted kerosene or solvent. After that, roofing material is rolled out on the prepared concrete base, the canvases of which should overlap. All joints should be treated with mastic, after which experts recommend laying another layer of waterproofing. If the developer decides to use liquid insulation, then he needs to apply it to the surface several times concrete base and after complete drying, continue construction work.
8. At the next stage, the slab is insulated. For these purposes, most developers use sheets of extruded polystyrene foam (15 cm thick). Such material is usually laid in two layers. Make sure that the top sheets overlap the joints of the bottom panels.
9. Reinforcement of the foundation structure is carried out, due to which its strength and load-bearing characteristics will increase.
10. The concrete solution is poured in several stages. After pouring the first batch, the developer must use a deep vibrator to remove air and eliminate the resulting voids. After that, the remaining solution is poured out.

After the concrete has set, the developer can continue construction work. In order to maximally protect the building from the harmful effects of harmful environments, he must also carry out internal insulation of the foundation. To do this, use sheets of extruded polystyrene foam, which are glued to the floor and walls of the premises and are subsequently finished.

An uninsulated foundation can lead to a lot of heat loss, unlike a tightly closed and well insulated home.

Insulation of foundations reduces the need for a large heating system and avoids moisture condensation, which often occurs as a result of temperature differences between the inside of the basement and the ground around the base.

A poorly designed foundation insulation system can cause many problems, such as moisture problems and insect infestations.

Basement exterior wall insulation

There are several options for installing insulation on the outside of the strip foundation base. External insulation has the following advantages and disadvantages:

Benefits:

• Minimizing thermal bonding and reducing heat loss through the foundation.
• Protection against moisture penetration into the interior finish.
• Insulation protects the foundation from the effects of the freeze-thaw cycle in extreme climatic conditions.
• Reduced condensation.
• Reduces wastage of interior space.

Disadvantages:

• An expensive installation for an existing building if also installed drainage system around the perimeter.
• Many external insulation materials are susceptible to infestation by pests.
• Many contractors are not familiar with the proper procedures in detail.

Experienced builders believe that the best way insulate the foundation, this is to insulate it from the outside. Carefully designed perimeter drainage system consisting of washed gravel, perforated plastic pipe and a fabric filter. Highly recommended for areas with poor soil drainage.

Some insulating foams are made with boric acid to keep termites out. However, borate can slowly leach out of most materials when it is exposed to groundwater.

Insulation of basement interior walls

In most cases, the best way is to insulate the inner walls of the strip foundation; this is also a less expensive option for a finished building. Such insulation has the following advantages and disadvantages:

Benefits:

• It is much cheaper than insulating exterior walls for existing buildings.
• There is a wider selection of materials as you can use almost any type of insulation.
• No insect threat.
• A space isolated from cold ground is more effective than using external insulation methods.

Disadvantages:

• Many insulations require a fire retardant coating as they release toxic gases when ignited.
• Reduces usable interior space by 3-5 cm.
• Does not protect against moisture penetration like external insulation.
• If the perimeter is poorly drained, the insulation can saturate moisture around the perimeter of the base and seep through the walls of the basement.

New methods of foundation insulation

Some new building systems make it possible to erect a ready-made insulated foundation without the use of wooden or metal formwork, this is a system concrete forms (ICF), simply put, fixed formwork made of expanded polystyrene, which uses rigid foam as molds for formwork, thereby insulating the inner and outer sides of the foundation.

Thermal panels

Of the new products, there is still insulation that does not require finishing, this is thermal panels made of expanded polystyrene with stone chips.

Polyurethane foam

Another synthetic resin material used for thermal insulation of foundations is polyurethane foam... It is prepared by mixing liquid components in a special technique. The production process takes place at the construction site.

This material is applied by spraying. Cured material for 17-20sec.

One of the main advantages is the extremely low thermal conductivity of 0.028 W / m0S. In addition, the spraying method promotes the formation of a solid insulation layer where there are no seams (even if the foundation has a complex geometry). Thus, it completely eliminates the possibility of cold bridges. The spraying process itself takes much less time than installing panels.

The disadvantage of polyurethane foam is the cost, including installation, is more expensive than extruded polystyrene.

The strength of this material depends on its density. For basic insulation, it is recommended to use polyurethane with a density of at least 60 kg / m3.

Blocks with insulation inserts

There are also blocks with foam insert. They are installed as blocks that do not require plastering. Some concrete block manufacturers add materials such as polystyrene or wood chips to the concrete mix to increase the thermal resistance of their product.

Despite the fact that filling the cavity of the blocks with insulation improves their thermal qualities, at the same time, this does not greatly reduce heat loss in comparison with insulation made on the surface of the walls, or on the outer or inner part of the foundation walls.

Research and computer simulations have shown that a filled block provides little heat savings because most of the heat passes through solid parts of the walls such as block material and masonry mortar.

Insulation of slab foundations

Slab foundations are often insulated at the outer edge of the slab support or between the screed and slab. The base of the slab is often insulated from the ground. Each approach has advantages and disadvantages.

Insulation of the outer part of the foundation or the edge of the slab reduces heat loss from both the foundation and the slab.

This method provides great protection for the foundation from freezing. It also allows for a shallow foundation without risking damage from heaving of the soil. All exposed parts of the insulation should be covered with metal, cement, or another type of membrane to protect it from damage.

When insulating a slab foundation, the insulation must be located between the support and the slab. This protects the insulation from insects and damage better than outdoor use and insulates the board from the cold substrate.

Insulating an existing slab is generally impractical.

However, it is possible to insulate the outside of the slab from top to bottom:

• Blind area.
• 3-8 cm of sand.
• 2-5 cm of rigid insulation.
• A 150 micron polyethylene layer as a moisture retarder.
• 10 cm of washed gravel and drain pipes under the slab.

Insulation can be applied over the existing board, from top to bottom, as follows:

• Finishing floor covering.
• RIP insulation
• Substrate
• Rigid polystyrene foam glued with moisture-resistant strips at the joints.
• Polyethylene layer 150 microns.

An alternative is a floating floor, which consists of:

• Finishing floor covering.
• RIP insulation
• 2 layers of 12.5 mm thick OSB or plywood should be screwed, overlapping all seams of the previous board by 30-60 cm, in the seams between the boards there should be a gap of 12.5 mm to compensate for thermal expansion. The same gap must be made from the edge of the wall.
• Rigid polystyrene foam glued with moisture resistant strips at the joints.

The above methods have the following advantages and disadvantages:

Benefits:

• Relatively easy installation.
• The floor is insulated from the ground.
• The floor surface is close to the room temperature.

Disadvantages:

• Expanded polystyrene requires fire resistant coatings.
• This can increase the freezing depth at the edge of the slab in extreme climates.
• In the summer, the floor will not receive any coolness from the ground.

Insulation of the basement floor from the inside

The insulation of the basement depends on whether it has ventilation. Traditionally, basements are ventilated to avoid moisture problems. However, this method does not always work well.

If the basement is to be ventilated, carefully cover all openings in the floor to prevent air from entering the house. Insulate the floor by pressing firmly against the base with fiberglass insulation.

Cover the insulated floor with a vapor barrier. Seal all seams carefully to keep out air and moisture. Secure insulation with mechanical fasteners so that it does not fall out between the beams. The insulation is fastened between the beams.

Place plastic sheeting, or other equivalent material, over the earthen floor. Seal all seams carefully with tape. Cover the plastic wrap with a layer of sand or concrete to protect it from damage. Do not cover the film with anything that could make holes in it, such as crushed gravel.

If the basement is not ventilated, then all of the above is done + wall and floor insulation.

1. To begin with, on the building site, the place of the foundation for the building is marked.
2. The top layer of continental soil must be removed to the depth of the foundation slab, the bottom of the excavation should be as even as possible.
3. The prepared area is covered with coarse sand, which needs to be tamped using vibratory rammers. A small layer of concrete is poured over a layer of sand, for which it is exposed.
4. After hardening concrete screed, lay out the insulation from expanded polystyrene plates, making sure that the mounting slots match as much as possible. Large gaps between the insulation boards must not be allowed.
5. On top of the laid polystyrene plates, a layer of polyethylene film is laid, which is glued with a special adhesive tape.
6. A construction formwork is being erected for pouring a slab base into which a spatial frame made of reinforcement with a diameter of 10 mm or more is mounted. The concrete is poured from the corner of the slab foundation, evenly leveled and compacted with a vibrator.
7. The foundation slab gains strength for about 28 days, the formwork can be dismantled two weeks after the structure is poured - by this moment the foundation is gaining up to 70% strength.
8. The side walls of the foundation slab are additionally insulated with expanded polystyrene plates.

The insulated monolithic slab will last for many years without damage to structures from adverse factors.

Warming a slab of any foundation is one of the most important things when building a house. It is best to do this in the warm season, and you cannot do it in rainy weather. Insulation of a monolithic foundation slab is especially important for cold regions where the ground freezes at great depths. When freezing, heaving soils can increase in volume, which leads to deformations of the entire building. Therefore, it is so important to take care of the external insulation of the foundation. This will help reduce the heat loss of the entire future building and preserve its durability.

What does foundation insulation give?

The better all the work is done, the longer and more reliable the building will stand. And most importantly, the house will remain warm even in severe frosts. Do not forget that most of the cold penetrates into the house through the foundation. And if the building has a basement (billiard room, gym), then you should take care of internal insulation. This is especially important if the basement is not heated. But the most important thing is the external insulation of any residential building.

The main reasons why insulation is necessary:

1. Improving waterproofing properties.
2. Reduced heat loss.
3. Reducing heating costs at home.
4. Preventing the formation of condensation on the walls.
5. Stabilization of the internal temperature of the building.

All this will help not only to always feel comfortable in your home, but will also increase its lifetime.

What kind of insulation to use for the foundation?

The most important part of the work when insulating a slab of a fresh foundation is required is the selection suitable material... It should not deform under soil pressure and absorb moisture. These are the most important parameters of any thermal insulation. Soft materials such as mineral wool will not work. The best options are polyurethane foam and extruded polystyrene foam. Both of them have excellent thermal insulation characteristics and a fairly low cost, which is also important during construction.

Polyurethane foam

This material is versatile, as it combines not only thermal insulation, but also sound and waterproofing properties. To use given view isolation, special equipment will be required, since it must be sprayed. For full-fledged insulation, 50 mm of insulation thickness, laid in several layers, is enough. All joints after insulation must be sealed.

This material has a number of positive properties:

• low heat permeability;
• good adhesion properties;
• reliability;
• durability.

And the main thing is that when using polyurethane foam there is no need to use additional means for steam, water and waterproofing. He has only one drawback - the need to use special equipment. Therefore, this method of insulation will require either considerable capital investments or the help of experienced specialists with the appropriate equipment.

Extruded polystyrene foam

This type of insulation is significantly lower than polyurethane foam, it is easier to install. Such material consists of plates that do not pass and do not absorb moisture. It retains its thermal insulation properties for a long time even in cold regions. Advantages of extruded polystyrene foam:

• high strength;
• long service life;
• reliable thermal insulation properties.

It is most often used when it is necessary to insulate the foundation, since it can be mounted independently, without the use of additional equipment.

Extruded polystyrene foam with grooves

This is a new type of insulation. Milling grooves on the surface of expanded polystyrene plates are excellent for warming the foundation. It is used in conjunction with geotextile fabric, as an attached drainage. Its main properties:

• good thermal insulation;
• protective layer of waterproofing;
• waterproofness.

Warming the foundation with expanded polystyrene

To insulate a monolithic slab, you can use both expanded polystyrene and polyurethane foam. But the first option is preferable. Expanded polystyrene is the most effective and less expensive, and most importantly, it is easy to install. Before proceeding with its installation, it is recommended to lay the waterproofing, then you can start laying the extruded polystyrene foam plates.

The most effective method of warming a foundation using this material is to use it in areas of soil freezing. The insulation is mounted to the depth of freezing. This is quite enough. When insulating, special attention should be paid to the corners: in such places, the used polystyrene foam should be thicker than in other areas. It is imperative to insulate the soil around the perimeter of the building. To do this, it is necessary to place a heater under the construction of the blind area.

All rows of extruded polystyrene foam boards should be stacked end-to-end, from bottom to top. Large joints are filled with polyurethane foam. This will provide high tightness, thermal insulation and waterproofing properties. Plates are planted on polymer glue or mastic, and then pressed with a layer of soil. When insulating, it is important to take into account that all the plates are of the same width, you cannot use already used material, this can break the tightness. This method is suitable for all types of foundations, including monolithic ones.

Insulation of the foundation with polyurethane foam

When insulation of a monolithic foundation is done using polyurethane foam, it is important that there are no breaks and gaps. The insulation must form a completely closed loop. This will allow you to achieve maximum thermal insulation properties. It is sprayed onto the foundation using special equipment. The material then hardens within 20 seconds. In general, the whole process of installing insulation is quite simple and quick. The application of polyurethane foam is done in several layers, after each of them has dried. One layer should be approximately 15 mm thick.

At the end of all work, it is done with soil. Equipment for the installation of such a heater can be purchased in specialized stores or rented. But it is easier and faster to use the services of professionals.

Insulation of a monolithic slab updated: February 26, 2018 by the author: zoomfund

It is difficult to build a solid foundation on unstable ground. In such cases, a slab base is used. It acts as a foundation of shallow depth, drifting along the site, while moving soil masses. Since the entire structure is moving, no destructive stresses arise.

For the correct operation of this type of foundation, it must be protected from freezing. Insulation of a monolithic foundation slab:

• prevents the destruction of concrete from temperature differences;
• contributes to the warm floor of the first floor;
• makes it possible to save on heating the building;
• reduces heaving of the soil under the building.

The choice of insulation

Not everyone, even the most effective material, is suitable for working in or near the ground. When choosing a material, you need to be guided by:

• moisture resistance. Being saturated with water from the soil, the product loses its insulating properties. Expanding when freezing, moisture violates the integrity of the coating, nullifying all work;
• strength. Seasonal movements of soil masses create perceptible pressure on the material. It is especially noticeable in rocky soils. Sharp edges can push through the product, leaving cracks or breaks in it;
• resistance to aggressive environments. Soils are often chemically and biologically active. The groundwater may contain an increased concentration of salts. All these factors lead to the premature destruction of the insulation.

When installing insulation inside the building, the material must be non-combustible. If there is a possibility of fire, no harmful substances should be released that can cause suffocation.

With all this, the service life of the insulation should be no less than the service life of the finishing material. In this case, you do not have to change it before the coating becomes outdated. Otherwise, it will be necessary to dismantle the finishing cloth that still meets the standards.

Extruded polystyrene foam is often used for zero cycle work. Insulation of the basement slab with expanded polystyrene, made in accordance with all the rules, allows you not to worry about the safety of concrete and saving heat.

Characteristics of expanded polystyrene

Expanded polystyrene is used for thermal insulation of the foundation slab:

• outside;
• from the inside;
• in the body of concrete

Outdoor insulation technology

The height of the slab can be from half a meter. Freezing around the perimeter is the most dangerous for the foundation. Therefore, in general, the insulation is attached precisely along the side surfaces.

Before covering the foundation with a layer of insulation, it must be waterproofed. Despite the fact that polystyrene foam is waterproof, the coating is not seamless. Moisture penetrates the seams between the slabs, which can destroy the slab.

Waterproofing is carried out by applying bitumen mastic or melting paraffin on the surface and edges of the slab. The second method is more economical and reliable. With the help of a gas burner, lumps of paraffin are melted. The material is evenly distributed over the surface, absorbing into it.

Waxing closes the pores of the concrete, creating a moisture barrier. Full adhesion helps to prevent flaking of the insulation. This means that you can easily attach insulation to it.

Expanded polystyrene plates are mounted on glue or on a cement-sand mortar. The first option allows insulation at subzero temperatures. The underground part is fixed only by gluing. This is necessary to avoid disturbing the hydro-barrier.

The basement part of the insulation of the slab foundation with expanded polystyrene is additionally fixed with plastic dowels. For this, holes are drilled through the glued plates. They go through all the insulation and part of the foundation.

The adhesive is applied around the perimeter of the board and in several stripes in the center. It is kept for 1 minute and the plate is pressed to the surface for a couple of minutes. After gluing, the bottom plates are sprinkled with a layer of sand. This helps to fix them in the mounting position.

The second row of insulation is mounted with offset seams. It is advisable to make bandaging and horizontal joints. This helps to avoid cold bridges.

If the thickness of the plates is not enough, the insulation is carried out in two layers. Products with maximum thicknesses are taken to avoid the installation of several layers. The plates of the upper layer must overlap the seams of the lower ones.

Fixation with umbrellas is carried out at five points of the slab. The dowels are mounted after the plates are completely glued, but no later than three days later.

After installation, the seams are sealed with polyurethane foam. Excess foam is trimmed and the surface is plastered over the mesh. The mesh is necessary for better adhesion of polystyrene foam and plaster.

Internal insulation technology

When insulating a monolithic foundation slab from the inside, the material is laid in two ways:

• Over the plate;
• In the body of concrete.

In the first method, the sequence of work is as follows:

• waterproofing is arranged along the foundation slab, with an approach to the wall;
• lags are screwed on top of the waterproofing layer;
• a layer of insulation is arranged between the lag;
• over the insulation, a waterproofing film is attached to the logs;
• a plank base, plywood or OSB boards are mounted on the film;
• over the subfloor, a cork, expanded polyethylene or pine needles backing is laid. A finishing floor is mounted on it.

You can do without lag. In this case, there is a complete insulation of the slab foundation with expanded polystyrene. The material is laid in a continuous layer. Immediately on top of it, the underlay and the final floor covering are laid.

When installing in concrete, the following work is performed:

• the base plate is waterproofed;
• a layer of insulation with a thickness of at least 100 mm is arranged. It is better to use products with a locking system;
• pVC film with a density of at least 1.42 g / cm3 is laid on the insulation;
• reinforcing mesh is laid. Its role can be played by a masonry mesh with a cell of 100 * 100 mm;
• the surface is filled with a screed not thinner than 5 cm;
• the finishing coating is laid on the screed.

For internal insulation, only self-extinguishing polystyrene foam should be used. For installation under a screed, products of the G4 flammability class can be used.

Insulation of the body of the foundation slab

Warm concrete is used in many areas of construction. It can be purchased in the form of a ready-made mixture or manufactured in a construction site. For preparation, granular polystyrene foam is added to the initial mixture to form the foundation slab.

For the construction of structural elements, polystyrene concrete with a density of D1200 is used. When preparing 1 cube, the composition includes:

• 300 kg of cement M400;
• 1.1 m3 of expanded polystyrene granules. It is better to use granular rather than crushed material. It has the shape of a ball, which leads to a better enveloping with a cement mixture;
• 800 kg of sand;
• PAD. Saponified resin is often added. Its presence in the composition provides better adhesion and increases heat-shielding properties.

When creating such concrete, you need to remember about shrinkage. It is 1mm per 1m of surface. The plate needs to stand for some time after curing. It is necessary to arrange a leveling screed over the surface.

The flammability class of such a product is G1. The concrete itself does not burn, but the insulation granules are exposed to fire. As a result, pores are created in the body of the foundation slab. They reduce the density of the structure and increase its moisture absorption.

The thermal conductivity of such a plate will be approximately 0.105 W / (m * C). The product requires additional insulation of the slab foundation from below. The thickness of the insulating material will be less than that of plain concrete.

The choice of the type and technology of insulation of the foundation slab depends on the design features of the building and the construction site. It is worth choosing the optimal solution based on the data of the heat engineering calculation and comparison of the estimated cost.