How to insulate a slab foundation at an operated house. What is slab foundation insulation? Advantages of slab thermal 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 foundations 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 under the house refers to floating non-buried foundations, it can also be shallow. 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 during frost heaving. Often such a foundation is the only possible solution. For example, on unstable, loose soils or on clays with a large freezing depth.

The monolithic slab foundation design is simple and reliable, but its manufacture requires a large amount of reinforcement and large volumes of high-grade concrete (not lower than 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 true, but it must be considered. In some cases, its cost is lower than that of a deep-laid strip due to less earthwork and less concrete.

The depth of laying a monolithic slab is determined depending on the mass of the house and the type of soil. With a small depth on heaving soils in winter, the house, together with the base, can rise and fall. With the correct calculation of the reinforcement and the thickness of the slab, this does not affect the integrity of the building. The plate 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 foundation:

• Classical. The reinforced concrete slab is placed on a sand and gravel pad 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 pit can be covered by 2/3 with sand and gravel.

  

• Insulated Swedish stove (UShP) with built-in underfloor heating. Firstly, it differs in that the formwork of the slab is fixed - from L-shaped polystyrene foam blocks. This significantly reduces heating costs - heat leakage 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. That is, after the foundation is made, the heating system is ready and the engineering systems are connected. This approach allows you to speed up construction, but the foundation itself is expensive. This type of foundation requires competent engineering calculation and the same execution: when calculating and laying communications, one cannot make mistakes, since alterations are impossible. There are also questions about the repair of systems immured in the foundation. It is impossible, because expensive materials with a long guarantee are laid.

  

  UShP - insulated Swedish stove with built-in underfloor heating

• Russian - a plate with stiffeners. To strengthen the structure for heavy houses and in difficult operating conditions (severe frost heaving), Russian scientists came up with the idea of ​​making more massive stiffening ribs. They are usually satisfied with bearing walls. At the same time, the complexity of the work increases - stiffening ribs are arranged separately, and a plate separately. 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 plate construction technology

  Saving energy is becoming a really hot topic, so few people build a foundation without insulation. Any slab foundation is a multi-layer structure, and in the case of insulation, there are even more layers. To achieve the desired level of quality, it is necessary to carefully perform each of the levels. Let's dwell on each in more detail.

  

  Foundation preparation

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

  

  Along the edge of the pit, just below the general level of the bottom, drainage pipes are laid, diverting 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 in, the humps are removed, everything is carefully leveled to the level of the horizon and compacted. It rolls out onto a leveled bottom. It should cover not only the bottom, but also the walls. The canvases are spread with an overlap, the edges are glued together with reinforced tape. Geotextiles prevent plant roots from germinating, and also prevent sand from washing out, 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 rammed in layers. A layer of sand that can be qualitatively compacted with a manual vibrating plate is 8-10 cm. Sand is laid in such layers. It must also be laid in a level, in an equal layer throughout the pit.

  

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

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

  

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

  Concrete preparation

  Formwork is placed around the perimeter of the pit. It is usually assembled from a board 40 mm thick or plywood 18-21 mm. The formwork height for a monolithic slab is the total thickness of the remaining layers. Along its edge, it is convenient to control the level of concrete during pouring, because 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 put up higher, reused for pouring 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 mass of concrete.

  A layer of concrete 100 mm is poured onto the compacted 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 more evenly distribute the load from the house.

  

  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 rolled. The base is first carefully dedusted, then impregnated with diluted kerosene or a primer solvent (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 stick well and the foundation will get wet. 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 panels are rolled out with an overlap, the connecting edges must be smeared with bituminous mastic and pressed well. When laying out, you need to make sure that there are no creases and waves.

  If the groundwater level is high, two layers of rolled waterproofing may be needed. It is then rolled across, and also glued to the primer ( bituminous waterproofing), but you can no longer breed.

  

  Double waterproofing of the monolithic foundation slab - coated and rolled

  From roll waterproofing materials Gidroizol, TechnoNIKOL Technoelast EPP-4 on high density polystyrene showed themselves best. Technolnikol 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. No matter how much you want to save money, you should not use roofing material. IN modern design it is too thin and brittle, quickly loses its properties. You cannot replace the waterproofing in the slab, so lay the best material.

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

  Warming

  High-density extruded polystyrene foam is used to insulate the slab foundation. The thickness of the insulation layer is 10-15 cm, depending on the region (for Middle Band 10 cm is enough). 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 less. If the plates will have an L-shaped lock, they can be laid in one layer.

  

  Since expanded polystyrene is “not friendly” with petroleum products, a dense plastic film is spread on it, and then heat-insulating material is already laid.

  Reinforcement

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

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

  

  When reinforcing, a cage is obtained, at each intersection the bars are tied together with a special soft steel wire. There are also connection techniques - using plastic clamps or welding. Tie with plastic clamps quickly, but not everyone trusts them. Welding is not recommended, because the weld is the most vulnerable place to rust, and the connection is too rigid. When using wire and clamps, the whole structure can “play” a little without destroying the ligament, and when welding, such movements lead to the seam bursting. 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 of at least grade B30 is used. The entire perimeter must be filled in one day, avoiding the appearance of vertical seams. Therefore, for concreting a slab foundation, most often concrete is brought ready-made: large volumes are required within a certain period.

  

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

  In extreme cases, you can fill the slab in horizontal layers. Vertical division in this case is unacceptable, since cracks are likely to appear at the joints.

  Curing

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

  Immediately after laying, the concrete is covered with a diaper or tarpaulin. This does not allow him to heat up from the sun, the wind does not affect him. The film is glued into large panels. The strips are laid with a stop of 10-15 cm, glued with adhesive tape. It is desirable that there are as few unglued 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 the film overlap one another by 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 can 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 overlap of two panels in order to reduce the windage, they can be spread out on the surface.

  If the air temperature is above +5°C, approximately 8 hours after pouring, the concrete is watered 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 pour a layer of sawdust, and cover it with a film on top. Covering material is watered, and it maintains the moisture content of 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 formwork

  

  Differences of the insulated monolithic Swedish plate and a video about its construction

  As mentioned earlier, the insulated slab under the house developed by Swedish builders is energy-saving. During its construction, it is used fixed formwork from extruded polystyrene foam. As a result, heat leakage into the ground is minimal. The second fundamental difference is the water-heated floor system built into the stove.

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

  

  In the following videos you will see the steps for making a Swedish stove for a specific house. Much has been described useful gadgets, which will facilitate the work, explanations are given for some features.

  And also look how the Germans pour such a slab. Also a lot of useful nuances.
  

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

How to calculate the thickness of the slab and the cross section of the reinforcement?

In this case, one should be guided by the standards (SP 50.101.2004 and SP 63.13330.2012). An easier way is to use finished projects, which are available from all major construction companies. To check the calculations and compare options, it is worth using special computer programs, such as Foundation, GIPRO, or WINBASE.

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

Is drainage required around and under the foundation slab?

In swampy and flooded areas, it is highly desirable. At the same time, the function of the draining layer is performed by backfilling of crushed stone of a large fraction (20–70 mm). The system will be more efficient if tubular drains (their optimal step is 1.5–2 m). A drain is also needed around the perimeter of the slab or blind area. Water should be drained to a drainage well or to a descending relief; when 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 soil freezing under the house, extend the life of the foundation and reduce the risk of cracking 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 the formation of distortions and cracks at the junction of the walls.

How to lay communications?

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

But sometimes a monolithic or masonry plinth is built first. Photo: Foundation 47

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

This is possible, but is associated with an increase in costs and the risk of reducing the reliability of the structure.

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 cold and lack of daylight hours.

The blind area is poured over the drainage cushion 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 building for economic purposes. If we are talking about a house, then this method is excluded, because when pouring concrete in small portions, numerous “cold” seams cannot be avoided, which will catastrophically reduce the rigidity of the slab and its resistance to cracking. When delivering ready-made concrete, the interval between the arrivals of automixers should be 3-4 hours.

It is desirable to perform 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 surface of the Swedish board?

Yes, as a rule, it is possible to do without. In extreme cases, add a thin layer of self-leveling mixture. Note that it is desirable to lay coatings that conduct heat well on the Swedish stove, 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, terrace board from larch or composite. Photo: ShutterStock/Fotodom.ru

3 myths about reinforcement

1. Reinforcement should be knitted, not welded, as welding adversely affects the strength of the metal. In fact, this applies only to alloyed reinforcement, which is practically not used in individual construction. Knitting reinforcement is easier and cheaper, which explains the popularity of this installation method.
2. You can knit reinforcement with anything and not necessarily tightly, since the connections are necessary only for mounting positioning of the frame elements. Meanwhile, according to building codes, when knitting lap and cruciform joints, the rods must be pulled up to each other without a gap. Overlaps (their length is equal to 40 reinforcement diameters) should be tied with steel wire in several places.
3. The diameter of the reinforcement is not important if the required reinforcement ratio is observed (the ratio of the cross-sectional area of ​​​​the reinforcement to the cross-sectional area of ​​\u200b\u200bthe concrete structure). In fact, the use of thin reinforcement (8 mm) increases the complexity of installation and complicates the quality control of the work performed.

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

Design option for insulated slab foundation

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

The underfloor heating system is tested in two stages. After the installation of the pipeline and before pouring the concrete slab, the integrity of the pipes is checked by a liquid pressure that is 1.5 times the working pressure. The duration of the test is 3 hours. As an exception, if a hydraulic test is not possible (for example, due to frost), a test with compressed air is allowed. When pouring concrete, the pipes must be filled with cold coolant and be under pressure (working or test). After the concrete has gained the required strength, a thermal test is carried out, which lasts seven days. First, a coolant heated to 20-25 ° C should circulate in the system for three days. 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

REHAU expert

Enlarged calculation of the cost of building an insulated slab foundation with an area of ​​80 m2

Name of works	Quantity	Cost, rub.
Geodetic stakeout		12 000
Excavation, pillow device		16 800
Drainage devices		18 000
Distribution of water and sewer pipes		14 500
Installation of formwork, insulation, reinforcing cage		32 000
Installation of underfloor heating pipes		34 200
Concreting, vibroconcreting		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
Rebar (bar 12 mm and mesh 8 mm)	1.1 t	32 000
XPS sheets CARBON ECO SP 1180 × 580 × 100	235 pcs.	79 900
Gaskets and fixing materials		7 500
Concrete M300	13 m3	44 200
Total
Total

On unstable soils, it is difficult to arrange a solid foundation. In such cases, a slab base is used. It acts as the foundation of a small depth, drifting around the site, when moving soil masses. Since the entire structure moves, no destructive stresses arise.

For the proper 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;
• promotes warm floor first floor;
• makes it possible to save on building heating;
• reduces the heaving of the soil under the building.

The choice of insulation

Not every, 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, reducing all work to nothing;
• strength. Seasonal movements of soil masses create tangible pressure on the material. It is especially noticeable in rocky soils. Sharp edges can push through products, leaving cracks or breaks in it;
• resistance to aggressive environments. Soils are often chemically and biologically active. Groundwater may contain high concentrations of salts. All these factors lead to premature destruction of the insulation.

When installing insulation inside the building, the material must be non-combustible. In the event of a fire, should not be emitted harmful substances which may cause suffocation.

With all this, the service life of the insulation should not be less than the service life of the finishing material. In this case, you do not have to change it before the coating becomes obsolete. Otherwise, you will have to dismantle the finishing sheet that still meets the standards.

Often, extruded polystyrene foam is used for zero-cycle work. Insulation of the foundation 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 within;
• in the body of concrete

External insulation technology

The height of the plate can be from half a meter. Freezing around the perimeter is the most dangerous for the foundation. Therefore, basically, the insulation is attached precisely to the side surfaces.

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

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

Waxing closes the pores of the concrete, creating a barrier to moisture. Full adhesion contributes to the exclusion of insulation peeling. This means that you can easily attach a heater to it.

Expanded polystyrene plates are mounted on glue or on a cement-sand mortar. The first option allows you to conduct insulation at sub-zero temperatures. The underground part is fixed only by gluing. This is necessary to avoid violation of the hydrobarrier.

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

Glue is applied along the perimeter of the plate and in several strips in the center. It is held for 1 minute and the plate is pressed against the surface for a couple of minutes. After gluing, the bottom plates are sprinkled with a layer of sand. This helps secure them in their mounting position.

The second row of insulation is mounted with offset seams. It is desirable to make a dressing 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. Plates of the upper layer must overlap the seams of the lower ones.

Fixation with umbrellas is carried out at five points of the plate. The dowels are mounted after the plates are completely glued, but not later than three days later.

After installation, the seams are sealed mounting foam. Excess foam is cut off and the surface is plastered over the grid. 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:

• On top of the plate;
• In the body of concrete.

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

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

You can do without lag. In this case, the slab foundation is completely insulated with polystyrene foam. The material is laid in a continuous layer. Immediately on top of it, a substrate and a finishing 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;
• a PVC film with a density of at least 1.42 g / cm3 is laid on the insulation;
• reinforcing mesh is laid. In its role can be a masonry mesh with a cell of 100 * 100 mm;
• the surface is poured with a screed no thinner than 5 cm;
• the finish coating is laid on the screed.

At internal insulation only self-extinguishing polystyrene foam should be used. For installation under the 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 the conditions of a construction site. For preparation, granulated polystyrene foam is added to the initial mixture for the formation of the foundation slab.

For device 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 of the cement mixture;
• 800 kg of sand;
• PAD. Often, saponified resin is 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 1 mm per 1 m of surface. The plate needs to stand for some time after curing. On the surface it is necessary to arrange a leveling screed.

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 plain concrete.

The choice of the type and technology of insulation of the foundation slab depends on design features buildings and construction sites. Choose optimal solution stands on the basis of data from a heat engineering calculation and a comparison of the estimated cost.

The slab base withstands 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. The building, when the soil moves, rises and falls along with the foundation, which protects the structure of the house from cracking.

general information

The design of the slab base consists of layers:

• geotextiles are covered with overlapping strips on the sandy layer, the joints are glued with adhesive tape;
• pour gravel, a layer of 15-20 cm;
• pour the leveling layer cement mortar, 5-10 cm thick;
• be sure to isolate the structure from moisture with the help of roll or coating materials;
• arrange a heat-saving layer;
• cover the plastic film with overlapping strips of 20 cm;
• lay the reinforcing 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 slab installation will be cheaper, and less land work will be required.

Advantages of the slab foundation

The slab base has the following advantages:

• the concrete slab acts as the floor of the first floor, which further reduces the cost of its installation;
• is great option for the foundation of a house, the construction of which is carried out on floating soils, the slab and the whole house together with it move simultaneously with the soil;
• you can mount the plate 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 building up to 3 floors.

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

Advantages of slab thermal insulation

Polystyrene foam, polystyrene foam, polyurethane foam are used as heat-insulating material. Mineral wool is unsuitable 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 built on a layer of heat-saving material, thanks to which the soil under the house does not freeze and does not 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 allows you to increase the efficiency of the warm floor;
• installation of the foundation is carried out without involving a large amount of construction equipment.

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

The design of the plate 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

Slab foundation is not always the best option. It is always necessary to carry out all the necessary calculations in advance and select the most suitable type grounds for the house.

Disadvantages of the plate:

• not suitable for erection in areas with a slope;
• to build a house with a basement on a slab, you need to deepen it to a great depth, it 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 a strip foundation is not possible.

Materials for insulation

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

№	Thermal insulation material	Characteristics
1	Styrofoam	Consists of cells filled with air. 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. Stack sheets in 1 or 2 layers. The second layer must be laid out so that the seams of the sheets of the first and second rows do not intersect. During installation, provide holes for moisture removal.
3	polyurethane foam	It is a kind of foamed plastic with many pores filled with air bubbles. The composition is prepared directly at the construction site. The two components are mixed, resulting in a dense hard foam, which is applied to the surface. The plate insulated with polyurethane foam has high rates of heat and sound insulation, withstands moisture. Refers to low-combustible materials, and some brands are slow-burning.

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

Installation of an insulated plate

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

Insulation of the slab foundation allows you to save significant funds on heating the premises during operation.

Site preparation

At the design stage, the project must take into account that the area for the foundation slab must be wider than the housing construction by at least 1 m on each side.

Instructions for performing preparatory work:

1. The site where construction is being carried out is cleared of debris, the root system of trees and shrubs.
2. Mark the position of the plate according to the project.
3. They clean and remove the fertile layer of soil. The degree of deepening of the plate depends on the geological and climatic conditions. Most often, the thickness of the plate varies from 20 to 30 cm, less often the base is buried 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. Lay the geotextile in overlapping strips. The material should cover the bottom and go to the walls along the entire height.
7. Drive in wooden stakes or metal rods. Stretch the cord strictly horizontally. It will serve as a guide for uniform backfilling 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 geotextiles.
10. Crushed stone is poured, evenly distributed around the perimeter, carefully rammed.
11. Conduct all necessary communications. They dig trenches under them in rubble a little wider than the section of pipes. The pipeline is laid, a layer of sand is poured on top.
12. The sandy surface is leveled.

If the pipeline is laid before the crushed stone compaction stage, the pipes may crack.

Plate insulation

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

1. They mount a removable formwork from boards, install props so that the structure does not fall apart under the weight of concrete.
2. A layer of concrete is poured, 50 mm thick.
3. After the cement mortar has completely solidified, sheets of foam plastic are laid on it close to each other and glued. The adhesive composition is applied with dots along the perimeter of the sheet and in the center. A layer thickness of 10-20 cm is sufficient. 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 intersect.
4. Spread dense polyethylene with overlapping stripes. The joints are sealed with adhesive tape.
5. The reinforcing cage is laid, the formwork is poured with concrete.

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

The insulated plinth helps to increase heat saving inside the room.

When installing insulation on bituminous insulation, you need to wait for it to dry completely. If laying on a wet layer, the materials may be damaged and the effect of thermal insulation and waterproofing will decrease.

Rules for installing heating pipes

When installing the UWB, heating pipes are used. There are such rules for their installation:

• Tighter pipe laying results in more high temperatures space heating.
• The distance between the outer walls and pipes should not exceed 150 mm. Closer to the center, the laying step 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 apart.

It is impossible to mount heating pipes at the junctions of monolithic plates. In this case, it is better to lay two circuits. The pipeline crossing the joint is insulated with steel sleeves 30 cm long.

How to make a warmed Swedish stove with your own hands can be seen in the video:

The insulated foundation slab reduces 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.

Each developer, when choosing a foundation structure for a future building, is guided primarily by its cost, reliability and durability. The ideal foundation that combines all these qualities are monolithic foundation slabs that can be built on various types 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

Warming 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 basement of the building and the upper part of the foundation wall should be closed with special material. Timely insulation of a monolithic foundation slab will protect the soil adjacent to the building and its walls from freezing, which will prevent frost heaving of the soil and minimize heat loss at home.

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

1. Tape (deep). Used for insulation various materials, 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 laid on the sole and vertical surfaces of the supporting structure.
3. Pile. Only the side surfaces of the piles deepened into the soil are subjected to insulation.
4. Monolithic tile construction. The foundation slab is insulated not only from below, but also on the sides.

The benefits of timely insulation

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

1. Developers save money concrete mortar, which is used in large volumes when pouring slab foundation structures.
2. Insulated foundation allows you to minimize heat loss. This has a positive effect on the indoor climate, as well as on utility bills, which are skyrocketing in winter time of the year.
3. Accelerating construction time.
4. The useful life of the supporting structure is maximized, since it ceases to be adversely affected by moisture and low temperatures.
5. Insulated base plate prevents condensation on the internal walls ah premises.
6. The service life of waterproofing materials, which are used in the process of building slab foundation structures, is maximized.

What materials can be used to insulate a slab foundation?

Currently, the domestic construction market has a huge range of materials 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 form a strong foam on concrete surfaces, which hardens almost instantly. This material helps to minimize heat loss, prevents the penetration of extraneous noise from the street into the premises, does not undergo putrefactive changes in constant contact with a humid environment, and is highly resistant to ignition.
2. Styrofoam. This material has been used for decades in construction industry as a heater. Its main disadvantage is its low mechanical strength, which requires additional cladding.
3. Expanded polystyrene extruded. 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 exactly 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 foam plastic for insulation?

In recent years, many developers prefer to insulate the foundation with foam plastic. The choice of this material is due to the fact that it is highly resistant to moisture, and also has the lowest possible thermal conductivity. Due to the fact that the slab supporting structure will have to be in contact with a humid environment for many decades, insulation of the foundation with foam plastic 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 plates and penoplex are cellular materials with a closed structure, due to which moisture is not able to penetrate into their cavities. That is why they are involved in carrying out warming measures.

Rules for the insulation of slab foundation structures

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

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

Carrying out insulation measures during the construction process

The procedure for warming the foundation with polystyrene foam 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 out, in which a monolithic concrete slab will be created. Its depth should be 1 meter. At the bottom, recesses are made into which drainage pipes are laid, the functions of which are to drain 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, geotextile, is rolled out on its surface. It will prevent the germination of rhizomes of trees and shrubs that can violate the integrity of the supporting structure.
3. A layer of sand and gravel is laid on top of the geotextile. Thus, a sand and gravel cushion is created at the bottom of the pit (thickness is approximately 30-40 cm).
4. Are being laid engineering Communication such as water and sewer pipes. After their laying, the surface is sprinkled with sand and leveled.
5. A formwork is constructed along the perimeter of the prepared pit. For these purposes, it is customary to use boards or sheets of moisture-resistant plywood. Outside, the formwork must be supported with jibs or stops in order to wooden structure able to withstand the load that the concrete mortar 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 hardens, the developer must begin to carry out 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, it is customary in the construction industry to use rolled material or coating. The concrete base must be thoroughly cleaned of debris, and then dusted. To increase its adhesive properties, it is recommended to treat it with diluted kerosene or a solvent. After that, a roofing material is rolled out on a prepared concrete base, the canvases of which must 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 several times to the surface concrete base and after complete drying continue construction works.
8. The next step is the insulation of the plate. For these purposes, most developers use sheets of extruded polystyrene foam (thickness 15cm). Lay such material, as a rule, in two layers. Care must be taken to ensure that the top sheets overlap the joints of the bottom panels.
9. The reinforcement of the foundation structure is being carried out, due to which its strength and 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.

After the concrete has hardened, the developer can continue construction work. In order to protect the building as much as possible from the harmful effects of harmful environments, he must carry out the internal insulation of the foundation. For this, sheets of extruded polystyrene foam should be used, which are glued to the floor and walls of the premises and are subsequently finished.

An uninsulated foundation can lead to a large amount of heat loss, unlike a tightly closed and well-insulated house.

Insulating foundations reduces the need for a large heating system and avoids moisture condensation, which often results from temperature differences between the inside of the plinth and the ground around the foundation.

A poorly designed foundation insulation system can cause many problems such as moisture problems and pest infestation.

Insulation of basement exterior walls

Installing insulation on the outside of the strip foundation plinth has several options. External insulation has the following advantages and disadvantages:

Advantages:

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

Flaws:

• Expensive installation for existing building if also set drainage system along the perimeter.
• Many exterior insulation materials are susceptible to pest infestation.
• Many contractors are not familiar with proper procedures in detail.

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

Some insulating foams are made with boric acid to prevent termite infestation. 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 internal walls of the strip foundation, it is also a less expensive option for a finished building. Such insulation has the following advantages and disadvantages:

Advantages:

• This is much cheaper than insulating the exterior walls of existing buildings.
• There is a wider choice of materials as you can use almost any type of insulation.
• There is no threat of insect invasion.
• A space insulated from cold ground is more effective than using external insulation methods.

Flaws:

• Many insulations require a fire protection coating as they emit toxic gases upon ignition.
• Reduces usable interior space by 3-5 cm.
• Does not protect against moisture penetration like external insulation.
• If the perimeter has poor drainage, the insulation can cause moisture to saturate around the perimeter of the base and seep through the foundation walls.

New methods of foundation insulation

Some new building systems make it possible to build a ready-made insulated foundation without the use of wooden or metal formwork, this is a system concrete forms(ICF), in other words, non-removable formwork made of expanded polystyrene, which uses rigid foam as formwork molds, thereby insulating the inside and outside of the foundation.

Thermal panels

Of the novelties, there is still a heater that does not require finishing, This thermal panels made of expanded polystyrene with stone chips.

polyurethane foam

Other synthetic polymer material used for thermal insulation of foundations is polyurethane foam. It is prepared by mixing liquid components in a special technique. Manufacturing process carried out at the construction site.

This material is applied by spraying. Hardened 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 contributes to the formation of a solid layer of insulation, where there are no seams (even if the foundation has a complex geometry). Thus, it completely eliminates the possibility of the appearance of cold bridges. The spraying process itself takes much less time than the installation of panels.

The disadvantage of polyurethane foam is the cost, including installation, are 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 a foam insert. They are installed as blocks that do not require plastering. Some concrete block manufacturers add materials such as polystyrene or wood shavings 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 it does not greatly reduce heat loss compared to insulation made on the surface of the walls, or on the outer or inner part of the foundation walls.

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

Insulation of slab foundations

Slab foundations are often insulated along the outer edge of a slab foot or between screed and slab. The base of the slab is often insulated from the ground. Each approach has its own advantages and disadvantages.

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

This method provides more protection for the foundation from freezing. It also allows shallow foundations without risking damage from heaving soil. All exposed parts of the insulation must be covered with metal, cement, or some other 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 applications and insulates the board from cold substrates.

Insulating an existing slab is generally not practical.

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 hard insulation.
• 150 micron polyethylene layer as moisture retarder.
• 10 cm of washed gravel and drainage pipes under the slab.

Insulation can be applied over an existing slab, from top to bottom, as follows:

• Floor finish.
• RIP isolation
• 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:

• Floor finish.
• RIP isolation
• 2 layers of 12.5mm thick OSB or plywood should be screwed, overlapping all the seams of the previous board by 30-60cm, there should be a gap of 12.5mm in the seams between the boards 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:

Advantages:

• Relatively simple installation.
• The floor is thermally insulated from the ground.
• The surface of the floor is close to the air temperature in the room.

Flaws:

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

Insulation of the basement from the inside

The isolation 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 ceiling to prevent air from entering the house. Insulate the ceiling by pressing it firmly against the base with fiberglass insulation.

Cover the surface of the floor to be insulated with a vapor barrier. Carefully seal all seams to prevent the passage of air and moisture. Fasten the insulation with mechanical fasteners so that it does not fall out between the beams. The insulation is fastened between the beams.

Lay a sheet of polyethylene, or other equivalent material, over the earthen floor. Seal all seams carefully with tape. Cover the plastic sheet with a layer of sand or concrete to protect it from damage. Do not backfill the film with anything that can 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 location of the foundation for the building is marked.
2. The top layer of the mainland soil must be removed to the depth of laying 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 compacted using vibrorammers. A small layer of concrete is poured over a layer of sand, for which it is exposed.
4. After curing concrete screed, spread the insulation from polystyrene boards making sure that the mounting grooves match as much as possible. Large gaps between the insulation plates should not be allowed.
5. A layer of polyethylene film is laid on top of the stacked polystyrene plates, which is glued together with a special adhesive tape.
6. A construction formwork is being erected for pouring the slab base, into which a spatial frame of reinforcement with a diameter of 10 mm or more is mounted. Concrete is poured from the corner of the slab foundation, evenly leveled and compacted with a vibrator.
7. The foundation slab gains strength in about 28 days, the formwork can be dismantled two weeks after the structure is poured - by this time 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 serve for many years without destruction of structures from the influence of adverse factors.

Insulation of the slab of any foundation is one of the most important things in the construction of a house. It is best to do this in the warm season, and you can not do this in rainy weather. Insulation of a monolithic foundation slab is especially important for cold regions, where the soil freezes at great depths. Heaving soils during freezing 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 provide?

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

The main reasons why insulation is necessary:

1. Improvement of waterproofing properties.
2. Reduced heat loss.
3. Reducing home heating costs.
4. Prevention 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 also increase its lifespan.

What kind of insulation to use for the foundation?

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

polyurethane foam

This material is universal, as it combines not only thermal insulation, but also sound and waterproofing properties. To use this species insulation, special equipment will be required, as it must be sprayed. For full insulation, 50 mm of insulation thickness, laid in several layers, is sufficient. All joints after insulation must be sealed.

This material has a number of positive properties:

• low thermal conductivity;
• good adhesive properties;
• reliability;
• durability.

And most importantly, when using polyurethane foam, there is no need to use additional funds for steam, water and waterproofing. It has only one drawback - the need to use special equipment. Therefore, for this method of insulation, either considerable capital investments or the help of experienced specialists with the appropriate equipment will be required.

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 Styrofoam with Grooves

This is a new kind of insulation. Milling grooves on the surface of expanded polystyrene boards are great for insulating the foundation. It is used together with a geotextile cloth as fastening drainage. Its main properties:

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

Insulation of the foundation with polystyrene foam

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

Most effective method insulation of the foundation with the help of this material is its use in areas of soil freezing. The insulation is mounted to the freezing depth. 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. Along the perimeter of the building, it is imperative to perform soil insulation. To do this, under the design of the blind area, it is necessary to place a heater.

All rows of extruded polystyrene boards must be laid end to end, from bottom to top. Large seams are filled with mounting foam. This will provide high tightness, heat-insulating and waterproofing properties. The 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; already used material cannot be used, this can violate the tightness. This method is suitable for all types of foundations, including monolithic ones.

Insulation of the foundation with polyurethane foam

When insulating a monolithic foundation using polyurethane foam, it is important that there are no gaps and gaps. The insulation must form a completely closed loop. This will achieve maximum thermal insulation properties. Its spraying on the foundation is carried out using special equipment. The material then hardens within 20 seconds. In general, the whole process of installing insulation is quite simple and fast. The application of polyurethane foam is done in several layers, after each of them dries. One layer should be approximately 15 mm thick.

Upon completion of all work, it is produced by soil. Equipment for the installation of such insulation can be purchased at 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: zoomfund

On unstable soils, it is difficult to arrange a solid foundation. In such cases, a slab base is used. It acts as the foundation of a small depth, drifting around the site, when moving soil masses. Since the entire structure moves, no destructive stresses arise.

For the proper 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 building heating;
• reduces the heaving of the soil under the building.

The choice of insulation

Not every, 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, reducing all work to nothing;
• strength. Seasonal movements of soil masses create tangible pressure on the material. It is especially noticeable in rocky soils. Sharp edges can push through products, leaving cracks or breaks in it;
• resistance to aggressive environments. Soils are often chemically and biologically active. Groundwater may contain high concentrations of salts. All these factors lead to premature destruction of the insulation.

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

With all this, the service life of the insulation should not be less than the service life of the finishing material. In this case, you do not have to change it before the coating becomes obsolete. Otherwise, you will have to dismantle the finishing sheet that still meets the standards.

Often, extruded polystyrene foam is used for zero-cycle work. Insulation of the foundation 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 within;
• in the body of concrete

External insulation technology

The height of the plate can be from half a meter. Freezing around the perimeter is the most dangerous for the foundation. Therefore, basically, the insulation is attached precisely to the side surfaces.

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

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

Waxing closes the pores of the concrete, creating a barrier to moisture. Full adhesion contributes to the exclusion of insulation peeling. This means that you can easily attach a heater to it.

Expanded polystyrene plates are mounted on glue or on a cement-sand mortar. The first option allows you to conduct insulation at sub-zero temperatures. The underground part is fixed only by gluing. This is necessary to avoid violation of the hydrobarrier.

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

Glue is applied along the perimeter of the plate and in several strips in the center. It is held for 1 minute and the plate is pressed against the surface for a couple of minutes. After gluing, the bottom plates are sprinkled with a layer of sand. This helps secure them in their mounting position.

The second row of insulation is mounted with offset seams. It is desirable to make a dressing 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. Plates of the upper layer must overlap the seams of the lower ones.

Fixation with umbrellas is carried out at five points of the plate. The dowels are mounted after the plates are completely glued, but not later than three days later.

After installation, the seams are sealed with mounting foam. Excess foam is cut off and the surface is plastered over the grid. 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:

• On top of the plate;
• In the body of concrete.

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

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

You can do without lag. In this case, the slab foundation is completely insulated with polystyrene foam. The material is laid in a continuous layer. Immediately on top of it, a substrate and a finishing 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;
• a PVC film with a density of at least 1.42 g / cm3 is laid on the insulation;
• reinforcing mesh is laid. In its role can be a masonry mesh with a cell of 100 * 100 mm;
• the surface is poured with a screed no thinner than 5 cm;
• the finish coating is laid on the screed.

For internal insulation, only self-extinguishing polystyrene foam should be used. For installation under the 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 the conditions of a construction site. For preparation, granulated polystyrene foam is added to the initial mixture for the formation of the foundation slab.

For the device 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 of the cement mixture;
• 800 kg of sand;
• PAD. Often, saponified resin is 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 1 mm per 1 m of surface. The plate needs to stand for some time after curing. On the surface it is necessary to arrange a leveling screed.

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 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. Choosing the optimal solution is based on the data of the heat engineering calculation and comparison of the estimated cost.