On the methods of insulating a monolithic foundation slab. Insulation of the foundation slab: the advantages of technology Is it necessary to insulate under the slab

The purpose of this article is to go beyond the scope of this project and tell on behalf of specialists the basic rules for working with material that can be useful to everyone.

During the construction of this type of foundation, extruded polystyrene foam (EPS) was used. In the format of a master class professional builders will tell you how to choose and how to work correctly with extruded polystyrene foam when insulating different types foundations. Namely:

Why you need to insulate the foundation.
What to look for when choosing a material for basement insulation.
How to properly fix the extruded polystyrene foam on the foundation.
What tool is needed for the job.

Why do you need to insulate the foundation

The foundation is the underground part of the structure, which transfers the load from the overlying structures to the prepared soil foundation. Foundations are of the following types:

Shallow slabs with spatial reinforcement. This gives the structure rigidity and allows it to absorb the loads arising from uneven soil movement without internal deformation.

Belt - laid below the freezing depth, and the so-called. MZLF is a shallow strip foundation, with a base depth higher than the estimated level of seasonal soil freezing.

... Insulated Swedish Stove. This foundation is a monolithic concrete slab mounted on a base insulated with extruded polystyrene foam. A water system is integrated into the foundation. underfloor heating and all engineering communications.

This type of foundation is considered the most technologically advanced and energy efficient. In one system, the foundation and low temperature system heating, eliminating the formation of local overheated zones and giving comfortable radiant heat. In addition, the foundation is not affected by the forces of frost heaving, because anti-heaving measures have been carried out. Namely, heaving soil was excavated and replaced with non-heaving soil (sand or crushed stone), a drainage system was mounted, the blind area and the base of the slab were insulated.

Up to 20% of the heat loss of the total heat loss of the building occurs through the foundation.

Kogut Andrey TechnoNICOL technician

To achieve maximum energy efficiency of the building, it is necessary to create a closed insulated loop. This means that in addition to basic structures such as walls, roof and basement, it is necessary to insulate the foundation as well.

In some cases, it is enough to insulate the floor and basement, but when organizing an exploited basement thermal insulation of the foundation walls is a prerequisite to achieve the required level of comfort and reduce heat loss.

In shallow strip and slab foundations, thermal insulation reduces the effect of frost heaving. Soil heaving is formed due to the freezing of water in the soil and its subsequent expansion. Different soils have different degrees of heaving. For example, sands pass water well through themselves, and it does not stay in them. Clay, on the contrary, does not allow water to leave, and due to the presence of a large number of small pores, it has a high capillary suction of moisture. Incorrect design on heaving soils can lead to serious consequences, up to the destruction of the foundation. If the foundation is left uninsulated, the heat flow will go down and warm the soil, protecting it from freezing. However, the house may not be constantly heated, in which case the ground will heave. Thermal insulation of the foundation and the blind area is one of the measures to combat frost heaving.

Basic principles for choosing thermal insulation for insulation of the foundation

So, summarizing all of the above, we conclude: the foundation needs to be insulated... For this, not just any insulation is suitable, but only a material that can work in aggressive environmental conditions. Those. thermal insulation, laid on "non-removability", must be moisture resistant, have long term service, during which it will not lose its heat-insulating properties, and have strength sufficient to withstand the load from the overlying structures.

Kogut Andrey

Extruded polystyrene foam (EPS) has a low thermal conductivity of 0.028 W / (m * ° C) and a minimum water absorption coefficient of 0.2% by volume. The insulation does not absorb water, is chemically resistant and does not rot. Compressive strength at 2% linear deformation - not less than 150 kPa (~ 15 t / sq. M) and higher. Service life in soils - at least 50 years.

High compressive strength allows the use of EPSP in loaded structures (foundations) and ensures the stability of the thermal insulation thickness under load.

The thickness of the thermal insulation layer should be taken on the basis of calculations, based on several conditions:

Purpose of the building (residential, administrative, industrial, etc.).
The insulation must provide the required heat transfer resistance for the given type of building.
Seasonal moisture accumulation in the structure should not occur.

Payment the thickness of the thermal insulation for the foundation is made according to the methodology set forth in SP50.13330.2012 "Thermal protection of buildings". The thickness of the insulation may vary from region to region, depending on the climatic conditions... It should also be borne in mind that increasing the thickness of the thermal insulation increases the energy efficiency of the building and, therefore, leads to a decrease in heating costs.

By choosing specifications thermal insulation, we are guided by the following principles:

With thermal insulation strip foundation When only the vertical wall is insulated, the increased strength of the material is not required, since in this case, the EPSS perceives the loads only from the backfill soil. Therefore for shallow foundations brands are suitable extruded polystyrene foam with a compressive strength (at 10% linear deformation) 150-250 kPa.
When laying EPSP boards under the base of the foundation or under the slab, the loads on it increase significantly, respectively, the requirements for its strength increase. In this case, it is recommended to use thermal insulation boards with a compressive strength of 250 - 400 kPa.
A material with a compressive strength at 10% deformation of 400 kPa and increased dimensions of the plates has been developed especially for the USHP to increase the installation speed. In addition, the increased dimensions of the slabs make it possible to reduce the number of seams and, accordingly, to increase the homogeneity of the layer.

The nuances of installing extruded polystyrene foam when insulating the foundation

Thermal insulation of the EPSP foundation, depending on its design, should be divided into a number of sequential steps:

Preparation of the base. When insulating the strip foundation with EPSPS, the walls must be flat, free from dirt and concrete layers. If necessary, remove irregularities and cover up shells, chips, etc. cement-sand mortar.

The choice of the method of fixing the EPS. To fix the insulation, we use polymer-cement mixtures or, to speed up installation, a special polyurethane adhesive foam.

Glue-foam is applied in a strip approximately 3 cm thick along the entire perimeter of the slab, as well as in one strip in the center of the insulation.

The distance of the strip of glue-foam from the edge of the plate is at least 2 cm.

Before installing the slab, we wait 5-10 minutes and only then glue it to the foundation wall.

Foam the gaps between the plates (if they exceed 2 mm).

If mechanical fixation of thermal insulation is provided, then the number of dowels is calculated as follows - for fixing 1 sq. m of thermal insulation on the central part of the foundation requires 5 pcs. fasteners. We fix the EPS on the corner parts of the foundation at the rate of 6-8 dowels per 1 sq. m.

When insulating the soles of a strip foundation or monolithic slab, EPSP is laid loosely on a prepared base (as a rule, on a compacted sand cushion). In this case, it is enough to foam the seams with glue-foam and, if necessary, fasten the adjacent thermal insulation boards together. You can use a nail plate for this.

In this case, special fasteners can be used, which are a spike with teeth for fixing in the material and a flat area with an adhesive layer.

Together with similar fasteners, gluing is performed on glue-foam for expanded polystyrene or on a special adhesive solvent-free mastic... If necessary, the seams are sealed with polyurethane foam or adhesive foam.

The layout of the EPSP plates during the construction of the USP is carried out as follows. We lay the first layer on a prepared base - a compacted sand cushion - with a gap between the seams relative to adjacent slabs. The side elements are "L" - blocks, which are two EPS plates, connected perpendicular to each other.

As a rule, such elements are manufactured by installing the formwork, but you can use ready-made elements that do not require the use of formwork. Such "L" - blocks can be manufactured in the factory, or you can assemble yourself at the work site. For this, a special corner fastener has been developed, which consists of corners and screws, and which is mounted at a distance of 300 mm from each other. All elements of corner fasteners are made of high-strength polyamide, which eliminates the formation of cold bridges.

Summarizing

In addition to improving the energy efficiency of the foundation, EPS insulation increases its service life, because the waterproofing is reliably protected durable material from various mechanical influences. By choosing the option of fixed formwork made of extruded polystyrene foam, you can significantly speed up and simplify all work on the construction of the foundation, because there will be no need for assembly and further disassembly of wooden formwork, which means that the developer's time and money will be saved.

Foundation - insulated Swedish slab (USHP) refers to slab foundations.

A distinctive feature is that this foundation, among many, is a more progressive and original type of foundation, which, in principle, meets the most modern requirements for energy efficiency at home, and, in principle, for the construction of the foundation as a whole. The UWB foundation for the post-Soviet era is a relatively young option.

For the first time, information about the foundation of the insulated Swedish plate appeared on construction forums 10 - 15 years ago. There he was very actively discussed. But a number of points that you should definitely know when using such foundations have been omitted. Mostly there were laudatory odes to this foundation.

Pros and cons of UWB

Advantages of USB, as well as of all slab foundations	Disadvantages of USB and all slab foundations
The loads are transferred fairly evenly, since the plate is in to a greater extent than just the tape distributes the loads and transfers them evenly to the base in the form of soil under the foundation.	They are susceptible to the risks of heaving and uneven settlement as they are located in an unfavorable zone of soils with a low bearing capacity, as well as in the freezing zone, because they are not deepened by the supporting base to the depth of freezing.
Monolithicity. Everything monolithic works for pouring the foundation with concrete are carried out in one step. When pouring, a concrete pump and a deep vibrator must be used. The result is a monolithic concrete layer, which is very important for the foundation.	There are nuances on the arrangement of communications and the relief of the site
Small amount of work. Unlike monolithic strip foundations, there is much less work on the USP, both earthen, and about tying reinforcement, concrete acceptance, and formwork.

Differences from a conventional slab foundation:

A large amount of insulation is used in the device of the UWB. It is used along the perimeter of the foundation and, as a rule, not to the depth of freezing, but to the depth of the foundation device, this is usually 600 mm, which corresponds standard size sheet of extruded polystyrene foam.

Also, the insulation is used directly under the stove and the blind areas are necessarily insulated.

This type of foundation, according to Dmitry Marchenko, is far from ideal. Marchenko believes that the choice of this type of foundation is more related to failure decisions than rational decisions.

After given type foundation was promoted on construction forums, it was actively picked up by the manufacturers of expanded polystyrene insulation made technological maps, instructions for arranging these types of foundations. As a result, the topic of USWB has received even greater status as a professional solution for arranging the foundation of a private house. It is not without reason that these manufacturers became interested in this particular technology of foundations - they used very more quantity insulation and most of it is used simply irrationally, one could easily do without it.

Marchenko expresses the opinion that this technology is rather beneficial not for the owners of the future house, not for builders, it is beneficial specifically for the producers of expanded polystyrene.

Dmitry Marchenko studied this foundation in detail and did not see any other persons interested in this foundation, except for the producers of extruded polystyrene foam.

How rational is the UWB foundation?
On many sites promoting this foundation, you can see a large list of its benefits. According to Dmitry Marchenko, most of these advantages are simply far-fetched and, in fact, have no evidence.

Reality and advertising by USB

ADVANTAGES SPECIFIED FOR USHP	VALIDITY OF THE USHB FOUNDATION
USB is enough cheap type foundation, because a much smaller volume of reinforcement and concrete is used, a much smaller volume of earthworks and monolithic works.	In comparison, a strip monolithic foundation is usually taken. Indeed, in USHP less concrete is used - the slab thickness is only 100 mm and less reinforcement - reinforcement is knitted in just one layer. But long-term practice shows that one layer of reinforcement is not enough here. You need 2 layers of reinforcement and they must be tied up with clamps with a certain step, make additional "pawns" from the reinforcement. But this is not the case in the proposed USWB technology. Therefore, the main disadvantage of this foundation is a weak slab. Also, a lot of high-quality insulation is used in this foundation. And any insulation will not work here, you need high-quality and expensive extruded polystyrene foam. And for example, for a house with a slab measuring 10 x 10 meters, 18 cubes of insulation are required. And the foundation with so much insulation becomes simply “golden” in value. At a price, it even covers a monolithic strip foundation. Therefore, such an advantage as a low price is fundamentally wrong. Also, not the cheapest pleasure is the device of a sand cushion. First you need to choose your native soil, then bring in the sand. The sand must be moistened in layers and compacted, all must be MUST be observed. These are additional costs.
USHP is suitable for the construction of houses on any soil, and heaving and non-rocky, and subsiding and non-subsiding, etc.
This foundation evenly distributes the loads.
Suitable for all types of houses - timber, brick and lightweight concrete, etc.

The thickness of the sand cushion is 300-400 mm, then it is very rare to achieve high-quality compaction of sand. Very often builders neglect this.

For example, they do not do it in layers or do not spill enough or, on the contrary, fill in the sand and then it cannot be tamped properly. And even if all this is carried out efficiently, all the same, uneven ramming places are possible over the entire area of the sand cushion. As a result, this will lead to the fact that the base of a sand cushion under the house, and it will not be local, but common to all slabs, may turn out to be uneven and will lead to uneven shrinkage of the foundation. uneven shrinkage of the foundation, in turn, will entail possible cracking of the foundation, and then the reinforcement in one layer will be extremely insufficient for the foundation to retain its geometry and not crack, which will result in a crack in the load-bearing structures of the house. Thus, the sand cushion affects the stability of the whole house.

Also, the disadvantage is the possible deformation of the EPS itself. Despite the fact that the manufacturer claims high technical and operational characteristics of its products, that the material has very high compression rates, practice shows that at high loads it works, at least, not as stated in its characteristics. This means that material deformations are possible, which will lead to uneven shrinkage of the foundation. Extruded polystyrene foam directly under the foundation slab receives enormous loads in the form of pressure from the side of the house, which means its durability is questionable. Despite the fact that manufacturers claim ideal qualities, there are very few stories of using EPS in this way, there is no information on its caking for 10-15-20 years, and this calls into question the integrity of the whole house. There is no certainty that a person will want to risk their investments in a house in order to experiment on themselves how the EC manufacturer was conscientious.

The disadvantages of this foundation, like other slab foundations, is a low base. Usually it is 10 cm already from the mark of the blind area and the wall structures of the house are very close to the ground, which means they will be in the zone high humidity, which is a very vulnerable moment for our climate. A plinth with a height of 10 cm is not enough for our climate, in our climatic conditions the plinth should have a height of 50-60 cm. This will provide sufficient distance from the ground for wall structures and will take away any moisture and snow from them. Like other types of slab foundations, this foundation will require a flat area and the absence of any slopes from either side towards the house. any rain or melt water will soak the side parts of the base of the foundation and these places will heave unevenly, undermine the blind area, it may even lead to the raising of some part of the foundation, and with an uneven play of the foundation, deformations may occur on the foundation or on the wall structures.

Most technological maps or instructions for arranging this foundation imply a drainage system. It must necessarily be arranged in a warm zone of the earth, otherwise the drainage will most likely simply burst with heaving in the first winter. It will be filled with water and in winter, when the temperature is below zero, it will simply freeze and burst. But any drainage system has a tendency to silting up, and in this case, this system just under the house will have a great tendency, because already at the stage of building the foundation of the house, it will be exposed to possible risks of clogging from the workers, the vibrating plate will work. Of course, protection is arranged in the form of geotextiles, but practice shows that there are junction points and some shortcomings of the builders, as a result, the drainage systems are flooded. There is a way out that partially solves the situation, inspection hatches are being built through which drainage systems can be flushed under the pressure of water, but in most cases, hidden drainage systems are not the most the best solution, especially if this will not be done by specialists in drainage, but by ordinary builders in the construction of the foundation. In such cases, very often important points are missed, because if there is no practice, it cannot be replaced with information from the Internet. All the more easy it is to lay drainage pipes not enough. It is necessary to make a branch with a slope, you need to make a receiving well, install a drain pump. This will further increase the cost of construction.

On the site you will have to allocate space for a drainage well., regularly maintain and monitor it, clean the drainage system, which is likely to become completely silted up in 5-10 years. And the maintainability of drainage systems in these places is simply impossible. Any excavation work in this location will simply result in foundation settlement. This is another disadvantage to questions about the price of this foundation. On this, we can already say, in principle, that this type of foundation is not profitable.

But his shortcomings do not end there.
Private houses are usually built outside the city, where rodents, ants, etc. are found in large numbers. And the insulation under the foundation for them is an ideal place for arranging holes. The insulation will not be complete, and the pressure from the house will remain the same. Hence, deformations, subsidence of the insulation are possible, and with it subsidence of the foundation. And within 10-5 years, the picture with the geometry of the foundation can drastically deteriorate.
There is a solution that is partially used in the construction of any house, since it is always rational to insulate the blind area of the house, to insulate the foundation in order to exclude freezing of the slab, to exclude frost penetration under the foundation, even a monolithic one, therefore, when installing insulation from EP, the right solution is always to equip a protective mesh ... But if you carry out the defense metal mesh of the entire volume of insulation, it is very expensive, and it is not a fact that ants cannot get there.

With regard to underfloor heating when constructing this foundation: The layout of pipes for underfloor heating can already be carried out at the stage of its construction. Underfloor heating pipes are fastened with clamps to fittings, which are located at the bottom of the slab. And as a result, after pouring, you get a ready-made foundation in which the pipes for the warm floor are located, which means you will not need to do classical system installation of warm floors on insulation, when an insulation is arranged on a monolithic slab of a house, pipes for a warm floor are laid, a screed is made, and as a result you also get a warm floor, but you pay extra money for this work.

The floor screed, which is arranged along the pipes of the warm floor, has a relatively low density, and, accordingly, the heat capacity, in comparison with a monolithic slab. This makes it possible for the underfloor heating pipes to relatively quickly warm up the screed layer and give off heat to the room. If you look at the underfloor heating system in the USHP, then in contrast to the classic screed. we get: the stove itself has a high density and high heat capacity, which means that in order to heat this stove, the boiler must work much more. and you will have to pay more for it to warm up the entire volume of concrete, and only then will it give high-quality heat to the room. And if from the pipes of the underfloor heating to the finishing coating the thickness is 5-6 cm, then in the case of the USHP this distance increases by 2-2.5 times. And in order to warm up your house, you have to warm up the stove itself for 1-2 days, and only then will some kind of thermal effect from the underfloor heating pipes begin. This system is very slow to warm up and cool down. therefore, if we compare the device of underfloor heating, then the classical system is more advantageous, because it allows, at a lower cost in heat energy, to quickly transfer this energy to the room.

Because Since this system is directly connected to water, then it may have problems with leaks. Builders can accidentally crush or damage the pipe, which could lead to the need for repairs. In the case of the classical system, the screed is broken, the place of breakdown is found and eliminated. It is not difficult to find the place of breakdown here, since it will show a wet stain on the floor. and in the case of a monolithic slab, finding the place of damage will be quite problematic, you will also have to make a lot of efforts to get to the pipe, and the solidity of the supporting structure of the house will be broken. And in the case of a screed for integrity load-bearing structures search and elimination of the hole will not affect in any way.

Like all other slab foundations, this foundation requires a clear technological calculation, as well as a clear understanding and a clear arrangement of zero cycle engineering systems already at the foundation stage. Those. if, when installing other types of foundations, you have the opportunity to think about moving the pipe leads before installing the plumbing, then with this system you cannot move the pipes that have already been removed. ,
If you are faced with the fact that pipes, sleeves come out of the foundation slab, always protect them, covering them with something is an incomplete solution, the most proven is to make boxes of wood. ...
The technology is beneficial for manufacturers of extruded polystyrene foam.

The slab base can withstand significant external influences and is suitable for construction in areas with complex, unstable soils, prone to frost heaving, with high level 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 structure, when the soil moves, rises and falls along with the foundation, which protects the structure of the house from the formation of cracks.

general information

The slab base structure consists of layers:

the geotextile is covered with overlapping strips 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;
obscure plastic wrap overlapping stripes by 20 cm;
lay the reinforcing mesh;
poured with concrete.

Installation and insulation of slab monolithic foundation is expensive due to the high consumption of 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, less volume will be required land works.

Advantages of a slab foundation

The slab base has the following advantages:

the concrete slab serves as the floor of the first floor, which will further reduce 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 along with it move simultaneously with the soil;
the slab can be mounted on any type of soil, even on peatlands 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 prolongs the life of the structure.

Advantages of slab thermal insulation

As thermal insulation material use polystyrene foam, polystyrene foam, polyurethane foam. Mineral wool not suitable due to its low strength and high degree of moisture absorption.

There is a technology for mounting a Swedish plate. The main difference is that concrete structure erected on a layer of heat-saving material, thanks to this, 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;
a heat-saving layer allows you to increase 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 do everything in advance. necessary calculations and select the most suitable type of base for your home.

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 the concrete and maintaining the desired temperature on the site.

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

Insulation materials

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

№	Heat insulating material	Specifications
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	It is able to withstand significant compressive loads without changing its size and structure. Produced in sheet form rectangular 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 the presence of 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 board insulated with polyurethane foam has high rates for 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 a heater under the foundation slab.

Insulated plate installation

The construction of a monolithic slab base 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:

They clean the construction site from debris, the root system of trees and shrubs.
Mark the position of the slab according to the project.
They clean and remove the fertile soil layer. The extent to which the slab is buried depends on the 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.
They dig a pit, manually level its bottom and side walls.
Pipes are installed around the perimeter to drain rain and melt water.
Spread the geotextile in overlapping strips. The material should cover the bottom and extend onto the walls along its entire height.
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.
Sand is poured, 20-30 cm thick. Sand is evenly distributed over the entire area, moistened with water and compacted well.
Spread out geotextiles.
Crushed stone is poured, evenly distributed around the perimeter, carefully tamped.
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.
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:

A removable formwork from boards is mounted, supports are installed so that the structure does not fall apart under the weight of concrete.
Pour a layer of concrete 50 mm thick.
After the cement mortar has completely solidified, sheets of foam are laid on it end-to-end and glued. Adhesive composition 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 overlap.
Spread the dense polyethylene in overlapping strips. The joints are sealed with tape.
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 contributes to the increase of 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 USHP. 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 paving 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 draw 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, 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 under the lungs of the house, it is relatively inexpensive, in difficult cases may 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 the 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, such a foundation is the only possible solution. For example, on unstable, loose soils or clays with great depth freezing.

The construction of the monolithic slab foundation is simple and reliable, but its manufacture requires a large number 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 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 is determined depending on the mass of the house and the type of soil. With 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 the thickness of the slab, 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. Reinforced concrete slab settles down 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 pillow layers depends on the depth of the fertile layer - it must be completely removed. The resulting excavation 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 - made of 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 base preparation - in a sand cushion. That is, after the foundation is made, the heating system is ready and engineering systems... 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, one cannot make mistakes, since alterations are impossible. Also, questions arise about the repair of systems embedded in the foundation. It is impossible, therefore, expensive materials with a long guarantee are laid.
USHP - insulated Swedish plate with built-in underfloor heating
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 making 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 load bearing capacity 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.

Preparation of the base

The dimensions of the pit for a monolithic slab must be at least 1 meter larger than the building itself. In this area, fertile soil is completely removed. Its thickness is different regions different - 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 with an overlap, the edges are glued together with reinforced tape. Geotextile prevents plant roots from germinating, and also prevents the washout of sand, 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 tamped with a manual vibrating plate with high quality - 8-10 cm. These are the layers that sand is laid. It should 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... 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, covered with sand, leveled, sand is compacted with a shovel or board. A 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, 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 placed higher, using it again 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 weight of the concrete.

A layer of concrete of 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 distribute the load from the house more evenly.

Waterproofing

Since the monolithic foundation slab is completely buried 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, the waterproofing roll adheres poorly 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 rolled 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 bituminous mastic and press 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

From roll waterproofing materials Gidroizol, TechnoNIKOL Technoelast EPP-4 on high density polystyrene showed the best results. 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 its modern design, it is too thin and brittle, it 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 inflow of moisture through the slab with the help of liquid impregnations such as Betonit. It significantly reduces moisture absorption. Penetrates to a depth of 50-60 cm, so that concrete preparation will saturate through and through. The downside 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 a 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 can 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 of the rods, they 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 weld- 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 poured 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 must be calculated so that you have time to distribute the first portion and compact it. Construction vibrators are used for compaction, which generate 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 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 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 could be laid 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 laid out on 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 foil on top. 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 freezing, 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, 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 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 placed on execution as well. Even small mistakes are critical. You can do the UWB yourself, but it is better to order the project. For an approximate cost breakdown, see 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.

Insulation is an important part of any construction. All external parts of the building must be insulated from heat loss: walls, roof, basement and foundation. Insulation of the basement of the building not only limits heat loss, but also prevents frosty heaving of the soil. How is the insulation of a monolithic foundation carried out? And what are the features of installing insulation on the wall and floor

Insulation of foundations

Insulation of the foundation is necessary in those parts that are located in the zone of soil freezing. The base and the top of the foundation wall are covered with insulation. In addition, thermal insulation boards are placed under the outer blind area around buildings. These measures help to protect the ground and walls from freezing and, therefore, avoid the earth around the house.

Various foundation designs have different ways insulation. Deep tape - only vertical walls near the surface of the earth are insulated, shallow tape - walls and soles. Pile foundation rests on non-freezing soil, therefore only the lateral surfaces of the piles are insulated.

Insulation of a monolithic foundation slab is performed from the sides and bottom. This is necessary due to the location of the slab in the zone of soil freezing. A monolithic slab foundation is a shallow structure. Its depth rarely exceeds 50 cm. Therefore, the entire slab is located in the zone of freezing soil and requires high-quality insulation. What materials are used to insulate the foundation slab?

Foundation insulation material: Penoplex

Increased requirements for moisture and water resistance are imposed on the foundation insulation. It comes into contact with moist soil, therefore, in addition to insulation, it must prevent moisture from penetrating into the walls of the house. Besides, foundation insulation must withstand compressive loads.

The ideal material for foundation insulation is extruded polystyrene foam. The trade name of the material is penoplex. It has a closed cell structure, due to which water and moisture do not penetrate into the material and do not form its destruction. Fluctuations in temperature near zero create an alternating liquid-ice state. When moisture is absorbed, the insulation cracks (as a result of freezing and expansion of water in the pores of the material). Therefore, ordinary expanded polystyrene (polystyrene) is not used in foundation insulation. You can use only moisture-resistant types of insulation: polyurethane foam or penoplex.

Water absorption characteristics

In addition to resistance to moisture and steam penetration, Penopex insulation can withstand significant compressive loads. Its price is higher than that of ordinary polystyrene. But it pays off in durability.

How to insulate: inside or outside?

How to properly insulate the foundation with penoplex - from the outside or from the inside? Theoretical calculations show that the location of the insulation on the outside protects the wall and slab from freezing. The location of the insulation inside the wall does not protect the wall and the slab, but it makes it possible to improve the microclimate in the room. This means that outdoor insulation is the most the best way for all building surfaces.

However, it is not always possible to carry out insulation from the outside. So for the foundation, external insulation is possible only at the construction stage. After that, the base can be insulated from heat loss only from the inside.

Insulation of the foundation slab from the inside gives a noticeable positive result: it becomes warmer and drier in the house. At the same time, the plate itself continues to freeze in the winter season, so its durability remains small.

If the slab was insulated during construction, then the foundation does not freeze and carries the load of the built house for a long time. How to insulate a slab foundation from the outside?

Penoplex insulation during the construction phase

Thermal insulation during the construction phase involves laying the insulation on the ground before pouring the concrete. We list the sequence of actions for insulation during construction:

To exclude uneven pressure of the foundation on the ground, part of the soil is removed and gravel and then sand backfill is made. A layer of sand is spilled with water and carefully tamped.
After that, a layer of waterproofing and insulation plates are laid.
Reinforcement rods are placed on top of the insulating material and concrete is poured. In this case, the reinforcement rods are placed in two rows, the lower row is supported by plastic beacons (so that after pouring the reinforcement is inside the concrete).

In this way, a light, durable and warm foundation is obtained, on which the walls of the building can be erected in a month.

Swedish foundation

Foundation insulated from below with polystyrene plates and equipped with warm pipes is called Swedish. The abbreviated abbreviation for the foundation sounds like "USHP" or Insulated Swedish Slab.

The thickness of the base plate can vary from 10 to 30 cm (depending on the type of soil and the severity of the structure). The depth of such a foundation is higher than the soil freezing line. At the same time, frost heaving is taken under control and compensated for by external insulation of the slab.

Additional arrangement of heating allows you to get a foundation and a warm floor near the house at the same time. This design saves not only weight but also money. The amount of concrete for casting the base is reduced by one third. Reduced construction costs.

USHP - Insulated Swedish Plate

Advantages of an insulated foundation

We list the advantages that make the insulation of the foundation slab a necessary element of construction:

Saving concrete, reducing construction costs.
Acceleration of the construction of a house.
Reduction of heat loss and reduction of utility bills.
Improving the indoor climate.
Increase the durability of the foundation slab and the entire structure.

Such high advantages indicate that the insulated slab foundation is one of the best designs the foundations of the house.

Insulation of the foundation slab updated: February 26, 2018 by: zoomfund