Calculation of insulation of the foundation. We determine the required thickness of the insulation. Insulation of the strip foundation with Penoplex

Insulation of the foundation and soil Insulation of the foundation and soil around the foundation has two strategic goals:

• On heaving soils: insulation of the foundation and adjacent soil in order to “push” the freezing of the soil away from the foundation, reduce the depth of soil freezing and thereby reduce the magnitude of the winter rise in the soil level.
• On non-rocky soils: reduce the heat loss of a heated house through the foundation during the cold season.

Foundation strip foundation to a depth less than the depth of seasonal freezing of soils is possible only when carrying out "special thermal engineering measures that exclude freezing of soils" [clause 2.29 of SNiP 2.02.01-83, clause 12.2.5 of SP 50-101-2004]. In territorial building codes TSN MF-97 of the Moscow Region indicates that when designing and constructing shallow foundations of low-rise buildings, it is recommended that “the use of heaters laid under the blind area” with mandatory protection by waterproofing. Recommendations for insulation of the foundation and soil are limited: insulation standards do not apply to construction on permafrost soils and in areas with an average annual outdoor temperature (AMHT) below 0 ° C or with a frost index (MI) value of more than 90,000 degree hours. For example, the measures for warming soils and foundations described below can be applied in Murmansk (SGTV = +0.6 ° C) or Irkutsk (SGTV = + 0.9 ° С), but cannot be used in Surgut, Tur, Ukhta, Vorkuta, Khanty-Mansiysk, Magadan, Vilyuisk, Norilsk, Yakutsk or Verkhoyansk (SGTV< 0°С). Также не требуется утепление фундаментов и грунтов с целью снижения морозного пучения и предупреждения деформации основания на непучинистых (гравелистых и крупно-песчаных) грунтах. Теоретической основой утепления грунта и фундамента в качестве меры по уменьшению морозного пучения, является представление о физических механизмах подъема уровня грунта при промерзании.

Frost heaving - a rise in the level of the soil as a result of the expansion of water freezing in the thickness of the soil can take place only when three mandatory conditions are added:

1. In the ground should be permanent source water
2. The soil must be fine enough to wet and hold water.
3. The ground had the ability to freeze through.

When water-saturated soil freezes, ice lenses are formed in it at the temperature interface, and higher from it to the freezing surface. When freezing, water expands by about 9%. The pressure force of the soil rising when freezing can vary from 0.2 kgf / cm2 to sandy soils up to 3 kgf / cm2, which may well balance or exceed the load from the building and cause deformation of the strip foundation. Silt (organic or inorganic soil with especially fine particles) is able to expand when frozen and in the absence of constant flow water (high groundwater level). The magnitude of the frosty rise of silty soils can be up to 20% of the thickness of the frozen layer.

Unheated basements and subfloors are exposed to high risk destruction due to the rise of soils associated with freezing of the soil to the surfaces of the walls of basements and subfloors. As a result of freezing, a fairly wide layer of dense bond is formed between the soil and the wall material. With a frosty rise, the soil is able to break the immaculate masonry of bricks or foundation blocks. Therefore, on heaving soils, firstly, it is recommended to arrange monolithic buried structures, and secondly, to isolate wall material from frozen heaving soils with drainage soil, drainage wall waterproofing, insulation or a sliding layer of film materials. Also, the external insulation of underground basement walls plays an important role in preventing the formation of condensate on the internal surfaces of the walls, and, as a result, the formation of mold.

Vertical insulation of the outer surfaces of the foundation with a 5 cm layer of extruded polystyrene foam reduces the heat loss of the building through the ground by about 20%. Although horizontal underground insulation of the base of the foundation and the adjacent soil has little effect on the heat loss of the building, and therefore can be regarded as ineffective in terms of energy saving, this type of insulation plays a significant role in preventing freezing of the soils under the foundation.

Methods of insulation of foundations on heaving soils Schemes of insulation of foundations of buildings differ depending on the mode of their operation (heating in the cold season). For buildings heated during the cold season (buildings in which the temperature is maintained year-round at a temperature not lower than +17 ° C), the insulation scheme combines external vertical and horizontal insulation of the foundation with the prevention of the formation of cold bridges and the absence of floor insulation on the ground. Floating floors not isolated from the ground make it possible, on the one hand, to warm up the soil under the building better, preventing it from freezing, and on the other hand, allow using the accumulated heat in the mass of soil bedding and getting 1-2 “free” degrees of geothermal. The horizontal insulation belt at the corners of the building (due to large heat losses compared to the middle part of the foundation) should be either wider or, which is more practical during construction, thicker. The width and thickness of the widely used domestic insulation Penoplex for insulating the soil and foundation is determined according to the tables given in the organization standard STO 36554501-012-2008, based on the frost index (MI), which characterizes the number of days in a given area with a negative temperature and the value of negative temperatures in degree days.

Insulation scheme for a building that is constantly heated during the cold period with thermal insulation of the floating floor from the underlying soil

If a house that is constantly heated during the cold season has floor insulation from the underlying soil, then the insulation parameters are calculated according to another table:

Table. EPPS insulation parameters for permanently heated buildings with floor insulation on heaving soils (according to Table No. 1 STO 36554501-012-2008)

Design parameters of EPPS (Penoplex) boards for permanently heated buildings with floor insulation

The task of soil insulation in unheated structures (structures in which the temperature in the cold season is less than + 5 ° C) is to reduce the freezing of the soil underlying the foundation. Therefore, the foundation itself is not insulated, but only the soil under it is insulated, so as to exclude cold bridges to the underlying soil through the foundation itself. In this case, the heat loss of the building is not taken into account, and an increase in the thickness of the horizontal insulation belt is not required. Many dachas are operated in variable mode, when heating is turned on only during periodic visits, and more time the house is without heating. In this case, the insulation scheme combines the insulation of the foundation itself to reduce heat loss during the heating period and the insulation of the entire underlying soil to reduce freezing during the period without heating. Keep in mind that if you plan to constantly maintain the house in the “non-freezing” mode of +3 +5 ° С, then such a house cannot be classified as constantly heated due to insufficient heat transfer to warm the soil.

Scheme of insulation of an unheated building in the cold period on heaving soils

Such a house requires insulation of the foundation and soil like a house with a variable heating regime. Insulation parameters for houses with a variable heating regime are calculated in the same way as for unheated houses. Additional insulation in the corners is not required due to short periods of heating.

Scheme of insulation of the foundation of a building with a variable heating mode on heaving soils *

Table. Parameters of insulation of foundations of unheated or periodically heated buildings on heaving soils (according to table No. 2 STO 36554501-012-2008).

IM, deg.-h

Thickness of horizontal thermal insulation (depending on the thickness of the material **), cm

Scheme of soil insulation of an unheated building in the cold period on heaving soils.

If heated buildings have cold extensions, for example, terraces, garages, then the horizontal insulation belt covers all extensions interlocked with the house. Its parameters on the extension site are calculated as for an unheated building. Thermal insulation is also required between the foundations of the unheated and heated parts of the building to prevent heat loss through the cold bridge. The underlying soil under the unheated part of the building is completely isolated from the foundation by insulation.

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How to insulate the foundation. Schemes and examples

Before deciding how to insulate the foundation, let's recall some information about soils. In particular, about such soil properties as heaving.

Wet clay soils, sands are dusty and fine, freezing in winter period, increase in volume, as a result of which there is a rise (buckling) of the soil within the depth of its freezing. This process is called frost heaving of the soil, and soils are heaving. When such soils freeze, frost heaving forces begin to act on the foundation, which lead to deformation and sometimes even destruction of the foundation and building structures.

Solving the question of how to insulate the foundation in relation to strip shallow foundations aims to move the freezing soil away from the foundation, reduce the depth of soil freezing and thereby reduce the amount of winter ground rise. If the soil is slightly heaving, then the insulation of the foundation is aimed at reducing heat loss through the foundation in winter.

In accordance with paragraph 2.29 of SNiP 2.02.01-83 and paragraph 12.2.5 of SP 50-101-2004, the depth of external foundations may be set regardless of the estimated freezing depth if:

...special thermal engineering measures are provided to prevent soil freezing.

At the same time, it should be taken into account that the measures proposed in this article are suitable for areas where the average annual outdoor temperature is above zero degrees Celsius or the frost index is less than 90,000 degree hours. That is, it is practically the entire European part of Russia.

frost index

How to insulate the foundation on heaving soils

The most common domestic insulation is Penoplex extruded polystyrene foam.

PENOPLEX® - heat-insulating boards made of expanded extruded polystyrene foam that meet the requirements of TU 5767-006-56925804-2007.

The solution to the question of how to insulate the foundation is to combine vertical and horizontal insulation of the foundation of the house with the prevention of the formation of cold bridges. The width and thickness of the insulation is determined according to the tables of the organization standard STO 36554501-012-2008, based on the frost index (MI), which characterizes the number of days in a given area with negative temperatures and the magnitude of negative temperatures in degree hours. Insulation schemes will differ depending on mode of operation of the house. Let's consider four such modes.

How to insulate the foundation. Scheme for buildings heated in winter and non-insulated floors on the ground

Vertical insulation of the foundation with a layer of "Penoplex" five centimeters entails a reduction in heat loss by 20%. Horizontal insulation of the base of the foundation and the adjacent soil does not have such a significant effect on reducing heat loss, but plays a significant role in preventing freezing of the underlying soils under the foundation. The insulation scheme is shown in Figure 1. The width and thickness of the insulation are shown in Table 1.

Picture 1

Table 1

How to insulate the foundation. Insulation scheme for a building that is constantly heated in winter with thermal insulation of the floating floor from the underlying soil

The insulation scheme is shown in Figure 2. If the house is constantly heated in cold weather, and the floors are thermally insulated from the underlying soil, the width and thickness of the insulation are calculated according to Table 2.

Figure 2

table 2

As can be seen from the table, in this case, the sufficient thickness of the vertical thermal insulation will be greater than in the first example.

How to insulate the foundation. Scheme of insulation of a building unheated in winter on heaving soils

This scheme is most suitable for cottages that are operated in the summer and preserved for the winter. In this case, the task is to reduce the freezing of the soil under the foundation. The scheme is shown in Figure 3. As can be seen from the figure, the foundation itself is not insulated, but the soil under it is insulated to exclude cold bridges. In this case, it is not required to increase the thickness of the horizontal insulation belt. The insulation parameters are shown in Table 3.

Figure 3

Table 3

Parameters of insulation of foundations of unheated or periodically heated buildings on heaving soils

(according to table No. 2 STO 36554501-012-2008)

Scheme of insulation of the foundation of a building with a variable heating mode on heaving soils

This scheme (Figure 4) is used to insulate the foundation of houses that are periodically operated in winter. For example, most of the time the house stands without heating, and during weekend visits it is heated. In this case, a combined scheme is used. The foundation itself is insulated to avoid heat loss during heating, and the underlying soil is insulated to reduce freezing when the house is without heating. The thickness and width of the thermal insulation layer is taken from table 3.

Figure 4

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When constructing a foundation, special attention should be paid to the issue of its thermal insulation, especially in regions with a harsh climate and deeply freezing soil.

About 80% of the territory of Russia is located in the zone of heaving soils, which pose a particular danger to foundations.

Heaving soils during seasonal or long-term freezing are able to increase in volume, which is accompanied by a rise in the soil surface. The rise of the soil surface during the winter can reach 0.35 m (15% of the depth of the freezing soil layer), which in some cases leads to deformation of the structure: freezing with the outer surface of the building envelope, the soil is able to lift it due to the tangential forces of frost heaving. When laying foundations above the freezing depth of heaving soils, or if the foundation slab was not insulated during construction in winter, normal frost heaving forces arise under its sole.

Horizontal thermal insulation of the foundation with cutting off the zone of frost heaving, allows you to reduce to zero the risks arising from the rise and thaw of heaving soils.

It has been established that the share of basement foundations and ground floors accounts for about 10-20% of all heat loss at home.

Insulation of buried structures reduces heat losses, protects the foundation structure from freezing, avoids condensation of water vapor on cold walls (associated with insufficient thermal insulation or ventilation in the room), and prevents dampness and mold development. At the same time, in country houses for summer living, the insulation of foundation and basement walls does not make sense, except when it is necessary to correct design flaws associated with the consequences of frost heaving of soils.

Thermal insulation requirements are not put forward for unheated basements.. However, it is necessary to insulate the walls at least in the basement area so that they do not freeze at the border of the ceiling between the unheated basement and the heated rooms on the first floor.

In addition, thermal protection is constituent element waterproofing system: protects the waterproofing coating from destruction and temperature aging.

Advantages

• eliminates or significantly reduces the impact on the foundation of the forces of frost heaving;
• reduces heat loss and reduces heating costs;
• provides the required and time-constant temperature inside the room;
• prevents formation of condensate on internal surfaces;
• protects waterproofing from mechanical damage;
• contributes to the extension of the durability of waterproofing.

Foundation insulation

Special requirements are imposed on the materials used to insulate the foundation from the outside:

• low water absorption;
• high compressive strength (with low thermal conductivity);
• resistance to aggressive underground waters;
• resistance to decay.

Mineral wool is not suitable due to compressibility when backfilled with soil and high water absorption.

Given the low water absorption (< 5%) and high strength ( 0.4-1.6 MPa), foam glass can be used for external vertical and horizontal thermal insulation. True, this option turns out to be several times more expensive.

Expanded polystyrene (styrofoam)

Low short-term compressive strength (

If ordinary foam is used to insulate foundations from the outside, then it is located under a waterproof layer (: foundation waterproofing - foam plastic - system waterproofing). Otherwise, a few years after installation, the foam will turn into a shapeless pile of balls. The moisture accumulated in the insulation, when frozen, will increase in volume and destroy its structure.

Under conditions of increased loads and humidity, the most optimal heat-insulating material is.

Due to the properties of the feedstock and the closed cell structure, which makes it difficult for water to penetrate inside, extruded polystyrene foam has excellent technical specifications and a long service life, which allows it to be used for insulation of the foundation.

EPPS has almost zero water absorption (no more than 0.4-0.5% by volume for 28 days and for the entire subsequent period of operation), so ground moisture does not accumulate in the thickness of the insulation, does not expand in volume under the influence of temperature changes and does not destroy the structure material throughout its service life (frost resistance more than 1000 freeze-thaw cycles).

Due to their strength, extruded polystyrene foam boards increase the life of the waterproofing coating, protecting it from mechanical damage and providing a positive temperature regime.

Thus, the insulation of the foundation and basement of the house with extruded polystyrene foam extends the life of the foundation.

Advantages

• stability of thermal insulation properties throughout the entire service life;
• service life of at least 40 years;
• compressive strength is from 20 to 50 t/m 2 ;
• is not a breeding ground for rodents.

Calculation of the thickness of the insulation

The required insulation thickness for the basement wall located above ground level is taken equal to the thickness of the insulation for the outer wall and is calculated by the formula:

The required insulation thickness for a basement wall located below ground level is calculated by the formula:

• δ ut- insulation thickness, m;
• R 0 pref.- reduced resistance to heat transfer of the outer wall, taken depending on the value of the GSOP, m 2 ° C / W;
• δ - thickness of the bearing part of the wall, m;
• λ - coefficient of thermal conductivity of the material of the bearing part of the wall, W / (m ° C);
• λ ut- coefficient of thermal conductivity of the insulation, W / (m ° C).

The required thickness of insulation from extruded polystyrene foam boards in the basement walls for all regional and republican centers RF is shown in the table:

The range of XPS materials includes specially designed thermal insulation boards with milled grooves on the surface. This material together with a geotextile fabric, it successfully works as a wall drainage, i.e. it performs three functions: insulation of the foundation, protection of the waterproofing from mechanical damage, and removal of water from the foundation in the drainage system.

How to insulate the foundation?

When insulating the vertical part of the foundation, expanded polystyrene is installed on soil freezing depth determined for each region individually. The effectiveness of insulation with a deeper installation is sharply reduced.

The thickness of the insulation in the corner areas should be increased by 1.5 times, at a distance of at least 1.5 m from the corner in both directions.

Insulation of the foundation from the outside is the most rational, provides a low level of heat loss.

Insulation of the foundation from the outside

Warming the soil around the perimeter of the house under allows you to reduce the depth of freezing along the walls and under the base of the foundation and keep the freezing boundary in a layer of non-porous soil - sand, gravel cushion or backfill soil. At the same time, extruded polystyrene foam must be laid with a predetermined blind area slope of ≥ 2% from the house.

Insulation width from extruded polystyrene foam around the perimeter should be at least the depth of seasonal freezing of the soil.

Thickness of horizontal thermal insulation must not be less than the thickness of the vertical thermal insulation of the foundation.

Insulation of the foundation from the inside

If it is impossible to insulate the foundation from the outside, thermal insulation from the inside of the room is allowed. Thermal insulation from the side of the room is made either by gluing extruded polystyrene foam to the wall surface using solvent-free compounds (for example, cement-based), or by fixing insulation boards mechanically followed by a finishing layer.

At the same time, it is obligatory to check the walls of the insulated structure for the possibility of accumulation of condensation moisture in it.

In the construction of a wall with extruded polystyrene foam, it shows that such a construction is acceptable.

How to fix polystyrene foam
for foundation waterproofing

Insulation is placed along the leveled outer surface of the walls of the insulated structure after waterproofing has been performed on it.

When insulating the foundation from the outside, mechanical fixation of XPS boards is not allowed, since in this case the continuous waterproofing coating will be broken!

Extruded polystyrene foam is attached to the waterproofing surface of the walls with glue or by melting the bituminous waterproofing layer at 5-6 points, followed by tight pressing of the plates.

Eps bonding should begin from below laying the plates horizontally in one row. The next row of plates is installed end-to-end to the already glued bottom row. It is not allowed to re-install the glued boards, as well as change the position of the insulation after a few minutes after gluing.

Thermal insulation boards must be of uniform thickness and fit snugly to each other and to the base. At the same time, they should be placed with offset joints (staggered). If the seams between the plates are more than 5 mm, they must be filled with mounting foam. It is better to use plates with a stepped edge. They are laid close to adjacent slabs so that parts of the L - shaped edges overlap each other. This installation eliminates the appearance of cold bridges. When installing thermal insulation from two or more layers of insulation, the seams between the plates are spaced apart.

The choice of adhesive depends on the waterproofing used. When applying waterproofing of a roll or mastic type on a bitumen basis, a special or is used. When choosing an adhesive, it must be ensured that it does not contain solvents and does not dissolve the styrofoam board when applied. For gluing plates to a vertical surface and for sealing joints, it is not recommended to use ordinary mounting foam, since due to the large volumetric expansion, “heaving” of the thermal insulation layer may occur, or the plates can be detached from the surface due to the occurrence of large stresses between them.

Below ground level, the adhesive layer can be applied with several points along the perimeter and in the center, so that the moisture that collects between the surface of the plate and the building base flows down unhindered.

It is forbidden to install insulation on bituminous waterproofing that has not yet dried for the following reasons:

• during the installation process, the waterproofing elements may "disperse", after which the tightness can no longer be guaranteed;
• cold bitumen based waterproofing agents may contain solvent particles which can damage the thermal insulation material. Therefore, when applying waterproofing from cold bitumen, before installing extruded polystyrene foam boards, it is recommended to allow the surface to dry for 7 days.

basement insulation

The plinth should be insulated around the perimeter to reduce thermal bridges and protect the foundation from frost damage and cracking due to thermal expansion.

The basement of the house is divided into two parts: above and below ground level and is in humid conditions, as it is in constant contact with the ground, moistened by rain, melt waters and spray drops.

The facade insulation system based on a non-water-resistant heat-insulating material, such as expanded polystyrene or mineral wool, should be located at a distance of at least 30-40 cm from the top edge of the ground so as not to be exposed to rain and melt water.

To insulate the basement, it is necessary to use materials that have zero water absorption and do not change their thermal insulation properties in a humid environment. Such material is extruded polystyrene foam.

underground part

In the recessed part of the house, the use of dowels is not required, the filled soil presses the glued insulation.

Aboveground part

In the basement area (above the ground level), extruded polystyrene foam is attached to polymer cement glue, or any other adhesive that provides good adhesion to the base.

If in the underground part of the house the fastening of the XPS is possible only with the help of adhesives, then in the above-ground part of the base it is obligatory to install facade dowels at the rate of 4 dowels per slab.

As a heat-insulating layer above ground level, it is possible to use a special brand of extruded polystyrene foam with a milled surface, which provides better adhesion of adhesive compositions. It is also possible to use standard grades of extruded polystyrene foam with a smooth surface, in this case, to improve adhesion, the surface should be milled with a brush with metal bristles or a hacksaw with fine teeth.

1. Fastening of the insulation (it is carried out similarly to fastening the insulation of the entire facade system to polymer cement glue)
2. Installation of the first layer of reinforcing glass mesh

   The prepared adhesive solution is applied with a long float from of stainless steel on the plate vertically in the form of a strip. The thickness of the adhesive should be about 3 mm. The solution begins to be applied from the corner of the house. After applying the adhesive solution on a segment equal to the length of the prepared mesh, it is leveled with the notched side of the grater until the same thickness of the solution is obtained over the entire surface. On a fresh adhesive solution, you need to attach the prepared piece of mesh, pressing it in several places to the glue with the edge of a grater or fingers. It is necessary to remember that the mesh edge overlaps by 10 cm. With the smooth side of the grater, it is necessary to drown the mesh in the adhesive solution - first vertically from top to bottom, then diagonally from top to bottom.

3. Doweling (performed through the first layer of reinforcing glass mesh)
4. Installation of the second layer of reinforcing glass mesh (similar to the first)
5. Plinth trim ( possible options):
   • decorative plaster;
   • stone slabs (attached with special glue);
   • ceramic tile(mounted on a special glue for decorative tiles).

Insulation of the base plate

If it is necessary to insulate the foundation slab, the heat-insulating slabs are laid on the waterproofing. If knitted reinforcement is planned to be used to reinforce a reinforced concrete monolithic foundation slab or power floor, then it is enough to protect the insulation slabs from liquid components concrete with a polyethylene film 0.15-0.2 mm thick laid in one layer. If it is planned to use welding for reinforcing work, then a protective screed of low-grade concrete must be made over the film or cement-sand mortar. Sheets of film are laid with an overlap of 10-15 cm on double-sided tape.

The use of insulation in the arrangement of the foundation is a common way to improve the thermal insulation performance of the building and protect the foundation from negative influences. sub-zero temperatures air. Among other heaters, extruded polystyrene foam has gained great popularity. Unlike conventional foam, the material has an increased margin of safety, in addition, the special shape of the plates makes it possible to significantly simplify the installation process.

Let's figure out how to insulate the foundation of the house with foam plastic from the outside with your own hands. The procedure is very similar to thermal insulation of walls. On the side parts of the foundation, which are located above and below the soil surface, special heat-insulating plates are fixed. The use of insulation allows you to reduce the rate of heat exchange between the walls of the foundation and the layers of soil.

Why insulate the foundation

Some owners of private houses refuse the basement insulation procedure, trying to save as much money as possible. At the same time, experts in the field of construction works insist that the thermal insulation of this part of the house is simply necessary, and it is better to fix the insulation just outside the structure.

The general scheme of insulation of the foundation with foam

The following arguments are put forward in favor of insulation:

• After insulation, the foundation becomes protected from the negative effects of sub-zero air temperatures. This factor is especially important in places with high humidity. If, when the temperature drops, moisture enters the cracks in concrete, it begins to expand rapidly and eventually breaks and damages the concrete structure;
• The degree of protection of the foundation from temperature fluctuations increases. The concrete structure experiences much fewer cycles of compression and expansion, as a result, the life of the building without a major overhaul of the foundation is significantly increased;
• The insulation becomes an additional barrier to groundwater, which tends to penetrate to the foundation.

How best to insulate the foundation: from the inside or outside

The foundation can be insulated from the inside or outside. Both methods have their advantages and disadvantages.

Internal thermal insulation

To the benefits internal insulation include:

• Improvement of the microclimate in the basement;
• Effective fight against dampness in the room;
• Basement protection against groundwater penetration.

The disadvantages of internal insulation include:

• Such thermal insulation does not protect the foundation from soil freezing;
• Moisture easily gets into the pores of the concrete base and destroys it;
• The dew point moves inward.

Warming from the outside

This insulation method has the following advantages:

• The foundation is reliably protected from freezing;
• The dew point is shifting towards the street;
• The concrete base is protected from any negative influence from the environment;
• Significantly increases the overall life of the premises;
• Some heaters are able to additionally strengthen the foundation;
• When installing a thermal blind area, it is possible to protect not only the foundation from freezing, but also the soil within a radius of about half a meter from the installed insulation.

External insulation will require more time and materials, and this is the only drawback of this method.

It is very important to understand that the external insulation of the foundation provides a reliable guarantee of protection for the whole house, and thermal insulation from the inside will protect only the basement from the cold.

After evaluating all the advantages and disadvantages of the external and internal methods it can be concluded that it is better to give preference to external insulation.

In order for the insulation to fully cope with the tasks assigned to it, it is worth remembering that the thermal insulation of the foundation should be carried out only after all the walls have been insulated. Be sure to process all the joints between the insulation with mounting foam - this will increase the efficiency of the thermal insulation of the room.

By the way, the preference for warming the foundation with inside given only if for some reason it is impossible to install a heater outside.

What is the best way to insulate

When planning the installation of thermal insulation for the foundation, the issue of choosing and purchasing a suitable insulation is initially resolved. The material for insulation of the foundation should be distinguished by the following characteristics:

• To have resistance to deformation against the background of constant pressure from the soil;
• Do not absorb moisture from the ground.

In the modern market, insulation materials are presented in a wide range, and a beginner in the construction industry can get confused in the abundance of offers. It is worth saying that the common mineral wool insulation is not suitable for thermal insulation of the foundation. Not only is it not durable, but it also absorbs moisture well, as a result of which all its positive performance characteristics are nullified.

Despite the fire resistance and low thermal conductivity, mineral wool has a significant drawback - high hygroscopicity.

In the modern construction of private houses, two materials are best suited for insulating the foundation:

• Polyurethane foam.

Polyurethane foam is a modern insulating material that guarantees thermal, sound and water protection of a concrete structure. The material is sprayed onto the surface with special equipment in several layers. This application technology eliminates the appearance of gaps and seams. The advantages of the material include:

• The ability to apply a heat-insulating coating without seams and gaps;
• Excellent adhesive characteristics;
• Low thermal permeability;
• Steam protection;
• Increased reliability;
• Long service life;
• No need to additionally purchase material for steam and water protection of the foundation.

The main and rather significant drawback is that special equipment is required for laying the material, as a result, the process becomes impossible to implement at home. In addition, polyurethane foam has a high cost.

Penoplex, in turn, does not require special skills and special equipment for installation. Among other things, it has the following advantages:

• The cellular structure does not let moisture in, as a result of which the plates do not collapse over time after freezing;
• Increased strength characteristics;
• Ensuring a long service life of the foundation;
• Low cost;
• Long service life of the material;
• Preservation thermal insulation characteristics during the entire period of operation;
• Rodents do not use the material as food, unlike regular foam.

Foam insulation reduces heat loss by 20% and helps the foundation last longer

Penoplex is an improved version of foam. The material passes moisture very easily, and after several cycles of defrosting and freezing, it will simply crumble into segments. We add that a few years ago, expanded clay was also in demand in the construction market as a heater for the foundation. The material is inferior to foam plastic due to the high cost, as well as reduced efficiency in the field of providing thermal insulation.

Calculation of the thickness of the insulation

In addition to the correct choice of insulation, it is necessary to pay attention to the calculation of its optimal thickness. If the penoplex is not thick enough, then this can result in freezing of the foundation and transfer of the dew point inside the basement, which will eventually lead to condensation on the walls and an increase in humidity levels.

You should not take too thick material either: the degree of thermal insulation will not increase from this, but the costs will significantly hit the family budget.

The correct calculation of the thickness of the insulation material is a guarantee of heat in the house, lack of humidity and minimal financial costs.

Thermal resistance is denoted by the Latin letter R. This value is constant, but for each region the value is different and depends on the general climatic conditions. For example, for the Moscow region it is equal to 3.28 m 2 K / W. For other regions of Russia, the value can be taken from the table:

Thermal resistance is calculated by the formula:

R \u003d h 1 / λ 1 + h 2 / λ 2

where h 1 is the thickness of the foundation (in meters), λ 1 is the thermal conductivity of the foundation (for a reinforced concrete foundation λ 1 = 1.69 W / m ° K); h 2 - the thickness of the insulation material (in meters); λ 2 - coefficient of thermal conductivity of the insulation (for foam λ 2 \u003d 0.032 W / m ° K).

Thermal conductivity coefficient of various materials

Therefore, the thickness of the insulation is calculated by the formula:

h 2 \u003d λ 2 (R-h 1 / λ 1)

Consider an example of calculating the thickness of a heat-insulating material for a private house in St. Petersburg with a reinforced concrete foundation half a meter thick (h 1 \u003d 0.5 m):

h 2 \u003d 0.032 (3.23-0.5 / 1.69) \u003d 0.094 m, that is, 94 mm.

The value must be rounded up to the nearest centimeter. Thus, the thickness of the foam for insulating a half-meter reinforced concrete foundation of a house in Leningrad region equals 10 cm.

Warming technology

Compliance with the sequence of foam insulation will allow even novice builders to cope with the process.

It is desirable to carry out work on the insulation of the foundation at the stage of construction of the future house. So the process is greatly simplified. But what to do if the house was built several years ago and was not initially insulated?

In this state of affairs, the foundation is dug to the ground. Ideally, dig to the depth of the soil, however, if working resources are limited, and it will not be possible to cope with such a volume of work, it is worth digging a trench near the foundation for the length of the insulation used.

The thickness of the trench is determined by adding the thickness of the insulation sheet used, as well as the minimum space required for the work. Making the trench too wide will be inconvenient, especially if you do not plan to involve specialized construction equipment in the process. Too small a trench will complicate the process of work.

If you decide to use special equipment for excavation, it is recommended to be careful not to damage the walls of the foundation.

The bottom of the excavated trench must be covered with sand, the layer of which should not be less than 20 centimeters. Be sure to carefully compact the sand and make a slight slope away from the foundation. Sand will act as additional protection against moisture.

After the foundation is completely dry, it is necessary to start preparing the future surface for laying sheets. We carefully clean the foundation wall and basement from adhering soil, damaged pieces of concrete and other contaminants. Cleaning is most convenient with a brush with stiff synthetic bristles.

After cleaning, it is necessary to level the surface: only a flat wall of concrete will ensure a secure fit of the waterproofing coating.

The alignment of the foundation walls is carried out according to the following principle:

• On a surface concrete walls install beacons, the distance between which should be at least 1 meter from each other. Beacons must be mounted on the entire surface, where insulation will be installed in the future;
• We prepare the solution. To do this, carefully mix 4 parts of sand and 1 part of cement in a container, after which we begin to add water. Make sure that the consistency is not too liquid or dry, otherwise the leveled surface will not be reliable;
• We throw the mixture on the surface from the bottom up;
• We apply the rule to the beacons and with a sharp movement from top to bottom we level the surface, while removing the excess solution;
• After the first layer of the mixture dries a little, you can apply the finish, which will finally level the surface.

To level the walls, it is recommended to use a rule about two meters long, since the work with a grater takes too much time

This method is suitable for more or less smooth walls. If differences of more than 2.5 centimeters are observed on the surface, a reinforced mesh is additionally used.

Proceed to the next stage of work only after the cement mixture is completely dry. On average, the process takes from 7 to 20 days. If a recently poured foundation is insulated, they switch to insulation no earlier than a month after laying.

It is better to isolate the foundation from moisture penetration in two layers with the application of bituminous mastic and waterproofing TechnoNIKOL.

It is recommended to buy ready-made bituminous mastic - it's easier than preparing the solution yourself. If you decide to do it manually, then be sure to add used engine oil to the mixture, which will protect the mastic from cracking when the air temperature drops.

It is most convenient to apply mastic with a roller. The layer thickness must be at least 2 mm. After the bitumen has dried, we proceed to the installation of TechnoNIKOL. Sheets are glued from top to bottom. The back side is melted with a burner, and the joints between the sheets are smeared with mastic. The material fills all small pores and cracks and does not allow moisture to contribute to the peeling off of TechnoNIKOL sheets.

To avoid cracking of the mastic under the influence of temperatures, it is recommended to add used machine oil to the solution at the rate of 5 liters of oil per 12 - 15 kg of bitumen

Penoplex installation

It is most convenient to install foam sheets using an adhesive solution or adhesive foam. Additionally, you can use dowels in the form of umbrellas, but they violate the integrity of the insulation sheet.

Apply glue to the sheet with a notched trowel, then the insulation will lie flat, without gaps between the sheet and the foundation wall.

Experts advise giving preference to glue-foam in cylinders. It not only allows you to simplify and speed up the process, but is also spent more economically.

After pressing against the wall, the adhesive must cover at least 40% of the foam board

If the laying of sheets is carried out in two levels, then it is necessary to observe a checkerboard pattern. In this case, the distance and gaps between the sheets of insulation should be minimal. Gaps can be additionally treated with foam.

Reinforced mesh and finish

To enhance the overall strength of the structure and protect the insulation from external sources, it is recommended to use a reinforced mesh. The material is used only if the foundation is above the ground and can be damaged in the future.

The grid is laid on foam sheets, and an adhesive solution is laid on top for fixation.

At the next stage, start finishing foundation. You can get by with ordinary plaster, use siding or any other material for exterior decoration.

If desired, the resulting trench can be covered with sand or expanded clay, and the materials will act as an additional layer of insulation.

The backfilling of the trench is not carried out to the end, but a place is left for the formation of a warm blind area. The work is carried out in several stages:

1. At a depth of about 30 cm from the surface of the earth, we fill up a layer of sand 10 cm thick and carefully tamp it down;
2. We spread a waterproofing material at the foundation (an ordinary roofing material is suitable, the joints between which are lubricated bituminous mastic). The borders should adjoin the foundation on one side and move away from it to a width of about a meter;
3. We lay foam sheets on the waterproofing layer, and treat all joints with glue or foam;
4. Next, a blind area of ​​​​concrete mixture is equipped. It is made necessarily at an angle from the foundation, which allows you to further drain wastewater.

The foundation is the basis of your home, so do not save money and make the insulation quality

Only the maximum observance of all the rules for laying insulation on the foundation will protect the foundation of the house from freezing and subsequent premature destruction. Savings on insulation of the foundation in the future can turn into more serious cash costs.