Reliable insulation of the foundation with expanded polystyrene (styrofoam). What is the thickness of the eps for foundation insulation? Extruded polystyrene foam for foundation

Many owners of private housing prefer to insulate the basement and foundation by covering them from the outside with polystyrene foam. This allows not only to save heat in the house, but also to protect the base of the building from premature destruction and cracking. In addition, the walls of the basement, if there is one in the project, will always remain dry.

The technology for performing such work is not very complicated. The main thing is to adhere to all the main stages of warming and not to violate the sequence of operations.

Before choosing polystyrene foam as the main insulation material, it is worth knowing all its qualities.

The unique pleasant properties that extruded polystyrene foam possesses are:

• high frost resistance;
• excellent thermal insulation;
• lack of toxins;
• low response to chemical influences;
• vapor impermeability;
• minimal moisture absorption;
• durability in operation;
• resistant to fungus and decay.

But there are also several not very pleasant qualities that the material possesses:

1. Flammability - additional treatment with special mastics is required in the basement areas.
2. Low resistance to physical influences - protection from rodents in the form of a metal mesh is required.
3. Mechanical damage - when backfilling, there should be no hard rocks in the soil.

But, despite this, the material is highly valued by professionals, as it is easy to mount, easy to use, well cut into small pieces. And it costs very little.

The choice of polystyrenes for insulation

When choosing a material for insulation, it is worth considering its three main properties:

• density characteristic;
• plate layer size;
• combustibility classes.

It is thanks to these parameters that it is possible to effectively insulate any foundation with polystyrene.

Since expanded polystyrene plates are used as a heater, for the convenience of users, manufacturers produce products whose thickness is not less than 30 mm and not more than 100 mm. This allows you to combine materials in such a way that the resulting insulation thickness is the most suitable for each individual case.

Density characteristics also matter. For foundations, it is better to use sheets with a density of at least 35 kg / m 3.

Combustibility classes matter only for the insulation of the basement and basement. After all, the underground part does not care what polystyrene foam will be used. But for the basement and basement, it is worth buying plates with the addition of fire retardants. This will provide some insulation from combustible structural elements of the house.

Preparatory work before insulation

Initially, it is worth preparing the foundation of the building for insulation operations. And for this you need:

1. Clear the base of soil and debris.
2. Treat with protective mastics.

If the foundation is just laid out, you just need to expand the trench (pit, place on all sides of the pit) by 45 cm. This will allow you to carry out work on warming the base from the outside with polystyrene without interference. True, after digging ditches, it is necessary to remove the formwork from the foundation.

The same operations should be carried out for the foundation that has long been used under the building. But here the difference will be additional cleaning work.

It will be necessary not only to remove the earth and adhering vegetation residues from the foundation walls, but also completely clear it of rust, chipping parts of the mortar, and pieces of external waterproofing.

Now you can start priming the outer walls of the foundation. The technology is quite simple and resembles the usual priming of any surface. The difference here is the compositions of the mastics themselves.

Since the primer at this stage of work is a waterproofing before laying the insulation, the choice of mastic should be approached responsibly.

It must be remembered that mastics with organic solvents should not come into contact with polystyrene. Otherwise, it will immediately deteriorate. It is better to take primers based on water.

Insulation of the foundation with polystyrenes

After the primer dries, you can begin the process of insulating the underground area of ​​\u200b\u200bthe foundation with polystyrene foam. Here, too, the technology is simple. The main thing is to perform all operations as the instruction suggests:

• dilute the adhesive mass in the proportions indicated on the container, let it stand;
• apply the mass to the finished cut polystyrene foam slabs, and not to the foundation walls;
• give time for the glue to grab the plate;
• press the prepared sheet to the foundation;
• check the correct position of the sheet using a level.

It is necessary to start fastening the slab to the base of the house from one of the corners. And only below. This will make it possible to lay out the sheets more evenly and without large seams.

It is better to use extruded polystyrene foam for such work. Its properties are much better than analogues.

Insulating the base of the building from the outside is always easier in pairs. After all, often you have to lay the material in several layers.

It is worth remembering that working with polystyrene requires care and attention. Before starting the insulation, it is better to prepare sheets of the optimal size by cutting them in advance.

Now it is worth protecting the insulation from external mechanical damage (rodents, sharp stones). To do this, a fiberglass mesh is applied to the outside of the insulation. It is also coated with adhesive solutions.

You can use a metal mesh or just wooden shields. They need to be fixed with dowels from the very bottom of the foundation to the ground level. For maximum effect, the network (shields) is plastered with an ordinary solution of small thickness. After the plaster has dried, you can backfill.

Don't forget about drainage. It is always performed when the walls of the base are insulated with extruded polystyrene foam.

Basement and basement insulation with polystyrene

Thermal insulation of the basement is not difficult. It is performed in the same way as the insulation of the base of the house. But there are some differences here.

After all, the base is above the ground, and external factors also affect it. And besides, in some houses there is no basement in the basement. Therefore, the decoration of such buildings will be simpler.

After the plates are glued to the walls of the basement, it is worth letting them dry well. And now it is necessary to strengthen the polystyrene sheets with additional dowels, which have a rather wide cap. Such fasteners will hold the plates on the surface of the base without damaging the sheets themselves.

In order for the dowel to fit tightly, but not damage the insulation, you need to drill small holes at the joints between the sheets. The length of the holes should be slightly longer than the length of the fastener.

Next, carefully hammer the dowel into the hole, and insert a nail into it. Drive the resulting structure into the basement wall. It doesn’t matter if the basement floor is with a basement or without a basement - the technological process for fixing the slab is the same.

It is important not to miss: for each plate there should be 3-4 fasteners. This will additionally protect the material from damage during further finishing.

Now it’s worth throwing a masking net on the insulated basement wall. And on it you can throw a solution in a thin layer. As the solution dries, irregularities will be visible. They can be removed with plaster. And only after that it is possible to carry out finishing work from the outside of the basement.

In order for the functions of the basement to serve as best as possible, it is better to finish the basement with ventilation material.

However, no less attention should be paid to the thermal insulation qualities of the foundation. If it does not have additional thermal protection, then almost a fifth of the heat from the premises will freely escape into space through the floors. To prevent this, a wide variety of heat-insulating materials are used, among which a special place is occupied by foam plastic and expanded polystyrene, which are similar in manufacturing technology and characteristics.

Is it possible to insulate the foundation with foam plastic?

Expanded polystyrene and polystyrene are synthetic heat-insulating materials, almost entirely consisting of air bubbles, which explains their extremely low thermal conductivity. Insulation of the foundation with polystyrene foam beneficial in many ways:

• low cost in comparison with analogues;
• a slight degree of water absorption;
• very wide operating temperature range;
• low density;
• availability of technology for warming foundations with their help.

Among the shortcomings only some fire hazard and modest mechanical strength can be attributed. However, in practice, they can be ignored, since the risk of fire on the outside of the foundation is extremely small, and it is very difficult to mechanically damage the material covered with decorative trim or soil.

Meanwhile, polystyrene and expanded polystyrene have slight differences in characteristics:

• expanded polystyrene has one and a half to two times lower thermal conductivity;
• polystyrene is several times stronger than polystyrene foam when compressed;
• expanded polystyrene is somewhat heavier than polystyrene and has the property of vapor permeability;

Insulation of the foundation of the house with polystyrene foam, extruded polystyrene foam from the outside

The effectiveness of insulation with foam or polystyrene foam is mainly depends on the thickness of their layer.

To determine the desired thickness thermal insulation for the foundation, you can use the following formulas:

According to the first of them, the thickness of the insulation is calculated for the part of the foundation above ground level, according to the second - for the underground part.

The accepted designations are deciphered as follows:

• δut is the thickness of the thermal insulation layer in meters;
• R0adv. - the reduced level of resistance to heat transfer of the foundation material, is taken according to the degree-days of the heating period (GSOP) and is expressed in m2 ° C / W;
• δ is the thickness of the foundation, m;
• λ is the coefficient of thermal conductivity of the foundation material, expressed in W / (m ° C);
• λ ut - coefficient of thermal conductivity of the foam (expanded polystyrene), W / (m ° C).

However worth understanding that the standard indicators are based only on average temperatures and the duration of the cold period. Therefore, it will be quite acceptable to use the traditional construction norms for the thickness of thermal insulation from foam materials:

• 50 mm for the south of the country;
• 50-100 mm for mid-latitudes;
• 100-150 mm for northern regions.

Warming technology

How to insulate the foundation of a house with foam, extruded polystyrene foam (EPS)? All foundation insulation work at home with foam sheets can be divided into several successive stages.

And here is a video about the insulation of the foundation of the house with polystyrene foam (styrofoam) from the outside.

The use of polystyrene foam and expanded polystyrene as a material for insulating foundations is the most rational way to reduce heat loss in a cottage, bathhouse or any other structure. With relatively low material costs, such thermal insulation can provide comfort and energy savings for many years.

In addition, the technology for laying thermal insulation from foam materials does not differ in any particular complexity, therefore quite affordable for even a novice home master to perform.

When constructing a foundation, the issue of its thermal insulation should be given special attention, 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 thawing of heaving soils.

It has been established that the share of basement and basement foundations accounts for about 10-20% of all heat losses 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 ground floor.

In addition, thermal insulation protection is an integral element of the waterproofing system: it 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 characteristics and a long service life, which allows it to be used for foundation insulation.

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 service 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 of the Russian Federation is given in the table:

In the range of XPS materials there are specially designed thermal insulation boards with milled grooves on the surface. This material, together with a geotextile fabric, successfully works as 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. The thermal insulation device on the side of the room is made either by gluing extruded polystyrene foam to the wall surface using solvent-free compositions (for example, cement-based), or by fixing the insulation boards mechanically, followed by the installation of 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

The 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 water 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 stainless steel trowel onto 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 with your 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 finish (possible options):
   • decorative plaster;
   • stone slabs (attached with special glue);
   • ceramic tiles (mounted on a special adhesive 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 plates from the liquid components of concrete with a polyethylene film 0.15-0.2 mm thick laid in one layer. If welding is planned for reinforcing work, then a protective screed of low-grade concrete or cement-sand mortar must be made over the film. Sheets of film are laid with an overlap of 10-15 cm on double-sided tape.

Traditionally, in construction, the thermal insulation of the foundation was designed to solve only one problem - counteracting soil heaving. However, trends in environmental friendliness, resource sustainability, climate management and energy conservation have had an impact on this local discipline as well. Foundation insulation with extruded polystyrene foam (EPS) is gradually becoming a constructive standard for low-rise housing construction, regardless of the climatic zone and architectural style.

Expanded polystyrene plate insulation is divided into two main types - EPS and foam. Styrofoam is made from the same raw materials as extruded insulation, but does not undergo pressure treatment, and therefore has less outstanding characteristics, but more attractive cost.

Extruded polystyrene foam is a popular and economical material for foundation insulation.

Speaking about the properties of various types of thermal insulation, it is important to understand that these materials have universal and specific characteristics (in terms of application specifically for foundations). Consider the parameters of polystyrene foam insulation, simultaneously clarifying their differences for XPS and foam.

Universal:

• Thermal conductivity. The lower this indicator, the higher the heat-insulating properties of the material. For XPS and foam plastics, the thermal conductivity lies in the range of 0.029 - 0.034 W / (m * K). With the same density, the energy efficiency of XPS is higher than that of foam. There is only one type of building thermal insulation with a lower thermal conductivity than polystyrene foams - this is polyurethane foam (PPU), which is applied by spraying.
• Fire resistance (fire hazard class). Expanded polystyrenes are combustible materials. Depending on the use of fire-fighting additives (flame retardants), XPS boards have a class G3 - G4. Foam plastics can be less flammable (up to G1 for PSB-S boards). Perhaps this is their only superiority over extruded heaters. In terms of fire resistance, expanded polystyrene insulation is inferior to mineral wool.

Specific:

• Compressive strength. Reaches 400 kPa and more for extruded boards. The most durable grade of foam plastic PSB-S-50 has an indicator of 160 - 250 kPa.
• Frost resistance. All expanded polystyrenes retain their properties in the temperature range from -70 °C to + 70 °C.
• Hygroscopicity. XPS practically does not absorb moisture in direct contact (no more than 0.02%). The performance of foam plastics is much worse - up to 2% and higher. Although, even they are much more hygroscopic than mineral wool.
• Biostability. XPS is not subject to biological types of destruction. Styrofoam can be destroyed by rodents. On their unprotected surfaces, under favorable conditions, colonies of algae, mold, other fungi and bacteria form.
• Life time. Manufacturers claim 40, 50, 60 and even 80 years of extruded polystyrene foam without loss of insulating properties. For foam plastics, the resource largely depends on the humidity of the environment.

Being one of the most effective heat insulators, XPS is ideal for insulating foundations, primarily due to its unique strength and high hygroscopicity. Strength allows you to work in compression, withstanding concrete foundations of small thickness. Hygroscopicity is important, since we are dealing with external insulation and direct contact with the ground.

External insulation of foundations with expanded polystyrene

Only external insulation of low-depth strip foundations (MZLF) solves a full range of issues: anti-frost protection (against heaving), energy saving, comfortable indoor microclimate.

The three main schemes of radical external thermal insulation in low-rise modern construction are the device for protecting foundations according to the UVF (insulated Finnish foundation), UShP (insulated Swedish plate) and warm pile underground schemes.

1. UFF involves the arrangement of the floor on the ground. In this case, on top of the backfill of anti-capillary rubble and sand, polystyrene foam slabs are laid, on top of which a concrete floor screed is poured. A shallow foundation tape is lined with insulation only from the side of the outer perimeter.
2. UShP is a kind of "trough" of EPPS or PSB-S slabs, into which a monolithic foundation slab is poured. Thus, the foundation is 100% of its contact area separated from the ground. The construction of two- and three-story houses with walls made of aerated concrete or bricks on the foundation of the UWB is possible only when using the most durable grades of XPS.
3. The insulation of pile foundations consists in the horizontal lining of the underground in combination with the thermal insulation of the basement. The concrete floor is lined with polystyrene foam insulation, and the wooden beam floor is lined with mineral wool. Horizontal insulation is carried out with XPS boards on a crate mounted on piles from the outside.

An additional element of the external insulation of the foundation is the thermal insulation of the blind area around the entire perimeter of the building. This measure eliminates the danger of tangential pressure of heaving soils on the side surfaces of the strip foundation and slab structures.

Almost all possible ways of external insulation of foundations are variations of the three schemes described. The main principles of the technology are to exclude cold bridges. To do this, polystyrene board materials are glued to the surface of the foundation blocks end-to-end with horizontal insulating planes and overlapped with the vertical thermal insulation of the walls.

At construction forums, the question “how to insulate the foundation with polystyrene foam?” is often raised. It arises because developers are interested not only in technological nuances, but also in ways to save on insulating materials. In principle, the techniques for insulating foundations with polystyrene are common to all types of slabs. The differences are associated with lower strength, hygroscopicity and biostability of foams. Therefore, here is a list of restrictions when it is possible to use only EPS:

1. If the design pressure exceeds 250 kPa.
2. In direct contact with the ground, it is impossible or economically inexpedient to provide reliable waterproofing of the insulation.
3. If there is a threat of destruction of insulation by rodents. (it is assumed that the use of protective layers in this case negates the cost advantage of foams over XPS).

In order to make an informed decision on the external insulation of the foundation of a house of a specific design, it is necessary to study each of the three described schemes. This will allow you to make the right choice and, if necessary, combine the nuances of various technologies.

Internal insulation of foundations with expanded polystyrene (from the inside)

The principle of internal insulation does not solve the issues of protecting foundations from freezing. In addition, the energy efficiency with this technology is lower than with external thermal insulation. An exceptional advantage of internal cladding with foam and XPS boards is the availability of work in already built buildings.

Internal vertical isolation of the foundation is available only if there is a basement. The principle of wall insulation and horizontal overlap differs in the outer layers. In the case of walls, it is enough to stick insulating boards and plaster them, or sew them up with plasterboard false walls. Work on the floors requires pouring an insulating layer with a cement-sand screed. If we are talking about a building without a basement with a floor on the ground, then it is permissible to carry out insulation without using an additional screed: the finishing floor covering is mounted on top of the leveling slabs made of moisture-resistant plywood, chipboard or OSB. In recent years, the use of XPS boards has become the standard for insulation work in these types of buildings due to their high compressive strength.

Differences between design and repair thermal insulation of foundations using EPPS

Design thermal insulation of the foundation in the vast majority of cases is possible only as one of the stages of construction. After its completion, access to external surfaces requiring insulation is impossible or difficult.

Options for insulating the foundations of already constructed buildings are considered repair. In most cases, such work consists in the internal insulation of the basement and the outer vertical lining of the basement itself. The estimated cost of the most popular slab foundation insulation is:

• 100 mm thick XPS boards: $8.0 - $9.0 per sq. m.
• PSB-S-50 slabs 100 mm thick: $ 6.5 - $ 7.0 per sq. m.

Why is horizontal insulation of the basement not to the full depth of the foundation acceptable and makes sense? The fact is that it is enough to ensure the joint of the basement insulation with the blind area slabs in order to protect the MZLF from freezing and heaving of soils.

Enlarged algorithm for the repair insulation of the basement with foam plastic

The basement is insulated with polystyrene foam in two layers.

1. Along the perimeter of the building, a trench is torn off with a depth to the proposed laying of blind area insulation boards.
2. The outer surface of the plinth is cleaned and dried.
3. Application of liquid waterproofing is recommended.
4. Styrofoam plates are mounted using special glue. Installation is carried out in 2 layers with overlap. All gaps are carefully foamed. The use of polystyrene grades with a “quarter” docking selection facilitates and speeds up work, as it eliminates the need for additional sealing of the seams. At the corners of the building, the thickness of the insulation increases by 2-3 times by a length corresponding to three thicknesses of the bearing wall.
5. Above the ground level, the insulating boards must be additionally fastened with umbrella-type dowels.
6. Thermal insulation is plastered.
7. If necessary, a drainage pipe is laid along the bottom of the trench and backfilled with crushed stone with a thickness of at least 20 cm. Further backfilling and compaction of the trench is carried out with excavated soil.

Summing up

Insulation of foundations with the help of polystyrene foam plates is a universal means of solving the problems of heaving soils and energy saving. The lightness and good machinability of the plates allows you to carry out most of the work yourself. The exceptional weather resistance of these materials makes it possible to insulate in several stages, without fear of loss of properties under the influence of temperature, moisture and solar radiation.

A large number of foundation insulation schemes using EPS and foam plastic speaks of the variety of issues to be resolved with a wide variety of building designs. We recommend developers and homeowners to study all popular technologies for the use of polystyrene insulation.

Currently, the most common and sought-after heat-insulating material is extruded Penoplex (aka).

This material is considered one of the varieties of expanded polystyrene. Thermal insulation of a modern foundation using a material such as Penoplex can be easily done by hand.

1 Features of the material used

Now, to ensure the thermal insulation of the house, a heater is used, which is divided into two main subspecies. It can be expanded polystyrene (Penoplex, EPS) and extruded - XPS.

The presented insulation for the house has the shape of a plate and can be assembled by hand without much effort.

Extruded or foamed Penople (simply) s, presented in the form of a plate, has its own production technology, which determines its important properties, one of which is the thickness of the material.

The technology of insulation of the foundation with expanded polystyrene implies the use of material with the XPS marking, since the EPS modification plates have a much higher heat transfer coefficient.

Such insulation is more difficult to install under the siding on any side of the house. In addition, its plates have underestimated indicators associated with thermal insulation properties.

High-quality insulation with expanded polystyrene

Their thickness is not large enough, it is quite difficult to fix them with your own hands, and the material has a high degree of hygroscopicity and low stability. Note that it is a very difficult task, while its price is still small.

Along with this, the foamed Penoplex used to insulate the foundation of a house has a very low cost.

It is worth considering that do-it-yourself insulation of the foundation of the house with polystyrene foam from the outside is the best option.

It is quite easy and simple to mount Penoplex on the foundation slab of the Penoplex house with your own hands, while the thickness of the slab of the house does not really matter.

After the insulation of the foundation with polystyrene foam is completed, the slabs are plastered or covered with finishing materials. Among the most significant advantages of the presented insulation material, it is worth noting:

• Complete lack of water absorption;
• Low level of thermal conductivity as in;
• Low vapor permeability;
• Long service life;
• High compressive strength;
• Ease and convenience during installation;
• High chemical resistance as at.

2 Cleaning and leveling the foundation before insulation

When the foundation of the house is already ready, before you start attaching Penoplex to it, you should carefully clean the plates.

To do this, using a synthetic brush, you need to carefully clean all the small pores in the foundation.

Most foundations do not have an ideal degree of evenness of the corners, and with large differences, in order for their surface to become geometrically correct, it is necessary to align with the beacons.

For this purpose, at a distance of 1-1.4 meters, guide beacons should be fixed.

After that, you need to start preparing a cement mortar using grade 500. The resulting mixture is applied with a trowel to the walls of the foundation from top to bottom.

Alignment and preliminary preparation of the foundation walls for insulation with Penoplex can take several days.

If the deviation of the walls from the accepted norm is more than 2.5 centimeters, then it will be necessary to carry out a reinforcement procedure using a chain-link mesh.

It can be attached with metal staples as with. An alternative option is the use of reinforcing bars with a diameter of up to 10 millimeters.

It will be possible to connect them to each other using a knitting wire. After completing the leveling of the foundation, you need to wait about 20 days for all the accumulated moisture to evaporate from it.

After that, you need to apply a thin layer of special acro-glue with a spatula. It is worth noting that such an adhesive composition is excellent for working with materials that have a high degree of porosity, and therefore Penoplex will hold on to it tightly.

2.1 Preliminary protection of the foundation from moisture

For this purpose, liquid bitumen is used. It is rolled out with a roller over the entire surface of the foundation.

It is worth remembering that this material needs periodic heating, because it hardens quite quickly.

When applying bitumen, be sure to wear a mask or respirator due to the high toxicity of this substance.

Before attaching expanded polystyrene to the foundation or making it, it should be isolated with technonicol.

The process of gluing it can be carried out using a conventional gas burner. The installation of such sheets is quite simple, however, the degree of moisture resistance of technonicol is several times lower than that of bitumen.

This is due to the fact that the presented product cannot completely fill all the cracks and pores of the foundation. Bituminous insulation can be applied with a conventional roller or with the assistance of a special sprayer.

2.2 How to insulate the foundation with polystyrene foam?

It has already been mentioned that when insulating the foundation, both ordinary polystyrene foam and its extruded modification, which has a stronger foam internal structure, can be used.

Extruded polystyrene foam is much more preferable due to its high degree of density.

Ordinary foam can easily crumble during installation. Also, the usual modification has a high coefficient of thermal conductivity and can be sintered from exposure to direct sunlight.

The product obtained in the extrusion process has a relatively low degree of density - approximately 35 kg per 1 cubic meter.

Penoplex is presented in the form of an effective heat insulator that perfectly protects the foundation from moisture and has a high degree of hardness. When choosing insulation boards, you should pay attention to the form of their release.

Products can have a smooth surface or be equipped with special protrusions that provide a high degree of reliability of the interlock.

Such products are very convenient, since with their help you can create a surface in which there will be practically no joints.

When laying foam sheets in a vertical position, they should be pressed tightly against each other, which is facilitated by such a locking connection.

In order to glue the expanded polystyrene plate to the foundation, you should use a special bituminous mastic or glue designed for foam products. This glue is characterized by:

• High degree of plasticity;
• Ease of use;
• Frost resistance;
• High level of adhesion.

In order to install plates made with expanded polystyrene, it is necessary to use dowel-nails or nails made of plastic.

This will lead to the fact that the occurrence of so-called "cold bridges" will be minimized.

The dimensions of the dowels directly depend on the thickness of the insulation layer. So, for example, for sheets with a thickness of 5 centimeters, it is necessary to use dowels with a length equal to 12 centimeters, with a diameter of 1 centimeter.

As a rule, 5-6 dowels are used per square meter of the slab. To make holes in the foundation, it is worth using a perforator drill.

Due to the fact that the foundation is made of concrete, it is necessary to carry out rotation, combining it with an impact mode.

The length of the drill should not be less than 16 centimeters. Next, 5-6 holes are drilled in the plate. One in each corner and two in the middle. After that, the dowels are hammered to the stop.

After they are clogged, all the inlets will need to be covered with acro-glue. The last sheets of insulation are laid in a horizontal position.

After the polystyrene layer is mounted, it will be possible to notice that the wall surface is not able to stand out above the foundation level.

To do this, the wall is insulated in such a way that it allows it to hang a little over the house foundation.

In this case, the thickness of the heat insulator layer should be equal to 2.5-3 centimeters. It is important to carry out the installation in such a way that the Penoplex layer is continuous, without cracks and gaps.

When using interlocking boards, this requirement will be satisfied - firmly adhering to each other, they form a perfectly even layer.

In the case when a hill begins to form above the surface of the foundation, it is necessary to cut the polystyrene foam with a hacksaw.

2.3 Creating protection for polystyrene foam

At the last stage of insulation of the foundation with the help of polystyrene foam, a layer is applied that has reinforcing properties.

It is also fixed with acro-glue. Strengthening should be carried out with the calculation of the consumption of 3-4 kilograms of glue per square meter of insulation.

Much depends on how neatly the plates are mounted together. When carrying out plastering of expanded polystyrene, a sequence of actions is also performed, as with the insulation of the facade sides of the building.

In order to ensure a reliable degree of reinforcement, fiberglass mesh should be used. This consumable must be facade, that is, fully applicable for external work.

Before attaching the mesh, it is cut into pieces of the desired size. After that, it is glued on with an overlap, and each edge should overlap the next by 10-15 centimeters.

Thanks to this technique, the reinforcing mesh will not crack and break off at the edges. In order to reduce the number of seams, the mesh should be located horizontally with respect to the plane of the wall.

The glue is spread in two layers, and the mesh is initially glued to the plates, after which it will need to be walked over with a spatula.

A day later, the coating is partially leveled. To strengthen the corners, you need to use perforated metal corners.

After a day, with the help of a grater made using hard foam, it will be necessary to smooth out all the irregularities that have arisen. After that, a layer of primer must be applied to the surface.

You can perform this action using a roller. At the end of the work, you should carefully make sure that the wall of the house protrudes above the foundation wall at a distance greater than 3 centimeters.

Thanks to this, an impromptu canopy will form above the base, which will prevent moisture from penetrating under the foundation.

The most optimal option is the one in which the value of the total thickness of the plaster layer and the heat insulator is 3.5 centimeters.

This result can be achieved due to a slight displacement of the bricks located on the outside.

The presented technology is able to provide not only high-quality and reliable insulation of the foundation, but also the appropriate level of waterproofing.

2.4 How to insulate the foundation with polystyrene foam with your own hands? (video)