≡× MENU

• Interior
• Window
• Walls
• Projects
• The buildings

How to insulate a monolithic slab foundation. Foundation insulation with polystyrene foam: technology for insulating the foundation of a house from the outside. Technology for constructing foundations from slabs

Some effective construction technologies created recently. This is explained by the appearance on the market of new materials with better or unique characteristics. Some of these techniques can be reproduced an ordinary person after relatively little study of the relevant materials. In this article we will look at the insulation process with my own hands the foundation of a private residential building or other relatively small building.

Why you may need to insulate a foundation slab

Improving the insulation parameters of a building will simplify and make its operation cheaper. This fact alone is enough to think about carrying out the appropriate work. Energy resources, despite temporary market fluctuations, will always have high value. By reducing their consumption, you can count on significant savings Money.

It should also be noted that correct engineering calculation will help to move the dew point beyond the contour of the main part of the building.

This means that moisture will not condense inside the structures. Thus, after modernization, the conditions for the appearance and development of mold will worsen, and hidden corrosion processes will stop. Separately, it is necessary to consider soil heaving. It happens in winter period . These mechanical impacts can create great pressure on the structural elements of the building. High-quality insulation

foundation slabs will prevent such and other harmful effects listed above. Any technology becomes clearer with examples that confirm the feasibility of its use. In this case, you should pay attention to the “insulated Swedish slab” foundation.

• Here are the main parameters of this foreign technique, which is increasingly used today in domestic private housing construction:
• It is a single structure made of cast concrete with reinforcement and stiffeners. It is installed on a cushion and surrounded by polystyrene foam boards.
• Sand is initially poured under the main insulation and on the sides of it.
• A system for collecting water and discharging it into drainage is pre-installed.
• Comfortable temperature conditions are ensured using the “warm floor” system. It is built into the foundation at the stage of its creation.

This name itself determines the country of origin of the technology. In Sweden it has been successfully used for more than half a century, and in Russia private individuals and construction companies They have been using similar techniques for about ten years. Such time frames are quite sufficient for valid conclusions. Practical tests confirmed the presence of the following features:

• This foundation construction technology is well suited for the construction of 1-2 storey buildings. For more tall buildings must be ordered individual project. It will then have to be agreed upon by all official authorities.
• To completely eliminate the possibility of flooding of a building during flood periods, it is necessary to install sand bedding required height. To determine it, you can use statistical data for the desired region with maximum levels. If necessary, additional measures are taken to improve the drainage and waterproofing system.
• On sandy soils savings can be made during the construction process. There is no need for a productive water drainage system here.
• Working with concrete, as in all other similar cases, is recommended only during the warm period. It is possible to fill the foundation in winter, but this will be accompanied by increased costs and will increase the risk of defects.
• This design works especially well in combination with a “warm floor”. In particular, when the heating is turned off, even in the cold season, heat will remain in the house for 72 hours.
• A professional company can complete a full cycle of work in 3-4 weeks.

Material for creating a high-quality insulating layer

You can make a choice based on analogues of materials that are used in Swedish technology. But first, let’s rule out unsuitable options:

• Mineral wool different types do not have the necessary rigidity, strength and absorb water too well.
• Expanded clay, other granular materials. They are also not suitable, since they cannot become a dense, moisture-proof base for the future foundation.
• Polymer foam materials that are created directly on work sites. Some of them can be applied. But the implementation of such a project will require certain skills. You will also need special equipment.

Using the method of elimination, we found the “winner” of this correspondence competition. This is factory-produced foam polystyrene, penoplex. We list below those characteristics of the material that will be useful for solving the tasks:

• Its production method involves the production of standardized products. Thus, if you purchase penoplex famous brand, then there can be no doubt that each slab will have the same parameters.
• Precise dimensions and low weight will facilitate transportation, storage, and installation operations.
• The uniform distribution of closed bubbles in the penoplex structure ensures excellent thermal insulation properties. To fully insulate a monolithic foundation, you do not need to create a layer that is too thick.
• This material is durable and does not allow moisture to pass through. Many types of slabs are made from it with special grooves along the edges, which makes it possible to ensure the tightness of butt joints without additional means.

Insulation of slab foundations

We have found out the main parameters of this technique, so we can proceed to the description of the working operations. Let's look at the steps that are used to insulate a foundation slab:

• For this group of works, it will be enough to create a layer of high-quality penoplex with a thickness of no more than 10 cm. It can be formed from two rows of slabs, which are laid in a checkerboard pattern with joint overlapping of the joint areas.
• Site preparation should be carried out taking into account the geology of the site and soil characteristics. When creating a recess, the bottom must be made level, so it is recommended to use manual labor in the final stages.
• Sand is backfilled and compacted, after which temporary formwork is installed, and the first layer of concrete is poured without reinforcing elements.
• When the base has hardened, foam boards are laid on it in the order indicated above. They are covered on top with thick plastic film. The seams between the individual strips are carefully sealed with wide tape.
• Next, the main foundation is created from reinforced concrete.
• After it hardens, attach to the end parts adhesive composition foam boards.

It is difficult to build a solid foundation on unstable soils. In such cases, a slab base is used. It acts as a shallow foundation, drifting across the site as soil masses move. Since the entire structure moves, no destructive stresses arise.

For proper operation This type of foundation requires protection from freezing. Insulation of a monolithic foundation slab:

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

Choice of insulation

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

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

When installing insulation inside a building, the material must be non-flammable. If there is a possibility of fire, it should not be released harmful substances which may cause suffocation.

With all this, the service life of the insulation must be no less than the service life of the finishing material. In this case, you will not have to change it before the coating becomes outdated. Otherwise, you will have to dismantle the finishing fabric that still complies with the standards.

Often, extruded polystyrene foam is used for zero-cycle work. Insulating the foundation slab with expanded polystyrene, done according to all the rules, allows you not to worry about the safety of concrete and heat conservation.

Characteristics of expanded polystyrene

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

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

External insulation technology

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

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

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

Waxing closes the pores of concrete, creating a barrier against moisture. Complete adhesion helps prevent insulation peeling. This means that insulation can be easily attached to it.

Expanded polystyrene boards are mounted on glue or on cement-sand mortar. The first option allows for insulation when sub-zero temperatures. The underground part is secured only by gluing. This is necessary to avoid violation of the hydraulic barrier.

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

The glue is applied around the perimeter of the slab and in several stripes in the center. Wait for 1 minute and press the plate against the surface for a couple of minutes. After gluing, the bottom plates are sprinkled with a layer of sand. This helps secure them in the mounting position.

The second row of insulation is installed with offset seams. It is advisable to bandage the horizontal joints as well. This helps to avoid the occurrence of cold bridges.

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

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

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

Internal insulation technology

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

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

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

• waterproofing is installed along the foundation slab, extending onto the wall;
• logs are screwed on top of the waterproofing layer;
• a layer of insulation is placed between the logs;
• a waterproofing film is attached to the joists on top of the insulation;
• mounted on film plank base, plywood or OSB boards;
• A backing made of cork, foamed polyethylene or pine needles is laid on top of the subfloor. The finishing floor is mounted on it.

You can do without lag. In this case it happens full insulation slab foundation with polystyrene foam. The material is laid in a continuous layer. Immediately lay a substrate on top of it and fine coating floor.

When installing in concrete, the following work is performed:

• the base plate is waterproofed;
• An insulation layer with a thickness of at least 100 mm is installed. It is better to use products with a locking connection system;
• PVC film with a density of at least 1.42 g/cm3 is laid on the insulation;
• fits reinforcement mesh. Her role can be played by masonry mesh with cell 100*100 mm;
• the surface is filled with a screed no thinner than 5 cm;
• The finishing coating is laid over the screed.

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

Insulation of the foundation slab body

Warm concrete is used in many areas of construction. It can be purchased in the form of already ready mixture or be manufactured under conditions construction site. For preparation, granulated polystyrene foam is added to the initial mixture to form the foundation slab.

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

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

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

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

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

The choice of type and technology of foundation slab insulation depends on design features buildings and construction sites. Choose optimal solution is based on data from thermal engineering calculations and comparison of estimated costs.

An uninsulated foundation can result in greater heat loss than a tightly sealed, well-insulated home.

Foundation insulation reduces the need for high power heating system and avoids moisture condensation, which often occurs as a result of the temperature difference between the inside of the plinth and the soil around the base.

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

Insulation of basement external walls

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

Advantages:

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

Flaws:

• Expensive installation for an existing building if also installed drainage system along the perimeter.
• Many external insulation materials susceptible to attack by insect pests.
• Many contractors are not familiar with the proper procedures in detail.

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

Some insulating foams are made with boric acid to prevent termite infestation. However, borate can slowly leach from most materials when exposed to groundwater.

Insulation of basement internal walls

In most cases, the best way is insulation interior walls strip foundation, this is also a less expensive option for a finished building. This insulation has the following advantages and disadvantages:

Advantages:

• This is much cheaper than insulating external walls for existing buildings.
• There are more wide choose materials, since you can use almost any type of insulation.
• There is no threat of insect infestation.
• Space isolated from cold earth more effective than using external insulation methods.

Flaws:

• Many insulations require a fire resistant coating because they release toxic gases when ignited.
• Reduces useful inner space by 3-5 cm.
• Does not protect against moisture penetration like external insulation.
• If the perimeter has poor drainage, the insulation can cause moisture to become saturated around the perimeter of the foundation and seep through the foundation walls.

New methods of foundation insulation

Some new building systems make it possible to build a ready-made insulated foundation without the use of wooden or metal formwork, is a system of concrete forms (ICF), simply put, permanent formwork made of polystyrene foam, which uses rigid foam as forms for formwork, thereby insulating the inside and outside of the foundation.

Thermal panels

Among the new products, there is also insulation that does not require finishing, This thermal panels made of polystyrene foam with stone chips.

Polyurethane foam

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

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

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

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

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

Blocks with insulation inserts

There are also blocks with foam inserts. They are installed as blocks and do not require plaster. Some concrete block manufacturers add materials such as polystyrene or wood shavings into the concrete mixture.

Despite the fact that filling the cavity of the blocks with insulation improves their thermal properties, at the same time it does not significantly reduce heat loss compared to insulation made on the surface of the walls, or on the outer or inner parts of the foundation walls.

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

Insulation of slab foundations

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

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

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

When insulating a slab foundation, the insulation should be located between the support and the slab. This protects the insulation from insects and damage better than external application and insulates the slab from the cold base.

Insulating an existing slab is generally not practical.

However, it is possible to isolate outside slabs from top to bottom:

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

The insulation can be applied over the existing slab, from top to bottom, as follows:

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

An alternative is a floating floor, which consists of:

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

The above methods have the following advantages and disadvantages:

Advantages:

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

Flaws:

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

Insulation of the basement floor from the inside

Isolation basement depends on whether there is ventilation in it. Traditionally, basements are ventilated to avoid moisture problems. However, this method does not always work well.

If the basement must be ventilated, carefully seal all openings in the ceiling to prevent air from entering the house. Insulate the ceiling by pressing fiberglass insulation tightly to the base.

Cover the insulated surface of the floor with a vapor barrier. Carefully seal all seams to prevent air and moisture from passing through. Secure the insulation with mechanical fasteners so that it does not fall out between the joists. The insulation is attached between the beams.

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

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

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

When constructing this type of foundation, extruded polystyrene foam (EPS) was used. In a master class format, professional builders will tell you how to choose and how to properly work with extruded polystyrene foam for insulation various types foundations. Namely:

• Why is it necessary to insulate the foundation?
• What to look for when choosing a material for foundation insulation.
• How to properly secure extruded polystyrene foam to the foundation.
• What tool is needed for the job?

Why is it necessary to insulate the foundation?

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

• Slab, shallow, with spatial reinforcement. This gives the structure rigidity and allows it to withstand loads arising from uneven soil movement without internal deformation.

• Tape - laid below the freezing depth, etc. MZLF is a shallow strip foundation, with a base depth above the calculated level of seasonal soil freezing.

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

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

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

Kogut Andrey TechnoNIKOL technical specialist

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

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

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

Basic principles for choosing thermal insulation for foundation insulation

So, summarizing all of the above, we conclude: the foundation needs to be insulated. Not every insulation is suitable for this, but only material that can work in aggressive conditions external environment. Those. thermal insulation designed to be “non-removable” must be moisture resistant, have a long service life during which it will not lose its thermal insulation properties, and have strength sufficient to withstand the load from the overlying structures.

Kogut Andrey

Extruded polystyrene foam (EPS) has a low thermal conductivity coefficient of 0.028 W/(m*°C) and a minimum water absorption coefficient of 0.2% by volume. The insulation does not absorb water, is chemically resistant and does not rot. Compressive strength at 2% linear deformation – no less than 150 kPa (~ 15 t/sq. m) and higher. Service life in soils is at least 50 years.

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

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

• Purpose of the building (residential, administrative, industrial, etc.).
• The insulation must provide the required heat transfer resistance for a given type of building.
• There should be no seasonal moisture accumulation in the structure.

Calculation thickness of thermal insulation for the foundation is made according to the methodology set out in SP50.13330.2012 “ Thermal protection buildings." For different regions The thickness of the insulation may vary depending on climatic conditions. It should also be taken into account that increasing the thickness of thermal insulation increases the energy efficiency of the building and, therefore, leads to lower heating costs.

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

1. When thermally insulating a strip foundation, when only insulation is vertical wall, increased strength of the material is not required, because in this case, the EPS absorbs loads only from the ground backfill. Therefore, for shallow foundations, brands of extruded polystyrene foam with a compressive strength (at 10% linear deformation) of 150-250 kPa are suitable.
2. When laying EPS slabs under the base of the foundation or under the slab, the loads on it increase significantly, and accordingly, the requirements for its strength increase. In this case, it is recommended to use thermal insulation boards with a compressive strength of 250 - 400 kPa.
3. A material has been developed specifically for USP with a compressive strength at 10% deformation of 400 kPa and increased slab sizes to increase installation speed. In addition, the increased dimensions of the slabs make it possible to reduce the number of seams and, accordingly, increase the uniformity of the layer.

The nuances of installing extruded polystyrene foam when insulating the foundation

Insulation of the EPPS foundation, depending on its design, should be divided into a number of sequential steps:

• Preparing the base. When insulating an EPS strip foundation, the walls must be smooth, free of dirt and concrete deposits. If necessary, we remove uneven surfaces and cover up sinkholes, chips, etc. cement-sand mortar.

• Choosing a method of fastening EPS. To attach the insulation, we use polymer-cement mixtures or, to speed up installation, special polyurethane adhesive foam.

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

• The distance of the adhesive foam strip from the edge of the slab is at least 2 cm.

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

• We foam the gaps between the plates (if they exceed 2 mm).

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

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

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

Together with similar fasteners, gluing is done using adhesive foam for polystyrene foam or to a special adhesive mastic that does not contain solvents. If necessary, the seams are sealed with mounting or adhesive foam.

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

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

Summarizing

In addition to increasing the energy efficiency of the foundation, EPS insulation increases its service life, because the waterproofing is reliably protected by durable material from various mechanical influences. Selecting an option permanent formwork made of extruded polystyrene foam, you can significantly speed up and simplify all work on the construction of the foundation, because there will be no need to assemble and further disassemble wooden formwork, which means the developer will save time and money.

Insulation of a monolithic foundation slab is necessary in areas with cold climatic conditions. Such measures are required in order to protect the base from harmful effects. environment, maintaining warmth, coziness and comfortable living conditions in the house. Some of the most common materials for insulation are polystyrene foam and polyurethane foam.

Insulation of a monolithic foundation with expanded polystyrene

Thermal insulation of base slabs in this way is a relatively new type of modification of private houses. It began to be used in the 50s - 60s of the XX century. This type of slab insulation is durable and has a long service life. According to statistics, the popularity of expanded polystyrene is growing steadily every day.

Strengthening monolithic slabs with polystyrene foam has proven to be very good decision during the construction of houses, because their service life is more than 50 years. After carrying out various tests and checks, it became clear that the material did not change in any way over the entire period of operation.

It follows from this that the growing popularity and steady increase in consumption of expanded polystyrene is a pattern. Over the past 20 years, its use has increased tenfold. The main consumers of this material are Europe and North America.

Extruded polystyrene foam for insulating a monolithic base slab is a material that has a uniform structure consisting of closed cells. Due to the low density of the material, its thermal insulation properties increase. You should also know that polystyrene foam has increased strength characteristics and can withstand quite heavy loads.

Expanded polystyrene practically does not allow water to pass through and is not afraid of exposure to chemically aggressive environments. Thermal insulation with this material is made in regions with severe winters and very cold weather. Expanded polystyrene copes well with multiple cycles of freezing and defrosting, while its performance characteristics do not change at all. Expanded polystyrene is usually sold in the form of slabs.

Return to contents

Why polystyrene and not another material?

1. The area for the foundation is marked.
2. The layer of soil on top is removed. The depth depends on the construction project. When removing soil, you must try to make the bottom as level as possible. To do this, the last 0.2 - 0.3 m is removed manually. A layer of sand is poured onto the prepared site and then compacted.
3. Temporary formwork is installed and a concrete base is prepared. The formwork is filled with a small layer of concrete. No base reinforcement is required.
4. After the concrete has hardened, laying begins polystyrene foam boards, in this case it is necessary to combine the mounting grooves and try not to leave large gaps.
5. A polyethylene film is placed on the laid insulation layer. The joints are glued using tape. Polyethylene creates a layer of waterproofing. In addition, the film prevents concrete leaks between the joints of insulation boards.
6. The construction of formwork and reinforced frame is in progress. Concrete is being poured.
7. After complete drying, the formwork is removed.
8. The side walls are additionally insulated with expanded polystyrene.

Some tips:

• work begins from any corner of the foundation;
• the slabs must be laid from bottom to top with offset rows, that is, the result should be something similar to brickwork;
• At a height approximately equal to the width of the slab, pull the rope. The horizontal tension is checked using a building level;
• The first row of the thermal insulation layer is laid. This is done so that subsequent rows of slabs do not diverge, otherwise all insulation will simply become useless.

Return to contents

How to properly install polystyrene foam boards on walls?

The foundation wall is covered with spread mastic. Then polystyrene foam is placed against it and pressed tightly. All row slabs are installed in a similar manner.

When carrying out work, you must carefully monitor the connection of adjacent slabs. It should be clear, without gaps and be locked.

The joints on the ridges of the locks at the corners are cut off. If necessary, the joints are additionally filled with polyurethane foam.

As the higher rows are laid, the lower rows are covered with soil. Such actions make the work easier and help press the material.

Plates located below ground level are glued only with mastic.

This is necessary to prevent damage to the waterproofing.

The insulation located above the ground can be further strengthened using dowel-nails (umbrellas). All this can be easily done with your own hands, you just need to be very careful. To attach the base to the walls, holes are drilled using a hammer drill. Umbrellas are fixed in the center and at the junction of adjacent slabs.

Foundations insulated with polystyrene foam are so popular for the following reasons:

• when using this technology you can save up to 40% of money;
• heat loss reduction reaches 20%;
• waterproofing layer the foundation will last 2 times longer;
• expanded polystyrene guarantees quality and long service life;
• the slabs reliably protect the waterproofing layer, ensuring drainage of accumulated groundwater.

From the above it becomes clear that, insulated with polystyrene foam, it will serve for a long time, and the house will be cozy, comfortable and warm. In addition, the material is absolutely safe from an environmental point of view and has a low cost, which clearly tilts the choice in its direction when long-term construction is ahead.