Insulation of the foundation from the outside - we keep warm and protect the house from destruction. How to insulate the foundation of a house from the outside with your own hands The best and cheapest way to insulate the foundation

It often becomes cool in the harsh winter in an old or newly built house. This is due to the fact that during the construction of the base, thermal insulation was not carried out. To save heat, you should insulate the foundation of a wooden house from the outside with your own hands. The choice of method depends on the types of substrate and material.

Why insulate the foundation from the outside

External insulation of the base solves several problems at once:

• retains heat in the house;
• plays the role of waterproofing, thereby protecting the basement (if any) from condensate;
• saves money on heating;
• maintains the integrity of the base during frost heaving.

It is much more efficient internal insulation, since the latter can only be used with sufficient ventilation of the basement. Otherwise, the dew point will be shifted, the foundation will be affected by low temperature and humidity. With external insulation, these moments are excluded. Depending on the choice of base (tape, columnar, pile or monolithic), the material is also chosen, which needs to be sheathed for the foundation of a wooden house.

The process of insulation should be carried out at the stage of foundation construction.

Types of heaters

For such work, polystyrene foam, polyurethane foam or polystyrene is usually used, and expanded clay is also used. These materials have high resistance to temperature changes, minimal water permeability and minimal thermal conductivity.

Styrofoam

Extruded polystyrene foam (EPS) insulation boards are available in various sizes and thicknesses. The material has many advantages:

• practically waterproof - moisture absorption is not more than 0.2%;
• the minimum thermal conductivity is 0.032 W / m K at a temperature of 20-30 degrees, which, with a thickness of 3 cm, corresponds to brickwork 55 cm thick;
• high rate of resistance to deformation;
• resistance to certain chemical compositions;
• resistance to temperature changes in the range of minus 50 - plus 75 degrees;
• service life - from 50 years;
• a light weight;
• small thickness;
• safe for health.

The disadvantages include its combustibility (class G4) and destructibility in the sun when exposed to UV rays. Therefore, when using EPPS, decorative finishing of the foundation of a wooden house from the outside is mandatory from above.

When working with expanded polystyrene, its contact with:

• solvents for oil paint;
• plasticizers containing coal tars (putties, adhesives);
• acetone;
• petroleum compounds, toluene;
• ethyl acetate used in paint stripping;
• some wood preservatives.

The structure of the material is homogeneous, even at the break, the edges are smooth, the resistance to mechanical pressure is high. When buying, you should pay attention to this attention and, if possible, check.

polyurethane foam

In terms of energy efficiency, foam is superior to polystyrene, but it is more expensive. On the other hand, polyurethane foam can be used where it is not possible to use slab basement insulation, for example, with its complex configuration, an old stone foundation or the house belonging to an architectural monument. Also, polyurethane foam (PPU) is effective when working with a large foundation area, when it is difficult to guarantee complete sealing of all joints when using plate materials. The speed of applying foam is another advantage of polyurethane foam.

In addition, it has the following features:

• soundproofing;
• compressive strength - up to 140 kPa (corresponding to polystyrene, inferior to EPPS);
• resistance to all organic solvents, acids and alkalis of medium concentration;
• moisture permeability - up to 1%;
• exceptionally high adhesion to the base;
• fire hazard - G1-G4;
• the cost is 3 times higher than the price of XPS and polystyrene.

Protection from ultraviolet radiation is required, otherwise destruction occurs in the sun within 3 days.

In addition to foam, PIR boards are also produced from polyurethane foam, according to technical characteristics they are similar to XPS, but lined with aluminum foil and are used mainly for internal basement insulation without additional decorative finishes.

Expanded clay

The material consists of light grain obtained by firing clay rock. Light fragments (5-40 mm in diameter) create air gaps, which are formed in the immediate vicinity of the outer side of the foundation. To do this, a wall is made at a certain distance from it, using boards for finishing the basement, and expanded clay of medium (1-2 cm) or large (2-4) fractions is poured into the resulting cavity.

In parallel, drainage work and waterproofing are carried out, since the material has a high moisture absorption capacity.

The positive properties include: low cost, ease of use, rodents do not live in it, does not rot, does not burn, does not collapse under the influence of frost.

Styrofoam

Or expanded polystyrene is cheap, non-hygroscopic, durable, not subject to deformation, resistant to any temperature. If you want to finish the plinth of a wooden house inexpensively, choose this particular material. The only drawback of the insulation is its fragility, therefore, it must be handled with care.

The thickness of the sheets can be different (2-10 cm), standard size is 1 x 2 m. The material has:

• some noise reduction;
• medium flammability - G4;
• low thermal conductivity;
• resistance to chemical compounds, including lime, hydrogen peroxide, gypsum, acids, with the exception of acetic and nitrogen high concentrations;
• resistance to bacterial attack;
• environmental safety.

However, it is not resistant to ultraviolet radiation, benzene, acetone, toluene, rodents and termites.

Features of insulation of different types of foundation

Any base requires insulation and cladding of the plinth of a wooden house. Depending on the type and condition of the soil, the base option is selected, respectively, and the method of insulation.

Strip foundation

This base is a strip of reinforced concrete that runs under all bearing walls and going into the ground different depth. External insulation strip foundation can be vertical, horizontal and mixed.

In the first case, the plates are designed to protect the walls of the base, in the second, the blind area is insulated (especially with shallow penetration) to avoid heaving, the third is used in regions with positive winter temperatures and lack of floor insulation on the ground. The wooden base is also insulated both vertically and horizontally, as it is very susceptible to external environmental influences.

Column Foundation

The presence of high air gap under the house provides good ventilation and minimal humidity. But in cold weather, the supports remove heat from the ground and contribute to its heaving. In addition, they are destroyed by temperature changes. To prevent this from happening:

• the space between the ground and the house is isolated from cold air and drafts;
• thermal insulation is installed on the surface of the supports;
• insulate the soil near the buried part of the pillars.

It is advisable to insulate the supports at the stage of their installation. This is done using expanded clay, the thickness of the layer around the post under it must be at least 25 cm. In addition, they equip drainage and surface insulation from XPS.

If the supports are made by pouring concrete, then it is also better to use XPS boards for formwork.

pile foundation

This type of foundation also needs to be insulated, since a metal or reinforced concrete grillage is a cold accumulator, which leads to a significant loss of heat at home. Not only the underground space needs insulation, but also the piles themselves, filled with concrete. Their insulation occurs by analogy with the supports of the columnar base, described above. After that, the pile foundation should be closed outside the house from the timber with slab insulation, followed by decorative trim. This will protect communications from freezing and improve the aesthetic perception of the structure.

Monolithic foundation

Before the direct pouring of the reinforced concrete monolith, a pillow is arranged in which a heater is placed (PPU, EPPS or foam plastic):

1. Priming.
2. Sand.
3. Geotextile.
4. Rubble.
5. Concrete preparation.
6. Waterproofing.
7. Insulation.
8. Protective polyethylene film.
9. Reinforced concrete slab.

Such a cake can significantly reduce heat loss at home.

The presence of a heat-saving layer increases the efficiency of underfloor heating.

Insulation of the monolith is possible only before the foundation is poured.

Step by step guide to insulation

most common in construction wooden houses is a strip foundation. Its insulation is as follows:

• Step 1. The most time-consuming - you need to dig the foundation along the perimeter to a width of 1 m and a depth - to the level of freezing.
• Step 2. The bottom of the trench is rammed and a layer of sand and gravel is poured.
• Step 3. The foundation walls are cleaned with a metal brush and dried for 1-2 weeks in the sun.
• Step 4 Defects in the base are identified and eliminated, cracks are expanded and sealed, the surface is leveled as necessary. Perhaps with a reinforcing mesh (for irregularities of more than 2 cm).
• Step 5. Waterproofing is in progress.
• Step 6. The insulation is mounted.
• Step 7. The trench is covered with soil, not reaching 30 cm to the soil level. The soil is rammed and covered with a layer of sand (15 cm), then rammed again. A waterproofing membrane is laid and with a slight slope from the house - a heater.
• Step 8. The concrete blind area is poured.

The last step is decorative finishing.

Waterproofing

As a waterproofing, it is more convenient to use water-based polymer, bitumen or rubber mastic. Organic solvents can destroy board insulation. Before applying the mastic, the surface is passed with a bituminous primer in order to improve adhesion. A day later, waterproofing is applied with a wide brush in two layers - the second after the first has hardened. A week is given for complete drying. Then proceed to warming.

Insulation installation

The insulation (PPU, EPS or polystyrene) is fixed with glue (Titan, Ceresit, ALLFIX). Plates are glued horizontal rows starting from the bottom.

Vertical ligation of joints is required.

The grooves should be tightly aligned, and the joints should be almost invisible. If laying of two layers of insulation is provided, then the seams bottom row covered with outer slabs.

The underground part does not require additional fastening, since it will be pressed against the soil, and the upper part, after the glue has dried, needs to be fastened with dowel-nails equipped with wide caps. To protect against damage, plaster with fiberglass mesh reinforcement is applied from above. A day later, they are leveled and after drying they are rubbed with sandpaper.

Facing

If the simple plastering of the owners does not suit you, then you can finish the foundation:

• slabs of natural stone;
• artificial stone panels;
• clinker tiles;
• basement thermal panels;
• basement siding and more.

Perhaps the most modern material is glass magnesite. It does not burn, frost-resistant, does not collapse and does not lose its decorative properties under the influence of ultraviolet rays. A special advantage of the material is its flexibility, which allows the use of glass magnesite on slightly uneven surfaces.

The thickness is only 8 mm, which does not detract from the strength of the material and does not weigh down the entire cladding as a whole. The insulated foundation for a wooden house is a guarantee of comfort and comfortable living in it, a guarantee of uninterrupted water supply and operation sewer system. And also, a significant reduction in energy costs.

It is better and more comfortable to engage in the construction and insulation of the foundation in the spring-summer-autumn period, when the air temperature is quite high and the humidity “does not go off scale” ... Let's figure out how to insulate the foundation from the outside correctly and efficiently!

Why is it necessary to insulate the foundation

Applying insulation for the foundation is just as important as insulating the walls of the house! Especially in areas that are characterized by a harsh climate and freezing of the soil to a great depth. The foundation of the building structure "gives" environment 10-20% of the total heat loss of the building.

A particular danger for building foundation structures is the freezing of so-called "heaving" soils. Such soils are capable of freezing during severe frosts and significantly increase in volume, which leads to a rise in the soil level.

Attention! At significant depths of soil freezing, it is possible to “move” its level by 35 cm. This value corresponds to 15% of the depth of soil freezing.

The rise in the ground level leads to deformation of the foundation of the building. If the foundation is laid above the freezing level and the foundation slab is not insulated, then during the freezing period, frost heaving forces arise under this slab, directed normally (perpendicularly) to the surface of the slab. Therefore, in the freezing zones, thermal insulation of the horizontal foundation slab is also carried out.

The quality of work in this heat-insulating direction will determine the operating conditions of the building as a whole and the comfort of living in it. The planning of insulation works of the foundation is carried out at the stage of its construction.

Since a large “amount” of cold enters the house through the foundation, when building a house, floor slabs raised above the ground are used. Cold air in large volumes is at the level of the foundation and floor, and warm air rises and, if the roof is poorly insulated, goes outside, making room for a new "portion" of cold air.

And if the basement is used for any functional purposes (not a cellar), then special attention should be paid to its insulation. Playroom, gym, billiard room, laundry - no matter what the purpose of the room is, what matters is the comfortable air temperature in it. And the presence of dampness without insulation of the foundation is guaranteed.

An unheated basement is "undemanding" to thermal insulation. But it is necessary to insulate the basement of the foundation. to reduce heat loss at the floor level of the first floor, which is heated.

Insulation of the basement of the foundation will allow you to save heat in the house, blocking the way to the house for cold air. Remember that high-quality insulation of the house, including the foundation, allows you to save from 30 to 50% of the money allocated for heating.

In addition to thermal insulation functions, the foundation insulation layer plays an integral role in its waterproofing.

So, basement insulation:

• reduces heat loss;
• reduces "heating" expenses;
• reduces or completely eliminates the impact on the foundation of the forces of frost heaving of the soil;
• stabilizes the temperature inside the building;
• prevents the formation of condensate on the inner planes of the walls;
• acting mechanical protection waterproofing;
• favorably affects the longevity of waterproofing and the foundation structure as a whole.

What insulation for the foundation to choose?

Planning of works on warming includes the main step - the choice of heat-insulating material. So, what is the best way to insulate the foundation of the house?

Such materials for the insulation of the foundation should:

• not deform under ground pressure;
• do not absorb moisture.

Today it is easy to "get lost" in all the variety of heat-shielding materials. It is clear that the common insulation material - mineral wool it is not suitable here because of its “softness” when backfilled with soil and high water absorption, which reduces its thermal insulation qualities.

To insulate the foundation today, experts recommend two main methods:

• insulation with extruded polystyrene foam;
• spraying polyurethane foam.

These heaters differ in different values ​​of thermal insulation parameters and cost. For optimal choice their advantages and disadvantages need to be studied.

This is a modern heat-insulating material that combines the functions of heat, hydro and sound insulation. For its use, special equipment is required, with the help of which polyurethane foam is sprayed layer by layer on the surface to be insulated. The thickness of the insulation layer is 50 mm and this is with a density of polyurethane foam of 36 kg / m 3. A similar insulating effect can be achieved when using expanded polystyrene with a thickness of at least 120 mm.

There are no gaps and seams in the polyurethane foam coating, which are cold bridges and a “path” for moisture to penetrate into the foundation. When insulating with foam plastic, it is necessary to seal and seal the joints, as well as use additional mounting fasteners, which increases the time installation work and their cost.

Benefits of using polyurethane foam:

• seamless coverage;
• high adhesive properties;
• low thermal conductivity;
• low vapor permeability;
• reliability;
• "longevity";
• no need for additional vapor and waterproofing.

The disadvantages of such a material include the need for special equipment and the "fear" of UV radiation.

In its defense, extruded polystyrene foam can only "present" a lower cost, the significance of which reduces the complexity of installation and lower thermal insulation properties.

Plates made of extruded polystyrene foam, due to their cellular-closed structure, practically do not absorb and, of course, do not let water through. And this means that the moisture in the plates will not destroy them when freezing. Therefore, extruded polystyrene foam is characterized by a long service life while maintaining its thermal insulation characteristics.

Note! To the question: “How to insulate the foundation with foam?”, We offer the following answer ...

The use of ordinary foam for insulation of the foundation can lead to the fact that after several cycles of seasonal “freezing - warming up” of the foundation, the insulation layer will crumble into a pile of balls. This will happen due to moisture, which is easily absorbed by ordinary polystyrene foam.

Vertical thermal insulation of the foundations of civil and industrial facilities is carried out with extruded polystyrene foam plates with a compressive strength of 250 kPa or more, private buildings allow the use of polystyrene foam with a strength of up to 200 kPa. For floor coverings, it is necessary to choose slabs with a strength of 500 kPa or more.

Such "strength" characteristics of extruded polystyrene foam favorably affect the integrity of the foundation waterproofing and are its integral element, ensuring the normal long-term existence of the foundation.

Among thermal insulation materials from extruded polystyrene foam there are plates with milled grooves. In collaboration with the geotextile fabric, this material perfectly performs the function of wall drainage, insulating the foundation, protecting the waterproofing and diverting water from the foundation into the drainage system.

Advantages of insulation with extruded polystyrene foam:

• long service life (at least 40 years);
• high compressive strength;
• constancy thermal insulation properties during the period of operation;
• "inedible" for rodents.

Warming of the foundation with expanded clay

Until recently, this was the most popular way to insulate the foundation from the outside. It was supplanted by the relative "cheapness" and high efficiency, the methods discussed above how to insulate the foundation from the outside.

How to insulate the foundation of the house with polystyrene foam from the outside

Proper and effective insulation of the foundation from the outside in the areas of soil freezing involves the installation of heat-insulating plates to the freezing depth. Insulation of the foundation (walls) below the level of soil freezing is not so effective and is often not performed.

The corner zones of the building require "reinforced" thermal insulation. Therefore, at a distance of 1.5 m from the corner, the thickness of the expanded polystyrene plates or the polyurethane foam layer increases by 1.5 times.

It is also necessary to carry out soil insulation around the perimeter of the building. An insulating layer of extruded polystyrene foam is located under the blind area structure. Its main purpose is to reduce the depth and degree of soil freezing along the walls, as well as to keep the freezing boundary in a layer of non-rocky soil (sand, gravel, etc.)

The laying angle of extruded polystyrene foam boards should be at least 2%, and the width of the blind area should correspond to the depth of soil freezing in this region. The optimal thickness of the plates corresponds to the thickness of the vertical layer of foundation insulation.

Before insulating the foundation of the house from the outside, the surface of the walls must be leveled and waterproofed.

Plates of extruded polystyrene foam during installation create an airtight shell of the foundation. Therefore, the use of mechanical fasteners for their fixation is unacceptable due to point depressurization of the insulation layer.

The fixation of the heat insulator plates is carried out by applying an adhesive composition on them or by “melting” a layer of bituminous waterproofing at 5 or 6 points, to which the expanded polystyrene plate is then pressed and held for some time until it hardens.

Installation of plates begins from the bottom, the rows are joined end-to-end. The thickness of the plates must be the same. Vertical seams adjacent to each other should be offset relative to each other (checkerboard order).

Attention! The use of torn-off plates for re-assembly is not allowed, as well as the displacement of the plates after the bitumen or adhesive mortar has cured.

Joints between plates with a thickness of more than 5 mm are filled mounting foam, it is more convenient to use plates with a stepped edge. Its gluing will ensure the tightness of the heat-insulating layer and additional waterproofing of the foundation.

The adhesive is selected based on the material of the waterproofing layer. Use of rolled or mastic waterproofing materials bitumen-based defines the use of bituminous mastics that do not contain aggressive ingredients for expanded polystyrene as an adhesive composition.

Attention! Before insulating the foundation from the outside, it is necessary to wait for the bituminous waterproofing to dry completely (5-7 days). Do not install extruded polystyrene foam boards on a dry bituminous waterproofing base, as the boards can “part” and break the waterproofing. Also, bituminous waterproofing may contain solvent particles, which, in a “dry” form, can harm expanded polystyrene boards.

Glue on the slabs located below ground level is applied with several points. This will allow moisture condensed between the surface of the insulation and the foundation wall to flow down unhindered.

The use of fixing dowels in conjunction with the adhesive composition of polymer cement adhesives is necessarily applicable to expanded polystyrene boards located above the ground level at the rate of at least 4 pcs. on one plate. The plates located in the ground are attached only to the adhesive composition and are pressed against a layer of soil.

Features of the installation of thermal insulation made of polyurethane foam

The insulation of the foundation with polyurethane foam is carried out in this way. Let's watch the video...

How to insulate the base plate?

Deciding how to insulate the foundation from the outside, for more effective insulation floor or basement, care should be taken to insulate the base plate of the foundation.

In this case, the insulation boards are laid on a waterproofing layer.

Further, in the case of using knitted reinforcement for pouring the power floor, it will be enough to cover the heat insulator layer with plastic wrap with an overlap of 100-150 mm and gluing with double-sided tape.

When using a welded reinforcement structure on top of the film, it is necessary to make a protective screed of concrete or cement-sand mortar, and already on top of it to perform welding work.

Foundation insulation

Most owners of private houses do not consider it necessary to insulate the foundation, believing that this is a waste of money. Thoughts about the need to insulate the basement from the outside come when problems with dampness and mold on the walls become visible, and the basement begins to crack. High-quality waterproofing will help to avoid these troubles, we will tell you how to do this in the article.

Basement insulation is as important an event as it is. Through the foundation, the room loses about 20% of heat. Many people think that it is enough to insulate only the basement, but this is a gross mistake. Since the destructive force of water and low temperatures continues to act on the base. Moisture, getting into the pores of the foundation, freezes when exposed to low temperatures and, expanding, destroys the structure. Microcracks appear, which become cold bridges, and when they grow, they can lead to the destruction of the building as a whole.

Insulation of the foundation prevents its destruction

External insulation eliminates the effect of low temperatures and groundwater. The dew point shifts to the insulation layer, and the foundation concrete does not change its properties. Warming is especially important in regions with a harsh climate and heaving soil. Such soil, freezing by 15%, is able to move 35 cm, which entails deformation of the base. On such soils, the depth of the foundation should be below the freezing point, and the insulation is done not only vertically, but also horizontally.

The benefits of insulation

With an uninsulated foundation, cold air from outside enters the living space through the flooring. Therefore, when building a house, the floors are raised above the ground level. Without insulation from the outside, constant dampness in the basement and cold floors in the house are guaranteed, which reduces the level of comfort. So, what facts speak in favor of insulation:

• the heat loss of the building is significantly reduced, which means that the financial part of the budget for heating will also be reduced;
• the effect of soil heaving forces is leveled;

Benefits of basement insulation

• prevents the formation of condensation and mold;
• prolongs the service life of the foundation structure;
• protects waterproofing from mechanical damage;
• it is easier to block the bridges of cold.

Advice. special attention building corners are required. In these places, the thickness of the heat-insulating material is doubled.

Warming methods

When choosing a material for insulation, attention is paid not only to the cost, but also to its main characteristics, namely: hygroscopicity and resistance to deformation. There are several ways to insulate:

1. Plate heaters: extruded polystyrene foam 200 kPa, foam glass, polyurethane foam and synthetic rubber in the form of foam.
2. Backfilling with bulk materials: expanded clay, boiler slag.

Most often, polyurethane foam or extruded polystyrene foam is used for insulation.

Advice. On the plates, which are located below ground level, glue is applied pointwise. This is necessary so that the condensate formed between the waterproofing and the insulation flows freely into the equipped drainage.

Expanded clay insulation

Before the advent of new generation insulating materials, expanded clay was often used. Its main advantage is its low price, but the level of thermal conductivity of the material suggests its use in large quantities. So dignity becomes a disadvantage. It is rational to put it into action as additional insulation.

Expanded clay insulation

Warming is carried out as follows:

• the foundation is dug up to the sole, to a trench width of 1 m;
• clean the surface of dust;
• in the absence of waterproofing, bituminous mastic is applied;
• equip drainage if the groundwater level is high;
• a film is placed at the bottom of the trench from the wall to the drainage;
• the trench is filled with expanded clay and a blind area is made.

Sheet insulation technology

When erecting a new building, insulation work begins after the installation of the floor slab. If the house has already been erected, then the foundation is dug around the perimeter to the base to a meter wide. The walls are dried, all dirt is removed. With a close level of groundwater, drainage is arranged. After complete drying, a latex-based primer is applied to the foundation walls. It fills small voids and provides a strong adhesion of the waterproofing to the basement surface. Rolled waterproofing is laid, strongly pressing with a roller. Joints are covered with sealant for reliability. Wait until the waterproofing dries, and then proceed to laying the insulation.

Scheme: insulation sheet material

Advice. Do not use plates torn from the surface or move them after the adhesive has hardened.

The advantage of extruded polystyrene

Styrofoam boards are considered the best option for private construction. Since they have a long service life and high compressive strength. Practically do not absorb and do not pass moisture. Keeps for a long time thermal insulation characteristics precisely because of its low hygroscopicity.

Thermal insulation of the base with extruded polystyrene foam

These plates are produced with special grooves. Moisture is drained through them. In tandem with geotextiles, polystyrene, in addition to insulation, performs the role of waterproofing and wall drainage.

Advice. Ordinary polystyrene, although it has an attractive price, is completely unsuitable for insulating the foundation. It absorbs moisture and breaks down quickly.

Insulation with liquid polyurethane foam

Polyurethane foam is applied in foamed form to the cleaned surface of the foundation. It combines the properties of waterproofing and thermal insulation. 50 mm of polyurethane foam is equal to 1.2 m of polystyrene foam. The material hardens very quickly, forming a cellular structure. Foam hermetically envelops the foundation, leaving no gaps and without forming seams, unlike tile insulation. The advantages of polyurethane foam insulation include:

• lack of seams in the coating;
• high adhesion of the material;
• no need for waterproofing;
• low vapor permeability;
• service life of more than 40 years;

Insulation with liquid polyurethane foam

• low thermal conductivity;
• environmentally friendly and biologically neutral.

There are only three cons. This is a high cost and the need to purchase special equipment for laying. Polyurethane foam is destroyed under the influence of solar ultraviolet radiation.

Water drainage from the basement

Together with insulation, it would be good to provide for drainage so as not to dig out the foundation twice. Drainage pipes are laid below the level of the base of the foundation or below the level of the basement, if any. A gravel cushion is poured with a slope of 5 degrees. A drainage pipe is placed on top of it, wrapped in geotextile, and gravel again on top. Geotextiles will prevent clogging of drainage holes. ground water pipes will drain into a drainage well.

Foundation drainage system

With knowledge of the advantages and disadvantages of insulation, you can choose the material that suits you best. Competently carry out construction work, and you will ensure comfort and warmth in the house for a long time, as well as a long service life of the building.

Insulation of the foundation with polystyrene foam: video

Master of Architecture, graduated from the Samara State University of Architecture and Civil Engineering. 11 years of experience in design and construction.

Thermal insulation of the foundation structure allows you to simultaneously solve two important problems: to reduce the heat loss of heated premises through the basement, soil or subfloor, and also to save the material of building structures from destruction during the winter freezing of the soil.

When arguing whether it is necessary to insulate the foundation of a house from the outside, it should be understood that both concrete and other materials from which foundations are built are only conditionally considered waterproof. Small upper layer concrete is able to absorb moisture, which will freeze at a negative temperature, expand and lead to a violation of the integrity of the foundation.

Comparison of thermal conductivity building materials.

As a result of repeated freezing of the soil and insufficiently reinforced hydraulic insulation, the building structure can be severely damaged or even destroyed.

Heat loss through the floors and the basement of the building can reach 15% of the total volume. This is especially noticeable in slab foundations and in the construction of houses without basements. Therefore, the insulation of the foundation of the house from the outside will allow in the future to save significant funds on energy resources, the cost of which is constantly growing.

Before warming.
After warming.

General requirements for insulation

The foundations of buildings are regularly exposed to moisture, temperature changes with possible freezing, they are subjected to constant soil pressure, both in the transverse and longitudinal directions. How to insulate the foundation of the house from the outside? First of all, the selected insulation must have:

• low thermal conductivity;
• resistance to temperature extremes in the range from -40°C to + 20°C;
• resistant to moisture, be impervious to it;
• good strength with structure retention under pressure on the surface;
• unattractive to mice and insects.

The combustibility of the material for external insulation of the foundation, located below ground level, does not matter, since the probability of exposure to a flame is extremely low. There are also no special conditions for vapor permeability, although water resistance already implies the presence of this parameter.

Types of heaters used

Among the heat-insulating materials that meet the above requirements and have an affordable cost, we can name:

• sprayed polyurethane foam;
• sheet expanded polystyrene;

Each of the listed types of thermal insulation has its own characteristics associated with the installation technology, the effectiveness of the insulation layer and the cost of purchasing the material.

Polyurethane foam (PPU)

Of all the listed heaters, sprayed polyurethane foam is the most expensive and requires the use of special equipment for its application to the surface of the material. However, it is also the most effective insulation of all existing polymeric materials.

His main feature lies in the fact that the polyurethane foam coating does not have connecting seams, representing a single continuous layer. This material for warming the foundation of the house from the outside:

• has excellent adhesion and excellent adhesion even on contaminated surfaces;
• has one of the lowest thermal conductivity coefficients;
• after complete hardening becomes waterproof;
• characterized by good hardness combined with high ductility;
• absolutely unattractive to rodents and insects.

The water resistance of polyurethane foam allows you to abandon the installation of a waterproofing layer. This significantly reduces the time required to insulate the foundation of the house from the outside, reduces the overall cost.

Ordinary polystyrene boards

This material is made by heating the feedstock poured into the mold with hot steam. Under the influence of temperature, expanded polystyrene granules expand, forming a porous mass that occupies the entire volume of the mold. This technology is used to make most soft foams.

PPS is supplied to the market in the form of flat slabs with a key notch at all ends. This form allows for partial overlapping of the seams at the junction of adjacent plates and avoiding the formation of cold bridges.

The material is cheaper than polyurethane foam, but the presence of connecting joints cannot guarantee the protection of the surface from moisture. Therefore, before installing the heat-insulating layer, a mandatory waterproofing device is required.

Extruded polystyrene foam

This material differs from the previous version in the manufacturing technology and quality of the plates. The molding of the plates involves the supply of a ready-made molten polymer mixture through a special extrusion machine. In this case, the foaming of the composition occurs due to filling it with neutral or carbon dioxide. Ordinary air is not used for this, because. this will affect the fire hazard.

Extruded polystyrene foam is somewhat more expensive than usual, but, thanks to this molding method, it does not have a single open pore on a smooth and even surface. This means a longer service life and improved thermal insulation properties.

Expanded clay

The main advantage of expanded clay granules is the lowest cost among all heaters used for foundations. For other technical indicators, expanded clay, frankly, loses to foamed polymers. Application of new modern technologies for the insulation of building structures made this material poorly in demand, its use is now rare.

The ability of expanded clay to partially absorb water over time increases its thermal conductivity by 25-30%. Therefore, ensuring the effectiveness of the bulk heat-insulating layer requires a large thickness, and, therefore, a significant consumption of material. This, in turn, leads to an increase in costs and, as a result, the complete leveling of the previously mentioned main advantage of expanded clay.

Features of the use of thermal insulation for foundations

Insulation is performed only for two types of foundation foundations - tape and slab. Speaking about the thermal insulation of pile and column structures, they mean the installation of insulation on the lower surface of the slab, which is the floor of the first floor, and the insulation of the foundation base from the outside.

There is simply no point in insulating support pillars and piles. In these places, there is practically no temperature difference between the surface of the building structure and the environment.

Application of polyurethane foam

For the professional performance of thermal insulation work, a two-component composition of polyurethane foam and special equipment for mixing and spraying the finished mixture are used.

Before starting work, the surface must be cleaned of old plaster layers and large contaminants. It should not have grease stains and loose layers of building materials. Thorough cleaning and priming is not required if the surface is dense and sound.

Styrofoam boards

Speaking about the installation of polystyrene foam boards, first of all, you need to study:

• the need for a waterproofing layer;
• method of fixing the plates on the vertical surface of the foundation;
• protection of the polymer from negative environmental influences.

Bitumen-impregnated roll materials are used as hydraulic insulation. They paste over the surface with hot bitumen.

Use primers or other liquid materials is not recommended, since they will not be able to ensure the normal fixing of the heat-insulating material on the surface.

Initially, PPS boards are fixed to the surface with a special adhesive. When installing adjacent elements, it is necessary to provide interlocks to seal the joints. The final fixing of the plates is carried out using special plastic nails with large round caps (fungi).

Plates made of ordinary PPS, which is thermally manufactured, are subject to protection from negative influences. This is due to the presence of open pores on the surface of the material. The treatment can be done with a cement or stable adhesive mortar, which is applied after the installation of the boards.

Expanded clay backfill

The foundation wall must be covered with a waterproofing layer of rolled materials. To insulate the strip foundation with expanded clay, a trench 40-60 cm wide is dug along the perimeter of the building to the depth of soil freezing.

A sand cushion 5-7 cm thick is poured onto its bottom. After that, the trench is completely covered with expanded clay granules to the level of the blind area, well tamped. The blind area is poured directly onto the expanded clay layer.

For slab foundations, a layer of expanded clay can be used as a support pad instead of sand. The granules are covered with an even layer 70-100 mm thick, the slabs of the main heat insulator are laid on them, on which concrete is then poured.

Instructions for warming the foundation outside with your own hands

The technology of installing thermal insulation on the foundation depends on the type of foundation structure and the season of work.

To insulate the underground part of the strip foundation, it is necessary to provide free access to the surface of the building structure. For a building under construction, this is easier to do. The insulation is installed immediately after the formwork has been removed and before backfilling is performed.

For already operated buildings around the perimeter of the house, it is necessary to dig a trench at least 500 mm wide and deep, to the freezing point of the soil.

The slab base is insulated with heat-insulating plates only during the installation of the structure.

Strip foundation

The most common option for insulating the vertical walls of the foundation tape from the outside is the use of extruded polystyrene foam boards.

The installation procedure in this case is as follows:

• dig a trench along the perimeter of the building with a width of at least 0.5 meters and a depth to the bottom of the base or the freezing point of the soil;

• thoroughly clean the surface of the wall from soil residues and other contaminants, allow time to dry well;
• apply a layer of bituminous soil in 2 times, which can be bought ready-made or made from a primer;
• using hot bitumen, stick two layers of rolled waterproofing, roofing felt or other similar material on the foundation wall;

• start the installation of polystyrene foam boards from laying the bottom row, providing primary fixation with a special mounting adhesive;

• perform the final fastening with wide-headed plastic mounting nails, using at least 5 pcs. on one plate.

When laying the slabs, it is necessary to observe the locking connection of adjacent insulation elements. The vertical seams of the second row should not coincide with the seams of the first.

After the installation of polystyrene foam plates is completed, it is necessary to backfill the trench with a layer-by-layer rammer. The blind area can be performed only after a year, when the final shrinkage of the soil occurs.

slab foundation

Insulation of the foundation slab is carried out on early stages building a house and is included in general composition foundation works.

Therefore, the instruction includes part construction works this stage:

• remove the topsoil layer to the design depth;
• level and compact the surface;
• spread a layer of geotextile, which is designed to prevent the capillary rise of groundwater and the germination of weeds;
• pour a layer of crushed stone-sand or expanded clay cushion 100 mm thick, compact it well;

• lay a layer of polyethylene film overlapping adjacent strips by 100-150 mm;

• lay on the surface polystyrene boards with the provision of locking joints and displacement of seams along horizontal rows;

• for reliable fixation of adjacent elements of the heat-insulating layer, connect them together using metal or plastic brackets;
• cover the plates with plastic wrap and fix it on the surface.

After that, you can proceed with the installation of the formwork and the collection of the reinforcing frame for pouring concrete.

When building a house, it is important not to forget to insulate the foundation. Some will say that there is no need to do this. But if the basement is not protected with insulation, then in the first winter the owner will notice that the rooms cool down quickly, the floors are cold and unpleasant dullness appears. This is all due to the fact that the frozen ground gradually destroys the foundation, and the cold penetrates into the rooms.

Under the influence of low temperatures, the soil begins to move, because small cracks appear in the material from which the foundation is made. Groundwater enters such pores and, freezing, expands them, which leads to the gradual destruction of the basement.

To avoid such consequences, the foundation is insulated even at the construction stage. You can install insulation material after the house has been in operation for some time. In order for the heat-insulating layer to serve for a long time, it is covered finishing materials. This design acts as a barrier against exposure:

1. moisture.
2. temperature fluctuations.
3. mechanical type.

In addition, thermal insulation retains heat inside the premises, which means you can spend less money on heating your home and at the same time have a pleasant microclimate.

Insulation requirements.

The foundation is that part of the building that is always affected by loads, therefore, increased requirements are put forward for materials for finishing or insulation. When choosing a thermal insulation coating, pay attention to:

1. Ability to withstand temperature fluctuations.
2. Thermal conductivity - indicators choose the minimum.
3. Water-repellent properties - the material should not absorb water at all.
4. mechanical strength.
5. Steam permeability - for the basement there is no particular importance, but it is better to select material according to indicators similar to that of which the foundation is made.

Fire safety is not the main criterion for choosing a heater, since the material will be hidden under a layer of soil and finishes.

What insulation for the foundation to choose?

Natural materials, such as mineral wool, are not commonly used to insulate the foundation. The insulation quickly absorbs and accumulates moisture, and shrinks under the mechanical action of the soil. All this leads to the fact that thermal insulation cannot perform its assigned functions.

A good option for such work would be the use of synthetic insulation. For example,

1. Styrofoam.
2. Extruded polystyrene foam.
3. Polyurethane foam.

Styrofoam

This material is often used not only as a heater for the walls of the facade, but also for the foundation. The base is covered with polystyrene plates with high density and a thickness of at least 5 cm. The main advantages are:

• Light weight for easy transport and installation.
• The rectangular shape allows you to quickly and efficiently complete the installation process for an experienced master and a beginner in this field.
• Low thermal conductivity.
• Soundproof properties.
• Chemical and biological inertness.
• Moisture repellent properties.

Extruded polystyrene foam

This is the closest relative of foam. In the manufacturing process, another step is added - extrusion, which gives the insulation improved characteristics. Because extruded polystyrene foam differs from polystyrene foam:

• Greater density for the same thickness of the board, which means that it can be used less under equal conditions.
• Absolute impermeability of steam and moisture.
• Increased strength characteristics.
• Possibility to install plates vertically and horizontally.
• biological inertia.

Builders call this one, but this is just one of the brands that produces extruded polystyrene foam.

polyurethane foam

The insulation of the foundation of the house from the outside is also carried out with the help of a liquid insulation, which is sprayed onto the base with the help of special equipment and quickly hardens. Polyurethane foam is able to protect concrete well from negative impacts, since, in addition to standard characteristics, it has a number of advantages:

• It is applied in a continuous layer without joints and gaps, which makes thermal insulation more effective.
• fills all cracks and potholes that may have appeared during operation.
• The composition hardens quickly because the base can be sheathed with finishing materials immediately after performing thermal insulation work.
• Performs the function of waterproofing.
• Adheres to concrete, brick and wooden base because it has excellent adhesion properties.

Thanks to these advantages, polyurethane foam is gradually replacing polystyrene and polystyrene foam in private construction. But there is one difficulty. It is impossible to apply insulation without special installation.

Expanded clay

Before the advent of modern synthetic materials expanded clay and slag were used. These materials are inexpensive and have low thermal conductivity.

But in order to correctly and effectively insulate the foundation with expanded clay, it must be used in in large numbers. In addition, the process of arranging bulk thermal insulation is multi-stage and time-consuming. Of course, there are also some advantages:

1. Economy option - affordable price.
2. Everything can be done by hand without the help of professional craftsmen.
3. Expanded clay is a cheap material.
4. Used for horizontal (on the ground) and vertical insulation.
5. Safety for human life and health, as well as the environment.

How to insulate the foundation of the house with polystyrene foam from the outside

In order to install tile insulation, you must first prepare a place for work. For this, the following activities are carried out:

1. A trench about 1 m wide is dug around the perimeter of the entire building. The depth will be different depending on the depth of the foundation and the freezing of the soil.
2. The surface of the base is cleaned of dirt with a stiff brush.
3. The open foundation is left for 10 days to evaporate moisture.
4. The surface is inspected for defects. If they are large, then they are engaged in plastering.
5. Small cracks and crevices close up.
6. Equip waterproofing. For this, mastics based on polymers, rubber or bitumen are used. Organic will not work, because they will destroy the insulation.

Before using the mastic, the foundation is treated with a bituminous primer, which will improve adhesion. Waterproofing is applied in 2 layers, carefully processing the corners, and leaving no bald patches.

After the mastic dries, glue the expanded polystyrene outside the base. Be sure to choose an adhesive that will withstand high humidity and temperature fluctuations. If the base was treated with bituminous mastic, then it is also used as an adhesive.

1. The adhesive solution is applied along the perimeter of the insulation plate and a few strokes in the center.
2. The element is applied to the lower left corner and pressed firmly.
3. After fixing, check the building level.
4. The next part is applied as close as possible to the next one so that a minimum gap remains.
5. If the polystyrene foam insulation needs to be laid in several rows, remember to bandage the vertical seams.
6. After completion of the work, the parts that will be above the ground level are additionally fixed with dowels with wide caps.
7. Joints are additionally filled with sealant.

After the glue has completely dried, the trench is filled up, leaving 30 cm to the ground level. The earth is carefully rammed, lined with a waterproofing film (it is placed on the foundation), laid drainage pipes, fall asleep with gravel and sand, ram again and make a blind area.

Insulation, which is above ground level, requires a decorative finish. For this, choose basement siding or other durable material. A block house made of wood should not be chosen as a finish; over time, the cladding will lose its attractiveness, and not become prettier.

Features of the installation of thermal insulation made of polyurethane foam

If polyurethane foam is used to insulate the foundation of houses, then it is not necessary to pre-level the surface and cover it with waterproofing. It will be enough:

• Dig a trench.
• Clean the foundation from contamination.
• Dry.
• Check out the base. If there are old pieces that peel off, they are removed and sealed.
• Then polyurethane foam is applied.

Everything dries out very quickly, so you can immediately start arranging the blind area, and then the exterior finish.

Insulation of the foundation in the backfill method

Like the previous two options, you need to dig a trench. To save your time, you can hire special equipment. The bottom of the trench is completely cleaned of plant roots, and the foundation wall is free of dirt, and dried. Be sure to cover the base with 2 layers of bituminous mastic.

• A waterproofing film is placed in the trench, the edges of which should go onto the foundation wall.
• Fall asleep a small layer of sand, rammed.
• Install drainage pipes.
• Expanded clay is poured with a slope of 5 degrees from the wall.
• Another layer of sand is added on top, rammed.
• They make a blind area.

Water drainage from the basement

Since precipitation constantly affects the foundation, care must be taken that the water does not stop near the walls, but is diverted away. To do this, equip drainage during warming.

1. Drainage pipes are best laid below the level of the base of the foundation or basement floor.
2. Communications are protected by geotextiles.
3. The pipes converge into a drainage well, which is located 5-6 m from the building.
4. When arranging the blind area, do not forget about the slope, which will help to remove moisture from the walls and direct it to the drainage.

Insulation methods for different types of foundation

For the construction of houses, choose the appropriate option for arranging the foundation. But each of them requires its own technology of insulation. Applying one for all is not worth it because it will be difficult to achieve the desired result.

Strip foundation

This type of foundation can be insulated in two ways:

1. Horizontally - fill in expanded clay and make a blind area.
2. Vertically - use sheet or liquid insulation.

Such options have been described above. They are perfect for a strip foundation and protect against negative influences. Insulation is carefully selected, because its quality determines how warm and comfortable it will be in the room, and how long the foundation will last.

Column Foundation

In this version of the arrangement of the foundation, everything is a little more complicated. First you need to make a pick-up, which acts as a foundation wall. To do this, choose brickwork or make a frame from metal profiles or wood.

For brickwork you need to make a small trench, which is filled with sand and gravel, and a metal profile is laid on top. This design will be the basis for a brick wall. Next, build a basement.

After the solution dries, the wall can be additionally insulated with foam (or foam) plates and plastered. For decorative finishes fit any durable material. If a frame made of metal or wood is chosen for the pile foundation, it is also filled with insulation and lined. The metal profile is fixed by welding.

slab foundation

The insulation of the slab foundation begins after the foundation pit is prepared. A sand cushion is poured to the bottom and rammed. A waterproofing film must be laid on top of the sand. Further, a heater is placed over the entire area of ​​\u200b\u200bthe house, each next row is shifted to dress the seams.

Then they begin to arrange the formwork around the perimeter of the laid insulation. Steel bars are placed in the formwork for reinforcement. Everything is filled with concrete. After the solution has completely hardened, proceed to create a blind area.