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 effectively!
Why is it necessary to insulate the foundation?
Using insulation for the foundation is just as important as insulating the walls of the house! Especially in areas characterized by a harsh climate and freezing of the soil to great depths. Foundation building structure"gives away" 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 increasing in volume, which leads to a rise in ground level.
Attention! At significant depths of soil freezing, a “movement” of its level by 35 cm is possible. This value corresponds to 15% of the soil freezing depth.
The rise in ground level leads to deformation of the building foundation. If the foundation is laid above the freezing level and the foundation slab is not insulated, then during the period of freezing, frost heaving forces arise under this slab, directed normally (perpendicularly) to the surface of the slab. Therefore, in freezing zones, thermal insulation of the horizontal foundation slab is also carried out.
The quality of work in this thermal insulation direction will determine the operating conditions of the building as a whole and the comfort of living in it. Planning of foundation insulation work 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, floors raised above ground level are used. Cold air in large volumes it is located at the level of the foundation and floor, and the warm air rises up 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. Games room, gym, billiard room, laundry room - no matter what the purpose of the room is, it is important comfortable temperature air in it. And the presence of dampness without insulation of the foundation is guaranteed.
An unheated basement is “undemanding” in terms of thermal insulation. But the basement part of the foundation should be insulated. to reduce heat loss at the floor level of the first floor, which is heated.
Insulating the base of the foundation will allow you to save heat in the house by blocking the path of cold air into the house. Remember that high-quality insulation of a house, including the foundation, allows you to save from 30 to 50% cash allocated for heating.
In addition to thermal insulation functions, the foundation insulation layer plays an integral role in its waterproofing.
So, insulating the foundation:
- reduces heat loss;
- reduces heating costs;
- reduces or completely eliminates the impact of frost heaving forces on the foundation;
- stabilizes the temperature inside the building;
- prevents the formation of condensation on the internal planes of the walls;
- plays the role of mechanical protection of waterproofing;
- has a beneficial effect on the longevity of waterproofing and the foundation structure as a whole.
Which foundation insulation to choose?
Planning insulation work includes the main step - choosing a thermal insulation material. So, what is the best way to insulate the foundation of a house?
Such materials for foundation insulation should:
- do not deform under soil pressure;
- do not absorb moisture.
Today it is easy to “get lost” in all the variety of heat-protective materials. It is clear that the common insulation material mineral wool is not suitable here due to 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 insulation materials differ in different thermal insulation parameters and costs. For optimal choice it is necessary to study their advantages and disadvantages.
This is a modern thermal insulation material that combines the functions of heat, hydro and sound insulation. To use it, you need special equipment with which polyurethane foam is sprayed layer by layer onto the surface to be insulated. The thickness of the insulating layer is 50 mm and this is with a polyurethane foam density of 36 kg/m 3. A similar insulating effect can be achieved by using polystyrene foam with a thickness of at least 120 mm.
There are no gaps or 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.
Advantages of using polyurethane foam:
- seamless coating;
- high adhesive properties;
- low thermal permeability;
- low vapor permeability;
- reliability;
- "longevity";
- no need for additional vapor and waterproofing.
The disadvantages of this 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 is reduced by the complexity of installation and lower thermal insulation properties.
Plates made of extruded polystyrene foam, due to their closed cellular structure, practically do not absorb and, naturally, do not allow water to pass through. This means that the moisture in the slabs will not destroy them when they freeze. Therefore, extruded polystyrene foam is characterized by a long service life while maintaining its thermal insulation characteristics.
Pay attention! To the question: “How to insulate a foundation with foam plastic?”, we offer the following answer...
Using ordinary foam plastic to insulate 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 ordinary polystyrene foam easily absorbs.
Vertical thermal insulation of the foundations of civil and industrial facilities is carried out with extruded polystyrene foam slabs with a compressive strength of 250 kPa or more; private buildings allow the use of expanded polystyrene with a strength of up to 200 kPa. For flooring, it is necessary to choose slabs with a strength of 500 kPa or more.
Such “strength” characteristics of extruded polystyrene foam have a beneficial effect on maintaining the integrity of the foundation waterproofing and are its integral element, ensuring the normal long-term existence of the foundation.
Among the thermal insulation materials made from extruded polystyrene foam there are slabs with milled grooves. In collaboration with geotextile fabric, this material perfectly performs the function wall drainage, insulating the foundation, protecting the waterproofing and diverting water from the foundation to the drainage system.
Advantages of insulation with extruded polystyrene foam:
- long service life (at least 40 years);
- high compressive strength;
- constancy of thermal insulation properties during operation;
- "inedible" for rodents.
Foundation insulation with expanded clay
Until recently, this was the most popular method of insulating the foundation from the outside. It has been supplanted by the relative “cheapness” and high efficiency of the methods discussed above on how to insulate the foundation from the outside.
How to insulate the foundation of a house with polystyrene foam from the outside
Correct and effective insulation of the foundation from the outside in zones of soil freezing involves installing heat-insulating slabs to the freezing depth. Insulation of the foundation (walls) below the soil freezing level is not as effective and is often not carried out.
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 polystyrene foam slabs or polyurethane foam layer increases by 1.5 times.
It is also necessary to insulate the soil around the perimeter of the building. An insulating layer made 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 maintain the freezing limit in a layer of non-heaving soil (sand, gravel, etc.) buried along the walls.
The laying angle of extruded polystyrene foam slabs must be at least 2%, and the width of the blind area must correspond to the depth of soil freezing in the given region. The optimal thickness of the slabs corresponds to the thickness of the vertical insulation layer of the foundation.
Before insulating the foundation of a house from the outside, the surface of the walls must be leveled and waterproofing must be done on it.
When installed, extruded polystyrene foam slabs create an airtight shell for the foundation. Therefore, the use of mechanical fasteners for their fixation is unacceptable due to point depressurization of the insulation layer.
The heat insulation boards are fixed by applying an adhesive composition to them or by “melting” a layer of bitumen waterproofing at 5 or 6 points, to which the polystyrene foam board is then pressed and held for some time until it hardens.
Installation of slabs begins from the bottom, the rows are connected end-to-end. The thickness of the plates must be the same. The vertical seams of adjacent ones should be offset relative to each other (checkerboard order).
Attention! The use of torn slabs for re-installation is not allowed, as is the displacement of slabs after the bitumen or adhesive solution has hardened.
The seams between slabs with a thickness of more than 5 mm are filled with polyurethane foam; it is more convenient to use slabs 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. The use of roll or mastic waterproofing materials on a bitumen basis determines the use of bitumen mastics as an adhesive composition that do not contain aggressive ingredients for polystyrene foam.
Attention! Before insulating the foundation from the outside, you must wait until the bitumen waterproofing has completely dried (5-7 days). You cannot install slabs of extruded polystyrene foam on a wet base of bitumen waterproofing, as the slabs can “move apart” and damage the waterproofing. Also, the composition of bitumen waterproofing may contain solvent particles, which, in their “undried” form, can harm polystyrene foam boards.
Glue is applied to slabs located below ground level in several points. This will allow moisture that has condensed between the surface of the insulation and the foundation wall to flow down without hindrance.
The use of fastening dowels together with the adhesive composition of polymer-cement adhesives is necessarily applicable for polystyrene foam slabs located above ground level at a rate of at least 4 pieces. for one slab. The slabs located in the ground are attached only to the adhesive composition and are pressed with a layer of soil.
Features of installation of thermal insulation made of polyurethane foam
Foundation insulation with polyurethane foam is performed in this way. Let's watch the video...
How to insulate a foundation slab?
When deciding how to insulate the foundation from the outside, for more effective insulation of the floor or basement, care should be taken to insulate the foundation slab.
In this case, the insulation boards are laid on a layer of waterproofing.
Further, if knitted reinforcement is used to fill the power floor, it will be enough to cover the layer of heat insulation with polyethylene film with an overlap of 100-150 mm and gluing with double-sided tape.
When using a welded reinforcement structure, it is necessary to make a protective screed of concrete or cement-sand mortar on top of the film, and then carry out welding work on top of it.
Foundation insulation For normal operation of the building, it is necessary to insulate the foundation of the house from the outside and lay expanded polystyrene under the blind area. The thermal insulation circuit solves several problems - expanding the frost-free zone, eliminating swelling, cold bridges and heat loss. The need for measures to eliminate swelling conditions (freezing + moisture + clay soil) is separately indicated in the standards SP 22.13330 (foundations), departmental VST, territorial TSN (for example, MF-97 for the Moscow region).
In order for an individual developer to insulate the foundation without errors, it is necessary to take into account that the owner’s expenses always consist of the construction estimate and the operating budget. Accordingly, by changing any of these points, you can automatically affect the other:
- by refusing to insulate the blind area or foundation, the owner saves on the purchase of expanded polystyrene, but heating and repair costs increase;
- By investing in thermal insulation, the developer increases initial costs, but automatically reduces operating costs.
By investing money in their own home, a young family receives an advantage in retirement in the form of significantly lower payments utilities due to energy savings and lack of foundation repairs.
Heat distribution diagram near the foundation. It can be seen that the freezing boundary is moving away from the foundation.
Depending on the operating mode of the building, the developer’s budget and the type of soil, horizontal and vertical insulation contours solve different problems:
- blind area - an EPS tape laid under it moves the freezing zone outward from the house, swelling is impossible in the soil layers adjacent to the foundation;
- outer vertical surface of the tape - protection of waterproofing, elimination of cold bridges, reduction of heat loss through the floor/floor of the house, shifting the dew point outward for normal operation of the underground floor;
- horizontal layer under the base of the MZLF - if the building does not have heating or is heated during periodic visits, to eliminate freezing of the soil underneath it is necessary to retain the heat of the subsoil with a continuous layer of polystyrene foam.
Important! A set of works to eliminate swelling must be carried out only on clay soils. However, heat loss in a complex plinth assembly with multilayer cladding, adjoining various designs from different materials can be prevented only by external thermal insulation of the vertical surfaces of the foundation.
Materials and technology for foundation insulation
Given the existing variety of thermal insulation materials, foundation insulation is most often done with extruded high-density polystyrene foam EPS, XPS, Carbon SP from TechnoNIKOL, Penoplex Foundation. Unlike mineral, glass and ecowool, polystyrene foam retains its heat-insulating properties, even when completely immersed in water. For comparison, basalt wool loses 30% of its properties when wet and begins to slide off vertical surfaces under its weight. It is prohibited to rest concrete structures on soft insulation materials.
Insulation materials
To protect the foundation of a private cottage, the following are most effective: thermal insulation materials:
- polyurethane foam - marked PPU, sprayed onto the surface, also available in the form of slabs, density 50 - 60 kg/m3, thermal conductivity corresponds to 0.028 units, costs twice as much as expanded polystyrene;
- extruded polystyrene foam – various designations from manufacturers, slabs different sizes, density 35 - 45 kg/m3, thermal conductivity 0.03, costs less than the previous option.
Insulation of the foundation with extruded polystyrene foam.
The polyurethane foam used to fill the seams of insulation is made of polyurethane foam. Therefore, when using Penoplex, EPS, the quality of the joints is higher than that of the main surface.
The main disadvantage of expanded polystyrene is its low chemical resistance - the material is dissolved by petroleum products. Therefore, it is not recommended to paste over concrete surfaces treated with bitumen mastics, fused roll materials having a bitumen layer. It is better to use polymer mastics, membranes or polyethylene films. Polyurethane foam is inert to petroleum products, acids, alkalis and salt solutions.
Budget foam plastic PSB-S has a density of 15 - 25 kg/m3, thermal conductivity of 0.04 units, and vapor permeability of 0.05. This insulation is used in the following cases:
- outer layer vertical crushable insulation;
- permanent formwork for a low grillage (lower horizontal deck).
In the first case, insulation is necessary to protect the main layer of heat insulation. In the second option, the foam plastic remains after the grillage is poured under the reinforced concrete structure, and is crushed by the soil during swelling, so that heaving forces cannot tear the grillage beams away from the pillars or piles, the heads of which are embedded in the structure.
Technology overview
Foundation insulation is carried out according to different schemes depending on the operating mode and design. Anti-swelling protection is required for columnar, strip and slab foundations. Heaving forces practically do not affect the piles, however, with a low grillage on bored piles, screw piles the beams must be positioned at least 10 cm above the ground.
Scheme for insulating the foundation and outside blind area for a house with constant heating.
There are three main operating modes at home:
- constant heating - insulation reduces heat loss, expands the zone of non-freezing soil around the building and protects the foundation from the effects of negative temperatures;
- heating is completely absent - eliminating heat loss in this case is pointless, however, it is necessary to preserve geothermal heat under the building to prevent soil freezing, so the blind area + the entire perimeter of the garden house under the sole is insulated;
- heating is turned on periodically (baths and cottages) - since episodic heating is present, it is necessary to reduce heat loss in the ceilings and floors, the outer surface of the grillage, strip, slab and blind area is insulated; when there is no heating, there is a need to preserve the heat of the subsoil, so the entire perimeter of the house under the sole is insulated foundation.
IN garden houses without heating, laying polystyrene foam at the level of the foundation base is not always economically profitable:
If the depth of the pillars or MZLF is within 40 cm, it makes sense to make a pit, since the fertile layer will still have to be completely removed in order to make floors on the ground.
If the strip or columnar foundation lies deeper, excavation work can be avoided by laying insulation according to a different scheme:
- under the blind area - the perimeter of soil freezing moves away;
- under the base of the foundation – protection against swelling;
- on the inner surface of the tape + under the floor along the ground - preservation of geothermal heat under the entire foundation structure.
If for some reason it is impossible to fill the pit openings with non-metallic material that does not contain clay and, accordingly, frost swelling, instead of the standard insulation of the outer surfaces of the strip foundation, a crush-sliding thermal insulation scheme should be used:
- pasting external concrete vertical surfaces with high-density polystyrene foam;
- covering it with polyethylene (attached only in the base part);
- installation of low-density polystyrene foam PSB-S close to the film without fastening (pressed with backfill material).
This option is especially relevant for deep-laying belts. The contact area of the side surfaces of the belt with clay soils is enormous, and the pull-out loads are very significant. When heaving forces occur, the soil crushes the foam and moves it upward along the slippery film. The main layer of insulation is not harmed; after the spring thawing of the soil, the outer layer moves down again.
Important! Insulation is only one method of eliminating swelling in a set of measures. Therefore, drainage and nonmetallic materials in the underlying layer and backfilling of sinuses cannot be canceled.
IN classical technologies monolithic foundations (slab, strip, pillars) to reduce the lower protective layer of concrete, level the base, eliminate leaks of cement laitance from the concrete at the time of pouring, a concrete screed is used.
If a building for seasonal, periodic operation is insulated with a layer of expanded polystyrene along the entire perimeter of the pit, then there is no need to make a concrete footing. This allows us to slightly reduce the construction budget.
Errors in foundation insulation
Due to lack of experience, individual developers often make mistakes when insulating foundations:
- cold bridges - the thermal insulation contour must be continuous, the seams must be foamed, the joints of the slabs must be displaced in the case of a multilayer contour in adjacent layers;
- the use of low-density materials - PSB-S is allowed only for the lower deck of the grillage, the outer layer of crushable thermal insulation;
- violation of thermal insulation schemes - for basements, MZLF buildings with constant heating, it is necessary to insulate the tape from the outside, without heating and when the heating is periodically turned on - from the inside;
Cold bridges, which negate the effectiveness of insulation work, usually occur at the junction points of the base elements:
- lack of lateral vertical thermal insulation along the perimeter of the floor screed on the ground;
- uninsulated concrete preparation;
- absence of polystyrene foam on the upper horizontal edge of the protruding base;
- incorrect combination of basement insulation and façade insulation.
Errors in pairing the insulation of the base and façade.
Important! It is impossible to correct the cold bridge created as a result of facing the facade with brick, the bottom row of which is installed directly on the protruding plinth.
Thus, despite the fact that it is recommended to mount the insulation on the outer surfaces of the foundation, this scheme is correct only for dwellings with a constant heating mode. In garden houses, thermal insulation is made along the inner edges of the tape. The blind area is always insulated; crushable thermal insulation is usually necessary for deep-lying tapes.
You can protect your home from freezing during the cold season by insulating the foundation of the house from the outside with polystyrene foam or other types of materials. Without insulation, heat from the room will escape through the cooling walls.
Foundation insulation with polystyrene foam is a common method of thermal insulation of the base of a building. Expanded polystyrene materials have a foamed structure. Foundation walls protected by these thermal insulators retain heat well and virtually do not allow water to pass through.
Polystyrene foam is a cheaper type of polystyrene.
Insulating the foundation with extruded polystyrene foam will cost the most.
Polystyrenes are produced in the form of slabs of different thicknesses. You can choose the appropriate size of material taking into account the type of foundation of the house, the presence of a basement or basement. When choosing, you should also take into account the characteristics of the local climate.
IN Russian conditions It is considered more acceptable to insulate the foundation with polystyrene foam 5 cm thick. If a wine cellar is equipped in the basement of the room, the temperature in which is about 10 ° C, then it will be better if the thickness of the polystyrene foam is 10 cm.
Increased attention is paid to gluing the corners of the foundation, since freezing of the entire structure begins precisely from them. For this purpose, slabs approximately 3-4 cm thicker than the main heat insulator are used.
In fact, not too many heat insulators are suitable for insulating the foundation. The choice is made according to the rule that the thermal insulation layer must have a service life approaching the durability of the structure itself. Based on this, we can conclude that it is better not to use polystyrene foam for insulating the foundation.
Considering that the service life of reinforced concrete is at least 100 years, and foam plastic is about 20-25 years, it is almost impossible to control the condition of PPS buried in the ground.
After using polystyrene foam, a problem will certainly arise associated with re-insulating the foundation. Despite the fact that thermal insulation with polystyrene foam is performed more often than insulating the foundation with polystyrene foam, this approach is not considered rational among professionals.
Properties of polymer insulation
In modern construction, the most suitable polymer materials are used to carry out foundation insulation work:
- penoplex;
- extruded polystyrene foam.
There are no fundamental differences between these polymer-type heat-insulating materials. This is explained by the fact that they are made on the basis of polystyrene. There are minor differences in the production technology of these heat insulators related to foaming. Penoplex and extruded polystyrene foam for the foundation have properties such as low thermal conductivity and high strength. These heat insulators are excellent for insulating the foundation of a cottage or private house. They can be used to provide insulation columnar foundation, shallow, strip, pile and other types.
The materials are similar in composition, which is reflected in their durability and quality. They do not absorb water, but polystyrene foam, which has lower thermal conductivity than polystyrene foam, is more durable.
The cost of expanded polystyrene is higher than that of polystyrene foam. Consequently, prices for insulation with these materials vary. These thermal insulators have an attractive appearance. According to some information circulating among builders, foam plastic is considered a material that can replace 50 cm brickwork. No one has conducted any experiments to compare the density of brick and foam plastic, but this indicator is lower for PPS, so the insulation has less thermal conductivity than brick.
Insulation of the foundation from the outside with polystyrene foam
Carrying out installation work on insulating the foundation with foam plastic is not difficult. Insulation should be applied to the waterproofing. Insulation of a strip foundation with polystyrene foam is carried out as follows:
- the wall is treated with a heat-insulating coating;
- the surface of the wall is covered with a waterproofing layer;
- measurements are taken of the freezing depth, to which 5-10 cm is added;
- the container (bucket) is filled 1/4 with water and foam glue is added;
- the composition is thoroughly mixed with a mixer until the consistency of thick sour cream;
- glue is applied to the foam sheet in several places and leveled using a notched trowel;
- the insulation sheet is pressed tightly against the foundation wall;
- the subsequent sheet is inserted into the lock of the previous one, if provided;
- the sheet is glued to the wall by pressing the material;
- the foam is covered with a PVC membrane;
- the dug trench is filled with sand.
All steps to insulate the foundation with foam plastic are not complicated. At the same time, experts do not recommend nailing the insulation to the foundation wall with nails, since you can break through the waterproofing.
The foam installation method is most suitable for beginners. This method cannot be compared in cost to spraying polyurethane foam. It is best to carry out insulation with an assistant, so that one person can cut and feed the sheets, and the second can apply glue and mount the insulation on the wall.
Application of thermal insulation in construction
The best method of thermal insulation of the base of a house is considered to be insulation of the foundation with penoplex. This method is used mainly at the stage of building a house. Fastening polystyrene foam to concrete in most cases involves the use of special bitumen mastic.
The entire surface is first leveled with a cement composition, and then the even wall of the foundation is cleaned. After this, the first layer of mastic is applied, that is, a bitumen primer, onto which a roll of waterproofing is glued, and a heat insulator is attached on top. An additional layer of geotextile is laid on top as a protective covering. Often, penoplex is simply covered with soil.
To create additional protection significant expenditures of money will not be required, but geotextiles can significantly extend useful term heat insulator services. The technology of foundation insulation using expanded polystyrene can be studied by watching the video.
Another method of insulating the base of a house where there is no basement is used to insulate foundations in the form of a solid concrete slab.
The essence of the method is that polystyrene foam is laid on a sand bed, and a concrete base is poured on top. At the same time, it remains possible to immediately install the heating circuit of the “warm floor” system into the monolithic foundation. The name of this design is Swedish stove. It refers to shallow foundations, which are insulated not only from below, but also along the entire perimeter.
Based on the beliefs of energy efficiency, this development is one of the best, but it requires scrupulous work. Otherwise, failure to comply with the technology can lead to cracks in the slab and subsequent damage to the “warm floor” system.
The main disadvantage Swedish stove is the inability to carry out repairs after cracking. A solid slab can be mounted on different soils, so it successfully replaces a strip foundation. Proper installation of the heat insulator should ensure a long service life of the base structure.
Insulating the structure of a Swedish stove is appropriate if the owner personal plot I decided to build my house from wood, planning to lay heated floors in the foundation of the building. This problem requires a serious approach, since after the house has already been built, it is impossible to do without dismantling work. In this case it is necessary to do:
- removal of plinth cladding;
- opening of the old blind area around the building.
If the foundation of the house is a shallow strip foundation, then you will have to dig a trench to its base in order to install heat-insulating material over the entire surface of the foundation. Another common option is to insulate the base and lay penoplex under the blind area. This will protect the underground part of the base from freezing.
Thermal insulation throughout the foundation and the soil under the blind area is the most best way insulation of the base of the house. If you decide not to dig to the foundation, you can dig a hole along the entire perimeter of the foundation. The width of the pit should be more than 1 m of the entire wall, and its depth should be 200-300 mm. The soil near the base must be compacted properly. Next you will need to do the following:
- clean the base;
- remove all sagging;
- seal cracks;
- dilute the glue in water;
- strengthen polystyrene boards to the base;
- fix the slabs with umbrella dowels;
- pour a layer of sand more than 10 cm wide into the hole;
- level and compact the sand;
- lay out slabs of penoplex (expanded polystyrene);
- strengthen geotextiles;
- refill the blind area;
- install the plinth cladding.
Choosing polystyrene foam for foundation insulation
Since process The production of extruded polystyrene foam is carried out under pressure, this makes it possible to produce insulation, the structure of which includes molecular bonds of high strength. EPPS is of higher quality than polystyrene foam (PSB). Often, extruded polystyrene foam becomes a material that is almost irreplaceable in cases where ordinary foam plastic simply cannot withstand the load.
Before choosing EPS, you need to understand what technical characteristics it has. Expanded polystyrene is manufactured in several modifications, since different areas of the house (roof, walls, foundation) require various types PPP. Each modification of PPS has different characteristics, so it can be used to insulate only a certain area of the house.
Markets building materials They sell polystyrene foam in 3 main brands:
- PSB-S-15.
- PSB-S-35.
For insulating the foundation, the last option is considered the most suitable, because this brand of heat insulator has protective sealed layers, so it does not absorb water. When purchasing expanded polystyrene, you should make sure that the material is marked “Foundation”. This will allow you to choose the one that suits all technical characteristics material.
The thickness of the EPS is selected depending on the climatic conditions in the region of construction. The width of this material can vary from 1 to 10 cm. For middle latitudes, a heat insulator 5 cm wide is suitable. Each manufacturer produces similar heat insulation boards of various sizes, so you must first determine how many of them will be needed.
Polystyrene can be strengthened to the foundation using either special glue or bitumen. It is worth considering: after gluing, polystyrene foam slabs remain movable for more than 20 minutes. Therefore, they need to be strengthened not only with glue, but also with plastic dowels, selected with a margin of length.
If polystyrene with a width of 5 cm is installed, then the dowels must have a length of more than 10 cm. To attach the slabs, glue of the Bitumast brand, Ceresit ST-84, cement-polymer, bitumen adhesives that do not contain gasoline, ether and acetone are used.
Properties of extruded polystyrene foam
Many home owners use foam plastic to insulate the foundation, which is considered a good thermal insulation material. Professionals believe that polystyrene foam is more suitable for thermal insulation of external walls than for insulating the foundation.
Foam plastic can be damaged by rodents, and its shelf life is not very long, since this heat insulator absorbs water, while having low strength and a very high deformation coefficient. Pressless expanded polystyrene (foam) begins to crumble into individual balls after just a few seasons. This occurs due to the hygroscopicity of the material.
Extruded polystyrene foam (EPS) is more durable than polystyrene foam. The duration of its operation significantly exceeds the shelf life of polystyrene foam. Builders often call EPPS Polpan. The technology for its production differs from the production process of polystyrene foam, since EPS is produced under pressure, initially representing a semi-liquid viscous foam mixture fed through a nozzle with a certain cross-section.
As a result, slabs of various sizes are produced. Modern developers often have to insulate the outside of houses with penoplex slabs, that is, extruded polystyrene foam. The material is orange in color.
Thermal insulation of a columnar foundation with polystyrene foam
Before you insulate a columnar foundation with your own hands, you will need to purchase a heat insulator and suitable glue for it. Then you should perform all the following types of operations in turn:
- Dig the foundation to its depth, making a trench around it.
- Cover the foundation with EPS at least to the depth of freezing of the soil.
- Clean the foundation, removing all crumbling or chipping concrete particles.
- Cover the surface of the foundation with a penetrating primer (2 layers) and let it dry until it is completely absorbed into the concrete.
- Waterproof the foundation with bitumen mastic.
- Apply glue onto the slab in spots.
The polystyrene foam is attached to the foundation 1 minute after applying the glue. If the size of the polystyrene board is 120x60 cm, you need to apply more than 8 strips of glue 1 cm wide. For this, a comb spatula is used. You need to start from the bottom, rising in rows.
If the polystyrene foam insulation does not have special locks, then after 3 days polyurethane foam is injected into the seams between its plates for sealing. Dowels can be used for fastening, so holes for them are drilled along the edges of the slabs and in the center of each of them.
When insulating a columnar foundation with your own hands, coating waterproofing can be used if protection from capillary water is required. The level of hydrostatic pressure can reach up to 0.1 MPa.
The technique of coating waterproofing is quite simple. It is performed using bitumen or polymer mastics that cover the surface of the foundation with a film with waterproof properties. The use of coating technologies is typical for vertical waterproofing of foundations.
When carrying out horizontal coating waterproofing, it is necessary to take into account the fact that due to their low strength they are used only as auxiliary waterproofing layers. After processing each hole a small amount polyurethane foam dowel-nails are driven into them. Then waterproofing is applied to the heat insulator with polymer mastic, and after it dries, the trench is covered with earth.
The foundation of any structure can serve not only as a support and foundation for the building. It can also perform quite utilitarian functions and serve as walls for habitable premises located on the semi-basement and ground floors.
Creating a useful volume inside the perimeter of the foundation (living space) is possible, as a rule, by laying a continuous strip foundation. The foundation is in the form of a concrete monolithic slab, usually does not involve the construction of basements. In principle, it is possible to build a room inside a columnar foundation, but you will still have to equip the outer perimeter walls for this.
In order to build a habitable room inside the perimeter of the foundation - foundation walls need to be insulated. Strip foundation in the vast majority of cases it is made of concrete (both from ready-made blocks and from self-formed concrete casting), and this material has very poor thermal insulation properties. In order for a person to feel comfortable in such a room, it is necessary to carry out thermal insulation work.
13.06.2014
More recently, in the 80s of the last century, utility bills accounted for only 3-4% of the total family income. Today, the share of communal services on average reaches 10-15% of family income, and payment for heating is 30% of this amount. It is not surprising that the majority of Russian citizens prefer to closely monitor expenses, and especially heat leaks in their homes. It has been established that the base and foundation account for about 20% of heat loss, so insulating the base of a house is as important and necessary as it is. Properly performed insulation will not only preserve expensive heat, but also avoid moisture condensation on the walls of the base, the formation and development of mold, and also protect the structure from freezing.
No. 1. Basement insulation: outside or inside?
The basement is called one of the most vulnerable parts of the house, because it bears not only a large load in the form of the weight of all the walls and ceilings, but also often high humidity. The base is the continuation that rises above ground level and goes into. Simply put, this is the connecting and building walls starting from the floor level of the first floor. It protects the house from the penetration of moisture and cold, and also plays a decorative role, since a house without a base looks somehow squat.
Theoretically, it is possible to insulate the base of the foundation both from the inside and from the outside, but the effectiveness will vary greatly. If you carry out internal insulation, then to a certain extent it will be possible to achieve insulation of the room from low temperatures, but condensation will accumulate between the wall and the insulation, which will damage the base. In addition, the latter will not be protected from the harmful effects of cold. The result will not be long in coming - the appearance of microcracks from freezing, their expansion, constant wetting, and later deformation and crumbling, a decrease in strength characteristics.
External insulation allows you to protect both the room and the base material from the cold, and the dew point shifts towards the insulation, which is much more resistant to moisture and low temperatures than the base. As a result, we get an extension of the service life of the structure. Thermal insulation work is best carried out during the construction of a house, but even after its construction it is possible to carry out effective insulation, although it will be a little more difficult.
No. 2. Is it necessary to insulate the basement of a house?
The peculiarity of the domestic mentality is such that you want to save on everything. Hence the popular question: Is it always necessary to insulate the basement of a private house? Thermal insulation may not really be needed in the following cases:
- if the house is intended only for summer living;
- if the house does not have a basement, but the basement is small (0.5 m) and is arranged to avoid flooding;
- if the house is located in an area where there is no severe winter.
In all these cases you can get by. If the climate in the region is harsh, the house is used for permanent residence, and the basement is supposed to store food, equip a boiler room or other utility rooms, then insulation is indispensable. 
No. 3. Materials for insulating the base
In the recent past, a mixture of clay and straw was used to insulate the base of the foundation. Over the past few decades, many new, more advanced and convenient ways to perform thermal insulation have appeared. A row moves towards them requirements:
In addition, the insulation must be durable, vapor-permeable, and rodent-resistant.
Today the following materials are used for insulation:
- thermal insulation boards (foam plastic, extruded polystyrene foam, mineral wool);
- polyurethane foam, which is applied by spraying;
- expanded clay is the most popular option for bulk thermal insulation;
- warm plaster;
- thermal panels;
- priming.
No. 4. Base insulation with extruded polystyrene foam
Extruded polystyrene foam – the most popular material for insulating the foundation base. Often it is also called penoplex by the name of the company that produces the material under the trademark of the same name. The insulation resembles the one familiar to us all, but it is stiffer and more durable, withstands soil pressure well, does not wrinkle or sag.
Advantages:
Moreover, penoplex has noise-insulating properties, and thanks to impregnation with fire retardants, it is resistant to fire. TO shortcomings include a large number of joints - a minus of all tile materials. Even the largest sheets of expanded polystyrene do not allow you to create a monolithic insulation structure, and the joints will have to be carefully covered or foamed. It is better to take sheets with a lock, thanks to which they fit together more tightly, reducing the risk of cold bridges. In regions with a harsh climate, it may be necessary to install penoplex in two layers, with the slabs of the second layer covering the seams between the slabs of the first.
In addition, although the material is not as fragile as polystyrene foam, it can withstand decent loads, but it crumbles when cut. Installation is simple, but requires care and attention, and takes a lot of time. It is better to do this in the summer, in warm, dry weather. 
A more affordable analogue of the material is polystyrene foam., which is not obtained by extrusion. It holds heat well, but has a lot of disadvantages. Firstly, it is fragility, so to protect the material from earth pressure, they build a wall half as thick. Secondly, it is damaged by rodents. Moreover, the material is capable of absorbing moisture, so you can’t do without a high-quality roll or bitumen-polymer, and the need to carry out all this work negates all the benefits of buying polystyrene foam, so the material is used less and less for insulating walls and basements.
No. 5. Foamed polyurethane foam for base insulation
No. 6. Mineral wool for basement insulation
No. 7. Insulation with expanded clay
No. 9. Insulation with warm plaster
The best insulation options, of course, are extruded polystyrene foam and polyurethane foam, but, as we see, under certain circumstances, other thermal insulation materials have the right to be used.