The manufacturer Penoplex has developed a number of design solutions for thermal insulation of load-bearing structures of buildings. The most popular standard among individual developers is STO 36554501-012, which allows construction to be carried out with a minimum budget. The technology was created specifically for shallow foundations and eliminates freezing of soils under the base of the cottage adjacent to reinforced concrete strata structures.

Application of Penoplex thermal insulation technology

Preserving the heat of the subsoil around the perimeter of the building is one of the methods for eliminating frost heave. However, the technology is effective only in combination with drainage and the use of non-metallic materials in the backfill and underlying layer. The developers of the standards STO 36554501-012 called foundation insulation with Penoplex using the TFMZ method (thermal insulated shallow foundation).

Technology suitable for 1 - 3 storey buildings on seasonally swelling soils with normal design soil resistance. Standard Penoplex boards made of extruded high-density polystyrene foam or similar products from other manufacturers corresponding to the XPS class are used.

Attention: With a guaranteed absence of swelling, the soles of the MZLF and columnar foundations are laid at levels of 30 - 40 cm, allowing a significant reduction in the construction budget. The technology cannot be used for permafrost, unstable soils.

Design nuances

Suitable for any heaving soil, it uses two heat-insulating contours - vertical along the outer surfaces of the foundation, horizontal at different levels (under the base of the foundation + under the blind area). In this case, various problems are solved:

Attention: The technology has modifications for cottages for permanent residence (heating in winter), houses for seasonal, temporary use (without heating or with periodic turning on of the boiler).

Thermal insulation technology step by step

Produced in several stages. Horizontal thermal insulation is laid on top of the underlying layer (sand, crushed stone) before installing/concreting the foundation. After the monolithic reinforced concrete structures gain strength and stripping, the outer edges of the foundation strip, pillars, and slabs are waterproofed.

Extruded polystyrene foam is then glued on top of this protective layer. Lastly, the blind area is insulated. If the project uses technology floors on the ground or the building is planned to be used seasonally, periodically, the heat insulation is laid around the entire perimeter of the house.

Pit

With a foundation depth of 30–40 cm, taking into account the thickness of the underlying layer of non-metallic material, the depth of the pit is:

To determine the size of the pit, it is necessary to take into account a number of factors:

• if the project involves laying floors on the ground, you need to remove the entire arable layer of black soil in the building spot, since it is impossible to fill the screed on such soil, which is rich in organic matter - it will sag
• for heated houses, trenches are cut, the width of which is equal to the size of the base of the foundation + the width of the insulation of the blind area (0.6 - 1.2 m)
• for unheated buildings, a pit to the specified depth is required, the insulation will lie as a continuous carpet

Attention: Expanded polystyrene in TFMZ technology is located under the bottom of foundation structures (without heating), therefore it is necessary to use only modifications of high-density heat insulator EPS or XPS to avoid drawdown. The blind area can be insulated with PSB-S materials, which have a lower density and are much cheaper.

Foundation pad, drainage

The underlying layer is necessary to replace heaving soils, level the bottom of the trench/pit, and drain the space around the foundation. It is allowed to make it from the following materials:

The same materials should be used to fill the sinuses of trenches and pits to eliminate the tangential heaving forces that tend to push the foundation to the surface. In both cases, layers of 10–15 cm are compacted using a platform vibrator (vibrating plate).

Attention: If crushed stone is used, the surface of the foundation pad must be leveled with a minimum layer of sand sufficient for this. Otherwise, the polystyrene foam may be destroyed by the sharp edges of the stones when transferring serious loads from the building that presses on it.

It is produced in slabs 5–10 cm thick in one or several layers. In any case, the contour must be continuous; the cracks are filled with polyurethane foam.

Heated cottage

If the home is used year-round, foundation insulation with Penoplex produced according to the following scheme:

In the case of flooring using beams, the interior of the building is not insulated. Under it, in any case, the temperature remains above zero; heat loss through the ceiling is prevented by laying thermal insulation between the rough and finished floors.

Thus, the foundation is covered from the outside with a layer of expanded polystyrene, and there are no cold bridges at all.

Attention: If the wall does not have insulation inside, then polystyrene foam in the upper part of the base is placed inside, under the wall material, to eliminate the cold bridge at the end of the base.

Building for seasonal, periodic use

In garden houses, dachas (without heating, with periodic heating, respectively) foundation insulation with Penoplex produced according to a different scheme:

This is due to the following factors:

Attention: In the corners of the strip foundation, the concentration of reinforced concrete is greater, which causes intense freezing of the adjacent soils. Therefore, two layers of EPS are used here, covering straight sections of 0.5 - 1.5 m, depending on the width of the tape and the size of the MZLF.

Main mistakes of TFMZ

The lower diagrams discuss the reasons for the occurrence of cold bridges in foundation insulation structures and methods for their elimination.

In the first case, the polystyrene foam layer is protected from mechanical damage by the brickwork on which the cladding of the plinth and facade rests. The continuity of the circuit is broken, which is very difficult to correct later. Therefore, laying should begin on top of the heat-insulating layer of the blind area.

In the second option, the cold bridge is the upper end of the base part of the MZLF. It is also not possible to correct the error after cladding the facade. Therefore, the insulation should be installed inside before starting masonry.

In the last scheme, the cold bridge is the base section of the MZLF tape, not lined with polystyrene foam. This error can be corrected at any stage of construction and operation.

Thus, the manufacturer Penoplex not only produces high-quality insulation, but has also developed standard solutions for all load-bearing structures of residential, industrial, and administrative buildings. This will help the individual developer avoid design and manufacturing errors.

For a person who is starting to build his own house for the first time and has not studied the “material parts” enough, the very fact that the foundation, it turns out, also needs thermal insulation may seem strange. It would seem - why insulate a reinforced concrete strip if there is no basement or basement? If there is no direct contact with the living rooms, are they located higher? Which one is better to use? Such a lack of understanding of the importance of the issue often leads to the fact that thermal insulation work on the foundation is not initially planned and is not included in the estimate.

Meanwhile, such neglect of this stage of work entails a lot of negative consequences - we’ll talk about this below. Moreover, the condition of the entire house as a whole directly depends on the strength of the building’s foundation and its durability. And a careless owner, looking for savings in such matters, places a “time bomb” under his possessions.

This publication will discuss foundation insulation with penoplex technology, calculations, important nuances of implementation, down to step-by-step instructions. Read, get acquainted, immediately consider it one of the mandatory stages of construction. Well, if someone’s house already stands on an uninsulated strip foundation, it’s not too late to correct the situation.

Is insulation of a reinforced concrete foundation really necessary?

So, to begin with, it seems necessary to dispel doubts about the advisability of insulating a reinforced concrete foundation. And several reasons can be cited as justification.

• It would be very naive to believe that insulating the walls and floors solves the problem of thermal insulation of the premises on the first floor. If the foundation in its recessed and basement parts remains “bare,” then, due to its enormous heat capacity, it turns into a powerful cold accumulator. And it will literally “pull out” the heat generated by the heating system. The consequences are clear: these include difficulties in providing comfortable living conditions and unnecessary overconsumption of energy resources. And with an insulated foundation, heating costs are very significantly reduced.
• If the foundation is not insulated, then the temperature of its upper buried part, above the freezing level, and even more so in the basement, will always be strikingly different from that in the area of ​​the sole (here it does not change much throughout the year). Such a temperature difference and the resulting difference in the linear expansion of the material create very significant internal stresses in the reinforced concrete foundation belt. And this, in turn, becomes a prerequisite for the appearance of cracks, accelerated aging of the structure, deformation and even gradual destruction. This means that it is necessary to take measures to eliminate such a “temperature gradient” - this is what will help to create a layer of thermal insulation.

• The eternal “enemy” is water, which penetrates into the pores of the material and leads to its erosion during freezing and thawing. Thermal insulation also combats this. Firstly, most of the insulation materials used in this area of ​​the building make a good waterproofing barrier on their own. Secondly, the thermal insulation layer brings the dew point outward, precisely into the insulation layer, and the foundation material no longer suffers so much from high humidity combined with temperature changes. Of course, high-quality concrete, according to its characteristics, has a fairly high frost resistance index (the permissible number of freezing and thawing cycles). But this inherent reserve of its strength should not be spent thoughtlessly.
• As a rule, insulation of the foundation is carried out in conjunction with the creation of an insulated blind area around the perimeter of the house. This combination of vertical and horizontal thermal insulation will not allow the soil to freeze in the area of ​​the foundation strip. And this, in turn, means that the forces of frost swelling will not act on the foundation.

• There is no need to convince anyone of the importance of waterproofing the buried part of the foundation, which is incorrect. And the insulation layer plays another very noticeable role here. Firstly, it does not allow direct contact of wet soil with the reinforced concrete strip. And secondly, it protects the waterproofing layer applied to the foundation from mechanical damage.

Please pay attention to an important nuance. All of the above positive properties of the thermal insulation layer will be possible only if it is located on the outside of the foundation strip. It should not be left “for later”, with the expectation of fixing the walls from the inside, “when you get around to it.” Yes, perhaps this will somewhat improve the microclimate in the basement or basement. But in fact, the foundation still remains without any protection. So - exclusively on the outside!

Why does penoplex seem to be the optimal material for foundation insulation?

The variety of modern thermal insulation materials is quite wide. But not all of them are suitable for the specific conditions of foundation insulation.

This is understandable - the insulation, in fact, is buried in the ground, that is, it will be subject to very serious mechanical stress. In addition, this is constant contact with the soil, which, especially in the upper layers, is saturated with soil moisture, often containing very aggressive chemical compounds.

That is, the material must have sufficient rigidity and strength, minimal hygroscopicity, a high degree of inertness to chemically aggressive substances, and at the same time not lose its thermal insulation qualities throughout its entire service life. There is such a material - it is extruded polystyrene foam (EPS). One of the most famous Russian manufacturers of EPS is the Penoplex company. And its name, slightly modified, has become a household name in our time - penoplex is often called any high-quality extruded polystyrene foam.

However, let’s look specifically at the branded Penoplex products. For individual construction, the company’s product range offers four brands of insulation boards - “Comfort”, “Foundation”, “Wall” and “Pitched Roof”. It is very convenient with names - you can immediately see which areas of the building the material is mainly intended for insulation.

By the way, all of the listed brands have a sufficient degree of versatility. But still, Penoplex ® Foundation slabs are adapted to the maximum extent to the specific operating conditions mentioned above.

These plates are given increased rigidity and mechanical strength in compression and fracture. And there is absolutely nothing wrong with the fact that they do not undergo special treatment to increase resistance to fire or ultraviolet irradiation. It is clear that hidden by a layer of soil, they are completely protected from both fire and sunlight. At the same time, their thermal insulation qualities are no worse than those of slabs intended for walls, roofs, ceilings, etc.

The main characteristics of Penoplex ® Foundation are shown in the table below:

Name	Test method	Unit	Numerical indicators
Compressive strength at 10% linear deformation, not less	GOST EN 826-2011	MPa (kgf/cm²; t/m²)	0,27
Ultimate strength at static bending	GOST EN 826-2011	MPa (kgf/cm²; t/m²)	0,4
Density	GOST 17177-94	kg/m³	27 ÷ 35
Water absorption in 24 hours, no more	GOST 17177-94	% by volume	0.4
Maximum water absorption during the first month of operation (it will not become higher subsequently)	GOST 17177-94	% by volume	0,5
Vapor permeability coefficient		mg/(m×hour×Pa)	0,005
Fire resistance category	F3-123	group	G4
Thermal conductivity coefficient at (25±5) °C	GOST 7076-99	W/(m×°С)	0,032
Operating temperature range	THAT	°C	-70 … +75
Standard sizes	Width	mm	600 (useful - 585)
	Length	mm	1200 (useful - 1185)
	Thickness	mm	50; 100
Estimated service life		years	at least 50
Approximate cost of one 50 mm slab		rub.	200

As you can see, the material is very light and quite durable. Almost complete waterproofness gives it the function of additional waterproofing. The chemical structure is highly stable (unlike, for example, a close “relative” of penoplex - ordinary white polystyrene foam), and is completely not susceptible to biological decomposition and damage.

You might be interested in information on how to make your own

The convenience of working with penoplex (as it will be called later in the article, meaning “Penoplex ® Foundation”) lies in the presence of joining edges along the perimeter of the slabs. When laying the material, L-shaped grooves (quarters) overlap the joint lines, thereby making the thermal insulation coating continuous, without through cold bridges.

If necessary, the material can be easily cut - cut with a hacksaw or even a sharp construction knife.

What scheme is used to insulate a strip foundation?

An approximate diagram of thermal insulation of a foundation with penoplex

To move on and understand all the nuances of foundation insulation technology, you first need to understand the general scheme by which it will be carried out. The diagram, of course, is given in some simplification, but still reflects all the main elements of the structure being created.

1 – soil at the construction site.

2 – sand (sand-crushed stone, sand-gravel, depending on the characteristics of the soil) cushion under the base of the foundation.

3 – shows a pipe of a ring drainage system, which is often provided around the perimeter of the foundation if it is being built on waterlogged or seasonally waterlogged soil.

4 – reinforced concrete reinforced foundation strip. (By the way, the foundation can be prefabricated, made of reinforced concrete blocks, rubble stones, etc.)

5 – mandatory outer layer of reliable waterproofing of the vertical walls of the foundation strip.

The basis of any home is a reliable foundation. The integrity, safety, durability of the building, and, to a certain extent, even the indoor microclimate directly depend on its condition. That is why it is necessary to use the most reliable and high-quality structures and materials to build a foundation. However, it is not enough to simply build this part of the house - it needs special protection from external influences.

One of the publications on our portal describes in detail. Usually, in combination with these measures, with the right approach, its insulation is immediately provided. For this purpose, various construction technologies can be used, but the most widespread, a simple, easy-to-do-it-yourself project is to insulate the foundation with penoplex.

This article will discuss the reasons for the need for thermal insulation of the foundation, the properties of the insulating material - penoplex, and outline the sequence of the process of carrying out such work and the technological methods used.

Why is the foundation insulated?

It would seem - why insulate the foundation? It may seem that it is enough to isolate it from moisture penetration, and this will completely ensure its safety. All living spaces are located above, do not directly interact with the basement part and have their own thermal insulation. This opinion is quite widespread, and therefore many homeowners simply discount the need for such work, without even including it in the construction plan. Meanwhile, foundation insulation is necessary for several reasons:

• The massive structure of the foundation and plinth becomes the “main route” for the penetration of cold. A significant part of the heat loss of a house is always associated with the poorly insulated floor of the first floor. But even with seemingly reliable thermo isolation a cold bridge operates from the foundation through the walls. This leads to significant losses in terms of energy costs and an uncomfortable indoor environment. And properly carried out insulation provides up to 30% of total heat savings.
• The base of the foundation is usually located below the freezing level of the soil, and its temperature is fairly constant due to the constant influence of geothermal heat. The upper part is subject to significant temperature changes. Such unevenness causes internal stresses in the reinforced concrete structure, associated with the difference in the linear expansion of the material, which leads to its rapid “aging”. In order for the entire foundation mass to have approximately the same heating, regardless of the time of year, reliable thermal insulation will be required.
• A layer of insulation on the foundation walls shifts the dew point outward, and concrete structures will not become damp from the formation of condensation caused by the difference in external and internal temperatures.
• Although any reinforced concrete structure has a certain reserve of frost resistance, expressed in the number of cycles of complete freezing and thawing, it is better not to waste this “internal reserve” by minimizing or completely eliminating the effects of negative temperatures.
• Along with insulating the foundation walls, it is advisable to also carry out thermal insulation of the adjacent layers of soil backfill by placing a horizontal thermal insulating belt at the level of the sole (with shallow foundations) or under a concrete blind area. This can reduce the risk of soil heaving during freezing, which is dangerous due to the appearance of deformations and violation of the integrity of the foundation.
• The insulation layer becomes another fairly reliable barrier to soil moisture. In addition, it well covers the applied waterproofing layer, which is vulnerable to mechanical stress.

Insulation of the foundation should be carried out along its outer wall. Thermal insulation material placed inside the basement (basement) room will only slightly improve the microclimate there, but will not solve the main problems.

Penoplex is the optimal material for foundation insulation

Of all the existing thermal insulation materials, penoplex is probably the most the most optimal for insulating the foundation and basement. Of course, other technologies are also used, for example, but still, for carrying out such work independently, it is still difficult to find better than penoplex both in terms of physical and operational qualities and price.

Penoplex is perhaps the best modern material for foundation insulation

Penoplex is an extruded slab. Extrusion technology, that is, melting a mixture of polystyrene granules, foaming it with special agents and then pressing it through a molding nozzle (extrusion head), makes it possible to obtain a high-density material while maintaining excellent thermal insulation qualities.

• The density of penoplex varies, depending on the brand, from 30 to 45 kg/m³. This allows the materials to withstand significant mechanical loads. Thus, the limit of compression force with volumetric deformation of up to 10%, even for the “lightest” penoplex, is at least 20 t/m², and for the densest it reaches 50 t/m². These indicators are quite sufficient not only for insulating the foundation walls, but also for laying a thermal insulator under its soles or installing it as a basis for pouring a slab foundation.

Video: testing extruded polystyrene foam for strength

• Due to its saturation with air, penoplex has excellent thermal resistance. Thus, the thermal conductivity coefficient is only 0.030 W/m×Cº - one of the lowest among all modern thermal insulation materials
• At the same time, the closed cellular structure of the material resists moisture penetration well. Water absorption on the first day does not exceed 0.2% of the total volume, within a month - no more than 0.4 — 0.5%, and subsequently this value does not change throughout the entire service life.
• The temperature range at which penoplex does not change its physical properties is from - 50 to + 75 ºС.
• The material is absolutely harmless from an environmental point of view, does not decompose over time, does not emit harmful substances, and its service life is estimated at no less than 30 — 40 years.

Penoplex is produced in the form of rectangular slabs, usually orange, 600 × 1200 mm in size, with a thickness of 20 to 60 mm (in 10 mm increments), 80 or 100 mm. The slabs have a locking tongue-and-groove part, which makes installation extremely simple and minimizes “cold bridges” at the joints of the panels.

Several types of penoplex are produced, which are divided into classes, from “Penoplex 31C” to “Penoplex 75”. The main difference is the level of density of the material, which is quite clearly expressed by a digital indicator. In addition, the composition of Penoplex 31 and 35 additionally contains fire retardants, which significantly increase their fire resistance. However, for external insulation of the foundation this indicator is not decisive. For such work, they usually purchase material of the “35C”, “45C” class, and for installation under a sole or under a slab foundation - “45”.

Prices for thermal insulation materials

Thermal insulation materials

Schemes and calculation of foundation insulation parameters

So, in order to achieve effective thermal insulation of the foundation and the thickness of the adjacent soil, the insulation system must include two sections:

• Vertical - a layer of insulation is installed directly on the foundation walls from the outside, from the very bottom to the top edge of the base. This solves the problem of eliminating “cold bridges” through the walls and basement of the building.
• Horizontal - laid out in a continuous layer around the perimeter of the building and prevents freezing of the soil around the foundation walls, thereby completely eliminating or reducing heaving processes to the maximum extent. Depending on the depth of freezing in a particular area, on the type of foundation and its depth, this layer can be located at the level of the base, or higher, at a depth above the freezing point. In practice, very often a horizontal layer of insulation is placed directly under the concrete blind area.

What should be the thickness of penoplex for the insulation to be effective and fully justify its purpose? There are special calculation methods used by specialists. With some simplification, you can make a similar calculation yourself.

The thickness of the penoplex for the vertical section can be determined based on the following formula:

R = h 1/λ 1 + h 2/λ 2

R– this is the value of heat transfer resistance, a constant established for specific regions, taking into account their climatic characteristics;

h 1 – thickness of the foundation walls;

λ 1 – thermal conductivity coefficient of the material from which the foundation is made;

h 2 and λ 2 – respectively, the required thickness of the penoplex layer and its thermal conductivity coefficient.

Meaning R It’s easy to check with any local construction organization - it is installed by SNiP 23 — 02-2003. For example, the table below shows this minimum value for some regions of Russia:

City (region)	R - required heat transfer resistance m2×°K/W
Moscow	3.28
Krasnodar	2.44
Sochi	1.79
Rostov-on-Don	2.75
Saint Petersburg	3.23
Krasnoyarsk	4.84
Voronezh	3.12
Yakutsk	5.28
Irkutsk	4.05
Volgograd	2.91
Astrakhan	2.76
Ekaterinburg	3.65
Nizhny Novgorod	3.36
Vladivostok	3.25
Magadan	4.33
Chelyabinsk	3.64
Tver	3.31
Novosibirsk	3.93
Samara	3.33
Permian	3.64
Ufa	3.48
Kazan	3.45
Omsk	3.82

h 1 = 0.5 m

λ 1 for concrete - W / m×° TO

λ 2 for penoplex – 0.032 W/m×° TO

3,28 = 0,5 / 1,69 + h 2/0,032

Simple arithmetic calculations give 0.0955 m. Of course, you should round up, and in the end you get a 100 mm layer of penoplex.

Calculator for calculating the thickness of foundation insulation

To make the work easier for site readers, we present a special built-in calculator that allows you to quickly and accurately calculate the thickness of thermal insulation for different materials and sizes of the foundation, and for various types of insulation materials appropriate in this case.

Floors play a significant role in retaining heat inside buildings. In an ordinary house, heat loss through floors without thermal insulation can reach 20% of the total heat loss.

When designing floors, we must not forget about the possible condensation of moisture on the surface of the floors and at the junctions of walls and floors, since condensation can result in the appearance of fungi and mold, which have a destructive effect on the building structure and an adverse effect on human health. The most effective way to combat these undesirable phenomena is the competent design and careful implementation of floor insulation. Materials used for these purposes are subject to increased loads, so they must have high compressive strength and a low degree of deformation during compression. The ideal material for thermal insulation of floors and foundations is extruded polystyrene foam - penoplex.

Important characteristics of extruded polystyrene foam, which make it possible to reduce the thickness of a building structure to a minimum, are low thermal conductivity and the ability to maintain the original thermal insulation properties for an almost unlimited period of time, even when exposed to moisture and mechanical loads. Penoplex thermal insulation boards have all of the above properties. Penoplex is easy to use, combines simplicity and speed of installation with a small amount of waste, which minimizes the total cost of thermal insulation work.

First floors

The advantage of penoplex becomes especially obvious when constructing “basementless” buildings, when the floors of the first floors are located directly on the base. The efficiency of thermal insulation made from extruded polystyrene foam remains at a high level even when used under the most extreme conditions: exposure to moisture, low temperatures and mechanical loads. Such a design becomes especially important if there are aquifers and groundwater in the construction areas.

Laying penoplex

Due to the closed-cell structure of penoplex, its slabs can be laid under waterproofing membranes on a rigid base made of coarse crushed stone with a leveling layer of sand with a thickness of the underlying layer of more than 100 mm.

With this method of thermal insulation, there is no need to use concrete preparation. Located on the warm side of extruded polystyrene foam insulation boards, the waterproof membrane also serves as a vapor barrier layer. The thickness of the distribution slab, which serves as the basis for the finished floor, is determined by calculation depending on the purpose of the building.

Laying a waterproofing membrane over thermal insulation should be done using the cold gluing method, which excludes the use of solvents and plasticizers in the adhesive.

Thermal insulation of floors, refrigerated warehouses, ice arenas

To avoid freezing of the foundation soil, refrigerated warehouses, especially deep-freezing chambers, require additional thermal insulation of the floor. "PENOPLEX" slabs retain their original thermal insulation properties at constantly low temperatures and high loads. With a distributed load of more than 10 t/m2, the deformation of the slabs is less than 2% of the thickness of the PENOPLEX slab.

Laying penoplex

It is recommended to lay the slabs in two layers in a checkerboard pattern so that the connections between the slabs of the underlying layer overlap the slabs of the upper layer. This will create continuous thermal insulation of the floor without heat-conducting bridges. In this case, the vapor barrier layer must be under the thermal insulation, while also performing the function of a waterproofing layer. Between the floor insulation layer and the reinforced concrete slab that serves to distribute the loads, it is necessary to provide a cushioning layer of thin polyethylene film or similar material. When constructing floors of refrigerated warehouses, the dimensions of the structure and the parameters of expansion joints must meet the requirements for floors designed for high loads. Thermal insulation of the floors of ice sports facilities is carried out in a similar way. But in this case, flexible coolant pipes are located in a layer of reinforced concrete slab of the upper base.

Industrial complexes, warehouses, motor vehicles

Laying penoplex

If foam boards are laid on a leveling layer, a waterproofing membrane can be placed on top of these boards. When using traditional roofing felt, the waterproofing membrane is laid directly on the concrete under the thermal insulation. In the case of low soil moisture and a low degree of evaporation of moisture from it, one or two layers of thin polyethylene film on top of thermal insulation laid on a gravel or crushed stone bed is sufficient. The film also serves as a spacer sheet and a vapor barrier layer on the warm side of the insulation. This solution is distinguished by its structural simplicity, ease of execution and a number of advantages from the point of view of building physics. In half-wall junctions, it is important to prevent the formation of cold bridges and to ensure the possibility of the necessary thermal expansion.

Warm floor

When you have an underfloor heating system, insulation is an absolute necessity. The role of thermal insulation in this case is to reduce the degree of radiation of thermal energy in undesirable directions. It is in this case, due to the absence of heat flow dissipation, that energy costs are significantly reduced. (Otherwise, not only your floor is heated, but also the ceiling of your neighbor or basement, respectively).

Laying penoplex

Penoplex thermal insulation boards are laid on the floor panel. The construction of the “warm floor” is made directly on them (according to the recommendations of the suppliers). If the hydromembrane is located under a layer of penoplex, flexible heating pipes can be attached directly to the slabs. To prevent cement “milk” from getting into the seams between the insulation boards, the seams must be closed (glued with tape) before pouring the screed. If a hydro- or vapor barrier membrane is placed on top of foam boards, an additional layer must be used to secure flexible heating pipes to ensure continuous waterproofing. Particular attention should be paid to the execution of expansion joints. In addition, measures should be taken to prevent the formation of heat-conducting bridges at the joints between the plates.

The optimal choice for self-insulation of the foundation (in terms of price-quality ratio) is Penoplex. In terms of performance characteristics, only sprayed polyurethane foam is better than this material. A foundation without high-quality hydro- and thermal insulation is not a reliable support for a building due to the effects of frost heaving, groundwater, and temperature changes.

Reinforced concrete has high thermal conductivity. Its periodic freezing gradually leads to destruction. Heat loss through the foundation is up to 20%.

Advantages:

• reducing heat loss through walls, saving heating costs;
• protection of communications from exposure to low temperatures;
• additional waterproofing, absence of mold, dampness in the basement;
• reduction of soil heaving and the resulting deformation of structures, extension of service life;
• on an insulated base, the dew point is located outside, which eliminates the appearance of condensation on the walls and communications from the difference in internal and external temperatures, which prevents dampening of the concrete and failure of pipes;
• increasing the level of soil freezing, which makes it possible to lay at a shallower depth;
• in winter, the above-ground part is exposed to lower temperatures than the underground, this leads to the appearance of internal stress in the concrete, the thermal insulation compensates for the difference.

Penoplex insulation effectively copes with all these tasks. The technology allows you to independently mount it on both a new and a long-established base; the old one is first dug in.

Characteristics of Penoplex foundation

Penoplex is a board made of extruded polystyrene foam, an improved version of polystyrene foam. It has a porous structure with small cells (up to 0.3 mm) filled with air. Thickness - from 20 to 100 mm, dimensions - 600x1200 mm. At the ends there is a tongue-and-groove lock, which makes it easier to connect the sheets together.

Advantages:

• easy to cut with a regular hacksaw;
• easy to install with your own hands;
• has a low specific gravity;
• very low level of thermal conductivity;
• does not require additional waterproofing, moisture penetrates only into the cut pores;
• good sound insulation characteristics;
• withstands 50 freeze-thaw cycles;
• not susceptible to rotting or fungal development;
• high degree of compressive strength - from 0.2 to 0.5 MPa;
• operating temperature range - from -100 to +75°C.

You need to purchase XPS only from trusted manufacturers, since many small companies add components that over time begin to release substances hazardous to human health. Penoplex is an officially recognized brand of expanded polystyrene. It is produced by the Russian company of the same name.

There are several varieties of this material. The name of each type indicates which surfaces it is intended for. You can insulate the base of a building using Penoplex Foundation, Geo, Comfort. They differ from other types in the absence of fire retardants (additives that impart fire resistance) and increased density.

Flaws:

• fire hazard (not suitable for baths at all); when burned, it can emit harmful gases;
• damaged by rodents;
• relatively high cost;
• upon contact with certain chemically aggressive compounds, it softens and melts.

List of substances that can damage Penoplex:

• acetone, methyl ethyl ketone, other ketones;
• gasoline, kerosene, diesel fuel;
• formalin, formaldehyde;
• coal tar, toluene, benzene, similar hydrocarbons;
• ethers;
• oil paints;
• epoxy resin hardeners (polyesters).

Step-by-step instructions for thermal insulation of a strip foundation

DIY vertical insulation technology:

1. After the poured foundation has dried, remove the formwork. Dig a trench 1 m wide around the perimeter. Its depth should coincide with the base of the building.

2. Clean the side surfaces with a stiff bristle brush. Remove sagging using a grinder with a concrete grinding wheel. It is not recommended to skip these operations, otherwise you will not achieve high-quality waterproofing and insulation. If defects are found, seal them with cement mortar.

3. Apply several layers of waterproofing bitumen mastic (primer) to the top and sides with a roller. It is more convenient to use a brush in the corners.

4. Cover the coated surfaces with roofing felt or weld-on roll material (such as TechnoNIKOL), starting from the sole. To work you will need a gas burner. One person heats it with a flame, the second unwinds the roll and glues the heated fragment onto the base. The strips should overlap each other by 100 mm.

5. If possible, then according to technology it is recommended to paste over with a second layer of waterproofing. The foundation will withstand any water pressure, even flood.

6. Prepare special glue for thermal insulation work according to the instructions. Instead, you can use bitumen mastic on a water-soluble basis (see the list of substances incompatible with Penoplex). There is a special mastic on sale.

7. Apply the glue pointwise with a notched trowel. Calculate the quantity in such a way that excess does not come from under the glued slabs. Let the glue set, this will take about one minute.

8. Press the insulation firmly onto the area covered with glue. It is recommended to glue in two layers so that the seams of the first are covered by the sheets of the second. Starting from the bottom, the thermal insulation layer should exactly follow the shape of the base.

9. In the upper above-ground part, using the Penoplex foundation insulation technology, you can additionally use mushroom anchors.

10. If there are any gaps left, seal them with foam, cut off the excess after drying.

11. Attach reinforcing mesh on top and plaster. Sometimes, instead of a plaster layer, they are finished with a profiled membrane.

12. Fill the trench with soil.

Step-by-step instructions for insulating a slab foundation with Penoplex

1. Create markup according to the diagram. Mark the first corner, use a square and fishing line (rope) to establish the position of the rest. Please note that the base protrudes beyond the walls by at least 10 cm, and the foundation pit is always 50-100 cm larger than the slab on all sides. This reserve is needed for drainage and blind areas. Measure the distance between the diagonal corners to ensure that the discrepancy does not exceed 2-3 cm.

2. Remove the top fertile soil layer. Many people use it in the future.

3. Dig a pit. If the soil is dense, then a depth of 50 cm is sufficient, but if the soil is very weak, then it is removed completely. In this case, the depth can be more than 100 cm.

4. Level the bottom.

5. Fill in sand (approximately 20 cm). Compact, water with water or cement laitance.

6. Lay geotextiles so that they completely cover the bottom and extend onto the walls of the pit. According to the technology, a layer of geotextile is placed under the base itself and the blind area.

7. Pour in crushed stone (also about 20 cm). Pour M50 concrete on top (up to 10 cm). It is needed to ensure that the waterproofing material is not damaged by the sharp edges of the crushed stone.

8. Spread overlapping strips of roofing felt or plastic film in two or three layers on the concrete slab.

9. Insulate the top horizontally with Penoplex Foundation or GEO (up to 30 cm).

10. Install the formwork, tie the frame from reinforcement, pour concrete.

11. After complete drying, clean the side surfaces with a brush. Remove the sagging with a grinder and a concrete grinding wheel. If there are small cracks, seal them with cement mortar.

12. Using a roller and brush, apply two layers of waterproofing bitumen mastic to the ends. The upper part of the slab base is insulated when installing the floor.

13. Glue roofing material or built-up roll waterproofing material overlapping onto the coated surfaces, overlapping by 100 mm in two layers.

14. Spread the glue pointwise with a notched trowel or bitumen mastic in a continuous layer with a brush.

15. Press the insulation firmly onto the surface coated with glue. Cover all the side parts of the foundation, connecting the sheets using grooves and ridges at the ends. Then create a second layer of Penoplex so that the seams of the first are closed. In the above-ground part, you can additionally use mushroom-shaped dowels.

16. Fill the cracks with polyurethane foam. Cut off excess after drying.

17. It is also better to insulate the blind area with Penoplex. Pour sand and gravel into the bottom. Lay drainage pipes parallel to the walls. Sprinkle another layer of sand on top. Then lay Penoplex horizontally, making sure that the boards fit snugly against the thermal insulation on the sides of the base. If you leave a gap, cold will pass through it.

18. Finish the ends with plaster or profiled membrane.

19. Cover with the final layer of sand and gravel and pour the concrete.

Effective insulation requires installation of thermal insulation in horizontal and vertical positions. The horizontal layer is laid out in a continuous layer at the level of the base base along the perimeter of the building to prevent freezing and heaving of the soil, creating cold bridges under the house. Often the insulation is laid directly under the blind area.

The most common mistakes:

• Applying waterproofing to wet concrete. The slabs will peel off along with the roofing felt.
• An adhesive containing substances that soften polystyrene foam.
• Using glue instead of bitumen mastic.
• Complete absence of coating waterproofing.
• Use of materials that have been damaged as a result of improper storage.
• Fastening Penoplex to the underground part of the foundation with fungal dowels, which are intended for installation on walls. This violates the integrity of the waterproofing, and due to soil pressure, strong fixation to the side parts of the base of the building will be ensured, so additional fastenings in this part according to the scheme are not necessary.
• No blind area.
• The gap between the horizontal and vertical layers.

Price

The final price of work per m2 consists of the necessary materials:

• Bitumen mastic - from 65 rubles/kg, consumption - 1 kg/m2.
• TechnoNIKOL built-up waterproofing - from 135 rubles/m2.
• Glue - from 24 rubles/kg, consumption - 6 kg/m2.
• Penoplex Foundation, thickness 50 mm - from 1900 rub/m2, when calculating, take into account that two layers are needed.
• Reinforcing mesh - from 30 rub/m2.
• Plaster - from 10 rub/kg, consumption - from 12 kg/m2.
• Profiled membrane (instead of mesh and plaster) - from 85 rubles/m2.

If it is not possible to do the thermal insulation yourself, then it is advisable to hire professional builders. Work on insulating the foundation with Penoplex will cost from 460 rubles/m2. The price includes the application of mastic, pasting with roll material, installation of insulation, finishing (membrane, plaster).