Why does heat leave the house and how to properly insulate brick walls? Layered masonry Construction of brick walls with insulation

According to formal criteria, only walls without finishing that affect the heat conservation and performance qualities of the main material of a self-supporting or load-bearing wall are considered single-layer. That is, finishing that increases the thermophysical properties of the wall is formally considered a layer of the wall.

All walls made of a homogeneous base material that determines the strength of the wall and one or more additional layers, each of which contributes to the thermophysical characteristics of the wall, are multilayer.

The well-known company in the Russian Federation, Ksella-Aeroblock-Center, in its catalog only offers more than a dozen options for multilayer walls made from aerated concrete.

Taking into account other materials that provide the main load on the wall, there will be several dozen structural options for multilayer walls.

One of the attempts to classify multilayer wall structures gave the following result - in the Russian Federation, four main types of multilayer walls are most often used:

well masonry;
internal thermal insulation (from inside the room);
ventilated facade;
external thermal insulation of “wet type”.

Russian masons under the leadership of the Russian engineer A.I. were the first to begin laying wells. Gerard in 1829. On this basis, about a dozen variants of three-layer wall structures were developed.

When are multi-layer walls needed?

Traditional single-layer walls have come under great attention heating specialists all over the world with the beginning of the energy crisis in the 70s of the twentieth century. In the USSR, and then in the CIS, this process shifted by 10 - 15 years. But the most serious shifts in this direction took place in the 2000s. In Russia, standards for thermal efficiency of buildings have become more stringent.

According to the new standards, to achieve the required thermal insulation characteristics, a single-layer wall must be of the following thickness:

from ceramic bricks (thermal conductivity coefficient - 0.8 W/(m °C)) - from 1.1 to 4.5 m;
from silicate (0.87) - from 1.2 to 4.8 m;
from ceramic hollow (0.5) - from 0.7 to 2.9 m;
foam blocks, with a density of 800 kg/cu.m. m. (0.37) - from 0.5 to 2 m, with a density of 400 (0.15) - from 0.2 to 0.8 m;
expanded clay 1,800 (0.9) - from 1.25 to 5 m;
the same at a density of 500 (0.23) - from 0.3 to 1.2 m;
reinforced concrete (1.8 - 2.1) - from 2.2 to 11.5 m.

It turns out that only from foam concrete with a density of less than 500 kg / cubic meter. m. you can get a “digestible” wall thickness.

If the thermal engineering calculation of the wall shows that a wall made of aerated concrete should be more than 0.4 m, and for hollow ceramics with micropores - more than 0.45 m, then it is cheaper to build houses with two-layer walls.

In addition, single-layer walls have the following disadvantages:

high humidity of the material, i.e. the thermal resistance of the wall is lower than the design value, and the house is colder;
irrational consumption of materials, because the thickness of the wall is much greater than that required for its strength.

Therefore, to meet the thermal technical requirements of the walls, you need to use two, three or more layers, one of which will give the wall strength, the second will protect the house from the cold, the third will ensure quick drying of the wall after construction, the fourth will protect from bad weather, UV radiation, or simply make the wall beautiful.

Multi-layer walls are not needed:

in areas with a mild climate and not frosty winters;
when materials make it possible to build a heat-saving wall of the required strength and acceptable thickness.

In this case, the following can be used:

poromaterials: porobrick, aerated concrete, gas silicate, expanded clay blocks, foam blocks, etc.;
hollow: hollow brick, ceramic, sand concrete, slag concrete and expanded clay hollow blocks, etc.;
large format blocks:
a) concrete foam blocks;
b) composite blocks: wood concrete, sawdust concrete, polystyrene foam concrete, etc.

Advantages and disadvantages of multi-layer walls

In double-layer walls, the thermal insulation layer is usually installed on the cold side, on the outside.

In three-layer structures, a layer of thermal insulation is installed between two layers of load-bearing material of equal thickness. That is, the wall is divided in half and a layer of thermal insulation is placed between the halves. The halves of the walls are “tied” together repeating after 5 - 8 rows:

one or two rows of solid brickwork;
galvanized steel reinforcement ties or meshes;
continuous reinforced concrete belts - vertical and horizontal.

But more often the outer layer is made of 0.5 bricks from a special facing bricks.

There are also other methods, but they are used less frequently.

Advantages of multilayer walls:

the wall is lighter, because strength provides relatively little a large number of material, and thermal insulation, by definition, weighs little;
highly efficient insulation provides thermal parameters with a reserve, and the facing (outer layer) provides appearance;
fire resistance;
simple materials;
You can build all year round and in winter too, etc.

Disadvantages of multi-layer walls:

heterogeneity of the average density of the wall material (cold bridges from connections, concrete diaphragms, etc.), which gives different thermal efficiency of the wall in different places;
highly qualified performers are required;
ceilings facing the outer surface of the wall provide up to 20% heat loss;*
load from temperature changes - the concrete of the floors is always warm, and the facing masonry is in the freezing/thawing zone; **
minor repairs are almost impossible;
accidental unintentional damage to thin layers is possible;
the volume of hidden work is large and defects are possible: incorrect or incomplete installation of insulation, incorrect installation vapor barriers and many others. etc;
high labor intensity;
the cost of a house is more than with two-layer walls, and even more so with single-layer ones.

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* When interfloor floor slabs on any type of wall face the outer wall, their steel reinforcement conducts heat much better than dense concrete, although concrete also has high thermal conductivity. Internal voids with a diameter of 130 to 250 mm, filled with air, also participate in this process.

To reduce heat losses:

the ends of the slabs are covered with standard (design) thermal insulation and external cladding;
the cavities of the slabs are filled with thermal insulation or foam-aerated concrete liners (at least 0.5 - 1 m). Precast concrete factories can do this on request during the production of slabs.

** When temperature changes occur, the floor concrete, protected from them by thermal insulation, has slight changes in size, while the entire facing masonry is under the influence of these changes. In the zone of their contact, crumbling of materials and gradual destruction are possible.

Materials used in the construction of multi-layer walls

For the construction of a load-bearing and self-supporting wall, providing load from its own weight, floors and all overlying floors, use:

solid, hollow, porous ceramic brick;
silicate solid 3, 11 and 14 hollow, etc.

With a small number of floors up to 3, sometimes 5 floors:

ceramic blocks - warm, hollow-porous;
arbolite and brisolite blocks, twin blocks;
foam, gas, slag, polystyrene, sawdust, expanded clay concrete and other types of large-format blocks,

As warmth insulating materials Highly efficient insulation materials are used:

A. Foams:

EPPS - extruded polystyrene foam;
other foamed plastics - polyethylene foam, propylene foam, polyurethane foam, etc.;
foam glass, expanded clay and other foamed materials;

B. Mineral wool - basalt, fiberglass, gabbro-basalt, marl, etc.

B. Natural organic materials:

ecowool - crushed cellulose impregnated with fire retardants, etc.;
crushed waste wood, bark, branches, etc.;
chopped fibers and plant stems, etc.

Features of multilayer wall construction technology

There are several ways to build multi-layer walls:

simultaneously lay the outer and inner walls and install soft or hard insulation boards;
layer-by-layer construction: lay the entire inner wall, strengthen the insulation on it and lay the outer wall:
a) at a distance - a fixed distance from the wall, leaving a ventilation gap with moldings or profiles between the thermal insulation and outer wall;
b) to the main wall through a layer of insulation with special anchors or dowels.

A sheathing is installed on the inner wall, between the elements of which slab mineral wool or expanded polystyrene slabs are reinforced and recessed relative to the sheathing. By using horizontal connections after 4 - 6 rows of masonry and after 0.5 - 0.6 m in a row, using the sheathing as a means of maintaining the width of the gap, lay the facing layer. A ventilation gap is formed between the outer wall and the thermal insulation. There is no gap between the inner wall and the thermal insulation.

Simultaneous construction of a three-layer wall

Let's consider the process of simultaneous construction of a three-layer brick wall with internal insulation:

The thickness of the internal masonry is determined by calculating the strength of the wall, but cannot be less than 250 mm - “1 brick”.
The thickness of the thermal insulation layer is determined by thermal engineering calculations and is at least 0.5 bricks.
The thickness of the external masonry - “cladding” - is no more than 0.5 bricks, but in a 1-2 storey building it may be less.
The masonry is carried out simultaneously in the inner and outer layers, leaving a gap of 120 mm, which is filled with mineral wool slabs. After 5 - 8 rows, a dressing is made steel ties made of stainless steel (mesh of 2 longitudinal and 2 transverse wires), horizontally - about 600 mm. You can use glass or carbon fiber reinforcement, placing it at an angle of 45 degrees. The segments are laid alternately at an angle of 45 and 135 degrees (approximately). This reinforcement does not bend, and its segments are laid at an angle relative to the axis of the wall. It is either very difficult to bend them (with small diameters) or even impossible.

An analysis of the collapses of facing walls in Moscow over the past 10 years has shown that “black” metal corrodes to complete destruction in 3 - 5 years.

The transition in the floor area is made in accordance with the design with mandatory thermal insulation of the end of the floor slab.

With a separate method of wall construction, insulation is installed in two ways:

wet lightweight - the insulation is glued to the wall with glue and steel or high-strength reinforced steel is fixed on its outer surface plastic mesh, along which plastering is carried out;
dry method - on finished wall with a sheathing made of profiles or wooden blocks, a heat-insulating layer is installed on the wall, on top of which a cladding made of brick, artificial stone, etc. is attached.

When constructing multilayer walls using permanent formwork are used ready-made blocks in the form of box-shaped reinforced structures made of polystyrene foam, wood concrete (chip concrete), porous ceramics, glass foam, etc.

These blocks, like a Lego set, are installed with bandaging and form a wall. Steel or composite plastic reinforcement is installed in the cavity of the blocks in a vertical position (if necessary, in a horizontal position) and filled with concrete. You can use ordinary concrete, or concrete with heat-insulating fillers, or foaming concrete.

Slabs from the most different types insulation. They are attached to the reinforcement frame of the future wall and concrete is poured layer by layer.

A horizontal reinforcement frame is mounted on the top of the wall and filled with dense concrete monolithic belt along the entire perimeter of the building and internal load-bearing walls. After the concrete has gained strength, floor slabs are installed.

Questions and answers on the topic

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If the walls are insufficiently insulated, about 60% of the heat used to heat the home is lost through them. However, heat conservation standards in force since 2000 required builders to use modern, highly efficient insulating materials that significantly increase the heat-insulating properties of walls

When asked what to build a house from - wood, brick, concrete or their many and varied combinations, everyone answers in their own way. The choice depends on many factors, among which personal preferences often play a much more significant role than practical considerations. We will try to dwell on practical aspects and will proceed from the fact that the decision was made to build a house of brick. Main advantage brick building- its undoubted strength and unlimited service life, of course, subject to proper construction and proper operation.

Thicker does not mean warmer

The thickness of solid brick walls is always (well, or almost always) a multiple of the size of half a brick, but it is never less than 25 cm, that is, one of its lengths. It is well known from the richest construction practice that even a wall of one brick is capable of bearing any uniformly distributed load that occurs in one, two-story houses from the structures above. Thermal engineering calculations show that at a temperature “overboard” of -30°C, namely this temperature is not uncommon in winter in most regions of the central part of Russia, in order to retain heat in the house, the thickness of its outer walls (with solid masonry without voids and on cement-sand solution) must be at least 160 cm. Walls made of sand-lime brick will be even thicker.

Ordinary red brick can be solid or hollow. For external walls, it is better to use a hollow one, the air spaces of which significantly improve the heat-shielding characteristics of the structure. In addition, the masonry itself must be carried out with the formation of voids, wells, widened seams filled with heat-insulating material, and the use of effective modern insulation materials and so-called warm masonry mortars. An equal or even more serious effect can be achieved using various types of insulation, masonry with the formation of voids, and porous brick.

The trick to laying brick walls is to use warm masonry mortars containing slag, expanded clay, tuff, perlite, etc. as filler. Conventional cement-sand masonry mortar has a thermal conductivity close to that of solid brick, and for a mixture with such fillers it turns out to be approximately 10-15% lower. This also quite significantly increases the heat-insulating properties of the walls, because the total area of the joints in the masonry is almost 10%.

Where does the heat go?

An important question that interests many potential customers sounds something like this: “Where should the insulation be located on the walls - inside the room, outside or in the body of the masonry?”

Even 20 years ago, the greatest heat loss in houses, including individual ones, was through windows. With double glazing, which was so widespread until recently, the specific heat flow through windows is 4-6 times higher than the heat flow through the walls. And this despite the fact that the area of windows rarely amounts to more than a fifth of the total area of enclosing structures. Let’s say right away that the use of multi-chamber PVC profiles with three- or four-chamber double-glazed windows significantly reduces heat losses. 9-10% of heat leaves the house through the roof and the same amount goes into the ground through basements. And 60% of losses come from uninsulated walls.

The location of the dew point depending on the type of wall insulation

Let's consider three options for wall construction: solid without insulation; with insulation on the room side; with external insulation. The temperature in the house is according to current standards, which determines the level comfortable stay, should be equal to +20°C. Measurements carried out by specialists show that at an outside temperature of -15°C, the temperature of the inner surface of a non-insulated wall is approximately 12-14°C, and the external surface is about -12°C. The dew point (the point at which the temperature corresponds to the beginning of moisture condensation) is located inside the wall. Considering that part of the enclosing structure has a negative temperature, the wall freezes.

If there is thermal insulation located on the walls inside the room, the picture changes significantly. The temperature of the inner surface of the wall (more precisely, the inner side of the insulation) in this design is approximately +17°C. In this case, the temperature of the masonry from the inside of the building is about zero, and from the outside - slightly lower than the street air temperature - about -14°C. A house with this internal thermal insulation You can warm it up quite quickly, but brick walls do not accumulate heat, and when the heating devices are turned off, the room quickly cools down. But something else is worse: the dew point is located between the wall and the thermal insulation layer, as a result, moisture accumulates here, mold and mildew may appear, and the wall still freezes. However, heat losses are slightly reduced compared to a non-insulated structure.

Finally, the third option is external thermal insulation. The surface temperature of the wall inside the house becomes slightly higher: 17-17.5°C, and outside it increases sharply - to a level of 2-3°C. As a result, the dew point moves inside the insulation layer, while the wall itself acquires the ability to accumulate heat, and heat losses from the room through the enclosing structures are significantly reduced.

External thermal insulation of walls helps solve several problems at once. First of all, when correct execution Such insulation allows you to achieve a high level of energy saving - the cost of heating the building is reduced by 50-60%

Layered masonry

The easiest way to increase thermal insulation properties brick walls - leave cavities in them, because air is an ideal natural heat insulator. Therefore, for a long time, closed air layers 5-7 cm wide have been made in the body of solid brick walls. This, on the one hand, reduces brick consumption by almost 20%, and on the other hand, reduces the thermal conductivity of the wall by 10-15%. This type of masonry is called well masonry. Air, of course, is an excellent insulator, but when strong wind Such walls can be blown through the vertical joints of the masonry. To prevent this from happening, the facades are plastered on the outside, and various insulation materials are placed in the air voids. Nowadays, a type of well masonry called layered is widely used: a load-bearing brick wall, then insulation and an outer layer of facing brick.

Options for wall insulation with a bond of two layers of brick with masonry (a) and metal embedded elements (b)

Thermal insulation in layered masonry, as a rule, is slabs made of mineral wool (based on stone fiber or staple fiberglass) or expanded polystyrene, less often - from extruded polystyrene foam (due to its high price). All materials have similar thermal conductivity coefficients, so the thickness of the insulating layer in the wall will be the same, regardless of the type of insulation chosen (the thickness of the layer is determined not only by the characteristics of the thermal insulation, but also by the climatic zone where construction is taking place). However, fibrous materials are non-flammable, which is fundamentally different from expanded polystyrene, which is flammable. In addition, unlike polystyrene foam boards, fiber boards are elastic, so during installation it is easier to press them tightly against the wall. Certain difficulties in using expanded polystyrene in layered masonry are also caused by the low vapor permeability of this material. At the same time, expanded polystyrene is approximately four times cheaper than mineral wool, and this advantage for many customers compensates for its disadvantages. Let us add that, according to SP 23-101-2004 “Design of Thermal Protection of Buildings”, when using combustible insulation in the building envelope, it is necessary to frame window and other openings around the perimeter with strips of non-combustible mineral wool.

A tight fit of the insulation is the key to its effectiveness, since if air pockets are allowed in the structure, heat can leak out of the building through them

The installation of any type of insulation system requires a thoughtful calculation of its vapor permeability: Each subsequent layer (from the inside to the outside) should allow water vapor to pass through better than the previous one. After all, if there is an obstacle in the way of the steam, then its condensation in the thickness of the enclosing structure is inevitable. Meanwhile, in the case of a popular solution - a wall made of foam blocks, fiber insulation, facing bricks - the vapor permeability of foam blocks is quite high, for insulation it is even higher, and the vapor permeability of facing bricks is less than that of insulation and foam blocks. As a result, steam condensation occurs - most often on the inner surface of the wall made of facing bricks (since in winter it is in the zone negative temperatures), which entails negative consequences. Moisture accumulates in the lower part of the masonry, causing destruction of the bricks of the lower rows over time. The insulation will become wet throughout its entire thickness, and, as a result, the service life of the material will be reduced and its heat-shielding properties will significantly decrease. The enclosing structure will begin to freeze, which will lead, in particular, to a decrease in the effect of using the insulation system, to deformation of the finishing of the room, to a gradual shift of the condensation zone into the thickness of the load-bearing wall, which can cause its premature destruction.

To one degree or another, the problem of vapor transfer is relevant for layered masonry with any type of insulation. To avoid dampening of the thermal insulation, it is recommended to provide for two points. First, you need to create air gap at least 2 cm between the insulation and the outer wall, and also leave a number of holes about 1 cm in size in the lower and upper parts of the masonry (a seam not filled with mortar) to achieve air inflow and exhaust to remove steam from the insulation. However, this is not complete ventilation of the structure (in comparison, for example, with a ventilated facade system), therefore, secondly, it makes sense to make special holes for draining condensate from the layered masonry in its lower part.

An important feature of layered masonry is the use of heat-insulating materials with sufficient rigidity and their reliable fixation so that they do not settle over time. For additional fastening of the insulation and pairing of the outer and inner brick layers with each other, flexible connections are used. They are usually made of steel reinforcement.

Replacing flexible steel ties with fiberglass ones allows (due to the thermal homogeneity of the wall structure) to reduce the design thickness of mineral wool by 5-10%

IN last years In individual construction, porous large-format ceramic stones are increasingly being used for the construction of walls. During their manufacture, organic and mineral materials are added to the ceramic composition, which contribute to the formation of closed pores during the firing of bricks. As a result, such stones become 35-47% lighter than solid bricks of the same size, and due to the porous structure, their thermal conductivity coefficient reaches 0.16-0.22 W/(m °C), which is 3-4 times higher, than that of solid clay brick. Accordingly, walls made of porous stone can be significantly less thick - only 51 cm.

Brickwork Due to the high heat capacity of the material, it has significant thermal inertia - the walls warm up for quite a long time and cool down just as slowly. For houses permanent residence this quality is certainly positive, since the temperature in the rooms usually does not fluctuate greatly. But for cottages where the owners visit periodically, with long breaks, the thermal inertia of brick walls already plays a negative role, because warming them up requires considerable expenditure of fuel and time. The construction of walls of a multilayer structure, consisting of layers of different thermal conductivity and thermal inertia, will help alleviate the problem.

External insulation

Today, external insulation systems are most widespread. These include ventilated facades with an air gap and “wet” facades with a thin plaster layer (the option with a thick plaster layer is slightly less popular). In facades with “thin” plaster, the number of heat-conducting inclusions is reduced to a minimum. This is how they differ from ventilated facades, where there are more heat-conducting inclusions and, accordingly, the insulation must be thicker, which affects the cost of the structure - for ventilated facades it is on average twice as high

External insulation scheme

The name “wet” facade is associated with its use in insulation systems plaster solutions. This is precisely what explains the main and, perhaps, the only limitation on their design - the seasonality of work. Since the technology involves “wet” processes, installation of the system can only be done at positive temperatures.

Such “wet” systems include many different components (insulation, mesh, mineral glue, plaster mixtures, dowels, profiles and a number of other components), but there are only three main layers: insulation, reinforcing and protective-decorative layers. Plates made of rigid thermal insulation material with a low thermal conductivity coefficient are used as insulation. These can be mineral or glass wool boards with a medium density (not lower than 145 kg/m³) or sheets of extruded non-shrinking self-extinguishing polystyrene foam with a density of at least 25 kg/m³. In this case, the thermal insulation properties of a 6 cm thick polystyrene foam layer correspond to approximately 120 cm of brickwork. The insulation is fixed to the wall using special glue and fasteners. A reinforcing layer of alkali-resistant mesh and a special adhesive solution is applied to the thermal insulation, which attaches it to the insulation board. And only then the outer layer is formed, consisting of a primer and decorative finishing.

The main advantage of a “wet” facade is the ability to obtain a wall with any required degree of insulation; moreover, such an insulation system is less expensive than layered masonry, while the appearance of the facade, where high-quality plasters are used, will be attractive for a long time. The costs of building the foundation will also be reduced, since the load on it from the insulation layer will be insignificant. The use of such systems makes it possible to reduce heat loss through building envelopes by three times and save up to 40% of funds spent on heating.

Construction of a three-layer wall with brick cladding

In low-rise construction, the design of an external three-layer wall is very popular: load-bearing wall - insulation-brick cladding (120 mm), Fig.1. This wall allows you to use effective for each layer materials.

Bearing wall made of brick or concrete blocks, is the strength frame of the building.

Insulation layer. fixed to the wall, provides the necessary level of thermal insulation of the outer wall.

Wall cladding made of facing bricks protects the insulation from external influences and serves as a decorative covering for the wall.

Fig.1. Three-layer wall.
1 - interior decoration; 2 - load-bearing wall; 3 - thermal insulation; 4 - ventilated gap; 5 - brick cladding; 6 - flexible connections

Multilayer walls also have disadvantages:

limited durability of the insulation material compared to the material of the load-bearing wall and cladding;
identification of dangerous and harmful substances made of insulation, albeit within acceptable standards;
the need to use special measures to protect the wall from blowing and moisture - vapor-tight, windproof coatings and ventilated gaps;
flammability of polymer insulation;

Load-bearing wall in three-layer masonry

Insulation of house walls with mineral wool slabs

Mineral wool slabs are fixed on a load-bearing wall with a ventilated air gap between the surface of the slabs and the brick cladding, or without a gap, Fig. 1.

Calculations performed humidity conditions walls show that in three-layer walls Condensation in the insulation occurs during the cold season in almost all climatic zones Russia.

The amount of condensate that falls varies, but for most regions it falls within the standards established by SNiP 02/23/2003 “Thermal protection of buildings”. There is no accumulation of condensate in the wall structure during a year-round cycle due to drying in the warm season, which is also a requirement of the specified SNiP.

As an example, the figures show graphs of the amount of condensate in the insulation based on calculation results for various options for cladding three-layer walls of a residential building in St. Petersburg.

Rice. 2. The result of calculating the humidity conditions of a wall with mineral wool insulation as a middle layer (expanded clay concrete - 250 mm, insulation -100 mm, brick -120 mm). Facing - ceramic brick without ventilation gap.

Rice. 3. The result of calculating the humidity conditions of a wall with mineral wool insulation and plaster coating (expanded clay concrete - 250 mm, insulation - 120 mm, plaster coating -10 mm). Facing - vapor permeable.

Rice. 4. The result of calculating the humidity conditions of a wall insulated with mineral wool slabs with a ventilated gap and a “siding” type coating (brick - 380 mm, insulation -120 mm, siding). Facing - ventilated facade.

The graphs above clearly show how the cladding barrier, which prevents ventilation of the outer surface of the mineral wool insulation, leads to an increase in the amount of condensation in the insulation. Although moisture accumulation in the insulation does not occur in the annual cycle, it when facing with bricks without a ventilation gap, a significant amount of water condenses and freezes in the insulation every year in winter, Fig.2. Moisture also accumulates in the layer adjacent to the insulation brick cladding

Moistening the insulation reduces its heat-shielding properties, which increases heating costs building.

In addition, when water freezes every year, it destroys the insulation and brickwork of the cladding. Moreover, cycles of freezing and thawing can occur repeatedly during the season. The insulation gradually crumbles, and the brickwork of the cladding collapses. I note that the frost resistance of ceramic bricks is only 50 - 75 cycles, and the frost resistance of insulation is not standardized.

Replacing insulation covered with brick cladding is expensive. Hydrophobized high-density mineral wool slabs are more durable under these conditions. But these plates also have a higher cost.

The amount of condensate is reduced or There is no condensation at all if you provide better ventilation of the insulation surface - Fig.3 and 4.

Another way to eliminate condensation is to increase the vapor permeability resistance of the load-bearing wall. To do this, the surface of the load-bearing wall is covered with a vapor barrier film or thermal insulation boards with a vapor barrier applied to their surface are used. When mounting on a wall, the surface of the slabs covered with vapor barrier must be facing the wall.

The construction of a ventilated gap and sealing of walls with vapor-proof coatings complicate and increase the cost of wall construction. The consequences of dampening the insulation in the walls in winter are described above. So choose. For construction areas with harsh winter conditions the installation of a ventilated gap can be economically justified.

In walls with a ventilated gap, mineral wool boards with a density of at least 30-45 are used. kg/m 3, covered on one side with a windproof coating. When using slabs without wind protection on the outer surface of the thermal insulation, windproof coatings should be provided, for example, vapor-permeable membranes, fiberglass, etc.

In walls without a ventilated gap, it is recommended to use mineral wool boards with a density of 35-75 kg/m 3. In a wall design without a ventilated gap, thermal insulation boards are installed freely in a vertical position in the space between the main wall and the facing layer of brick. The supporting elements for the insulation are the fastenings provided for attaching the brick cladding to the load-bearing wall - reinforcing mesh, flexible connections.

In a wall with a ventilation gap, the insulation and windproof coating are attached to the wall using special dowels at the rate of 8 -12 dowels per 1 m 2 surfaces. The dowels should be buried 35-50 deep into the thickness of the concrete walls. mm, brick - by 50 mm, in masonry made of hollow bricks and lightweight concrete blocks - by 90 mm.

Insulation of walls with polystyrene foam or polystyrene foam

Rigid slabs of foamed polymers are placed in the middle of a three-layer brick wall structure without a ventilated gap.

Plates made of polymers have a very high resistance to vapor permeation. For example, a layer of wall insulation made from expanded polystyrene boards (EPS) has a resistance 15-20 times greater than that of a brick wall of the same thickness.

When installed hermetically, insulation acts as a vapor-tight barrier in a brick wall. Steam from the room simply does not reach the outer surface of the insulation.

With the correct thickness of insulation, the temperature of the inner surface of the insulation should be above the dew point. If this condition is met, steam condensation on the inner surface of the insulation does not occur.

Mineral insulation - low density cellular concrete

Recently, another type of insulation has been gaining popularity - products made from low-density cellular concrete. These are heat-insulating boards based on materials already known and used in construction - autoclaved aerated concrete, gas silicate.

Thermal insulation boards made of cellular concrete have a density of 100 - 200 kg/m 3 and thermal conductivity coefficient in dry condition 0.045 - 0.06 W/m o K. Mineral wool and polystyrene foam insulation have approximately the same thermal conductivity. Slabs are produced with a thickness of 60 - 200 mm. Compressive strength class B1.0 (compressive strength not less than 10 kg/m3.) Vapor permeability coefficient 0.28 mg/(m*year*Pa).

Thermal insulation slabs made of cellular concrete are a good alternative to mineral wool and expanded polystyrene insulation.

Well-known in the construction market trade marks thermal insulation slabs made of cellular concrete: “Multipor”, “AEROC Energy”, “Betol”.

Advantages of thermal insulation slabs made of cellular concrete:

The most important thing is higher durability. The material does not contain any organic matter - it is an artificial stone. It has a fairly high vapor permeability, but less than mineral wool insulation.

The structure of the material contains a large number of open pores. The moisture that condenses in the insulation in winter dries quickly in the warm season. There is no moisture accumulation.

Thermal insulation does not burn and does not emit harmful gases when exposed to fire. The insulation does not cake. Insulation boards are harder and mechanically stronger.

The cost of insulating a facade with cellular concrete slabs, in any case, does not exceed the cost of thermal insulation with mineral wool insulation or expanded polystyrene.

When installing heat-insulating slabs made of aerated concrete, the following rules are followed:

Thermal insulation slabs made of aerated concrete with a thickness of up to 100 mm attached to the facade using glue and dowels, 1-2 dowels per slab.

From slabs more than 100 thick mm A wall is laid close to the insulated wall. The masonry is laid using glue with a seam thickness of 2-3 mm. The masonry of insulation boards is connected to the load-bearing wall with anchors - flexible ties at the rate of five ties per 1 m 2 walls. Between the load-bearing wall and the insulation you can leave a technological gap of 2-15 mm.

It is better to connect all layers of the wall and brick cladding with a masonry mesh. This will increase mechanical strength walls.

Wall insulation with foam glass

Three-layer wall of the house with foam glass insulation and brick cladding.

Another type of mineral insulation that has appeared on the construction market relatively recently is foam glass slabs.

Unlike heat-insulating aerated concrete, foam glass has closed pores. Due to this, foam glass slabs do not absorb water well and have low vapor permeability. A ventilated gap between the insulation and the cladding is not needed.

Foam glass insulation is durable, does not burn, is not afraid of moisture, and is not damaged by rodents. It has a higher cost than all the types of insulation listed above.

Installation of foam glass slabs on the wall is carried out using glue and dowels.

The thickness of the insulation is selected in two stages:

They are chosen based on the need to provide the required resistance to heat transfer of the outer wall.
Then they check for the absence of steam condensation in the thickness of the wall. If the test shows otherwise, then it is necessary to increase the thickness of the insulation. The thicker the insulation, the lower the risk of steam condensation and moisture accumulation in the wall material. But this leads to increased construction costs.

A particularly large difference in the thickness of the insulation, selected according to the two above conditions, occurs when insulating walls with high vapor permeability and low thermal conductivity. The thickness of the insulation to ensure energy saving is relatively small for such walls, and To avoid condensation, the thickness of the slabs must be unreasonably large.

When insulating aerated concrete walls(as well as from other materials with low resistance to vapor permeation and high resistance to heat transfer - for example, wood, from large-porous expanded clay concrete), the thickness of the polymer thermal insulation, according to the calculation of moisture accumulation, is much greater than that required by energy saving standards.

To reduce steam inflow, it is recommended to arrange vapor barrier layer on the inner surface of the wall(from the warm room side), Rice. 6. To install a vapor barrier from the inside, materials with high resistance to vapor permeation are selected for finishing - a deep penetration primer is applied to the wall in several layers, cement plaster, vinyl wallpapers.

The installation of a vapor barrier from the inside is mandatory for walls made of aerated concrete and gas silicate for any type of insulation and façade cladding.

It should be borne in mind that the masonry of the walls of a new house always contains a large amount of construction moisture. Therefore, it is better to allow the walls of the house to dry thoroughly from the outside. It is recommended to carry out façade insulation work after the interior finishing is completed, and not earlier than a year after the completion of this work.

Cladding the external walls of a house with bricks

Cladding the external walls of a house with bricks is durable and, when using special colored facing bricks, even better clinker bricks. quite decorative. The disadvantages of cladding include the relatively large weight of the cladding, the high cost of special bricks, and the need to widen the foundation.

It is especially necessary to note the complexity and high cost of dismantling the cladding to replace the insulation. The service life of mineral wool and polymer insulation does not exceed 30 - 50 years. At the end of its service life, the heat-saving properties of the wall are reduced by more than a third.

With brick cladding it is necessary use the most durable insulation materials, providing them with conditions in the wall structure for the longest possible operation without replacement (minimum amount of condensation in the wall). It is recommended to choose high-density mineral wool insulation and polymer insulation made from extruded polystyrene foam, EPS.

In walls with brick lining, in most profitable to use mineral insulation made of autoclaved aerated concrete or foam glass, with The service life of which is much greater than that of mineral wool and polymer.

Brick cladding is laid in half a brick, 120 mm. on ordinary masonry mortar.

A wall without a ventilated gap, insulated with high-density slabs (mineral wool - more than 50 kg/m 3, EPPS), you can veneer with brickwork on edge - 60 mm. This will reduce the overall thickness of the outer wall and plinth.

The masonry of brick cladding is connected to the masonry of the load-bearing wall with steel wire or reinforcement mesh, protected from corrosion, or with special flexible connections (fiberglass, etc.). The grid or connections are placed vertically in increments of 500-600 mm.(height of the insulation board), horizontally - 500 mm., while the number of connections per 1 m 2 blank wall - at least 4 PC. At the corners of the building along the perimeter of window and door openings 6-8 PC. by 1 m 2.

The brick lining is longitudinally reinforced with masonry mesh with a vertical pitch of no more than 1000-1200 mm. The masonry mesh must fit into the masonry joints of the load-bearing wall.

For ventilation air gap in the bottom row of facing masonry, special vents are installed at the rate of 75 cm 2 for every 20 m 2 wall surface. For lower vents, you can use a slotted brick placed on the edge so that outside air through holes in the brick was able to penetrate the air gap in the wall. Upper vents are provided in the eaves of the wall.

Ventilation holes can also be made by partially filling the vertical joints between the bricks of the bottom row of masonry with cement mortar.

The placement of windows and doors in the thickness of a three-layer wall should ensure minimal heat loss through the wall at the installation site.

In a three-layer insulated wall from the outside, a window or door frame installed in the same plane with the insulation layer at the border of the heat-insulating layer- as it shown on the picture.

This arrangement of the window and door along the thickness of the wall will ensure minimal heat loss at the junction.

Watch the video tutorial on the topic: how to properly lay a three-layer wall of a house with brick cladding.

When facing walls with brick, it is important to ensure the durability of the insulation layer. The longest service life will be ensured by thermal insulation with slabs of low-density cellular concrete or foam glass.

It is also important to reduce the amount of moisture in external walls during the winter. The less moisture condenses in the insulation and cladding, the longer their service life and the higher the heat-shielding properties. To do this, it is necessary to take measures to reduce the vapor permeability of the load-bearing wall, and for vapor-permeable insulation it is recommended to create a ventilated gap at the border with the cladding.

To insulate a three-layer wall with mineral wool, it is better to use slabs with a density of at least 75 kg/m 3 with a ventilated gap.

A wall insulated with mineral wool with a ventilated gap dries out construction moisture faster and does not accumulate moisture during operation. The insulation does not burn.

September 5, 2016
Specialization: facade finishing, interior finishing, construction of summer houses, garages. Experience of an amateur gardener and gardener. We also have experience in repairing cars and motorcycles. Hobbies: playing the guitar and many other things that I don’t have time for :)

Cladding walls with brick is a reliable and durable way of finishing the facade, which can transform the appearance of the house. However, brick itself does not insulate walls much, so if you want your home to be warm and energy-saving, you need to place insulation between the main and facing walls. In this article I will tell you in detail how to insulate the walls of a house under brick cladding.

Technology of insulation and wall cladding

The technique of facing bricks with insulation is quite complex and includes several main stages:

Below we will get acquainted with the main nuances of work at each of these stages.

Selection and preparation of materials

Before you begin work on insulating the wall and further finishing it, you need to decide on the type of insulation. Currently, there are quite a lot of thermal insulation materials, however, the following thermal insulators are most often used for the stated purposes:

mineral mats are an environmentally friendly and durable material that is absolutely fireproof. The disadvantage of mats is high level moisture absorption and relatively high cost. In addition, keep in mind that the fibers of mineral mats getting on the skin, mucous membranes or respiratory tract cause irritation, so when working with this material it is necessary to use personal protective equipment;

expanded polystyrene is lightweight material, which has a much lower level of moisture absorption than mineral wool and is cheaper. However, keep in mind that polystyrene foam is less durable, also supports the combustion process and is toxic in the event of a fire;
extruded polystyrene foam - is a type of conventional polystyrene foam, but is characterized by greater strength and durability, as well as a zero level of moisture absorption, therefore, in terms of performance, it is also excellent for walls under facing bricks. The disadvantage, in addition to toxicity and fire hazard, is the high cost.

The thickness of insulation for walls made of brick or other materials depends on the climate in your region. If the winter temperature often drops below 25 degrees Celsius, 150 mm thick insulation should be used. If you live in a warmer climate, 100 mm thick insulation is sufficient.

As you can see, all materials have their own disadvantages and advantages. Therefore, everyone must decide for themselves which insulation is best to use.

In addition to insulation, it is necessary to prepare other materials. You will need:

antiseptic primer for treating walls (if the walls are wooden, you will need a protective impregnation for wood;
vapor barrier film;
umbrella dowels;
flexible connections (anchors that allow you not only to secure the insulation, but also to tie load-bearing wall with facing);

Preparing the wall

The next step is preparing the walls. To do this, you need to do the following manually:

start work by dismantling all existing hanging elements. These can be antennas, all kinds of canopies, ebbs, window sills and other parts that will interfere with the insulation of the facade;
if the facade has peeling and crumbling areas, they must be removed. To do this, you can use a chisel and a blade;
if the house is wooden, log or timber, it is necessary to insulate the roof gaps. To do this, you can use tow, polyurethane foam, latex sealant or other suitable thermal insulation;
after this, the walls must be treated with a protective deep-penetrating compound or wood impregnation. Instructions for using the compositions are always available on the packaging.

If the house is recently built, you can start insulating and cladding it after completion interior decoration, i.e. after the walls have dried. Otherwise, the wall material will absorb moisture, which will lead to a number of negative consequences, such as wet insulation, mold, etc.

At this point, the work on preparing the facade is completed.

The diagram shows the construction of a brick wall with insulation

Wall insulation

The next step is the installation of insulation. It must be said that insulation is often mounted on flexible connections during the construction of the facing wall. However, it is more convenient to first “grab” the slabs with dowels, then build the wall and install flexible connections.

Regardless of what type of insulation you use to insulate the walls, the installation instructions look like this:

First of all, you need to waterproof the blind area. To do this, you can coat it with bitumen mastic and then glue roofing felt to it. The latter should overlap about 10 cm, and the joints should also be coated with bitumen mastic.
It must be said that instead of roofing felt, other rolled waterproofing materials can be used, however, roofing felt is the most budget-friendly solution;
Now you need to fix the insulation to the wall. To do this, you should use special dowels, which are popularly called umbrellas or mushrooms. Installation of insulation should start from the corner and be done in rows.

During the installation process, make sure that there are no gaps between the insulation boards, as well as between the insulation and the waterproofed blind area.

To attach the insulation, simply press it against the wall and drill holes for the dowels through the slabs. After this, insert umbrellas into the holes and drive expansion nails into them.

To begin with, to simply “grab” the thermal insulation, a couple of dowels per slab are enough;

Now attach the vapor barrier membrane to the insulation, placing it overlapping. To attach the film, also use umbrella dowels.
If you line the walls with facing bricks, then you don’t need to perform a vapor barrier, since this material has an almost zero moisture absorption coefficient.

People often ask on forums whether insulation is needed between gas silicate and brick? Despite the fact that gas silicate itself has a low thermal conductivity coefficient, additional insulation will make your home even more comfortable and energy-saving.

It should be noted that according to this scheme, insulation is installed only on monolithic, brick and wooden walls. If the walls are made of aerated concrete, the work is carried out somewhat differently:

First of all, you need to mark the location of the flexible connections, taking into account the fact that they should be laid in horizontal joints between the bricks. Therefore, measure the height of the brick from the foundation.
The anchors should be located in increments of about 50 centimeters, both vertically and horizontally;
now you need to drill holes along the diameter and length of the tips (sleeves) of the flexible connections;

After this, you need to screw the anchor tips into the holes using a special key. In this case, the sleeves must be completely immersed in aerated concrete;
Next, insulation should be pinned onto the protruding flexible connections. Install it so that there are no gaps between the plates;
after that, attach a vapor barrier membrane over the insulation, which is also pinned onto the anchors;
At the end of the work, secure the insulation and vapor barrier film clamps that are put on the anchors and snap into place, thus pressing the vapor and heat insulation against the wall.

A vapor barrier in an aerated concrete house must be installed not only between the block and the brick, but also from the inside, i.e. from the side of the room.

After installing the insulation, you can begin laying bricks.

Nuances of laying a facing wall

First of all, I would like to note that facing wall has quite a lot of weight, so it must be built on a foundation. If the foundation of the house was not originally designed for the construction of a facing wall, an additional shallow shallow foundation needs to be built around the perimeter of the house.

On our portal you can find detailed information about how it is done. The only thing to keep in mind is that there should be a space of a few centimeters between the insulation and the facing wall.

Before laying bricks, it is necessary to waterproof the foundation. To do this, lay several layers of roofing material on top of it. Further work carried out in the following sequence:

work begins with laying the first row. In this case, beacons and a building level must be used to ensure an even row position;
if flexible connections have not been installed in advance, a hole is drilled in the wall above the first row of bricks to the required depth and an anchor is driven into it. After this, a limiter is put on the anchor, which additionally holds the thermal insulation;

the end of the flexible connection is laid between the bricks to a depth of about 10 cm. To do this, a solution is placed directly on it;
In the second row, ventilation is performed. To do this, leave a vertical seam unfilled with mortar every two bricks;

The entire facing wall is built according to this principle, taking into account that flexible connections should be located in increments of 50 cm vertically and horizontally. In addition, they are installed around the perimeter of window and door openings;
in the top row of bricks, i.e. Vents are made under the overhangs according to the scheme described above. This is necessary to ensure ventilation of the space between the wall and the insulation.

Here, in fact, is all the information on how to insulate walls under facing bricks. The only thing, in conclusion, I would like to note that the cladding process itself is quite complex, requiring highly qualified masons, so it is better to entrust this stage of work to specialists. True, the price of this service is also not small - on average it starts from 800 rubles per square meter.

The three-layer wall design is very popular. Such walls have an excellent appearance, they are durable, practical, and well insulated. Let's take a closer look at how a three-layer structure is erected and how the heat insulator is laid inside.

Is the inner layer made of heavy materials?

A three-layer wall consists of three layers. The first layer (from the inside of the building) is load-bearing, calculated for strength, and must be made according to design solutions, from strong materials of the required thickness.

The construction of this layer from hydrophobic (water-afraid) materials, such as aerated concrete, expanded clay concrete, requires special control over ventilation or other measures aimed at preventing an increase in its humidity.

Humidification can significantly reduce the durability of walls or even lead to emergency situation, - such situations should not be allowed.

Compared to brickwork, lightweight concrete does not provide much savings, especially when we're talking about about a three-layer wall. But problems can create significant ones.

Application of bricks

The usual material for the inner layer is ceramic brick. More often, according to design calculations, for a 1-2 storey building, a load-bearing layer thickness of 36 cm is sufficient, which corresponds to a masonry of 1.5 bricks.

But in accordance with special measures that may be provided for by the project, the load-bearing layer of a one-story building (with an attic) can be made of one brick - up to 25 cm thick.

The outer layer is a facade layer, usually made of hard facing bricks with a frost resistance of at least F50, which has an excellent appearance.

The laying is usually carried out in half brick with jointing (curly seams), the layer thickness is 12 cm. But it is possible to lay a layer thickness of 6 cm with special facade bricks or in? ordinary brick.

Connections between layers through insulation

There must be many mechanical connections between the outer and inner layers of a three-layer wall. It is enough to provide flexible connections. Rigid ones made of bricks will be significant bridges of cold, and insulating the walls will lose its meaning.

Flexible ties are made from fiberglass reinforcement or similar material that does not stretch over time. Their thermal conductivity coefficient is about 0.5 W/mS.

For comparison, steel reinforcement of the same diameter would have a thermal conductivity coefficient of 50 W/mS. The ties are laid in the seams between the bricks to a depth of 7–8 cm in the masonry.

The distance between the connections along the length of the wall is 50 - 100 cm, and in height it is usually taken to be 50 - 60 cm. The thicker the insulation layer, the greater the distance between the outer and inner layers, the higher the installation density of the connecting reinforcement.

What insulation to use for a three-layer wall

A three-layer wall is not collapsible design. Replacing or repairing the insulating layer in it will be extremely expensive and problematic. Therefore, during the construction of the wall, the most reliable insulation materials must be used immediately.

Experts agree that dense mineral wool slabs are better suited for difficult-to-repair structures with long-term use. And there are several reasons in favor of their choice.

Benefits of mineral wool

High quality slabs from basalt wool from famous manufacturers with a density of 60 kg/m3, the cube does not stretch or change shape over time.
The service life of minerals is long, practically the same as that of brick.
Mineral wool slabs are not eaten by rodents, and living creatures do not live in them, which is critical for a structure that cannot be repaired.
It is necessary to use hydrophobized boards with water absorption of no more than 1% by volume, so that possible dew does not damage the insulation over time.

Polystyrenes, polyurethanes too possible variant, but with them, at least, it is necessary to take special measures to prevent living creatures from entering the wall, which is not always possible, and stopping the outflow of steam through the wall, although small, is still a step better side by all measures...

How much insulation is needed

The thickness of the insulation layer is calculated based on the regulatory requirements for heat transfer resistance for a given region. For example, the heat transfer resistance of a brick wall made of solid brick will be 0.36 m / 0.7 W/mS = 0.51 m2C/W.

For a temperate climate in the middle zone, the heat transfer resistance of the wall should be at least 3.1 m2C/W.
Then the heat transfer resistance of the insulation layer should be 3.1 – 0.5 = 2.6 m2C/W.

The thickness of the insulation layer will be 0.04x2.7=0.1 meters. We accept 10 cm thick basalt fiber slabs for insulation.
Their calculated thermal conductivity coefficient of 0.04 W/mS is 10 percent more than what the manufacturer claims. This takes into account the actual moisture content of the slab during operation on the wall.

Above is a simplified calculation of the required insulation thickness for the building envelope. But in most cases, for private construction and solving household insulation issues, the accuracy of this calculation is quite acceptable.

Providing a ventilation gap above the insulation

The vapor-transparent insulation in a three-layer wall must be constantly ventilated. For normal ventilation and unimpeded air movement over the insulation, the ventilation gap between the insulation layer and the outer layer must be at least 3 cm.

To fix the insulation and constantly press it against the inner layer, plastic clamps are placed on the interlayer connections over the insulation.

Ventilation holes are made at the bottom and top of the façade layer. Cold air will flow to the insulation through the lower vents, then, due to heating from the heat entering through the insulation, a stable upward draft will arise, as a result of which the insulation will be constantly ventilated. The required area of the air supply openings is at least 40 cm2. per 10 sq. m. walls. The same area applies to the air outlets.

Preventing bed blowing

For individual species of insulation, the manufacturer provides for the use of a superdiffusion membrane, the role of which is to prevent the blowing out of insulation fibers.

If the slabs need such protection, then the insulating layer during the construction process must be covered with such a membrane with a vapor permeability of at least 1700 g/m2 per day.

Experts also strongly recommend using a windproof membrane in a ventilated facade system to prevent convection heat loss from the insulation (20% or more) with a slab density of less than 80 kg/m3 in wind zones up to 5 and a slab density of 180 kg/m3 in any wind zones and for high-rise buildings.

Are there fewer problems with polystyrene foam?

As you can see, mineral wool slabs in a three-layer wall are used using proven “ventilated facade” technology. The use of blown polyurethane foam or extruded polystyrene foam boards will reduce the overall thickness of the wall due to the insulation thickness being 20 percent less (less thermal conductivity coefficient) and the absence of a ventilation gap.

In this case, the strong layers will be separated by steam; the steam exchange of each layer will occur within its “own” atmosphere. But, as stated above, the inherent disadvantages of plastics in general do not make their use preferable.

It remains to be noted that floor slabs should not be embedded in the insulation and not extend beyond the inner layer of the wall. During the construction process, it is unacceptable to use a low-quality vapor diffusion membrane; reduce ventilation gap, or failure to provide ventilation openings in the outer façade layer.