Three-layer walls with brick cladding. Three-layer brickwork: advantages and disadvantages Three-layer structures of external walls with effective insulation

Features of insulation of three-layer walls made of bricks and small blocks

In the last publication, our readers and I began to build a warm, cozy house and at the first stage they tried to build a reliable foundation, which is not afraid of any abysses and hardships. The advantages of using extruded polystyrene foam for thermal insulation of underground structures were especially considered.

Today we would like to give you some professional advice on building warm exterior walls. At this stage of construction, each owner will have to choose a truly highly efficient, environmentally friendly, durable material from the variety of different building thermal insulation on the market today. Unfortunately, limited by the scope of this article, we cannot give comparative analysis modern thermal insulation products. We will only say that, in terms of the totality of technical and operational parameters, it is most preferable to use non-combustible mineral wool boards based on basalt fiber, with high thermal insulation characteristics(type rockwool). It is a water-repellent, non-rotten, deformation-resistant material. It is important that its shape and dimensions remain unchanged during the entire period of operation. It is easy and convenient to work with plates - no special skills are required during installation.

Further, each private developer inevitably faces another difficult choice: like a good fellow in a Russian epic, he stands at a mossy stone, thinks about it, calculates options ... which way of warming should he go?

As you know, there are three main options:

place heater on inner surface walls;
hide it inside, into the wall itself (the so-called layered masonry);
arrange insulation of the building envelope from the outside.

So, "if you go to the left - you will lose your horse, if you go to the right - you will find happiness, if you go straight - do not take your head off" ... Each of possible ways comes with its own challenges and dangers. As the most "unfabulous" we immediately dismiss the first method. It has a whole collection of shortcomings, and the absolute absence of any advantages. illustrative example to that bad experience operation of light Finnish houses, when insulation from the inside entailed severe waterlogging of wooden walls and their subsequent biocorrosion (destruction due to damage by fungi, bacteria and other microorganisms). You shouldn't agree to it.

most attractive and effective way is the external insulation of the facade (thermal insulation under plaster, the so-called "wet type" or the installation of hinged ventilated facades). Strong and weak sides These systems will be discussed in more detail in subsequent publications.

Today I would like to talk about the features of the construction of three-layer walls made of bricks or small blocks - the design of the most widely known and widely used.

Returning to the past, we note that back in the old days, a competent designer inevitably came into conflict with engineering conscience, since, in order to provide thermal comfort for the residents of the future house, according to the then existing standards, he had to use walls with a thickness of 64 cm or more. On the other hand, an accurate calculation for loads and impacts showed that such a thickness was two times higher than the value necessary for the stability of the structure. Today, remorse would have tortured this designer completely. Since to meet the new requirements building codes for the thermal protection of the building, using the traditional single-layer solution, our friend would have to lay a one and a half meter brick wall into the project. So wastefully and with such a huge margin of safety in the old days, only defensive fortifications were built.

Meanwhile brickwork everything is also loved, demanded and desired by man. And to this day it retains the charm of antiquity, beauty and strength. In order not to return to the era of Tsar Ivan Vasilyevich, a three-layer wall construction was invented. Between the outer and inner walls (lined with bricks or blocks) a layer of heat-insulating material was placed - mineral wool based on basalt fiber. For comparison: a 5 cm thick basalt wool slab is equivalent in terms of thermal parameters to brick wall 1 m thick. Thus, a truce was concluded between structural mechanics and heat engineering. Modern analogue -.

What are these details? Firstly, the repair and restoration work of such a design is extremely expensive and time-consuming, therefore, the insulation used must be approached with special responsibility. There are two main requirements: high resistance to shrinkage (and only plates with a density of at least 45-60 kg / m 3 can ensure this condition), in addition, the material must be hydrophobized (water absorption by volume is not more than 1%). talk about the simplicity of brickwork. But the competent use of a three-layer structure for insulating the walls of your house requires a good study of the entire anatomy of the building and does not tolerate neglect of the laws of building physics. Here you need to know the price of parts.

Secondly, in the system under consideration, the inner layer of masonry is an atlas, on which it bears all the mechanical loads that fall on the outer walls (its thickness is determined from the strength calculation). Therefore, only reliable and durable stones can compose it: clay or silicate brick, concrete, expanded clay concrete, gas silicate and other blocks. The only exception to this series will be slag concrete blocks, which, like a sponge, are quickly saturated with moisture and dry very slowly. Keeping warm in a house with damp insulation is like trying to keep warm in a wet shirt. For the same reason, when using silicate bricks, a reliable horizontal waterproofing is sure to be arranged. But for the basement, basement and walls of rooms with high humidity, this material is not at all suitable, it is replaced with a more hydrophobic one. In general, the use of any waterlogged materials for masonry (moisture content above 6% by weight) is strictly prohibited.

Thirdly, we note that the outer layer has two completely different, but no less important tasks: to decorate the facade and protect the insulation. Therefore, the outer wall is always thinner and slimmer than the inner one. If we talk about the aesthetics of the outer layer, made of quality bricks or ceramic stone, then it is desirable not to hide, but rather to expose the poetic brick texture, making it tectonic, as the architects say. Plastering is usually resorted to in the case of using concrete or expanded clay concrete blocks. Moreover, we will immediately make a reservation that cellular concrete and expanded clay concrete, due to the hydrophilicity of the first and the low vapor permeability of the latter, test for Cohabitation in one system do not pass.

Fourthly, in order for the loaded and unloaded layers in the system to work together, special connections are used. In such a design, it would be an unforgivable mistake to make them rigid, i.e. from the same stone materials from which the layers are made. The reason is that brick lintels, dissecting the insulation, turn into "cold bridges" through which precious heat flows from the house to the street. The most effective solution to improve thermal uniformity and reduce heat loss is the use of flexible fiberglass or basalt-plastic reinforcement. The thermal conductivity coefficient of such bonds is 0.45 W/m·°C versus 50 W/m·°C for flexible steel bonds. They are laid in the seams of masonry to a depth of 60-80 mm at a distance of 600 mm from each other along the height of the wall and 500-1000 mm along the wall (2-5 pieces per 1 m 2).

Fifth, I would like to warn you against one more design error, which leads to the formation of the ubiquitous "cold bridges". Beams and floor slabs should rest only on the inner wall and not go into the thickness of the insulation.

In conclusion, let's dwell on the "narrowest" place in the construction of a three-layer brick wall. The fact is that thermal insulation properties any multilayer construction are directly dependent on the humidity regime, which, in the end, will be established in the built house. Therefore, it is necessary to carefully calculate and weigh all the pros and cons of a particular sequence of arrangement of layers of heat and vapor barrier, i.e. thoroughly study the entire anatomy of the building. At this stage, water vapor will create certain difficulties for us. The pressure difference makes them rush out - out of the room, so these dangerous saboteurs always diffuse (penetrate and spread) in the thickness of the building envelope, waterlogging the insulation, and, in the end, can reduce all measures taken for insulation to zero. A vapor barrier device, even the most reliable and effective, in this context is a double-edged sword, since in its absence "precipitation" (the so-called condensation plane) will be observed on the cold surface of the insulation. AT winter time in addition to worsening the temperature and humidity conditions inside the building, this can lead to bulging and other various deformations of the front brick layer. The presence of a vapor barrier is also not a panacea, since there is a danger of condensation between the vapor barrier and the inner verst, which negatively affects the state of the loaded part of our structure, and also threatens to form mold. A lifesaver here will be a few rules:

the outer wall is made of a more vapor-permeable, as a rule, less dense material than the inner one;
it is always better to provide an air gap - 5-10 mm, between the insulation and the outer wall. To do this, along with glass or basalt bonds, a special plastic retainer is used that presses the insulation plate against inner wall;
to ventilate the air gap, special vents are arranged in the lower and upper parts of the wall. The area of such holes is taken at the rate of 75 cm 2 for every 20 m 2 of the wall surface. To do this, use either a hollow brick laid on the edge, or in the lower row of masonry, not all vertical seams are filled cement mortar.
another option that allows you to get rid of the condensate that accumulates in the lower part of the wall is the construction of special outlet channels from polyethylene pipes with a diameter of 10 mm every 1000 mm around the entire perimeter of the building at the lowest point of the insulation;
vapor barrier is placed as close as possible to the inner surface of the wall, on the "warm" side of the insulation;
the best result is achieved in the case of using foil vapor barrier material("Polycraft" by Monarflex).

In conclusion, I would like to wish readers more happiness and warmth in the built house. And the choice of insulation option should always be approached through the prism of common sense, and do not hesitate to contact specialists for competent comprehensive advice.

Three-layer brick wall with air gap

circuit diagram

Gypsum boards;
Vapor barrier (Polykraft type);
Brickwork;
Mineral wool boards (Rockwool type);
Windproof vapor permeable membrane (type Tyvek);
Flexible connections with clamps (d=6 mm);
Ventilated air gap, 20-30mm;
Front brickwork;
Floor slab;
Waterproofing;
Condensate drain channel (polyethylene tube, d=10 mm;
Foundation;

In some new built buildings, insulation is placed centrally (in the middle) in the building envelope. With this option, the insulation is very well protected from mechanical damage and there are more opportunities for decorating facades. However, the risk of damage due to humidity is much higher than with external insulation, therefore, the layer structure must be carefully planned and executed without defects.

This design consists of three layers: load-bearing walls, walls made of facing material and insulation, which is located between them. Carrier and wall cladding rest on the same foundation. The outer layer is most often made of either facing brick, or from construction with subsequent plastering, coating with artificial stone, clinker tiles etc.

Advantages

handsome and respectable appearance when using expensive facing materials;
high durability, subject to proper design and qualified installation of the structure.

disadvantages

high labor intensity of construction;
low breathability;
the possibility of moisture condensation between the heterogeneous layers of such a wall.

It is very important that all layers of the structure are combined with each other in terms of vapor permeability. Compatibility is determined only by the calculation of the system as a whole.

Underestimating this circumstance can lead to the accumulation of moisture in the interior of the walls. This will create favorable environment for the development of mold and fungus. The insulation from the possible formation of condensate will get wet, which will shorten the life of the material and significantly reduce it heat-shielding properties. The enclosing structure will begin to freeze, which will lead to inefficiency of insulation and may cause its premature destruction.

Types of structures

Standard Solutions layered masonry devices can be divided into two types: with device air gap and without it.

The air gap device allows you to more effectively remove moisture from the structure, since excess moisture from the load-bearing wall and insulation will immediately go into the atmosphere. At the same time, the air gap increases the total thickness of the walls, and, consequently, the foundation.

Insulation inside masonry walls

To some extent, the problem of steam transfer is relevant for layered masonry with any type of insulation.

Construction insulation mineral wool is the most preferred. In this case, it becomes possible to arrange an air gap between the insulation and the outer wall for better moisture removal from the load-bearing wall and insulation.

For layered masonry, use semi-rigid mineral wool insulation. This will allow, on the one hand, to fill in well all the defects in the masonry, to create a continuous layer of thermal insulation (the plates can be “squeezed” a little, avoiding cracks). On the other hand, such plates will maintain geometric integrity (do not shrink) throughout the entire service life.

Certain difficulties in the use of expanded polystyrene in layered masonry are caused by the low vapor permeability of this material.

Three-layer brickwork with insulation

Interior of a brick wall
Mineral wool
Exterior brick wall
Connections

The traditional material for the interior of the walls is solid red ceramic brick. Masonry is usually done on cement-sand mortar in 1.5-2 bricks (380-510 mm). outer wall usually done from face brick 120 mm thick (in half a brick).

Products

In the case of a system with an air gap 2-5 cm wide, for its ventilation, vents (holes) are arranged in the lower and upper parts of the wall, through which vaporous moisture is removed to the outside. The size of such holes is taken at the rate of 75 cm 2 per 20 m 2 of the wall surface.

The upper ventilation ducts are located at the cornices, the lower ones - at the plinths. At the same time, the lower holes are intended not only for ventilation, but also for water drainage.

Air gap 2cm
Lower part of the building
Top part building

To carry out ventilation of the layer, a slotted brick laid on the edge is installed in the lower part of the walls, or a brick is laid in the lower part of the walls not close to each other, and not at some distance from each other, and the resulting gap is not filled with masonry mortar.

Establishing links

The inner and outer parts of a three-layer brick wall are interconnected by special embedded parts - ties. They are made of fiberglass, basalt-reinforced plastic or steel reinforcement with a diameter of 4.5–6 mm. It is preferable to use fiberglass or basalt-reinforced plastic links due to the greater thermal conductivity of steel links.

These connections also perform the function of fixing the insulation boards (the insulation is simply
poke at them). They are installed in the process of laying in a load-bearing wall to a depth
6-9 cm in increments of 60 cm horizontally and 50 cm vertically, based on an average of 4 pins per
1 m 2.

To ensure a uniform ventilated gap over the entire area of the insulation, fixing washers are attached to the rods.

Often, instead of special connections, bent reinforcing bars are used. In addition to connections, the outer and inner walls of the masonry can be connected with a steel reinforcing mesh laid every 60 cm vertically. In this case, additional mechanical fastening of the plates is used for the air gap device.

Insulation plates are installed with dressing of seams close to each other, so that between separate slabs there were no cracks or gaps. At the corners of the building, the plates are geared to avoid the formation of cold bridges.

Masonry technology with insulation

Laying the facing layer to the level of connections
Installation of a heat-insulating layer so that its top is 5-10 cm higher than the facing layer
Laying the carrier layer to the next level of connections
Installing ties by piercing them through the insulation

if the horizontal seams of the bearing and facing layers of the wall in which the ties are placed do not coincide by more than 2 cm in the bearing layer of brickwork, the ties are placed in a vertical seam

Laying one row of bricks in the bearing part of the wall and the facing layer

Mounting sequence
(Alternative option)

Such designs have been used for a long time, they can use various materials. These are the previously mentioned cellular concrete, expanded clay concrete and porous ceramic blocks, as well as materials that, due to their thermal characteristics, are not suitable for the construction of single-layer or two-layer walls - ceramic and silicate bricks and stones. Due to their design, three-layer walls have good thermal performance, they accumulate heat well.

Unfortunately, the construction of such walls is a laborious process, since masons essentially have to build two layers of masonry - bearing and finishing. In addition, when working with small-piece bricks, the construction time of buildings increases significantly.

At the same time, three-layer walls, in the case of using traditional materials, are relatively thick and usually have a thickness of 50 to 65 cm. This is somewhat larger than two- and one-layer walls made of effective structural materials. This feature entails the need to build a wider foundation, lintels, parapets and, accordingly, increases the consumption of materials for these purposes.

In addition, it should be borne in mind that if thicker walls are erected in a house of a certain size, then effective area interior spaces decrease. If, in order to save the area, try to increase the external dimensions of the house, then this will result in a large consumption of materials for the construction of the foundation and roof. And this is an increase in the cost of construction.

The traditional three-layer wall consists of the following layers. The carrier layer, which, as we have already noted, is usually made of cellular concrete, expanded clay concrete or porous ceramic blocks, ceramic or silicate bricks (stones). As a rule, the thickness of the bearing layer is from 25 to 50 cm. The thickness of the bearing layer is determined by the strength requirements for the building.

Mineral or glass wool, extruded or ordinary polystyrene foam boards can be used as the inner layer. Recently, as a heat-insulating layer, blocks of cellular concrete reduced density. The thickness of the inner layer is determined by the requirements of the thermal protection of the building and is usually 50–150 mm.

One of the important tasks in the design of three-layer walls is the removal of moisture that forms inside the structure. As a rule, for this purpose, an air gap is arranged between the insulation and the front layer of the wall, designed for ventilation and removal of condensate. The gap width is determined by thermal engineering and is usually 40–60 mm.

In addition, when using mineral wool boards as a heater, it is recommended to arrange wind protection in the form of a diffusion film. As an option, high-density mineral wool board can be used. To ensure effective ventilation, ventilation elements are mounted in the seams of the front layer at the bottom and top of the wall. The purpose of the front layer is to protect the insulation from external influences and to give the building the necessary architectural appearance. In fact, the front layer in the construction with a ventilated layer plays the layer of the outer layer of the ventilated facade.

The layer thickness is determined by the strength characteristics of the material and is usually 65–120 mm. As a rule, during the construction of this layer, materials are used that do not require further finishing: front ceramic or silicate brick, clinker, natural or artificial stone, decorative blocks from heavy concrete.

Bricks and blocks can have both a smooth texture and a chipped one, which resembles the texture of a wild stone. In addition, sand-lime bricks and concrete blocks can be colored in mass, and ceramic bricks or clinker can even be glazed. This provides the material with a low water absorption rate and, therefore, long term services.

In this regard, it should be noted that silicate brick, on the contrary, has a relatively high rate of water absorption. Therefore, when constructing a facing layer of this material, it is still worth using, for example, facing ceramic bricks in elements that are most susceptible to moisture (plinth, belts, parapets, etc.).

As the outer layer, cellular concrete blocks, ordinary bricks or other Construction Materials that require further finishing, in particular, plastering and painting. In this case, traditional decorative protective plasters for outdoor use are used.

However, this option of building a three-layer wall ultimately results in additional labor costs and an increase in the cost of materials and finishing work. The cost of a front brick as a result turns out to be lower than the price of an ordinary brick, together with plaster and paint. Also, do not forget that plastered walls require high maintenance costs in the future.

Incidentally, within this material we will not consider such facade finishing options as siding or wall cladding with ceramic or clinker tiles, thermal panels. These finishing options are widely used not only in the construction of three-layer walls, but much more often single-layer and two-layer ones. Therefore, such methods exterior finish facades of individual houses require consideration in a separate article.

The technology of erecting a three-layer wall requires, at the first stage, the laying of the carrier layer, then the fastening of the insulation and the laying of the front layer. Usually, the load-bearing and front walls are built in parallel. But current technologies make it possible to divide the construction of a house into stages: in one season, you can put a load-bearing wall, and in the next, insulate it and build a front layer.

The bearing and finishing layers are interconnected by flexible or rigid links. Flexible connections are rods (4–8 mm in diameter) or narrow plates made of of stainless steel. As a rule, at least two flexible connections are used per 1 m 2 of wall masonry. At the same time, it should be noted that the bonds are cold bridges and reduce the resistance to heat transfer of the entire enclosing structure. In this regard, in recent years, fiberglass-based ties have become increasingly widespread. This material has good thermal conductivity resistance and solves the problem of cold bridges.

As a rule, flexible connections are laid in the seams during the construction of a load-bearing wall. Then a layer of insulation is threaded through them and attached to the wall with the help of disk-shaped spring washers. At the same time, it is possible to install the connections after laying the carrier layer. In this case, holes are drilled in the wall in which ties are attached to the dowels.

The first option is cheaper and faster, so it is used more often. However, with the second one, it is possible to achieve greater accuracy of matching the bonds with the seams of the masonry of the front layer.

Separately, it is worth mentioning the so-called well masonry, in which the outer and bearing layers of the wall are connected by rigid ties - bricks. In this case, a significant amount of heat is lost through the formed cold bridges. In addition, well masonry is used if the load-bearing wall and the front wall are designed from the same material. However, with the advent of new effective wall materials on the market, manhole masonry has been used less recently.

The three-layer wall construction is very popular. Such walls have an excellent appearance, they are durable, practical, well insulated. Let us consider in more detail how a three-layer structure is erected, how a heat insulator is laid inside.

Heavy material inner layer?

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

The construction of this layer from hydrophobic (water-resistant) materials, such as aerated concrete, expanded clay concrete, requires special control over the provision of 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, such situations should not be allowed.

Compared to masonry, lightweight concrete does not offer much savings, especially when it comes to a three-layer wall. But problems can be significant.

Application of brick

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

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

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

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

Bonding layers through insulation

Between the outer and inner layers of a three-layer wall, there must be many mechanical connections. It is enough to provide flexible connections. Rigid bricks will be significant cold bridges, and wall insulation will lose its meaning.

Flexible connections are made from fiberglass reinforcement or similar non-stretch material. Their coefficient of thermal conductivity is about 0.5 W/mS.

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

The distance between the bonds along the length of the wall is 50 - 100 cm, and the height 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 density of installation of the connecting reinforcement.

What insulation to use for a three-layer wall

The three-layer wall is not a collapsible structure. Replacement, repair of the insulation layer in it will be extremely expensive and problematic. Therefore, during the construction of the wall, you must immediately apply the most reliable insulation materials.

Experts agree that dense mineral wool boards are better suited for hard-to-repair structures with long-term operation. And there are several reasons for choosing them.

Benefits of mineral wool

Quality basalt wool slabs from well-known manufacturers with a density of 60 kg / m cube do not stretch, do not change shape over time.
The service life of minerals is long, in fact the same as that of a brick.
Mineral wool slabs are not eaten by rodents, living creatures do not settle 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 harm the insulation over time.

Polystyrenes, polyurethanes too possible variant, but with them, at least, special measures must be taken to prevent living creatures inside the wall, which is not always possible, and the cessation of the outflow of steam through the wall, although small, is still a step for the worse in all respects ...

How much insulation is needed

The thickness of the insulation layer is calculated based on regulatory requirements on 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 m2S/W.

For temperate climate middle lane the heat transfer resistance of the wall must be at least 3.1 m2S/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 for insulation slabs of basalt fiber 10 cm thick.
The coefficient of thermal conductivity accepted for calculation at the level of 0.04 W / mS is 10 percent more than the manufacturer claims. This takes into account the actual dampening of the slab during operation on the wall.

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

Providing a ventilation gap above the insulation

A vapor-transparent insulation in a three-layer wall must be constantly ventilated. For normal ventilation, unhindered 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 its constant pressing against the inner layer, plastic clamps are put on the interlayer bonds over the insulation.

Ventilation holes are made at the bottom and top of the facade layer. Cold air will flow to the insulation through the lower vents, then, due to heating from the heat coming through the insulation, a steady upward draft will occur, 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 for the air outlets.

Bed Blow Prevention

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

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

Also, experts strongly recommend the use of a windproof membrane in the ventilated facade system to prevent convection heat leakage from the insulation (20% or more) at a plate density of less than 80 kg/m3 in wind zones up to 5 and a plate density of 180 kg/m3 in any wind zones and for tall buildings.

Is Styrofoam less of a problem?

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

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

It remains to be noted that the floor slabs should not be embedded in the insulation and should not go beyond the inner layer of the wall. During the construction process, it is unacceptable to use a poor quality vapor diffusion membrane, reduce the ventilation gap, or not provide ventilation holes in the outer facade layer.

Construction of a three-layer wall with brick cladding

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

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

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

wall cladding of facing brick protects the insulation from external influences and serves decorative coating walls.

Fig.1. Three layer wall.
1 — interior decoration; 2 - load-bearing wall; 3 - thermal insulation; 4 - ventilated gap; 5 - brick lining; 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 from a heater, albeit within acceptable limits;
the need to use special measures to protect the wall from blowing and moistening - vapor-tight, windproof coatings and ventilated gaps;
combustibility of polymeric heaters;

Bearing wall in three-layer masonry

Insulation of the walls of the house with mineral wool boards

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

The calculations of the moisture regime of the walls show that in three-layer walls condensate in the insulation falls in the cold season in almost all climatic zones Russia.

The amount of condensate falling out is different, but for most regions it fits into the norms established by SNiP 23-02-2003 "Thermal protection of buildings". There is no accumulation of condensate in the wall structure during the year-round cycle due to drying in the warm season, which is also a requirement of these SNiP.

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

Rice. 2. The result of the calculation of the moisture regime of the wall with mineral wool insulation as the middle layer (expanded concrete - 250 mm, insulation -100 mm, brick -120 mm). Facing - ceramic brick without ventilation.

Rice. 3. The result of the calculation of the moisture regime of the wall with mineral wool insulation with plaster coating (expanded concrete - 250 mm, insulation - 120 mm, plaster coating -10 mm). Facing - vapor permeable.

Rice. 4. The result of calculating the moisture regime of a wall insulated with mineral wool boards with a ventilated gap and a "siding" type coating (brick - 380 mm, insulation -120 mm, siding). Facing - ventilated facade.

From the above graphs it is clearly seen how the lining barrier, which prevents ventilation of the outer surface of the mineral wool insulation, leads to an increase in the amount of condensate in the insulation. Although in the annual cycle of moisture accumulation in the insulation does not occur, but 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 accumulates in the layer adjacent to the insulation brick cladding

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

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

Replacing a heater covered with brick cladding is an expensive pleasure. Hydrophobized high-density mineral wool boards are more durable under these conditions. But these plates have a higher cost.

The amount of condensate is reduced or no condensation at all if you provide better ventilation of the surface of the insulation - 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 bearing wall is closed vapor barrier film or use heat-insulating boards with a vapor barrier applied to their surface. When mounting on a wall, the surface of the boards covered with a vapor barrier must face the wall.

The arrangement of a ventilated gap, sealing the walls with vapor-tight coatings complicates and increases the cost of the wall structure. What does moistening the insulation in the walls in winter lead to is written above. Here also choose. For construction areas with harsh winter conditions the device 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 kg / m 3, pasted over on one side with a windproof coating. When using plates without wind protection on the outer surface of the thermal insulation, wind protection 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 construction without a ventilated gap, heat-insulating boards are installed freely in vertical position in the space between the main wall and the facing layer of brick. The supporting elements for the insulation are fasteners provided for fastening the brick cladding to the load-bearing wall - reinforcing mesh, flexible connections.

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

Wall insulation 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.

Polymer boards have a very high vapor permeability. For example, an expanded polystyrene (EPS) wall insulation layer has a resistance 15-20 times greater than that of a brick wall of the same thickness.

Insulation with hermetic laying is a vapor-tight barrier in a brick wall. Steam from room to outer surface the heater just doesn't fit.

With the right thickness of the insulation, the temperature of the inner surface of the insulation must be above the dew point. When 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 is gaining popularity - products from low-density cellular concrete. These are heat-insulating slabs based on materials already known and used in construction - autoclaved aerated concrete, gas silicate.

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

Heat-insulating slabs made of cellular concrete are a good alternative to mineral wool and polystyrene foam insulation.

Known in the construction market trade marks heat-insulating slabs made of cellular concrete: "Multipor", "AEROC Energy", "Betol".

Advantages of cellular concrete thermal insulation slabs:

The most important one 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. Moisture that condenses in the insulation in winter dries quickly in the warm season. There is no accumulation of moisture.

Thermal insulation does not burn, under the influence of fire does not emit harmful gases. The heater does not stick. Insulation boards are harder and mechanically stronger.

The cost of facade insulation 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 plates made of aerated concrete, the following rules are followed:

Heat-insulating slabs of aerated concrete up to 100 thick mm fastened to the facade with glue and dowels, 1-2 dowels per plate.

From plates with a thickness of more than 100 mm close to the insulated wall lay out the wall. Laying is carried out on glue with a seam thickness of 2-3 mm. With bearing wall masonry from insulation boards are connected with anchors - flexible links from the calculation, five bonds per 1 m 2 walls. Between the bearing wall and the insulation, you can leave a technological gap of 2-15 mm.

It is better to tie all layers of the wall and brick cladding with 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 plates poorly absorb water 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 of the above types of heaters.

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

The thickness of the insulation is chosen in two stages:

They are chosen based on the need to provide the required resistance to heat transfer of the outer wall.
Then 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 an increase in construction costs.

A particularly large difference in the thickness of the insulation, selected according to the above two 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 plates should be unreasonably large.

When warming aerated concrete walls(as well as from other materials with low resistance to vapor permeability and high resistance to heat transfer - for example, wood, from large-porous expanded clay concrete), the thickness of polymer thermal insulation, according to the calculation of moisture accumulation, turns out to be much larger than it is necessary according to the standards for energy saving.

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

A vapor barrier from the inside is mandatory for walls made of aerated concrete, gas silicate for any type of insulation and facade cladding.

It should be borne in mind that the masonry of the walls of a new house always contains a large amount of building moisture. Therefore, it is better to let the walls of the house dry well outside. It is recommended to carry out facade insulation works after the interior decoration is completed, and not earlier than one year after the completion of these works.

Facing the exterior walls of the house with bricks

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

It should be especially noted 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 the service life, the heat-saving properties of the wall are reduced by more than a third.

With brick cladding use the most durable insulation, providing them with conditions in the wall structure for maximum long-term operation without replacement (minimum amount of condensate in the wall). It is recommended to choose mineral wool insulation high density and polymer extruded polystyrene foam, XPS.

In brick-lined walls, best to use mineral heaters from autoclaved aerated concrete or foam glass, with the service life of which is much longer than mineral wool and polymer.

Brick cladding is done in half a brick, 120 mm. on conventional masonry mortar.

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

Brick cladding is connected to the bearing wall masonry with corrosion-protected steel wire or reinforcing mesh, or with special flexible ties (fiberglass, etc.). Vertically, the grid or connections are arranged in increments of 500-600 mm.(height of the insulation plate), horizontally - 500 mm., while the number of bonds per 1 m 2 blank wall - at least 4 PCS. At the corners of the building along the perimeter of window and door openings 6-8 PCS. for 1 m 2.

The laying of brick cladding is longitudinally reinforced with masonry mesh with a vertical step of not more than 1000-1200 mm. The masonry mesh should go into the seams of the masonry of the bearing wall.

To ventilate the air gap in the bottom row of facing masonry, special vents are arranged at the rate of 75 cm 2 for every 20 m 2 wall surface. For the lower airways, you can use a slotted brick laid on the edge so that outside air through the holes in the brick had the opportunity to penetrate into 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 lower row of masonry with cement mortar.

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

Such an arrangement of the window, 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 a brick lining.

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

It is also important to reduce the amount of moisture in the outer walls in winter period. The less moisture condenses in the insulation and lining, 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 bearing wall, and for a vapor-permeable insulation, it is recommended to arrange a ventilated gap at the border with the cladding.

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

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

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