Constructive solutions for external walls in brick buildings. Topic: Constructive solutions for brick walls. General requirements and classification

External wall structures are classified according to the following criteria:

The static function of the wall, determined by its role in the structural system of the building;

Materials and construction technology determined by the building’s construction system;

Constructive solution - in the form of a single-layer or layered enclosing structure.

According to the static function they distinguish (Fig. 4.4) load-bearing walls (4.3), self-supporting walls(4.4) and curtain walls (4.5).

Fig.4.4. Classification of external walls by bearing capacity: a – load-bearing; b – self-supporting; c - non-load-bearing

Non-load-bearing walls are supported floor by floor on adjacent internal structures of the building (floors, walls, frame).

Load-bearing and self-supporting walls perceive horizontal loads along with vertical ones, being vertical elements of rigidity of structures. In buildings with non-load-bearing external walls, the functions of vertical stiffening elements are performed by the frame, internal walls, diaphragms or stiffening trunks.

Load-bearing and non-load-bearing external walls can be used in buildings of any number of floors. Height itself load-bearing walls limited in order to prevent operationally unfavorable mutual displacements of self-supporting and internal load-bearing structures, accompanied by local damage to the finishing of the premises and the appearance of cracks. IN panel houses, for example, it is permissible to use self-supporting walls with a building height of no more than 4 floors. The stability of self-supporting walls is ensured by flexible connections with internal structures.

Load-bearing external walls are used in buildings of various heights. The maximum number of storeys of a load-bearing wall depends on the load-bearing capacity and deformability of its material, design, the nature of the relationships with internal structures, as well as on economic considerations. For example, the use of lightweight concrete panel walls is advisable in buildings up to 9–12 floors high, load-bearing brick exterior walls in mid-rise buildings, and steel lattice shell walls in 70–100 storey buildings.

Based on the material, there are four main types of wall structures: concrete, stone, non-concrete materials and wood. In accordance with the construction system, each type of wall contains several types of structures: concrete walls - made of monolithic concrete, large blocks or panels; stone walls - brick or small blocks, walls made of large stone blocks and panels; wooden walls - chopped, frame-panel, panel and panel.

External walls can be of single-layer or layered construction. Single-layer walls are erected from panels, concrete or stone blocks, monolithic concrete, stone, brick, wooden logs or beams. In layered walls, different functions are assigned to different materials. Strength functions are provided by concrete, stone, wood; durability functions – concrete, stone, wood or sheet material ( aluminum alloys, enameled steel, asbestos cement, etc.); thermal insulation functions - effective insulation materials (mineral wool boards, fiberboard, expanded polystyrene, etc.); vapor barrier functions – roll materials(pasting roofing felt, foil, etc.), dense concrete or mastics; decorative functions - various facing materials. An air gap may be included in the number of layers of such a building envelope. Closed - to increase its resistance to heat transfer, ventilated - to protect the room from radiation overheating or to reduce deformations of the outer cladding layer of the wall.

Study and analyze the above material and answer the proposed question.

The article we bring to your attention is devoted to the design of the external walls of modern buildings in terms of their thermal protection and appearance.

Looking at modern buildings, i.e. buildings that currently exist should be divided into buildings designed before and after 1994. The starting point in changing the principles of constructive design of external walls in domestic buildings is the order of the State Construction Committee of Ukraine No. 247 dated December 27, 1993, which established new standards on thermal insulation of building envelopes of residential and public buildings. Subsequently, by order of the State Construction Committee of Ukraine No. 117 dated June 27, 1996, amendments were introduced to SNiP II -3-79 “Construction Heat Engineering”, which established the principles for designing thermal insulation of new and reconstructed residential and public buildings.

After six years of action of the new norms, questions about their appropriateness no longer arise. Years of practice have shown that it has been done right choice, which, at the same time, requires careful multilateral analysis and further development.

In buildings designed before 1994 (unfortunately, the construction of buildings according to old thermal insulation standards still occurs today), external walls perform both load-bearing and enclosing functions. Moreover, the load-bearing characteristics were ensured with fairly small thicknesses of the structures, and the implementation of enclosing functions required significant material costs. Therefore, the reduction in construction costs followed the path of a priori low energy efficiency due to well-known reasons for an energy-rich country. This pattern applies equally to buildings with brick walls and to buildings made of large-sized concrete panels. Thermally, the differences between these buildings were only in the degree of thermal heterogeneity of the outer walls. Brick walls can be considered as fairly homogeneous thermally, which is an advantage, since a uniform temperature field inner surface outer wall- this is one of the indicators of thermal comfort. However, to ensure thermal comfort, the absolute value of the surface temperature must be sufficiently high. And for the external walls of buildings created according to standards before 1994, the maximum temperature of the internal surface of the external wall at the design temperatures of internal and external air could only be 12 ° C, which is not enough for thermal comfort conditions.

The appearance of the brick walls also left much to be desired. This is due to the fact that domestic technologies for making bricks (both clay and ceramic) were far from perfect, as a result, the bricks in the masonry had different types. The buildings from sand-lime brick. IN last years In our country, bricks appeared, manufactured according to all the requirements of modern world technologies. This applies to the Korchevat plant, where they produce bricks with an excellent appearance and relatively good thermal insulation characteristics. From such products it is possible to construct buildings whose appearance will not be inferior to their foreign counterparts. Multi-storey buildings in our country they were mainly built from concrete panels. This type of wall is characterized by significant thermal heterogeneity. In single-layer expanded clay concrete panels, thermal heterogeneity is due to the presence of butt joints (photo 1). Moreover, its degree, in addition to structural imperfections, is also significantly influenced by the so-called human factor - the quality of sealing and insulation of butt joints. And since this quality was low under Soviet construction conditions, the joints leaked and froze, presenting residents with all the “charms” of damp walls. In addition, widespread non-compliance with the technology for manufacturing expanded clay concrete led to increased density of the panels and low thermal insulation.

Things weren't much better in buildings with three-layer panels. Since the stiffening ribs of the panels caused thermal inhomogeneity of the structure, the problem of butt joints remained relevant. The appearance of the concrete walls was extremely unpretentious (photo 2) - we did not have colored concrete, and the paints were not reliable. Understanding these problems, architects tried to add variety to buildings by applying tiles to the outer surface of the walls. From the point of view of the laws of heat and mass transfer and cyclic temperature and humidity influences, such a structural and architectural solution is absolute nonsense, which is confirmed by the appearance of our houses. When designing
after 1994, the energy efficiency of the structure and its elements became decisive. Therefore, the established principles of designing buildings and their enclosing structures have been revised. Energy efficiency is based on strict adherence to the functional purpose of each design element. This applies both to the building as a whole and to the enclosing structures. The so-called frame-monolithic buildings have confidently entered into the practice of domestic construction, where the strength functions are performed by a monolithic frame, and the external walls have only enclosing (heat and sound insulation) functions. At the same time, they have been preserved and are successfully developing design principles buildings with load-bearing external walls. The latest solutions are also interesting because they are fully applicable for the reconstruction of those buildings that were discussed at the beginning of the article and which require reconstruction everywhere.

The design principle of external walls, which can be equally used for the construction of new buildings and for the reconstruction of existing ones, is continuous insulation and insulation with air gap. The effectiveness of these design solutions is determined by the optimal selection of thermophysical characteristics of a multilayer structure - load-bearing or self-supporting wall, insulation, textured layers, outer finishing layer. The material of the main wall can be any and the determining requirements for it are strength and load-bearing.

The thermal insulation characteristics of this wall solution are fully described by the thermal conductivity of the insulation, which is used as polystyrene foam PSB-S, mineral wool boards, foam concrete, and ceramic materials. Expanded polystyrene is a thermal insulation material with low thermal conductivity, durable and technologically advanced for insulation. Its production is established at domestic factories (Stirol plants in Irpen, factories in Gorlovka, Zhitomir, Bucha). The main disadvantage is that the material is flammable and, according to domestic fire standards, has limited use (for low-rise buildings, or in the presence of significant protection from non-combustible cladding). When insulating the external walls of multi-storey buildings, PSB-S is also subject to certain strength requirements: the density of the material must be at least 40 kg/m3.

Mineral wool boards are a heat-insulating material with low thermal conductivity, durable, technologically advanced for insulation, and meet the requirements of domestic fire standards for external walls of buildings. In the Ukrainian market, as well as in the markets of many other European countries, mineral wool boards from the concerns ROCKWOOL, PAROC, ISOVER, etc. are used. Characteristic feature These companies have a wide range of products produced - from soft boards to hard ones. Moreover, each name has a strictly targeted purpose - for roof insulation, inside walls, facade insulation, etc. For example, for facade wall insulation according to the design principles under consideration, the ROCKWOOL company produces FASROCK slabs, and the PAROC company produces L-4 slabs. A characteristic feature of these materials is their high dimensional stability, which is especially important when insulating with a ventilated air layer, low thermal conductivity and guaranteed product quality. Due to their structure, these mineral wool slabs are no worse in thermal conductivity than expanded polystyrene (0.039-0.042 WDmK). Targeted production of slabs determines the operational reliability of insulation of external walls. The use of mats or soft mineral wool slabs for the design options under consideration is completely unacceptable. Unfortunately, in domestic practice there are solutions for insulating walls with a ventilated air layer, when mineral wool mats are used as insulation. The thermal reliability of such products raises serious concerns, and the fact of their fairly widespread use can only be explained by the absence in Ukraine of a system for commissioning new design solutions. An important element in the design of walls with facade insulation is the outer protective and decorative layer. It not only determines the architectural perception of the building, but also determines the moisture state of the insulation, being at the same time protection from atmospheric influences and, for continuous insulation, an element for removing vaporous moisture that enters the insulation under the influence of heat and mass transfer forces. Therefore, it takes on special significance optimal selection: insulation - protective and finishing layer.

The choice of protective and finishing layers is determined primarily by economic possibilities. Facade insulation with a ventilated air gap is 2-3 times more expensive than continuous insulation, which is no longer determined by energy efficiency, since the insulation layer in both options is the same, but by the cost of the protective and finishing layer. At the same time, in the total cost of the insulation system, the price of the insulation itself can be (especially for the above-mentioned incorrect options for using cheap non-slab materials) only 5-10%. When considering facade insulation, one cannot help but dwell on the insulation of premises from the inside. Such is the nature of our people that in all practical endeavors, regardless of objective laws, they look for extraordinary ways, be it social revolutions or the construction and reconstruction of buildings. Internal insulation attracts everyone with its low cost - the cost is only for insulation, and its choice is quite wide, since there is no need to strictly comply with reliability criteria, therefore, the cost of insulation will no longer be high with the same thermal insulation indicators, finishing is minimal - any sheet material and wallpaper , labor costs are minimal. The useful volume of the premises decreases - these are trifles compared to the constant thermal discomfort. These arguments would be good if such a solution did not contradict the laws of formation of the normal heat and humidity regime of structures. And this regime can be called normal only if there is no accumulation of moisture in it during the cold period of the year (the duration of which for Kyiv is 181 days - exactly half a year). If this condition is not met, that is, when vaporous moisture condenses, which enters external structure Under the influence of heat and mass transfer forces, the structural materials and, above all, the thermal insulation layer become wet in the thickness of the structure, the thermal conductivity of which increases, which causes an even greater intensity of further condensation of vaporous moisture. The result is loss of thermal insulation properties, the formation of mold, fungi and other troubles.

Graphs 1, 2 show the characteristics of the heat and humidity conditions of the walls during their internal insulation. An expanded clay concrete wall was considered as the main wall, and the most commonly used foam concrete and PSB-S were considered as the heat-insulating layers. For both options, there is an intersection of the lines of partial pressure of water vapor e and saturated water vapor E, which signals the possibility of vapor condensation already in the intersection zone, which is located at the insulation-wall boundary. What does such a solution lead to in buildings that are already in use, where the walls were in an unsatisfactory heat and humidity regime (photo 3) and where they tried to improve this regime with a similar solution, can be seen in photo 4. A completely different picture is observed when changing the places of the terms, that is, placing a layer of insulation on front side of the wall (graph 3).

Chart No. 1

Chart No. 2

Chart No. 3

It should be noted that PSB-S is a material with a closed-porous structure and a low coefficient of vapor permeability. However, even for this type of material, as when using mineral wool boards (Graph 4), the thermal and moisture transfer mechanism created during insulation ensures the normal moisture state of the insulated wall. Thus, if it is necessary to choose internal insulation, and this may be the case for buildings with the architectural value of the facade, it is necessary to carefully optimize the composition of the thermal insulation in order to avoid or at least minimize the consequences of the regime.

Chart No. 4

Walls of well brick masonry buildings

The thermal insulation properties of walls are determined by the insulation layer, the requirements for which are mainly determined by its thermal insulation characteristics. The strength properties of insulation and its resistance to weathering do not play a decisive role for this type of structure. Therefore, PSB-S boards with a density of 15-30 kg/m3, soft mineral wool boards and mats can be used as insulation. When designing walls of such a structure, it is necessary to calculate the reduced heat transfer resistance, taking into account the influence of solid brick lintels on the integral heat flow through the walls.

Walls of frame-monolithic buildings.

A characteristic feature of these walls is the ability to provide a relatively uniform temperature field over a sufficiently large area of ​​the internal surface of the external walls. At the same time, the load-bearing columns of the frame are massive heat-conducting inclusions, which necessitates mandatory verification of the compliance of temperature fields regulatory requirements. The most common use of quarter-brick, 0.5-brick or one-brick brickwork as the outer layer of the walls of this scheme. In this case, high-quality imported or domestic brick is used, which gives the buildings an attractive architectural appearance (photo 5).

From the point of view of forming a normal humidity regime, the most optimal is to use an outer layer of a quarter of a brick, but this requires High Quality both the brick itself and the masonry work. Unfortunately, in domestic practice, it is not always possible to provide reliable masonry even 0.5 bricks, and therefore the outer layer of one brick is mainly used. Such a decision already requires a thorough analysis of the thermal and humidity conditions of structures, only after which can a conclusion be made about the viability of a particular wall. Foam concrete is widely used as insulation in Ukraine. The presence of a ventilated air layer allows moisture to be removed from the insulation layer, which guarantees normal heat and humidity conditions of the wall structure. The disadvantages of this solution include the fact that in terms of thermal insulation, the outer layer of one brick does not work at all; the external cold air directly washes the foam concrete insulation, which necessitates the need for high demands on its frost resistance. Considering that foam concrete with a density of 400 kg/m3 should be used for thermal insulation, and in practice domestic production There is often a violation of the technology, and the foam concrete used in such structural solutions has an actual density higher than indicated (up to 600 kg/m3), this structural solution requires careful control during the installation of walls and upon acceptance of the building. Currently developed and are in

stage of pre-factory readiness (production line is being built) promising heat and sound insulation and, at the same time, Decoration Materials, which can be used in the construction of walls of frame-monolithic buildings. Such materials include slabs and blocks based on the ceramic mineral material “Siolit”. Very interesting solution External wall structures are made of translucent insulation. In this case, a heat and humidity regime is formed in which there is no condensation of vapors in the thickness of the insulation, and the translucent insulation is not only thermal insulation, but also a source of heat during the cold season.

Dedyukhova Ekaterina

The resolutions adopted in recent years were aimed at solving the issue of thermal protection of buildings. Resolution N 18-81 dated 08/11/95 of the Ministry of Construction of the Russian Federation introduced changes to SNiP II-3-79 “Building Heat Engineering”, which significantly increased the required heat transfer resistance of building envelopes. Taking into account the complexity of the task in economic and technical terms, a two-stage introduction of increased requirements for heat transfer during the design and construction of facilities was planned. Decree of the State Construction Committee of the Russian Federation N 18-11 dated 02.02.98 “On the thermal protection of buildings and structures under construction” establishes specific deadlines for the implementation of decisions on energy saving issues. Almost all objects that have begun construction will use measures to increase thermal protection. From January 1, 2000, the construction of facilities must be carried out in full compliance with the requirements for heat transfer resistance of enclosing structures; when designing from the beginning of 1998, change indicators No. 3 and No. 4 to SNiP II-3-79, corresponding to the second stage, should be applied.

The first experience of implementing solutions for thermal protection of buildings raised a number of questions for designers, manufacturers and suppliers building materials and products. Currently, there are no established, time-tested structural solutions for wall insulation. It is clear that solving thermal protection problems by simply increasing the thickness of the walls is not advisable either from an economic or an aesthetic point of view. Thus, the thickness of a brick wall, if all requirements are met, can reach 180 cm.

Therefore, a solution should be sought in the use of composite wall structures using effective thermal insulation materials. For buildings under construction and being reconstructed, in constructive terms, the solution can fundamentally be presented in two versions - the insulation is placed with outside load-bearing wall or from the inside. When the insulation is located indoors, the volume of the room is reduced, and the vapor barrier of the insulation, especially when used modern designs windows with low air permeability leads to an increase in humidity inside the room, cold bridges appear at the junction of internal and external walls.

In practice, signs of thoughtlessness in resolving these issues are foggy windows, damp walls with the frequent appearance of mold, and high humidity in the premises. The room turns into a kind of thermos. There is a need for a device forced ventilation. Thus, monitoring of a residential building at 54 Pushkin Avenue in Minsk after its thermal sanitation allowed us to establish that relative humidity in residential premises increased to 80% or more, that is, 1.5-1.7 times higher than sanitary standards. For this reason, residents are forced to open windows and ventilate living rooms. Thus, installing sealed windows if available supply and exhaust system ventilation significantly deteriorated the quality of indoor air. In addition, many problems already arise when operating such tasks.

If, with external thermal insulation, heat loss through heat-conducting inclusions decreases with thickening of the insulation layer and in some cases they can be neglected, then with internal thermal insulation, the negative impact of these inclusions increases with increasing thickness of the insulation layer. According to the French research center CSTB, in the case of external thermal insulation, the thickness of the insulation layer can be 25-30% less than in the case of internal thermal insulation. The external location of the insulation is more preferable today, but so far there are no materials and design solutions that would fully ensure fire safety building.

To do warm house from traditional materials- brick, concrete or wood - the thickness of the walls must be more than doubled. This will make the structure not only expensive, but also very heavy. The real solution is the use of effective thermal insulation materials.

As the main way to increase the thermal efficiency of enclosing structures for brick walls, insulation is now proposed in the form of external thermal insulation that does not reduce the area interior spaces. In some aspects, it is more efficient than the internal one due to the significant excess of the total length of heat-conducting inclusions at the junction points internal partitions and ceilings to the external walls along the facade of the building above the length of heat-conducting inclusions in its corners. The disadvantage of the external method of thermal insulation is that the technology is labor-intensive and expensive, and the need to install scaffolding outside the building. Subsequent subsidence of the insulation cannot be ruled out.

Internal thermal insulation is more beneficial when it is necessary to reduce heat loss in the corners of a building, but it requires a lot of additional expensive work, for example, installing a special vapor barrier on window slopes

The heat storage capacity of the massive part of the wall with external thermal insulation increases over time. According to the company " Karl Epple GmbH» with external thermal insulation, brick walls cool down when the heat source is turned off 6 times slower than walls with internal thermal insulation with the same insulation thickness. This feature of external thermal insulation can be used to save energy in systems with controlled heat supply, including through its periodic shutdown. especially if it is carried out without eviction of residents, the most acceptable option would be additional external thermal insulation of the building, the functions of which include:

protection of enclosing structures from atmospheric influences;


equalization of temperature fluctuations of the main mass of the wall, i.e. from uneven temperature deformations;


creation of a favorable mode of operation of the wall according to the conditions of its vapor permeability;


formation of more favorable microclimate premises;

architectural design of the facades of reconstructed buildings.

Upon exception negative influence atmospheric influences and condensed moisture on the fencing structure increases the overall durability load-bearing part of the outer wall.

Before installing external insulation of buildings, it is first necessary to carry out examination condition of facade surfaces with an assessment of their strength, presence of cracks, etc., since the order and volume depend on this preparatory work, determination of design parameters, for example, the depth of embedding of dowels in the thickness of the wall.

Thermal rehabilitation of the facade involves insulating the walls effective insulation materials with a thermal conductivity coefficient equal to 0.04; 0.05; 0.08 W/m´° C. In this case, facade finishing is carried out in several options:

— brickwork made of facing bricks;

- plaster on mesh;

- screen from thin panels installed with a gap in relation to the insulation (ventilated facade system)

The costs of wall insulation are affected by the design of the wall, the thickness and cost of the insulation. The most economical solution is with mesh plaster. Compared to brick cladding, the cost of 1 m 2 of such a wall is 30-35% lower. The significant increase in price of the option with facing brick is due to both the higher cost exterior finishing, and the need to install expensive metal supports and fastenings (15-20 kg of steel per 1 m2 of wall).

The structures with a ventilated facade have the highest cost. The increase in price compared to the brick cladding option is about 60%. This is mainly due to the high cost of facade structures used to install the screen, the cost of the screen itself and mounting accessories. Reducing the cost of such structures is possible by improving the system and using cheaper domestic materials.

However, insulation made by URSA boards in outer wall cavities. In this case, the enclosing structure consists of two brick walls and URSA thermal insulation boards reinforced between them. URSA slabs are fixed using anchors embedded in the joints of the brickwork. A vapor barrier is installed between the insulating boards and the wall to prevent condensation of water vapor.

Insulation of enclosing structures outside during reconstruction can be done using a heat-insulating binder system "Fasolit-T" consisting of URSA boards, glass mesh, construction adhesive and facade plaster. At the same time, URSA slabs are both thermal insulating and bearing element. Using construction adhesive, the boards are glued to outer surface walls and are attached to it with mechanical fasteners. Then a reinforcing layer of construction adhesive is applied to the slabs, over which the glass mesh is laid. A layer of construction adhesive is again applied to it, over which the final layer of facade plaster will go.

Thermal insulation walls outside can be produced using particularly rigid URSA boards fixed to wood or metal frame external wall with mechanical fasteners. Then, with a certain calculation gap, cladding is performed, for example, a brick wall. This design allows you to create ventilated space between the cladding and thermal insulation boards.

Thermal insulation interior walls in the cavity with air gap can be produced by device "three-layer wall" In this case, a wall is first built from ordinary red brick. Thermal insulation boards URSA with hydrophobic treatment are placed on wire anchors, previously laid in the masonry of the load-bearing wall, and pressed with washers.

With a certain thermal calculation of the gap, a wall is then built, opening, for example, into an entrance, loggia or terrace. It is recommended to perform it from facing bricks with jointing, so as not to spend additional money and effort on processing external surfaces. When processing, it is advisable to pay attention to good joining of the plates, then cold bridges can be avoided. With insulation thickness URSA 80 mm It is recommended to apply a two-layer dressing with an offset. Insulation boards must be forced without damage through wire anchors protruding horizontally from the load-bearing upper wall.

Fastenings to URSA mineral wool insulation German concern "PFLEIDERER"

As an example, let’s consider the most affordable option with plastering the façade insulation layer. This method has been fully certified in the Russian Federation , in particular, the Isotech system TU 5762-001-36736917-98. This is a system with flexible fasteners and mineral wool slabs type Rockwooll (Rockwool), produced in Nizhny Novgorod.

It should be noted that Rockwool mineral wool, being a fibrous material, can reduce the influence of one of the most irritating factors in our daily environment - noise. As is known, wet insulating material significantly loses its heat and sound insulation properties.

Impregnated Rockwool mineral wool is a water-repellent material, although it has a porous structure. Only in heavy rain a few millimeters of the top layer of material may get wet, moisture from the air practically does not penetrate inside.

Unlike isolation rockwool, slabs URSA PL, PS, PT (according to advertising brochures they also have effective water-repellent properties) are not recommended to be left unprotected during long breaks in work; unfinished work should be closed brickwork from rain, since moisture that gets between the front and back shells of the masonry dries very slowly and causes irreparable damage to the structure of the slabs.

Structural diagram of the ISOTECH system:

1. Primer emulsion ISOTECH GE.
2 Glue solution ISOTECH KR.
3. Polymer dowel.
4 Thermal insulation panels.
5 Reinforcing mesh made of glass fiber.
6. Primer layer for plaster ISOTECH GR.
7. Decorative plaster layer ISOTECH DS .

Thermal engineering calculation of enclosing structures

Initial data for thermotechnical calculation We will accept according to Appendix 1 of SNiP 2.01.01-82 “Schematic map of climatic zoning of the territory of the USSR for construction.” The building and climatic zone of Izhevsk is Ib, humidity zone is 3 (dry). Taking into account the humidity regime of the premises and the humidity zone of the territory, we determine the operating conditions of the enclosing structures - group A.

The climatic characteristics required for calculations for the city of Izhevsk from SNiP 2.01.01-82 are presented below in tabular form.

Temperature and water vapor pressure of outdoor air

When performing technical calculations of insulation, it is not recommended to determine the total reduced heat transfer resistance of the outer fence as the sum of the reduced heat transfer resistance of the existing wall and additionally installed insulation. This is due to the fact that the influence of existing heat-conducting inclusions changes significantly in comparison with what was initially calculated.

Reduced resistance to heat transfer of enclosing structures R(0) should be taken in accordance with the design assignment, but not less than the required values ​​determined on the basis of sanitary, hygienic and comfortable conditions adopted at the second stage of energy saving. Let us determine the GSOP indicator (degree-day of the heating period):
GSOP = (t in – t from.trans.) ´ z from.trans. ,

Where t in
– design temperature of internal air,° C, accepted according to SNiP 2.08.01-89;

t from.lane, z from.lane . - average temperature,° C and - duration of the period with an average daily air temperature below or equal to 8° From day.

From here GSOP = (20-(-6)) ´ 223 = 5798.

Fragment of table 1b*(K) SNiP II-3-79*

Using the interpolation method, we determine the minimum value R(o)tr ,: for walls - 3.44 m 2 ´° C/W; for attic floors - 4.53 m 2 ´° C/W; for windows and balcony doors - 0.58 m 2 ´° WITH
/W

Calculation insulation and thermal characteristics of a brick wall is made on the basis of preliminary calculations and justification of the accepted thickness insulation.

Thermal characteristics of wall materials

Where X– unknown thickness of the insulation layer.

Let us determine the required heat transfer resistance of enclosing structures:R o tr, setting:

n — coefficient taken depending on the position of the outer

Surfaces of enclosing structures in relation to outside air;

t in— design temperature of internal air, °C, taken according toGOST 12.1.005-88 and design standards for residential buildings;

t n— estimated winter outside air temperature, °C, equal to the average temperature of the coldest five-day period with a probability of 0.92;

D t n- standard temperature difference between the internal air temperature

And the temperature of the inner surface of the enclosing structure;

a V

From here R o tr = = 1.552

Since the selection condition R o tr is the maximum value from the calculation or table value, we finally accept the table value R o tr = 3.44.

The thermal resistance of a building envelope with successively arranged homogeneous layers should be determined as the sum of the thermal resistances of the individual layers. To determine the thickness of the insulating layer, we use the formula:

R o tr ≤ + S + ,

Where a V— heat transfer coefficient of the inner surface of enclosing structures;

d i - layer thickness, m;

l i — calculated thermal conductivity coefficient of the layer material, W/(m °C);

a n— heat transfer coefficient (for winter conditions) of the outer surface of the enclosing structure, W/(m2 ´ °C).

Of course, the importance X should be minimal to save money, so the necessary
the value of the insulating layer can be expressed from the previous conditions, resulting in X ³ 0.102 m.

We take the thickness of the mineral wool board equal to 100 mm, which is a multiple of the thickness of manufactured products of the P175 brand (50, 100 mm).

Determining the actual value R o f = 3,38 , this is 1.7% less R o tr = 3.44, i.e. fits into permissible negative deviation 5% .

The above calculation is standard and is described in detail in SNiP II-3-79*. A similar technique was used by the authors of the Izhevsk program for the reconstruction of buildings of the 1-335 series. When insulating a panel building that has a lower initial R o , they adopted foam glass insulation produced by Gomelsteklo JSC according to TU 21 BSSR 290-87 with a thicknessd = 200 mm and thermal conductivity coefficientl = 0.085. The additional heat transfer resistance obtained in this case is expressed as follows:

R add = = = 2.35, which corresponds to the heat transfer resistance of a 100mm thick insulating layer made of mineral wool insulation R=2.33 accurate to (-0.86%). Taking into account the higher initial characteristics of brickwork with a thickness of 640 mm In comparison with the building wall panel of the 1-335 series, we can conclude that the total heat transfer resistance we obtained is higher and meets the requirements of SNiP.

Numerous recommendations of TsNIIP ZHILISHCHE provide a more complex version of the calculation with dividing the wall into sections with different thermal resistances, for example, in places where floor slabs support, window lintels. For a building of series 1-447, up to 17 sections are introduced on the calculated wall area, limited by the height of the floor and the repetition distance of the facade elements that affect the heat transfer conditions (6 m). SNiP II-3-79* and other recommendations do not provide such data

In this case, the coefficient of thermal heterogeneity is introduced into the calculations for each section, which takes into account non-parallel vectors heat flow loss of walls in places where window and doorways, as well as the impact on losses of neighboring areas with lower thermal resistance. According to these calculations, for our zone we would have to use a similar mineral wool insulation with a thickness of at least 120 mm. This means that, taking into account the multiple sizes of mineral wool slabs with the required average density r > 145 kg/m 3 (100, 50 mm), according to TU 5762-001-36736917-98, the introduction of an insulating layer consisting of 2 slabs 100 and 50 mm thick will be required. This will not only double the cost of thermal remediation, but will also complicate the technology.

Compensate for possible minimal discrepancies in thermal insulation thickness when complex scheme calculations can be made using minor internal measures to reduce heat losses. These include: rational selection of window filling elements, high-quality sealing of window and door openings, installation of reflective screens with a heat-reflecting layer applied behind the heating radiator, etc. Construction of heated areas in attic floor also does not entail an increase in overall (pre-reconstruction) energy consumption, since, according to manufacturers and organizations that perform facade insulation, heating costs are even reduced by 1.8 to 2.5 times.

Calculation of thermal inertia of an external wall start with a definition thermal inertia D enclosing structure:

D = R 1 ´ S 1 + R 2 ´ S 2 + … +R n ´Sn,

Where R – heat transfer resistance of the i-th layer of the wall

S - heat absorption W/(m ´° WITH),

from here D
= 0,026 ´ 9.60 + 0.842 ´ 9.77 + 2.32 ´ 1.02 + 0.007 ´ 9,60 = 10,91.

Calculation heat storage capacity of the wall Q carried out in order to prevent too rapid and excessive heating and cooling of interior spaces.

There are internal heat storage capacity Q in (if there is a temperature difference from inside to outside - in winter) and outside Q n (if there is a temperature difference from outside to inside - in summer). Internal heat storage capacity characterizes the behavior of the wall during temperature fluctuations on its internal side (heating is turned off), external - on the external side ( solar radiation). The greater the heat-storing capacity of the fences, the better the indoor microclimate. Large internal heat storage capacity means the following: when the heating is turned off (for example, at night or during an accident), the temperature of the internal surface of the structure decreases slowly and for a long time it gives off heat to the cooled air in the room. This is the advantage of a design with a large Q c. The disadvantage is that when the heating is turned on, this design takes a long time to warm up. The internal heat storage capacity increases with increasing density of the fencing material. Lightweight thermal insulation layers of the structure should be placed closer to the outer surface. Placing thermal insulation from the inside leads to a decrease in Q V. Fencing with small Q in They warm up quickly and cool down quickly, so it is advisable to use such structures in rooms with short-term occupancy. Total heat storage capacity Q = Q in + Q n. When evaluating alternative fencing options, preference should be given to structures with O greater Q V.

Calculates heat flux density calculate

q = = 15.98 .

Inner surface temperature:

t in = t in – , t in = 20 – = 18.16 ° WITH.

External surface temperature:

t n = t n + , t n = -34 + = -33,31 ° WITH.

Temperature between layers i and layer i+1(layers – from inside to outside):

t i+1 = t i — q ´ R i ,

Where R i – heat transfer resistance i– th layer, R i = .

The internal heat storage capacity will be expressed:

Q in = S with i ´r i ´d i ´ ( t iср - tн),

Where with i – heat capacity of the i-th layer, kJ/(kg ´ °С)

r i – layer density according to table 1, kg/m 3

d i – layer thickness, m

t i avg - average layer temperature,° WITH

t n – estimated outside air temperature,° WITH

Q in = 0.84 ´ 1800 ´ 0.02 ´ (17.95-(-34)) + 0.88 ´ 1800 ´ 0.64 ´ (11.01-(-34))

0.84 ´ 175 m

According to the calculation results in t-coordinates d The temperature field of the wall is constructed in the temperature range t n -t c.

Vertical scale 1mm = 1°C

Horizontal scale, mm 1/10

Calculation thermal resistance of the wall according to SNiP II-3-79* is carried out for areas with an average monthly temperature of July 21° C and above. For Izhevsk, this calculation will be unnecessary, since the average temperature in July is 18.7° C.

Check external wall surfaces for moisture condensation performed subject tot V< t р, those. in the case where the surface temperature is below the dew point temperature, or when the water vapor pressure calculated from the wall surface temperature is greater than the maximum water vapor pressure determined from the internal air temperature
(e in >E t ). In these cases, moisture may precipitate from the air on the wall surface.

Estimated air temperature in the room t in according to SNiP 2.08.01-89	20°C
relative humidity room air	55%
Temperature of the inner surface of the enclosing structure t in	18.16°C
Dew point temperature t p, determined by id diagram	9.5°C
Possibility of moisture condensation on the wall surface	No	Dew point temperature t r determined by i-d diagram.

Examination Possibility of condensation in outer corners rooms is complicated by the fact that it requires knowing the temperature of the inner surface in the corners. When using multilayer fencing structures, the exact solution to this problem is very difficult. But with enough high temperature surface of the main wall, it is unlikely that it will decrease in the corners below the dew point, that is, from 18.16 to 9.5 ° WITH.

Due to the difference in partial pressures (water vapor elasticity) in the air environments separated by the fence, a diffusion flow of water vapor occurs with an intensity of - g from an environment with high partial pressure to an environment with lower pressure (for winter conditions: from inside to outside). In a section where warm air suddenly cools in contact with a cold surface to a temperature ≤ t r moisture condensation occurs. Determination of the zone of possibility moisture condensation in the thickness fencing is carried out if the options specified in clause 6.4 of SNiP II-3-79* are not met:

a) Homogeneous (single-layer) external walls of rooms with dry or normal conditions;

b) Two-layer external walls of rooms with dry and normal conditions, if inner layer the wall has a vapor permeation resistance of more than 1.6 Pa´ m 2 ´ h / mg

Vapor permeation resistance is determined by the formula:

R p = R pv + S Rpi

Where R pv – resistance to vapor permeation of the boundary layer;

Rpi – layer resistance, determined in accordance with clause 6.3 of SNiP II-3-79*: Rpi = ,

Where d i, m i- respectively, the thickness and standard resistance to vapor permeation of the i-th layer.

From here

R p = 0,0233 + + = 6,06 .

The resulting value is 3.8 times higher minimum required that already guarantees against moisture condensation in the thickness of the wall.

For residential buildings mass series in the former The GDR developed standard parts and assemblies for both pitched roofs, and for buildings with a roofless roof, with a basement of different heights. After replacing the window fillings and plastering the facade, the buildings look much better.

External walls erected in sliding and adjustable formwork can be single-layer, two-layer or three-layer (see Fig. 6.2). When constructing walls in sliding formwork, it is recommended to use monolithic single-layer and three-layer ones, and in adjustable formworks - monolithic single-layer, monolithic or prefabricated monolithic two-layer and three-layer ones.

The concrete class for monolithic concrete walls in terms of compressive strength must be at least B7.5 for heavy concrete and B5 for lightweight concrete. For reinforced concrete B12.5.

The thickness of the external walls should be determined based on strength and thermal engineering calculations.

Internal monolithic load-bearing walls should be designed as single-layer, their thickness should be determined by the requirements of static reliability, fire resistance and sound insulation.

In monolithic walls erected in sliding formwork with subsequent installation of floors, nests are installed at the floor level to allow connections between walls and floors. Interfloor ceilings Monolithic and prefabricated-monolithic buildings can be prefabricated, monolithic and prefabricated-monolithic. Monolithic floors are carried out in adjustable formwork, prefabricated - from panels manufactured in a factory.

Prefabricated monolithic floors are usually made from prefabricated reinforced concrete. slabs (shells) with a thickness of at least 4...6cm and a monolithic layer with a thickness of at least 10...12cm. Prefabricated shells are mounted on monolithic walls. Telescopic inventory racks are installed in the span under the shells, after which the monolithic layer is concreted.

A) - single layer wall without façade protective and finishing layer;

b) – the same with the façade protective layer;

c) – two-layer walls with a façade protective and finishing layer and a structural and thermal insulation layer;

d) – the same with a heat-insulating layer located with outside walls;

e) – the same with a heat-insulating layer located with inside walls;

f) – three-layer wall;

1 – load-bearing layer of concrete;

2 – protective and finishing layer;

3 – structural and thermal insulation layer;

4 – load-bearing layer of heavy or light concrete;

5 – flexible connections;

6 – thermal insulation layer;

7 – vapor barrier layer;

8 – internal finishing layer;

9 – outer layer;

10 – protective and finishing layer.

Figure 6.2 – Structural solutions for external walls

When designing prefabricated monolithic floors Special attention attention must be paid to ensuring reliable adhesion between the precast slab and the monolith to ensure they work together.

Foundations can be designed in the form of flat or ribbed reinforced concrete. slabs, cross strips, box type or pile. The type of foundation is selected based on a technical and economic comparison of options.

Constructions of external walls of civil and industrial buildings classified according to the following criteria:

1) by static function:

a) load-bearing;

b) self-supporting;

c) non-load-bearing (mounted).

Load-bearing external walls perceive and transfer to the foundations their own weight and loads from adjacent building structures: floors, partitions, roofs, etc. (at the same time they perform load-bearing and enclosing functions).

Self-supporting external walls take vertical load only from their own weight (including the load from balconies, bay windows, parapets and other wall elements) and transfer them to the foundations through intermediate bearing structures– foundation beams, grillages or plinth panels (simultaneously performing load-bearing and enclosing functions).

Non-load-bearing (curtain) external walls, floor by floor (or through several floors), rest on adjacent load-bearing structures of the building - floors, frames or walls. Thus, curtain walls perform only an enclosing function.

Load-bearing and non-load-bearing external walls are used in buildings of any number of floors. Self-supporting walls rest on own foundation, therefore their height is limited due to the possibility of mutual deformations of the external walls and internal structures of the building. The higher the building, the greater the difference in vertical deformations, therefore, for example, in panel houses, the use of self-supporting walls is allowed when the building height is no more than 5 floors.

The stability of self-supporting external walls is ensured by flexible connections with the internal structures of the building.

2) According to the material:

a) stone walls are built from bricks (clay or silicate) or stones (concrete or natural) and are used in buildings of any number of floors. Stone blocks are made from natural stone (limestone, tuff, etc.) or artificial (concrete, lightweight concrete).

b) Concrete walls are made of heavy concrete of class B15 and higher with a density of 1600 ÷ 2000 kg/m3 (load-bearing parts of the walls) or light concrete of classes B5 ÷ B15 with a density of 1200 ÷ 1600 kg/m3 (for heat-insulating parts of the walls).

For the production of lightweight concrete, artificial porous aggregates (expanded clay, perlite, shungizite, agloporite, etc.) or natural lightweight aggregates (crushed stone from pumice, slag, tuff) are used.

When constructing non-load-bearing external walls it is also used cellular concrete(foam concrete, aerated concrete, etc.) classes B2 ÷ B5 with a density of 600 ÷ 1600 kg/m3. Concrete walls are used in buildings of any number of floors.

V) Wooden walls used in low-rise buildings. For their construction, pine logs with a diameter of 180 ÷ 240 mm or beams with a section of 150x150 mm or 180x180 mm are used, as well as board or glue-plywood panels and panels with a thickness of 150 ÷ ​​200 mm.

d) walls made of non-concrete materials are mainly used in the construction of industrial buildings or low-rise civil buildings. Structurally, they consist of outer and inner cladding made of sheet material (steel, aluminum alloys, plastic, asbestos cement, etc.) and insulation (sandwich panels). Walls of this type they are designed as load-bearing only for one-story buildings, and for larger numbers of floors - only as non-load-bearing.

3) according to a constructive solution:

a) single-layer;

b) two-layer;

c) three-layer.

The number of layers of the building’s external walls is determined based on the results of thermal engineering calculations. To comply with modern standards for heat transfer resistance in most regions of Russia, it is necessary to design three-layer external wall structures with effective insulation.

4) according to construction technology:

a) by traditional technology Hand-laid stone walls are being erected. In this case, bricks or stones are laid in rows over a layer of cement-sand mortar. Strength stone walls is ensured by the strength of the stone and mortar, as well as the mutual bandaging of the vertical seams. To further increase the load-bearing capacity of masonry (for example, for narrow walls) it is used horizontal reinforcement welded mesh after 2 ÷ 5 rows.

The required thickness of stone walls is determined by thermal engineering calculation and linked with standard sizes bricks or stones. Brick walls with a thickness of 1; 1.5; 2; 2.5 and 3 bricks (250, 380, 510, 640 and 770 mm, respectively). Walls made of concrete or natural stones when laying 1 and 1.5 stones, the thickness is 390 and 490 mm, respectively.

5) by location window openings:

From considering these options, it can be seen that functional purpose of a building (residential, public or industrial) determines the design of its external walls and overall appearance.

One of the main requirements for external walls is the necessary fire resistance. According to requirements fire safety standards Load-bearing external walls must be made of fireproof materials with a fire resistance rating of at least 2 hours (stone, concrete). The use of fire-resistant load-bearing walls (for example, wooden plastered walls) with a fire resistance limit of at least 0.5 hours is allowed only in one- and two-story houses.