Thermal conductivity of sawdust according to the table. Thermal conductivity of basic building materials. Comparative characteristics of the thermal conductivity of building materials

durable and warm house- this is the main requirement that is presented to designers and builders. Therefore, even at the design stage of buildings, two types of building materials are laid in the structure: structural and heat-insulating. The former have increased strength, but high thermal conductivity, and it is they that are most often used for the construction of walls, ceilings, bases and foundations. The second are materials with low thermal conductivity. Their main purpose is to cover structural materials with themselves in order to lower their thermal conductivity. Therefore, to facilitate calculations and selection, a thermal conductivity table is used. building materials.

Read in the article:

What is thermal conductivity

The laws of physics define one postulate, which states that thermal energy tends from the medium with high temperature to a low temperature environment. At the same time, passing through the building material, thermal energy spends some time. The transition will not take place only if the temperature is at different sides from the building material is the same.

That is, it turns out that the process of transferring thermal energy, for example, through a wall, is the time of heat penetration. And the more time it takes, the lower the thermal conductivity of the wall. Here is the ratio. For example, the thermal conductivity of various materials:

• concrete -1.51 W/m×K;
• brick - 0.56;
• wood - 0.09-0.1;
• sand - 0.35;
• expanded clay - 0.1;
• steel - 58.

To make it clear what we are talking about, it is necessary to indicate that concrete structures will not, under any pretext, pass through itself thermal energy, if its thickness is within 6 m. It is clear that this is simply impossible in housing construction. This means that it will be necessary to use other materials with a lower indicator to reduce thermal conductivity. And cover them concrete structure.

What is the coefficient of thermal conductivity

The coefficient of heat transfer or thermal conductivity of materials, which is also indicated in the tables, is a characteristic of thermal conductivity. It denotes the amount of thermal energy passing through the thickness of the building material for a certain period of time.

In principle, the coefficient denotes a quantitative indicator. And the smaller it is, the better the thermal conductivity of the material. From the comparison above, it can be seen that steel profiles and designs have the highest coefficient. So, they practically do not keep heat. Of the building materials that retain heat, which are used for the construction of load-bearing structures, this is wood.

But there is another point to be made. For example, all the same steel. This durable material is used for heat dissipation where there is a need to make a quick transfer. For example, radiators. That is, high rate thermal conductivity is not always a bad thing.

What affects the thermal conductivity of building materials

There are several parameters that greatly affect thermal conductivity.

1. The structure of the material itself.
2. Its density and moisture

As for the structure, there is a huge variety: homogeneous, dense, fibrous, porous, conglomerate (concrete), loose-grained, and so on. So it is necessary to indicate that the more heterogeneous the structure of the material, the lower its thermal conductivity. The thing is that to pass through a substance in which a large volume is occupied by pores different size, the more difficult it is for energy to move through it. But in this case, thermal energy is radiation. That is, it does not pass uniformly, but begins to change directions, losing strength inside the material.

Now about density. This parameter indicates the distance between the particles of the material inside it. Based on the previous position, we can conclude: the smaller this distance, which means the greater the density, the higher the thermal conductivity. And vice versa. The same porous material has a density less than a homogeneous one.

Humidity is water that has a dense structure. And its thermal conductivity is 0.6 W/m*K. A fairly high figure, comparable to the coefficient of thermal conductivity of a brick. Therefore, when it begins to penetrate into the structure of the material and fill the pores, this is an increase in thermal conductivity.

The coefficient of thermal conductivity of building materials: how it is applied in practice and the table

The practical value of the coefficient is the correct calculation of the thickness of the supporting structures, taking into account the insulation used. It should be noted that the building under construction consists of several enclosing structures through which heat escapes. And each of them has its own percentage of heat loss.

• up to 30% of the thermal energy of the total consumption goes through the walls.
• Through the floors - 10%.
• Through windows and doors - 20%.
• Through the roof - 30%.

That is, it turns out that if it is incorrect to calculate the thermal conductivity of all fences, then people living in such a house will have to be content with only 10% of the thermal energy that emits heating system. 90% is, as they say, money thrown to the wind.

Expert opinion

HVAC design engineer (heating, ventilation and air conditioning) LLC "ASP North-West"

“The ideal home should be built from heat insulating materials, in which all 100% of the heat will remain inside. But according to the table of thermal conductivity of materials and heaters, you will not find the ideal building material from which such a structure could be erected. Because the porous structure is low bearing capacity designs. Wood may be an exception, but it is not ideal either.”

Therefore, in the construction of houses, they try to use different building materials that complement each other in terms of thermal conductivity. It is very important to correlate the thickness of each element in the total building structure. In this plan perfect home can be considered a framework. Him wooden base, we can already talk about a warm house, and heaters that are laid between the elements frame building. Of course, taking into account the average temperature of the region, it will be necessary to accurately calculate the thickness of the walls and other enclosing elements. But, as practice shows, the changes being made are not so significant that one could talk about large capital investments.

Consider several commonly used building materials and compare their thermal conductivity through thickness.

Thermal conductivity of bricks: table by variety

Thermal conductivity of wood: table by species

The coefficient of thermal conductivity of cork wood is the lowest of all wood species. It is cork that is often used as a heat-insulating material during warming measures.

Thermal conductivity of metals: table

This indicator for metals changes with a change in the temperature at which they are used. And here the ratio is - the higher the temperature, the lower the coefficient. The table shows the metals that are used in the construction industry.

Now, regarding the relationship with temperature.

• Aluminum at -100°C has a thermal conductivity of 245 W/m*K. And at a temperature of 0 ° С - 238. At + 100 ° С - 230, at + 700 ° С - 0.9.
• For copper: at -100°С -405, at 0°С - 385, at +100°С - 380, and at +700°С - 350.

Table of thermal conductivity of other materials

Basically, we will be interested in the table of thermal conductivity of insulating materials. It should be noted that if for metals this parameter depends on temperature, then for heaters it depends on their density. Therefore, the table will list the indicators taking into account the density of the material.

And table thermal insulation properties building materials. The main ones have already been considered, let's denote those that are not included in the tables, and which belong to the category of frequently used ones.

The coefficient of thermal conductivity of the air gap

Everyone knows that air, if left inside a building material or between layers of building materials, is an excellent insulator. Why is this happening, because the air itself, as such, cannot hold back heat. For this, it is necessary to consider the air gap itself, enclosed by two layers of building materials. One of them is in contact with the zone of positive temperatures, the other with the zone of negative.

Thermal energy moves from plus to minus, and meets a layer of air on its way. What's going on inside:

1. Convection warm air inside the layer.
2. Thermal radiation from a material with positive temperature.

Therefore, the heat flow itself is the sum of two factors with the addition of the thermal conductivity of the first material. It should be immediately noted that radiation occupies a large part of the heat flux. Today, all calculations of the heat resistance of walls and other load-bearing building envelopes are carried out on online calculators. As for the air gap, it is difficult to carry out such calculations, therefore, the values ​​\u200b\u200bthat were obtained by laboratory studies in the 50s of the last century are taken.

They clearly stipulate that if the temperature difference of the walls bounded by air is 5°C, then the radiation increases from 60% to 80% if the thickness of the interlayer is increased from 10 to 200 mm. That is, the total volume of the heat flux remains the same, the radiation increases, which means that the thermal conductivity of the wall decreases. And the difference is significant: from 38% to 2%. True, convection increases from 2% to 28%. But since the space is closed, the movement of air inside it has no effect on external factors.

Calculation of wall thickness by thermal conductivity manually using formulas or a calculator

Calculating wall thickness is not easy. To do this, you need to add up all the thermal conductivity coefficients of the materials that were used to build the wall. For example, brick plaster mortar outside plus outer cladding if one is to be used. Internal leveling materials, it can be the same plaster or drywall sheets, other slab or panel coverings. If there is an air gap, then take it into account.

There is the so-called specific thermal conductivity by region, which is taken as a basis. So the calculated value should not be more than the specific value. In the table below, the specific thermal conductivity is given by city.

That is, the further south, the less the total thermal conductivity of materials should be. Accordingly, the thickness of the wall can also be reduced. As for the online calculator, we suggest watching the video below, which explains how to use such a settlement service correctly.

If you have any questions that you thought you did not find answers to in this article, write them in the comments. Our editors will try to answer them.

What to build a house from? Its walls should provide a healthy microclimate without excess moisture, mold, cold. It depends on their physical properties: density, water resistance, porosity. The most important is the thermal conductivity of building materials, which means their ability to pass thermal energy through themselves at a temperature difference. In order to quantify this parameter, the thermal conductivity coefficient is used.

To brick house was as warm as wooden frame(from pine), the thickness of its walls should be three times the thickness of the walls of the log house.

What is the coefficient of thermal conductivity

This physical quantity is equal to the amount of heat (measured in kilocalories) passing through a material 1 m thick in 1 hour. At the same time, the temperature difference in opposite sides its surface should be equal to 1 °C. Thermal conductivity is calculated in W / m deg (Watt divided by the product of a meter and a degree).

The use of this characteristic is dictated by the need for competent selection of the type of facade to create maximum thermal insulation. it necessary condition for the comfort of people living or working in the building. Also, the thermal conductivity of building materials is taken into account when choosing additional insulation at home. In this case, its calculation is especially important, since errors lead to an incorrect shift in the dew point and, as a result, the walls get wet, the house is damp and cold.

Comparative characteristics of the thermal conductivity of building materials

The coefficient of thermal conductivity of materials is different. For example, for pine, this figure is 0.17 W / m deg, for foam concrete - 0.18 W / m deg: that is, they are approximately identical in terms of their ability to retain heat. The coefficient of thermal conductivity of a brick is 0.55 W / m deg, and that of an ordinary (solid) brick is 0.8 W / m deg. From all this it follows that in order for a brick house to be as warm as a wooden log house (made of pine), the thickness of its walls must be three times the thickness of the walls of the log house.

Practical use of materials with low thermal conductivity

Modern production technologies heat-insulating materials provide wide opportunities for the construction industry. Today it is absolutely not necessary to build houses with thick walls: you can successfully combine different materials to build energy-efficient buildings. The not very high thermal conductivity of a brick can be compensated for by using additional internal or external insulation, for example, expanded polystyrene, the thermal conductivity coefficient of which is only 0.03 W / m deg.

Instead of expensive brick houses and inefficient from the point of view of energy saving monolithic and frame-panel houses made of heavy and dense concrete, buildings are now being built from cellular concrete. Its parameters are the same as those of wood: in a house made of this material, the walls do not freeze through even in the coldest winters.

Heat loss at home as a percentage.

This technology allows you to build cheaper buildings. This is due to the fact that the low coefficient of thermal conductivity of building materials has simplified the construction minimal cost on financing. It also reduces the time spent on construction works. For lighter structures, it is not required to arrange a heavy, deeply buried foundation: in some cases, a light strip or column foundation is sufficient.

This principle of construction has become especially attractive for the construction of lungs frame houses. Today, using materials of low thermal conductivity, more and more cottages, supermarkets, storage facilities and industrial buildings. Such buildings can be operated in any climatic zone.

The principle of frame-panel construction technology is that between thin sheets of plywood or OSB boards heat insulator is placed. It can be mineral wool or polystyrene foam. The thickness of the material is selected taking into account its thermal conductivity. thin walls do a good job of thermal insulation. In the same way, the roof is arranged. This technology allows for short time build a building with minimal financial costs.

Comparison of the parameters of popular materials for insulation and construction of houses

Expanded polystyrene and mineral wool have taken a leading position in the insulation of facades. The opinions of experts are divided: some argue that cotton wool accumulates condensate and is suitable for use only when used simultaneously with a vapor-tight membrane. But then the walls lose their breathable properties, and the quality of the application is in question. Others claim that the creation of ventilated facades solves this problem. At the same time, expanded polystyrene has a low heat conductivity and breathes well. For him, it proportionally depends on the density of the sheets: 40/100/150 kg/m3 = 0.03/0.04/0.05 W/m*ºC.

Another important characteristic that must be taken into account during construction is vapor permeability. It means the ability of the walls to pass moisture from the inside. In this case, there is no loss of room temperature and there is no need to ventilate the room. Low thermal conductivity and high vapor permeability of the walls provide an ideal microclimate for human living in the house.

Based on these conditions, it is possible to determine the most efficient houses for human habitation. Foam concrete has the lowest heat conductivity (0.08 W
m*ºC) at a density of 300 kg/m3. This building material also has one of the highest degrees of vapor permeability (0.26 Mg / m * h * Pa). The second place is rightfully occupied by wood, in particular - pine, spruce, oak. Their thermal conductivity is quite low (0.09 W / m * ºC) provided that the wood is processed across the fibers. And the vapor permeability of these varieties is the highest (0.32 Mg / m * h * Pa). In comparison, the use of pine treated along the grain increases the heat output to 0.17-0.23 W/m*ºC.

Thus, foam concrete and wood are best suited for building walls, as they have the best parameters to ensure environmental cleanliness and a good indoor climate. Polyurethane foam, expanded polystyrene, mineral wool are suitable for facade insulation. Separately, it should be said about the tow. It is laid to exclude cold bridges during the laying of the log house. It enhances the already excellent properties wooden facade: the thermal conductivity coefficient of tow is the lowest (0.05 W/m*ºC), and the vapor permeability is the highest (0.49 Mg/m*h*Pa).

It is better to start the construction of each object with the planning of the project and careful calculation of thermal parameters. Accurate data will allow you to get a table of thermal conductivity of building materials. Proper construction of buildings contributes to optimal climatic parameters in the room. And the table will help you choose the right raw materials that will be used for construction.

The thermal conductivity of materials affects the thickness of the walls

Thermal conductivity is a measure of the transfer of heat energy from heated objects in a room to objects with a lower temperature. The heat exchange process is carried out while temperature indicators do not equalize. To designate thermal energy, a special coefficient of thermal conductivity of building materials is used. The table will help you see all the required values. The parameter indicates how much heat energy is passed through a unit area per unit time. The larger this designation, the better the heat transfer will be. When constructing buildings, it is necessary to use material with minimum value thermal conductivity.

The thermal conductivity coefficient is a value that is equal to the amount of heat passing through a meter of material thickness per hour. The use of such a characteristic is mandatory to create better thermal insulation. Thermal conductivity should be taken into account when selecting additional insulating structures.

What affects the thermal conductivity?

Thermal conductivity is determined by such factors:

• porosity determines the heterogeneity of the structure. When heat is passed through such materials, the cooling process is negligible;
• an increased density value affects the close contact of the particles, which contributes to faster heat transfer;
• high humidity increases this indicator.

Use of thermal conductivity values ​​in practice

Materials are represented by structural and heat-insulating varieties. The first type has high thermal conductivity. They are used for the construction of ceilings, fences and walls.

With the help of the table, the possibilities of their heat transfer are determined. In order for this indicator to be low enough for a normal indoor microclimate, walls made of some materials must be especially thick. To avoid this, it is recommended to use additional heat-insulating components.

Thermal conductivity indicators for finished buildings. Types of insulation

When creating a project, all methods of heat leakage must be taken into account. It can exit through walls and roofs, as well as through floors and doors. If you do the design calculations incorrectly, you will have to be content with only the thermal energy received from heating appliances. Buildings built from standard raw materials: stone, brick or concrete need to be additionally insulated.

Additional thermal insulation is carried out in frame buildings. Wherein wooden frame gives rigidity to the structure, and the insulating material is laid in the space between the uprights. In buildings made of bricks and cinder blocks, insulation is carried out outside the structure.

When choosing heaters, it is necessary to pay attention to such factors as the level of humidity, the effect of elevated temperatures and the type of structure. Consider certain parameters insulating structures:

• the thermal conductivity index affects the quality of the heat-insulating process;
• moisture absorption has great importance when insulating external elements;
• thickness affects the reliability of insulation. Thin insulation helps keep usable area premises;
• flammability is important. High-quality raw materials have the ability to self-extinguish;
• thermal stability reflects the ability to withstand temperature changes;
• environmental friendliness and safety;
• soundproofing protects against noise.

The following types are used as heaters:

• mineral wool is fire resistant and environmentally friendly. To important features refers to low thermal conductivity;

• foam is lightweight material with good insulating properties. It is easy to install and is moisture resistant. Recommended for use in non-residential buildings;
• basalt wool different from mineral best performance resistance to moisture;
• penoplex is resistant to moisture, high temperatures and fire. It has excellent thermal conductivity, easy to install and durable;

• polyurethane foam is known for such qualities as incombustibility, good water-repellent properties and high fire resistance;
• extruded polystyrene foam undergoes additional processing during production. Has a uniform structure;

• penofol is a multilayer insulating layer. Contains polyethylene foam. The surface of the plate is covered with foil to provide reflection.

Bulk types of raw materials can be used for thermal insulation. These are paper granules or perlite. They are resistant to moisture and fire. And from organic varieties, you can consider fiber from wood, flax or cork. When choosing, Special attention pay attention to indicators such as environmental friendliness and fire safety.

Note! When designing thermal insulation, it is important to consider the installation of a waterproofing layer. This will avoid high humidity and increase resistance to heat transfer.

Table of thermal conductivity of building materials: features of indicators

The table of thermal conductivity of building materials contains indicators various kinds raw materials used in construction. Using this information, you can easily calculate the thickness of the walls and the amount of insulation.

How to use the table of thermal conductivity of materials and heaters?

The heat transfer resistance table of materials shows the most popular materials. When choosing a particular option for thermal insulation, it is important to consider not only physical properties, but also such characteristics as durability, price and ease of installation.

Did you know that the easiest way is to install penooizol and polyurethane foam. They are distributed over the surface in the form of foam. Such materials easily fill the cavities of structures. When comparing solid and foam options, it should be noted that the foam does not form joints.

Values ​​of heat transfer coefficients of materials in the table

When making calculations, you should know the coefficient of resistance to heat transfer. This value is the ratio of temperatures on both sides to the amount of heat flow. In order to find the thermal resistance of certain walls, a thermal conductivity table is used.

You can do all the calculations yourself. For this, the thickness of the heat insulator layer is divided by the thermal conductivity coefficient. This value is often indicated on the packaging if it is insulation. Household materials are self-measured. This applies to thickness, and the coefficients can be found in special tables.

The resistance coefficient helps to choose a certain type of thermal insulation and the thickness of the material layer. Information on vapor permeability and density can be found in the table.

At correct use tabular data you can choose quality material to create a favorable indoor climate.

Thermal conductivity of building materials (video)

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The thermal conductivity table of building materials is necessary when designing the protection of a building from heat loss in accordance with the SNiP standards of 2003 under the number 23-02. These measures ensure the reduction of the operating budget, the maintenance of a year-round comfortable microclimate inside the premises. For the convenience of users, all data are summarized in tables, parameters are given for normal operation, conditions high humidity, since some materials, with an increase in this parameter, sharply reduce their properties.

Thermal conductivity is one of the ways in which heat is lost by living quarters. This characteristic is expressed by the amount of heat that can penetrate a unit area of ​​​​the material (1 m 2) per second at a standard layer thickness (1 m). Physicists explain the equalization of the temperatures of various bodies, objects through heat conduction by the natural desire for thermodynamic equilibrium of all material substances.

Thus, each individual developer, heating the premises in winter, receives losses of thermal energy leaving the dwelling through the outer walls, floors, windows, and roofs. In order to reduce energy consumption for space heating, while maintaining a comfortable microclimate for operation inside them, it is necessary to calculate the thickness of all enclosing structures at the design stage. This will reduce the construction budget.

The table of thermal conductivity of building materials allows you to use accurate coefficients for wall structural materials. The SNiP standards regulate the resistance of the facades of the cottage to the transfer of heat to the cold air of the street within 3.2 units. By multiplying these values, you can get the required wall thickness to determine the amount of material.

For example, when choosing cellular concrete with a coefficient of 0.12 units, laying in one block 0.4 m long is sufficient. Using cheaper blocks of the same material with a coefficient of 0.16 units, you will need to make the wall thicker - 0.52 m. pine, spruce is 0.18 units. Therefore, in order to comply with the heat transfer resistance condition of 3.2, a 57 cm beam is required, which does not exist in nature. When choosing brickwork with a coefficient of 0.81 unit, the thickness of the outer walls threatens to increase up to 2.6 m, reinforced concrete structures - up to 6.5 m.

In practice, walls are made multi-layered, laying a layer of insulation inside or sheathing the outer surface with a heat insulator. These materials have a much lower thermal conductivity coefficient, which makes it possible to reduce the thickness many times over. Structural material ensures the strength of the building, heat insulator reduces heat loss to an acceptable level. Modern facing materials used on facades, internal walls also have resistance to heat loss. Therefore, all layers of future walls are taken into account in the calculations.

The above calculations will be inaccurate if you do not take into account the presence of translucent structures in each wall of the cottage. The table of thermal conductivity of building materials in the SNiP standards provides easy access to the thermal conductivity coefficients of these materials.

An example of calculating the wall thickness by thermal conductivity

When choosing a typical or individual project, the developer receives a set of documentation necessary for the construction of walls. Power structures are necessarily calculated for strength, taking into account wind, snow, operational, structural loads. The thickness of the walls takes into account the characteristics of the material of each layer, therefore, heat losses are guaranteed to be below the permissible norms of SNiP. In this case, the customer may file a claim with the organization involved in the design, in the absence of the necessary effect during the operation of the dwelling.

However, during the construction of a dacha, a garden house, many owners prefer to save on the purchase of project documentation. In this case, wall thickness calculations can be made independently. Experts do not recommend using services on the websites of companies that sell structural materials, insulation. Many of them overestimate the values ​​of thermal conductivity coefficients of standard materials in calculators in order to present their own products in a favorable light. Similar errors in calculations are fraught for the developer with a decrease in the comfort of the interior during the cold period.

Self-calculation is not difficult, a limited number of formulas, standard values ​​are used:

• thermal resistance of the wall - 3.5 or more of this number (according to SNiP), is the sum of the thermal resistances of all layers that make up the load-bearing wall
• coefficient of thermal conductivity of building materials - each manufacturer of structural material, translucent structures, insulation indicates it without fail, however, it is better to additionally check the table in the SNiP standards
• thermal resistance of an individual wall layer - calculated by multiplying the layer thickness (m) by the thermal conductivity of the material

For example, in order to bring the thickness of a brick wall in line with the normative thermal resistance, it will be necessary to multiply the coefficient for this material, taken from the table, by the normative thermal resistance:

0.76 x 3.5 = 2.66 m

Such a fortress is unnecessarily expensive for any developer, therefore, the thickness of the masonry should be reduced to an acceptable 38 cm by adding insulation:

• half-brick cladding 12.5 cm
• inner wall in brick 25 cm

The thermal resistance of brickwork in this case will be 0.38 / 0.76 \u003d 0.5 units. Subtracting the result obtained from the standard parameter, we obtain the required thermal resistance of the insulation layer:

3.5 - 0.5 = 3 units

When choosing basalt wool with a coefficient of 0.039 units, we get a layer with a thickness of:

3 x 0.039 = 11.7 cm

Having given preference to extruded polystyrene foam with a coefficient of 0.037 units, we reduce the insulation layer to:

3 x 0.037 = 11.1 cm

In practice, you can choose 12 cm for a guaranteed margin, or get by with 10 cm, given the external, internal wall cladding, which also has heat resistance. The necessary stock can be obtained without the use of structural materials or heaters by changing the design of the masonry. The closed spaces of air gaps inside some types of lightweight masonry also have heat resistance.

Their thermal conductivity can be found in the table below, located in SNiP.

In recent years, when building a house or repairing it, much attention has been paid to energy efficiency. With the already existing fuel prices, this is very important. And it seems that further savings will become increasingly important. In order to correctly select the composition and thickness of materials in the pie of enclosing structures (walls, floors, ceilings, roofs), it is necessary to know the thermal conductivity of building materials. This characteristic is indicated on the packaging with materials, and it is necessary at the design stage. After all, it is necessary to decide what material to build walls from, how to insulate them, how thick each layer should be.

What is thermal conductivity and thermal resistance

When choosing building materials for construction, it is necessary to pay attention to the characteristics of the materials. One of the key positions is thermal conductivity. It is displayed by the coefficient of thermal conductivity. This is the amount of heat that a particular material can conduct per unit of time. That is, the smaller this coefficient, the worse the material conducts heat. Conversely, the higher the number, the better the heat is removed.

Materials with low thermal conductivity are used for insulation, with high - for heat transfer or removal. For example, radiators are made of aluminum, copper or steel, as they transfer heat well, that is, they have a high thermal conductivity. For insulation, materials with a low coefficient of thermal conductivity are used - they retain heat better. If an object consists of several layers of material, its thermal conductivity is determined as the sum of the coefficients of all materials. In the calculations, the thermal conductivity of each of the components of the "pie" is calculated, the found values ​​are summarized. In general, we get the heat-insulating ability of the building envelope (walls, floor, ceiling).

There is also such a thing as thermal resistance. It reflects the ability of the material to prevent the passage of heat through it. That is, it is the reciprocal of thermal conductivity. And, if you see a material with high thermal resistance, it can be used for thermal insulation. An example of thermal insulation materials can be popular mineral or basalt wool, polystyrene, etc. Materials with low thermal resistance are needed to remove or transfer heat. For example, aluminum or steel radiators used for heating, as they give off heat well.

Table of thermal conductivity of thermal insulation materials

To make it easier for the house to keep warm in winter and cool in summer, the thermal conductivity of walls, floors and roofs must be at least a certain figure, which is calculated for each region. The composition of the "pie" of walls, floor and ceiling, the thickness of the materials are taken in such a way that the total figure is not less (or better - at least a little more) recommended for your region.

When choosing materials, it must be taken into account that some of them (not all) conduct heat much better in conditions of high humidity. If during operation such a situation is likely to occur for a long time, the thermal conductivity for this state is used in the calculations. The thermal conductivity coefficients of the main materials used for insulation are shown in the table.

Part of the information is taken from the standards that prescribe the characteristics of certain materials (SNiP 23-02-2003, SP 50.13330.2012, SNiP II-3-79 * (Appendix 2)). Those material that are not spelled out in the standards are found on the manufacturers' websites. Since there are no standards, different manufacturers they can differ significantly, therefore, when buying, pay attention to the characteristics of each purchased material.

Table of thermal conductivity of building materials

Walls, ceilings, floors, you can do from different materials, but it so happened that the thermal conductivity of building materials is usually compared with brickwork. Everyone knows this material, it is easier to make associations with it. The most popular diagrams, which clearly demonstrate the difference between various materials. One such picture is in the previous paragraph, the second is a comparison brick wall and log walls - below. That is why for walls made of bricks and other materials with high thermal conductivity choose thermal insulation materials. To make it easier to select, the thermal conductivity of the main building materials is tabulated.

Wood is one of the building materials with relatively low thermal conductivity. The table provides indicative data for different breeds. When buying, be sure to look at the density and coefficient of thermal conductivity. Not all of them are the same as prescribed in the regulatory documents.

Metals conduct heat very well. They are often the bridge of cold in the design. And this must also be taken into account, to exclude direct contact using heat-insulating layers and gaskets, which are called thermal breaks. The thermal conductivity of metals is summarized in another table.

How to calculate wall thickness

In order for the house to be warm in winter and cool in summer, it is necessary that the enclosing structures (walls, floor, ceiling / roof) must have a certain thermal resistance. This value is different for each region. It depends on the average temperature and humidity in a particular area.

Thermal resistance of enclosing
structures for Russian regions

In order for the heating bills not to be too large, it is necessary to select building materials and their thickness so that their total thermal resistance is not less than that indicated in the table.

Calculation of wall thickness, insulation thickness, finishing layers

For modern construction a typical situation is when the wall has several layers. Except load-bearing structure there is insulation, finishing materials. Each layer has its own thickness. How to determine the thickness of the insulation? The calculation is easy. Based on the formula:

R is thermal resistance;

p is the layer thickness in meters;

k is the thermal conductivity coefficient.

First you need to decide on the materials that you will use in construction. Moreover, you need to know exactly what type of wall material, insulation, finish, etc. will be. After all, each of them contributes to thermal insulation, and the thermal conductivity of building materials is taken into account in the calculation.

Thermal resistance is calculated first structural material(from which the wall, ceiling, etc. will be built), then the thickness of the selected insulation is selected “according to the residual” principle. Can also be taken into account thermal insulation characteristics finishing materials, but usually they go "plus" to the main ones. So a certain reserve is laid "just in case". This reserve allows you to save on heating, which subsequently has a positive effect on the budget.

An example of calculating the thickness of the insulation

Let's take an example. We are going to build a brick wall - one and a half bricks, we will insulate with mineral wool. According to the table, the thermal resistance of the walls for the region should be at least 3.5. The calculation for this situation is given below.

If the budget is limited, mineral wool you can take 10 cm, and the missing will be covered finishing materials. They will be inside and outside. But, if you want your heating bills to be as low as possible, better finish let "plus" to the calculated value. This is your reserve for the time of the most low temperatures, because the norms thermal resistance for enclosing structures, they are calculated according to the average temperature for several years, and winters are abnormally cold. Because the thermal conductivity of building materials used for decoration is simply not taken into account.