Calculation of wall insulation. Determine the required thickness of insulation. Calculation is a serious matter
September 7, 2016Specialization: master of internal and exterior decoration(plaster, putty, tiles, drywall, lining, laminate and so on). In addition, plumbing, heating, electrical, conventional cladding and balcony extensions. That is, renovations in an apartment or house were done on a turnkey basis with all necessary types works
Of course, the calculation of insulation for walls in own home, this is a very serious job, especially if this was not done initially and the house is cold. And here you will have to face a number of questions.
For example, what kind of insulation should be, which one is better and what thickness of material is needed? Let's try to understand these issues, and also watch the video in this article, which clearly demonstrates the topic.
Wall insulation
Inside or outside
If you decide to use a calculator to calculate the thickness of insulation for walls, then you will not receive accurate data. Manually you can get more accurate and reliable information. In addition, the location of the insulation, which can be laid both inside and outside the building, is important, which must be taken into account when making calculations!
Features of internal and external insulation:
- Imagine that you are using a calculator to calculate insulation for walls, but at the same time you are laying insulation indoors, will the calculation results be correct? Notice the diagram above;
- no matter how thick the insulation in the room is, the wall will still remain cold and this will lead to certain consequences;
- that is, it means that the dew point or the area where warm air When it encounters cold, it turns into condensation and is transported closer to the room. And the more powerful internal insulation, the closer this point will be;
- in some cases, this zone extends to the surface of the wall, where moisture promotes the development of fungal mold. But even if it remains inside the wall, then the service life does not increase in any way;
- therefore, the instructions and common sense indicate that internal insulation should be installed only as a last resort or when sound insulation is needed ;
- with external insulation, the dew point will fall on the insulation zone, which means that you can increase the shelf life of your wall and avoid the occurrence of dampness.
Calculation is a serious matter!
| No. | Wall material | Thermal conductivity coefficient | Required thickness (mm) |
| 1 | Expanded polystyrene PSB-S-25 | 0,042 | 124 |
| 2 | Mineral wool | 0,046 | 124 |
| 3 | Glued wooden beam or solid solid spruce and pine across the grain | 0,18 | 530 |
| 4 | Laying ceramic blocks with thermal insulation glue | 0,17 | 575* |
| 5 | Laying gas and foam blocks 400kg/m3 | 0,18 | 610* |
| 6 | Laying polystyrene blocks with glue 500kg/m3 | 0,18 | 643* |
| 7 | Laying gas and foam blocks 600kg/m3 | 0,29 | 981* |
| 8 | Adhesive laying of expanded clay concrete 800kg/m3 | 0,31 | 1049* |
| 9 | Masonry of ceramic hollow bricks on CPR 1000 kg/m3 | 0,52 | 1530 |
| 10 | Ordinary brick masonry at CPR | 0,76 | 2243 |
| 11 | Masonry from sand-lime brick at the CPR | 0,87 | 2560 |
| 12 | Concrete products 2500kg/m3 | 2,04 | 6002 |
Thermal calculation of various materials
Note to the table. The presence of the * sign indicates the need to add a coefficient of 1.15 if the building has lintels and monolithic belts from heavy concrete. There is a diagram at the top for clarity - the numbers coincide with the table.
So, calculating the thickness of the insulation is the determination of its thermal resistance, which we denote by the letter R— a constant value that is calculated separately for each region.
Let's take the average figure for clarity R=2.8(m2*K/W). According to State Building Regulations this value is the minimum acceptable for residential and public buildings.
In cases where thermal insulation consists of several layers, for example, masonry, polystyrene foam and eurolining, then the sum of all indicators adds up - R=R1+R2+R3. And the total or individual thickness of the thermal insulation layer is calculated using the formula R=p/k.
Here p will indicate the layer thickness in meters, and the letter k, this is the thermal conductivity coefficient of a given material (W/m*k), the value of which you can take from the table of thermal engineering calculations given above.
In fact, using these same formulas, you can calculate the energy efficiency of window sill insulation or find out the thickness of floor insulation. Use the R value according to your region.
In order not to be unfounded, I will give an example, let’s take a brickwork of two bricks ( regular wall), and as insulation we will use polystyrene foam boards PSB-25 (twenty-fifth polystyrene foam), the price of which is quite reasonable even for budget construction.
So, the thermal resistance we need to achieve should be 2.8 (m2*L/W). First, we find out the thermal resistance of a given brickwork. The brick is 250 mm from end to end and the mortar between them is 10 mm thick.
Hence, p=0.25*2+0.01=0.51m. The silicate coefficient is 0.7 (W/m*k), then Rbrick=p/k=0.51/0.7=0.73 (m2*K/W)- we got thermal conductivity brick wall, calculating it with your own hands.
Let's move on, now we need to achieve overall indicator for a layered wall 2.8 (m2*K/W), that is, R=2.8 (m2*K/W and for this we need to know required thickness polystyrene foam This means Rfoam=Rtotal-Rbrick=2.8-0.73=2.07 (m2*K/W).
In the photo - local protection with foam plastic
Now, to calculate the thickness of polystyrene foam, we take as a basis general formula and here Pfoam=Rfoam*kfoam= 2?07*0?035=0?072m. Of course, we can’t find 2 cm in PSB-25, but if we take into account the interior decoration and the air gap between the bricks, then 70 cm will be enough for us, and that’s two layers
Wooden houses will certainly never lose their relevance and will not go away from the peak of popularity. The warm, pleasant structure of high-quality wood, beneficial for human health, cannot be compared with either stone or mortars, and especially not with any polymers. Nevertheless, the thermal insulation qualities of wood, although quite high, are still not enough to ensure the most comfortable microclimate in the house, and one has to resort to additional insulation walls
Insulation wooden walls- a very delicate matter, since it is necessary to ensure that the thermal insulation layer is sufficient, but at the same time not to allow excessiveness. In addition, much depends on the type of external and interior decoration walls, if provided. In a word, it is impossible to do without thermal engineering calculations. And in this matter, a calculator for calculating wall insulation should serve well wooden house.
A warm house is the dream of every owner; to achieve this goal, thick walls are built, heating is provided, high-quality thermal insulation. In order for insulation to be rational, it is necessary to choose the right material and correctly calculate its thickness.
The size of the insulation layer depends on the thermal resistance of the material. This indicator is the reciprocal of thermal conductivity. Each material - wood, metal, brick, foam plastic or mineral wool - has a certain ability to transmit thermal energy. The thermal conductivity coefficient is calculated during laboratory tests, and is indicated on the packaging for consumers.
If the material is purchased without labeling, you can find a summary table of indicators on the Internet.
The thermal resistance of a material ® is a constant value; it is defined as the ratio of the temperature difference at the edges of the insulation to the force of the heat flow passing through the material. Formula for calculating the coefficient: R=d/k, where d is the thickness of the material, k is the thermal conductivity. The higher the value obtained, the more effective the thermal insulation.
Why is it important to correctly calculate insulation indicators?
Thermal insulation is installed to reduce energy loss through the walls, floor and roof of a home. Insufficient insulation thickness will cause the dew point to move inside the building. This means the appearance of condensation, dampness and fungus on the walls of the house. An excess layer of thermal insulation does not make a significant difference temperature indicators, but requires significant financial costs, therefore it is irrational. This disrupts air circulation and natural ventilation between the rooms of the house and the atmosphere. To save money while ensuring optimal conditions residence requires an accurate calculation of the thickness of the insulation.
Calculation of the thermal insulation layer: formulas and examples
To be able to accurately calculate the amount of insulation, it is necessary to find the heat transfer resistance coefficient of all materials in a wall or other area of the house. It depends on the climatic indicators of the area, therefore it is calculated individually using the formula:
GSOP=(tv-tot)xzot
tв - indoor temperature indicator, usually 18-22ºC;
tot - average temperature value;
zot - duration heating season, day.
Values for calculation can be found in SNiP 01/23/99.
When calculating the thermal resistance of a structure, it is necessary to add up the indicators of each layer: R=R1+R2+R3, etc. Based on the average indicators for private and multi-storey buildings Approximate coefficient values have been determined:
- walls - at least 3.5;
- ceiling - from 6.
The thickness of the insulation depends on the building material and its size; the lower the thermal resistance of the wall or roof, the larger the insulation layer should be.
Example: a wall made of sand-lime brick 0.5 m thick, which is insulated with foam plastic.
Rst.=0.5/0.7=0.71 - thermal resistance of the wall
R- Rst.=3.5-0.71=2.79 - value for foam plastic
For foam plastic, thermal conductivity k=0.038
d=2.79×0.038=0.10 m - foam boards 10 cm thick will be required
Using this algorithm, it is easy to calculate the optimal amount of thermal insulation for all areas of the house except the floor. When making calculations regarding base insulation, you must refer to the soil temperature table in your region of residence. It is from this that the data is taken to calculate the GSOP, and then the resistance of each layer and the required value of insulation are calculated.
Popular ways to insulate a home
Thermal insulation of a building can be carried out during the construction stage or after its completion. Among the popular methods:
- Monolithic wall of significant thickness (at least 40 cm) made of ceramic bricks or wood.
- The construction of enclosing structures by well masonry is the creation of a cavity for insulation between two parts of the wall.
- Installation external thermal insulation in the form of a multilayer structure made of insulation, lathing, moisture-proof film and decorative finishing.
Using ready-made formulas, you can calculate the optimal thickness of insulation without the help of a specialist. When calculating, you should round the number to big side, a small reserve of thermal insulation layer will be useful for temporary temperature drops below the average.
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Online calculator for calculating the cost of a plaster facade.
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To insulate the attic, you should select materials using this service.
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Calculation of insulation for a flat roof
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Thermal calculator for calculating dew point
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KNAUF calculator Calculation of the required thickness of thermal insulation
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Rockwool calculator for calculating the thickness of wall insulation
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IN lately There are very heated discussions about wall insulation. Some advise insulating, others consider it economically unjustified. It is difficult for an ordinary developer who does not have special knowledge of thermal physics to understand all this. On the one side warm walls are associated with lower heating costs. On the other hand, the “price of the issue” is that warm walls will cost more for the developer.
Let's give an example. According to calculations, it turns out that 50 mm of foam plastic will reduce the heat loss of 50 cm of foam concrete by only 20%. Those. 80% of the heat in the house will be saved by foam concrete and only 20% by polystyrene foam. Here you really need to think: is it worth insulating the house? Is the game worth the candle? On the other hand, when insulating a 50 cm brick wall, foam plastic will reduce heat loss by 1.5 times. Brick will save 40%, and foam plastic – 60% of heat. Calculating the thickness of insulation for walls online will help you deal with this issue.
From this we conclude that in each special case You should consider the required thickness of thermal insulation material for the walls of your house and calculate how much you will save on heating after heating and how long it will take for you to pay for the purchased materials and all the work.
