In order to choose the optimal insulation, you need to know how to calculate its thickness in each specific case, taking into account the materials used.
Compliance with technology will allow you to significantly save on heating in the future and save you from high energy costs. Also, you will not have to spend money on possible repairs to the building due to the appearance of fungus, mold, structural failure or other negative consequences of improper insulation.
Thermal conductivity table
| Material |
Density kg/m3 |
Coefficient of thermal conductivity, W/(ms) |
| Mineral wool | 100 | 0, 056 |
| Mineral wool | 50 | 0, 048 |
| Mineral wool | 200 | 0, 07 |
| Marble | 2800 | 2, 91 |
| Wood sawdust | 230 | 0.070-0.093 (increases with density and moisture) |
| Dry tow | 150 | 0, 05 |
| Aerated concrete | 1000 | 0, 29 |
| Aerated concrete | 300 | 0, 08 |
| Styrofoam | 30 | 0, 047 |
| PVC foam | 125 | 0, 052 |
| Styrofoam | 100 | 0, 041 |
| Styrofoam | 150 | 0, 05 |
| Styrofoam | 40 | 0, 038 |
| Expanded polystyrene foam EPS | 33 | 0, 031 |
| Polyurethane foam | 32 | 0, 023 |
| Polyurethane foam | 40 | 0, 029 |
| Polyurethane foam |
60 |
0, 035 |
| Polyurethane foam | 80 | 0, 041 |
| Foamglass | 400 | 0, 11 |
| Foamglass | 200 | 0, 07 |
The table shows that the lowest density polyurethane foam occupies the leading position. Even considering the high price compared to other heaters, this material is gaining more and more popularity. This is especially noticeable in private construction. In addition to its ability to retain heat, the material is not combustible and is not at all afraid of moisture.
Comparison of different types
- When choosing the right option, you should also know that the higher its density, the lower the thermal insulation properties. This is due to the fact that the air contained in the insulation is displaced by the material itself. In an example, it looks like this: using 30 kg/m foam for floors3, you will get them more durable, but not as warm as if you used lower density foam.
- Mineral wool and Styrofoam have almost the same thermal conductivity. Choose a specific material, starting from the installation features. Mineral wool at high humidity loses its thermal insulation properties. Therefore, if the operation of the insulation is expected with the risk of getting wet, then it is better to choose foam, because even if a fifth of the cotton wool gets wet, it will reduce its thermal insulation properties by half.
- The use of sawdust increases the risk of spontaneous combustion. They also absorb moisture very well and lose their thermal insulation properties. Of the advantages of such a heater, it can be noted that it is an environmentally friendly material.
- Foam glass is a new generation option, quite light and inexpensive, but at the same time, very fragile and environmentally friendly material.
The formula for calculating the thickness of the insulation
There are a lot of resources on which you can calculate this indicator online. First you need to choose the optimal material. To do this, follow:
- Check out the heat resistance regulations in your area. Their meanings are spelled out in SNiP.
- Choose the appropriate option from the table above.
- Carry out a thermal calculation of the thickness of the insulation using the formula:
R=p / k where
R is the thickness of the thermal insulation layer;
P – layer thickness in meters;
K - thermal conductivity of the insulation
If several different types are used, the thermal resistance will be equal to the sum of the indicators of such materials.
Features of using multiple layers of insulation
- Make sure that there is no space between the layers, and the air will not cool the insulation, and, accordingly, the building itself.
- When calculating the indicator, also add the heat resistance of the structure itself, and especially the load-bearing walls, as this will reduce the total cost of construction. From the material and thickness of the wallsthe final calculation of the thickness of the insulation will depend.
- Material with lower thermal conductivity will have higher thermal resistance.
Below, let's look at the features of the work of various structural elements.
Roof
Calculation of the thickness of the roof insulation is carried out according to the above formula, but it is necessary to take into account all the layers involved in the construction: wood or concrete for the ceiling, floor material, plaster thickness, etc. The most popular option, which has an excellent price-to-price ratio thermal conductivity, is mineral wool. It is great for indoor use where it will be weatherproof.
When choosing bas alt wool for the roof, give preference to the one that is designed to insulate this particular part of the building. This is especially important if you plan to equip the attic.
Don't choose Styrofoam for the roof. It is prohibited by the norms of SNiP due to its flammability and harmful fumes.
When calculating the thickness of the floor insulation, take into account the fact that rolled materials shrink over time and, accordingly, lose their properties. For the roof, only slab types are recommended.
In addition to mineral wool, extruded polystyrene foam boards are also a good choice, because despite the absence of precipitation, condensation can collect under the roof.
Gender
Thickness calculationinsulation for the floor is no different from all the above calculations. All layers of materials involved in the construction of the building should be taken into account, as well as the presence or absence of a cold basement under it.
It is not recommended to use polystyrene foam, foam plastic, mineral wool as a heater inside residential premises. The first two materials because of their combustibility and harmful fumes, and the last one because of their good ability to absorb moisture, which can subsequently lead to mold, fungus and rot.
A good option for the floor will be cork insulation. The disadvantages include its rather high price. However, it is also a very good sound insulator, so that two construction tasks can be solved at once. This material is strong enough, it is recommended to use it under a concrete screed and self-leveling floors. Beautiful texture allows you to leave the material as a top coat, treating the top layer with a special varnish.
When choosing cork material for laying on the floor, as well as any other, it is important to correctly calculate the thickness of the insulation, since the principle “more is better” does not work here. Not only will you significantly raise the level and reduce the usable area of the building, but you will also unnecessarily increase the cost of construction.
Ceiling
When calculating the thickness of the ceiling insulation, you should also determine what goals you want to achieve. For example, ceilings in multi-storey apartment buildings do not require insulation at all if the construction was carried out withouttechnological violations. In such houses, it is enough to lay a layer of sound insulation and thereby significantly reduce the material costs of repairs.
Private houses, on the contrary, often require insulation not only of the floor, but also of the ceiling. Let's look at the situations when it is really necessary to carry out work.
- Under the roof is an unheated attic. If, according to the project, there will be an unheated and non-residential premises under the roof, then at the construction stage it is necessary to lay insulation in the interceiling beams, sewing it up and down.
- It's very cold indoors in winter. It is possible that an incorrect calculation of the thickness of the insulation for the building was initially made. In this case, you should act on the basis of a specific situation. First, you need to sheathe the ceiling, if this was not done at the construction stage, and see how the overall temperature in the room changes. If the situation does not improve, then the entire building insulation system will most likely need to be reviewed.
- Attic space is residential but not used in winter. In this case, the same principle applies as in non-residential premises. The temperature in the attic is much lower than in the living room and, accordingly, there is a large loss of heat from the living room. As you know, warm air rises and penetrates through the ceiling into the attic. In addition, when in contact with a cold surface, it turns into condensation, which leads to mold and rotting of wooden ceilings.
It is most expedient to lay the insulation in the ceiling beams. Both mineral wool and cork material can be used for these purposes, since the moisture content in residential premises is low. Styrofoam is better not to use under the ceiling.
