The modern construction market today is simply overwhelmed with many heat-insulating materials. They differ not only in the features of manufacturing technology, but also in their properties, as well as their purpose. However, one of the most popular is extruded polystyrene, which will be discussed below. It can be used not only for thermal insulation, but also to protect the building from external noise. To increase efficiency, you can lay the material in several layers.
Description
EP has unique heat-insulating qualities, and in appearance resembles the foam, which is used today to insulate the facade. Technical characteristics significantly exceed the performance of traditional polystyrene foam. It is made of polystyrene granules, which melt under the influence of high temperature and form a viscous state. At high pressure, carbon or freon, each of which is a foaming agent, is injected into the chamber. The resulting mass is extruded through the extruder and forms a specific shape.
For reference
This technology allows you to create extruded foam, which has a cellular closed structure and resists the penetration of heat and moisture. It is resistant to aggressive media like alkalis and acids, and it can be used at extremely low temperatures, which can reach -50 ° . If we are talking about the highest possible temperature, then it is kept at around +70 ° C.
Material thickness
If you decide to purchase extruded polystyrene, you should know about its thickness. Different companies have this parameter different, therefore, on sale you can find plates starting from 20 mm and ending with 20 cm. This raises the question of what thickness to choose for carrying out certain works. To do this, you should know what is the resistance to heat transfer of materials from which objects in need of insulation are built.
There are established norms and rules that indicate the nominal heat transfer resistance in certain regions. For example, in the center of Moscow, the wall resistance will be 4.15 m 2 ° C / W, while for the southern regions this figure will be a maximum of 2.8 m 2 ° C / W.
Once you determine the norm of the region, you should calculate the resistance of the material and subtract it from the norm. The resulting value will indicate the resistance of expanded polystyrene. If you have results, then from the table you can determine the desired thickness of the insulation.
Material density
Extruded foam, the density of which is from 28 to 40 kg / m 3 , is represented by the brand PBS-S-40. Sometimes the manufacturer tries to mislead the buyer, because it will take less money to produce expanded polystyrene foam of lower density. Therefore, you should not focus solely on the number in the brand name, you need to ask about the technical characteristics that should be indicated in the certificates.
It will be great if they tell you how the material is made. If the density is 35 kg / m 3 , then this is extrusion. In the usual way, you can achieve a density that does not exceed the performance of 17 kg / m 3 .
Thermal Conductivity
Extruded polystyrene foam, the thickness of which was mentioned above, should be selected by the consumer not only on the basis of these data, but also taking into account thermal conductivity. The insulation described in the article is a huge number of air bubbles that are separated by thin shells of polystyrene. In this case, the ratio is: 98% air and 2% polystyrene. The result is a semblance of solid foam. Air is trapped inside the bubbles, which keeps the material warm. The air gap without movement is an excellent heat insulator.
If we compare with mineral wool, then the coefficient of its thermal conductivity will be higher. It will make indicators from 0.028 to 0.034 W / (m · K). The denser the foam, the greater the coefficient of thermal conductivity. Thus, for extruded polystyrene foam, whose density is 45 kg / m 3 , this parameter is 0.03 W / (m · K). It should be borne in mind that the ambient temperature should not be above +75 ° C and below -50 ° C.
Basic properties
Extruded foam, the thermal conductivity of which was mentioned above, has certain properties, among which there is an almost complete absence of water absorption and low thermal conductivity. Even if the stove is completely immersed in water for 10 days, the cells will not allow moisture to pass through, since they are isolated, only the side open honeycombs will be filled. The heat conductivity was discussed above, it should also be mentioned that this parameter is much less in comparison with other heat-insulating materials. Plasticity is also not so high, but fragility is impressive, especially if you draw a parallel with expanded polystyrene.
The material has the ability to transmit light, and its compressive strength is quite high. The thermal insulation does not rot and is highly frost resistant. Extruded foam freely tolerates the effects of:
- acids;
- water;
- caustic alkalis;
- oils;
- bleach;
- saline solutions;
- dyes;
- alcohol;
- hydrocarbon;
- cement;
- acetylene;
- paraffin wax;
- propane;
- butane.
One cannot but mention safety for humans.
Specifications
Extruded foam, the characteristics of which were partially mentioned above, has minimal water absorption, which varies from 0.2 to 0.4%. The weight is quite small and can vary from 25 to 45 kg / m 3 . Among the disadvantages, poor vapor permeability can be distinguished, which is 5 times lower compared to traditional polystyrene foam. This value is 0.013 Mg / (m * h * Pa). Which increases the requirements for ventilation systems at home, which will be insulated with extruded polystyrene foam.
Extruded polystyrene foam, the technical characteristics of which will be of interest to the consumer, has another drawback, which is expressed in high combustibility. The material belongs to the class G3-G4, however, today many manufacturers use special additives that have achieved almost non-combustible characteristics. Therefore, this thermal insulation can sometimes be attributed to classes G1 and B1.
Nevertheless, if you look at the sanitary norms and rules, it can be emphasized that extrusion plates, which have a high degree of combustibility, can be used in building structures. If increased fire safety requirements are imposed on the building, then extruded polystyrene foam, which belongs to the G3 combustibility group, should be used.
Conclusion
Recently, a federal law on combustible heat-insulating materials has been issued; it contains information on indicators of the toxicity of combustion products. For high-quality expanded polystyrene, the toxicity does not exceed T2, which suggests that this thermal insulation is moderately hazardous. This indicator is inherent in wood materials, for example, parquet. The service life is comparable to the life of the building, and for quality manufacturers this figure reaches 40 years.