What density to use foam
The scheme of application of various grades of foam.
The following main types of expanded polystyrene are produced, differing in their density and other characteristics:
- PSB-S-15, foam density up to 15 kg/cu.m.
- PSB-S-25, from 15 kg/cu.m. to 25 kg/cu.m.
- PSB-S-35, from 25 kg/cu.m. to 35 kg/cu.m.
- PSB-S-50, from 35 kg/cu.m. to 50 kg/cu.m.
The designation of plate brands is an alphanumeric code. For example, PSB stands for pressless polystyrene. The numbers indicate the value of the upper limit of the density. The letter "C" in the designation of the PSB-S code stands for self-extinguishing.
Properties of heat insulator PSB-S-15 and its application
Expanded polystyrene plates PSB-S-15 allow you to create unloaded thermal insulation. This is due to the absence of loads on the insulation, the thermal conductivity and density of which is not more than 15 kg / m3.
Characteristics of PSB-S-15.
Among polystyrene foams, prices for PSB-S-15 are the most affordable. The main properties of the PSB-S-15 brand insulation are as follows:
- The compressive strength of PSB-S-15 is 10% strain >0.05 MPa.
- The value of ultimate strength in bending >0.07 MPa.
- The thermal conductivity of the PSB-S-15 brand is no more than 0.042 W/mK.
- Water absorption in 24 hours should be no more than 3% of the total volume.
Another indisputable advantage that PSB-S-15 expanded polystyrene has is associated with its low deformability, convenient installation, and cost-effectiveness. Polyfoam PSBS-15 is widely used for the purpose of thermal insulation of change houses, containers, wagons and other structures used in construction.
How to apply insulation PSB-S-25?
The density of foam is calculated by analogy with determining the density of a brick. If one cube of foam plastic has a density of 25, then its mass is 25 kg. The compressive and flexural strength of the foam depends on its density. The brand of foam and its density are completely different characteristics. So, depending on the brand of foam, for example, SPB-S25 or SPB-S50, the density characteristic fluctuates in the range of 15-25 or 35-50.
Characteristics of PSB-S-25 plates.
For example, PSB-S-15 foam plastic can be used to insulate the facades of houses with it. This type of insulation is practically not used in construction. It is used in structures adjacent to structures. These can be verandas or open balconies that perform a decorative function. With the help of foam of this type, figures for facades are created, which allows:
- frame windows, corners of the house;
- divide the floors with a cornice.
Styrofoam with a density of 25 is used to insulate the facade of the house. Styrofoam is taken as the standard, which has a thickness of 5 cm. This type of insulation is used for many purposes. Its thickness varies, depending on the preferences of the customer.
The thickest foam is used to insulate walls exposed to the influence of atmospheric air masses. They can isolate the walls, which prevents the formation of fungus.
How to use foam plastic PSB-S-35?
Characteristics of PSB-S-35 plates.
In order to perfectly align the walls, you can change the thickness of the foam board. The size of the material thickness should not be abused, since this will cause certain difficulties in fixing the drainage system at the corners of the building.
Before choosing a heater of the required thickness, you should see how much stock is available from the gas pipe, since it cannot be closed categorically, as this will violate the aesthetics of the type of building
In this case, it is important to correctly decide on the purchase of PSB-S-35 foam with a thickness of 5 cm, rather than the type of material with a density of 25 with a thickness of 10 cm. Although their prices are practically the same
Insulation with a density of 35 can be used to insulate the facades of buildings, slopes of windows and doors. It has a price twice that of polystyrene material with a density of 25. The latter can be used to insulate garages and non-residential structures if its thickness is 5 cm.With a thickness of such a heater of 7 cm, it can be used for thermal insulation of residential premises.
Due to the normal level of density, it is possible to use a heat insulator with the smallest thickness, which is not associated with a deterioration in the quality of insulation. If the polystyrene foam heat insulator is harder, then it can be used to ideally insulate basements, walls and foundations.
If expanded polystyrene was stored outdoors for a long time, then its structure could undergo changes due to precipitation and solar radiation. The plates turn yellow, and their useful properties disappear.
4 Types of expanded polystyrene and their technical characteristics
The classification of expanded polystyrene used for thermal insulation is based on the density of the insulation. The most popular materials for insulation are expanded polystyrene grades:
Its thermal insulation properties directly depend on the density of expanded polystyrene. The lower the density, and, accordingly, the more air in the insulation, and the smaller the polystyrene walls, the lower the thermal conductivity of the material will be.
And vice versa, the more expanded polystyrene is compressed, the less air is closed inside the insulation cells, and the lower its thermal conductivity will be. However, it must be borne in mind that the strength characteristics of the insulation directly depend on its density.
Let's compare the technical characteristics of the most popular types of polystyrene foam heaters PSB-15, PSB-25 and PSB-35 in thermal insulation:
- Material density, kg/m³: PSB-15 – from 8 to 15; PSB-25 - from 15 to 25; PSB-35 - from 25 to 35;
- Thermal conductivity coefficient, W/mk: PSB-15 – 0.037; PSB-25 - 0.039; PSB-35 - 0.043;
- The coefficient of vapor permeability for all types of expanded polystyrene is not higher than 0.05 mg / mchPa;
- The resistance of the material to compression at a deformation of 10% of the volume, MPa: PSB-15 - 0.04; PSB-25 - 0.07; PSB-35 - 0.16;
- Material resistance to bending, MPa: PSB-15 - 0.06; PSB-25 - 0.018; PSB-35 - 0.25;
- Moisture absorption percentage by volume for 24 hours: PSB-15 - 4, PSB-25 - 1, PSB-35 - 1.
Thermal insulation of the roof with polystyrene foam insulation
All classes of expanded polystyrene belong to the G3 combustibility group - normally combustible materials, the boundary temperature of their operation is 80 degrees, above which the polystyrene granules begin to sinter, as a result of which the insulation itself is deformed.
5 Comparison of conventional and extruded polystyrene foam
Extruded polystyrene foam is made from the same polystyrene granules as the insulation considered in this article, however, using a much more complex technology, which causes the differences in price and technical characteristics of these materials.
The cost of these materials can vary by 2-2.5 times, in order to understand whether it makes sense to overpay, let's compare their main technical characteristics:
- Thermal conductivity coefficient, W/mk: extruded polystyrene foam (EP) – 0.028; expanded polystyrene (P) - 0.038;
- The percentage of moisture absorption by volume for 24 hours: EP - 0.2; P - 2;
- The percentage of moisture absorption by volume for 30 days: EP - 0.4; P - 4;
- Vapor permeability coefficient, mg / mchPa: EP - 0.018; P - 0.05;
- Density, kg / m³: EP - from 28 to 45, P - from 15 to 35.
The combustibility class for materials based on polystyrene is identical - G3, or, in the case of adding refractory additives - G2.
The difference in thermal conductivity between EP and expanded polystyrene determines that for the same thermal insulation efficiency, you will need a greater thickness of expanded polystyrene insulation than EP boards.
Structure of extruded polystyrene foam
The density varies within 10 kg / m³, which is also quite significant. Expanded polystyrene, the density of which is minimal, cannot be used to insulate loadable facades, while there are no such restrictions for EP insulation, the density of which is 28 kg / m³.
Expanded polystyrene, unlike EP-plates, is eaten by mice. Despite the fact that the EP is made from the same raw materials as polystyrene foam, mice do not eat it, since the structure and density of the material does not allow them to damage the insulation.
Given the above, if you want to equip thermal insulation with polystyrene foam, all mice must be pre-etched. Do not neglect this, because otherwise, you risk money and time spent on insulating your home.
However, mice are dangerous for the most part only for houses - rodents are extremely rare in apartments. However, even if the mice wound up, it is likely that they will initially be interested in ordinary food. Rodents (mice and others) are usually rarely taken for heat-insulating materials.
When choosing between thermal insulation made of expanded polystyrene and EP, consider the conditions under which the material will be used. For example, to insulate the foundation or basement, it is better to choose EP, since it is more stable, strong and durable, while ordinary polystyrene foam is perfect for thermal insulation of the facade.
Scope of insulation PSB-S-35
The material has a porous structure, which provides high rates of heat and vapor barrier. In addition, PSB belongs to the category of artificial building materials. It is obtained by foaming plastic, so the insulation is neutral to almost any external environment, it has a long service life
Due to its excellent technical characteristics, PBS S 35 is considered a universal material with a multifaceted scope. It can be used to perform the following types of work:
-
insulation of wall structures, external and internal partitions;
-
increasing the sound insulation of rooms;
-
installation of multilayer heat-insulating panels;
-
arrangement of parking lots;
-
waterproofing engineering communications;
-
insulation of foundations, fences and loggias;
-
thermal insulation of basements and utility rooms;
-
arrangement of paths with heating systems.
In principle, expanded polystyrene has practically no restrictions on its use, therefore it can be used equally effectively in residential and industrial construction.
How does the density of foam affect its cost?
Foam production.
There are several points of view related to the concept of density. The unit of this parameter is kilogram per meter cubed. This value is calculated from the ratio of weight to volume. It is impossible to determine with absolute accuracy the qualitative characteristics of polystyrene foam associated with its density. Even the weight of the insulation does not affect its ability to retain heat.
Thinking about the issue of buying a heater, buyers are always interested in its density. Based on these data, one can judge the strength of the material, its weight and thermal conductivity. Foam density values always refer to a certain range.
During the production of expanded polystyrene boards, the manufacturer determines the cost of production. Based on the formula for determining the density, the weight of the insulation will affect this value. The greater the weight of the material, the denser it is, so its cost is higher. This is due to the fact that polystyrene, as a raw material for heat insulator plates, plays an important role. It is about 80% of the total cost of finished products.
How does a change in the thermal conductivity of foam affect its density?
Styrofoam is made from expanded polystyrene balls containing air.
Any thermal insulation material contains air in the pores. The improved thermal conductivity depends on the amount of atmospheric air contained in the material. The larger it is, the lower the thermal conductivity coefficient. Styrofoam is produced from expanded polystyrene balls containing air.
From this we can conclude that the density of expanded polystyrene does not affect its thermal conductivity. If this value changes, then changes in thermal conductivity occur within the limits of percentages. One hundred percent air content in the insulation is associated with its high heat-saving ability, since air is characterized by the lowest coefficient of thermal conductivity.
Due to the low thermal conductivity of the insulation, a high degree of energy saving is ensured. If we compare polystyrene with bricks, then their energy-saving ability will differ significantly, since 12 cm of the thickness of the heat insulator corresponds to 210 cm of the thickness of a brick wall or a 45 cm wooden wall.
The coefficient of thermal conductivity of the foam, expressed in digital terms, belongs to the interval 0.037 W / mK - 0.043 W / mK. This value can be compared with the thermal conductivity of air equal to 0.027 W/mK.
