Gas-filled plastics, externally representing material from foam cells, belong to the class of foams. Depending on the production technology and the polymer used, several types of materials that have different fields of application belong to this class. All of them have thermal insulation properties and are not toxic. The popular facade foam for insulation PSB-S-25 meets sanitary and hygienic requirements and is a universal basis for any type of plaster.
General information
With the increase in the cost of energy resources, an urgent problem is the protection of the building envelope from unintentional heat release to the outside. The low density of the foam provides the material with high thermal insulation performance. Therefore, the insulation of facades with foam is a modern solution for saving energy. Although this is far from the only area of application of this material.
It is also used:
- as a placeholder for ship compartments, which ensures their unsinkability;
- in the manufacture of lifejackets, buoys and floats;
- as a material for the production of medical containers that are used to transport donor organs;
- as protection for fragile goods;
- as a heat insulator in refrigerators and other household appliances.
Types of insulation
There are statistics that have not been confirmed by any regulatory documents that heat loss through walls is 40%, through a roof - 25%. Therefore, it is possible to achieve maximum protection of housing from heat loss by warming walls.
There are two ways to isolate a room from moisture and cold air currents: inside and out. It is believed that to protect the wall from freezing and at the same time preserve the internal area of the housing when choosing external insulation. And another advantage of the facade protection of the building is the fact that a condensation zone forms between the internal insulation and the bearing wall. And this is an ideal environment for the development of fungus and mold. But the wall protected from the outside retains heat longer and does not cool.
Although there are cases, for example, in the case of a beautiful decoration of the house or elevator shaft, when foam insulation from the outside is technically impossible. Then apply the internal protection of the walls. In addition to polystyrene, builders use other materials.
Types of materials
Popular heaters: mineral wool, polyurethane foam and expanded polystyrene. Mineral wool is mounted only on a metal frame, which then needs to be sheathed with plasterboard sheets, siding or other finishing material. Polyurethane foam has a temporary advantage, since it is applied automatically, using a spray. In this case, the material fills all the cracks in the frame, forming a monolithic coating. However, protecting walls in this way will cost more than using polystyrene for insulation.
Polystyrene foam is produced in two ways, as a result of which there is a non-pressed and pressed material. Marking PS-1 means that the foam plastic is press-made, and PSB-S is a material with self-extinguishing ability. That is, polystyrene with low combustibility was used in its manufacture.
Quality characteristics
Insulation of facades with foam begins with the choice of material. The main characteristics that you need to know when acquiring insulation are plate sizes, density and thickness. According to GOST 15588-86, the nominal dimensions of the plates can be:
- thickness in increments of 10 mm: 20-500 mm;
- lengthwise in increments of 50 mm: 900-5000 mm;
- in width with a step of 50 mm: 500-1300 mm.
But it is allowed by prior agreement to produce plates of non-standard sizes. Foam slabs are produced with the following density indicators: 15, 25, 35 and 50 kg / m 3 . The higher this indicator, the stronger the material and the lower its ability to absorb moisture. A sheet with a density of 35 kg / m3 with a thickness of 50 mm is similar in physical and chemical properties to a material with a density of 25 kg / m 3 and a thickness of 100 mm. However, the cost of the foam is higher, the higher the density of the insulation.
To choose a heater of a certain thickness, it is necessary to take into account a number of factors and make a simple calculation.
Choosing the right thickness material
The thickness of thermal insulation depends on the value of the normative resistance to heat transfer of the external walls, which is a constant value for different climatic zones, and the thickness, material of the walls of the building.
For example, the minimum allowable heat resistance of walls for St. Petersburg is 3.08 m 2 * K / V. There is a brick house, the walls of which are erected from one and a half ceramic hollow bricks. The thermal resistance of this design is 1.06 m 2 xK / W. It is necessary to calculate what thickness to take polystyrene foam for insulation.
To achieve a value of 3.08, it is necessary to find the difference between the standard thermal resistance and the existing one: 3.08-1.06 = 2.02 m 2 xK / W. That is, the value that the foam should have has become known. The PSB-25 heater of the highest quality has a thermal conductivity (according to GOST) of 0.039 W / (m · K).
Based on the formula that the thermal resistance is the quotient of the layer thickness by the thermal conductivity of the material, we have: 2.02 * 0.039 = 0.078 m. In this case, it is necessary to purchase PSB-25 foam with a thickness of 80 mm. In this calculation, the heat resistance of the plaster layer, which is both inside and outside the building, was not taken into account. Therefore, in reality, the requirements for the thickness of the foam will be less than 80 mm.
What else can be insulated with polystyrene foam?
Due to the low coefficient of water absorption, the material is often used in places of high humidity. Foam sheets are laid in the foundation structures, used in the construction of basement houses.
To prevent freezing of the foundation of the house, it is recommended to lay the cellular insulation in its horizontal and vertical parts. As sound insulation, foam can be laid in a false wall between rooms. Expanded polystyrene is also used to warm floors, balconies, loggias. In addition to protecting structures from heat loss, the material is used in refrigeration units.
Styrofoam Cost
This section shows the cost of insulation from the foam class at November 2015 prices.
Expanded polystyrene made by extrusion is called styrofoam. Such plates are more durable than polystyrene, and their price is much higher. The cost of one plate (1200x600x50 mm) is 183 rubles, in terms of 1 m 3 it is 5080 rubles.
On sites for the sale of insulation is often found such a product name as polystyrene 50 mm. This is a common sheet material with dimensions of 1000x2000 mm. The price of one stove is 180 rubles. Now, in comparison with foam plastic, it is clear that a cube of a regular 50 mm thick plastic foam costs 1800 rubles, and this is 3200 rubles cheaper than extruded polystyrene foam.
So, a cube of polystyrene foam, depending on the density, costs:
- PSB-S15 - 2160 rubles;
- PSB-S25 - 2850 rubles;
- PSB-S35 - 4479 rubles;
- PSB-S50 - 6699 rubles.
Myths that polystyrene for insulation is harmful
The first invention is associated with the coined term "breath of the walls." There is an opinion that when insulated with polystyrene foam, the penetration of water vapor decreases, thereby the microclimate worsens, and high humidity is formed inside the room. In construction, the term “breathing wall” is absent, and the streams of water vapor that actually circulate between the street and the house through the wall are very small. The formation of mold and mildew in the room after warming the walls with polystyrene foam is a consequence of poor ventilation.
The second myth is the environmental friendliness of the material. Expanded polystyrene refers to materials without harmful chemical additives. It consists of 98% air and 2% polystyrene. It does not have radioactivity and can be 100% recycled. Operating temperature: -200 ... + 80 degrees. But expanded polystyrene is susceptible to acetone, benzene, so when choosing a paint for the final decoration of the facade, this fact should be taken into account.