Why is polystyrene an ideal material for outdoor insulation?
Polymer material has absorbed the most useful qualities of representatives of the group of thermal insulators:
- low coefficient of thermal conductivity( 0,037-0,041 W /( m × K));
- lightness, strength and durability;
- biological and chemical neutrality.
As it should be any novelty, polystyrene possesses an exclusive property, which allows to compete with the best representatives of the classic "heat-detachment".It is waterproof and is not afraid of direct or partial contact with water. Such a "attack" will not withstand any famous cotton wool, which under the influence of moisture is stony and rapidly losing its unique useful qualities.
And here to a styrofoam - all at all! Yes, and its value is so nice caresses the soul of the thrifty owner, that this material is preferred by most developers when building a "coat" for the house.
But the external insulation of the walls with polystyrene is fraught with one serious problem. The heat insulator belongs to the category of flammable materials, that is, when a fire breaks out quickly and maintains the power of a devouring flame. Moreover, polystyrene not only burns well, but also emits a caustic poisonous smoke.
The developers have tried to maximally eliminate such a discriminating gap in the reputation of the polymer, creating a special "fire-neutral" type of foam.
Foam plastic PSB-S for insulation of external walls with a flame resistant "coat"
The usual foam is actually made of. .. air. When it was made, polystyrene( type B emulsion) was used which, under the influence of high temperature and special chemical additives( for example porophores), foamed, forming a huge number of smallest bubbles( 5-15 mm) that were caked together.
The cells are closed and filled with air, in fact the polystyrene in the finished material contains only 2-3%.The captured gas is the reason for such record-breaking indicators of its heat conductivity. For example, additional insulation of walls with foam plastic( a layer of 12-13 cm) is equivalent to an "additive" to the existing box of a brickwork building 2 meters thick!
But what about the "flammable nature" of the material?
In the production of a special extruded type of foam, flame retardant is used. An effective additive does its good work - the PSB-C material( such its factory marking) does not support combustion. Under the influence of flame, this foam does not smoke, but simply melts. Once the fiery "aggressor" has been eliminated, it will self-extinguish within 4 seconds.
Extruded polystyrene foam PSB-S on average will cost 20-25% more than a simple analogue of the material, but for safety and peace of mind it is worth paying. In addition, it retains all the useful properties of its predecessors and is very easy to use because:
- is available in sheet form;
- is easily cut with a conventional hacksaw;
- there are three types of material density.
For external insulation of walls with foam plastic, the average type of PSB-S-25 is used.
The technology of insulation of external walls with polystyrene
The best way to learn how to perform insulation of walls with polystyrene from the outside is a video lesson from a practicing master. But the theory should not be dismissed, so we will describe in detail all the stages of this type of finishing works.
The technology of insulation of walls with polystyrene from the outside includes such operations:
- Thorough cleaning of the working surface. Walls should be free of dirt and dust, even an extra sticky solution is removed. It is necessary to check the strength of the substrate: if it has "slab"( old exfoliated plaster, cracks), then they must be repaired.
- Fixing the material to the wall. Thermal insulation of foam with their own hands is strictly according to technology, any concession to the side is fraught with negative consequences. So remember: to fix the material you need to use both glue and dowels! To begin with, the walls are covered with a primer, then the solution is applied to a sheet of foam( using a blot or a continuous layer) and firmly pressed against the wall. The first row starts from the corners and stacks along the previously established starting profile. Each sheet is additionally nailed with at least 3 plastic dowels( complete set - 5 pcs).
- Installing the binding mesh. You will need a special adhesive( not to be confused with the mounting solution for the polymer thermal insulator) and a fiberglass mesh with a density of 140 g / m3.It is necessary to ensure that the insulation of the outer wall with foam does not prevent a strong fixation to the "pie" of the future plaster. The grid will create a reliable basis for further finishing the facade. To do this, a white "coat" is covered with a thin layer of glue( up to 5 mm) and the glass-fiber "mini-reinforcement" is embedded in it.
- Finishing the facade. The final stage is the application of the plaster and the painting of the facade by the means selected by the developer.
Traditionally, for the insulation of external walls with foam plastic material layer of 5 cm is used. In fact, the technology assumes a 10-centimeter ball of polymer, laid in two consecutive rows with mandatory bandaging of the seams. This technique provides reliable protection of the surface from the "bridges" of cold.