A thermal insulation material is, generally speaking, a material used in construction and other industries to improve the thermal behavior of building envelopes. All the materials that are used in construction show higher or lower resistance to thermal transmittance. In some cases, such as metals, thermal resistance is very low; other more traditional materials such as wood or brick show medium resistance; and, finally, there is a group of insulating materials that offer very good behavior and high resistance.
Among thermal insulation materials, we can find mineral wool, extruded polystyrene compound and polyurethane foams. However, it is necessary to understand that the insulation of the enclosure not only improves the energy efficiency of the enclosure but also makes the building be healthier. The correct configuration of the envelope will be essential to ensure health and comfort inside buildings, therefore the current legislation specifies the minimum insulation necessary to ensure thermal comfort and indoor air quality.
Insulation of air chambers
When talking about insulation in building facades, we are referring to the insulation that is mostly performed in double-walled walls with an air chamber. These walls are made of two parallel rows of bricks or blocks, leaving a separation between them that is called air chamber. The filling of this air chamber is fundamental to guarantee a correct isolation of the building and to comply with the current regulations.
Depending on the inner conditions of the chamber, the age of the building or the possible thermal bridges, the choice of insulation material and technique will be one or the other. However, the injection techniques of different insulation systems are highly developed and allow great control during their execution.
Advantages of insulated insulation for the insulation of air chambers
Blown or injected insulation is the simplest and most efficient way to insulate homes in less than 24 hours, obtaining thermal insulation benefits from the first day. As there are no major works, there is no discomfort of any kind for its occupants and its application only reports an improvement in thermal comfort and efficiency.
Injection is the best insulation technique to isolate buildings that have facades with air chambers, being the most used constructive solution from 1930 to the present day. Injected insulation can thermally isolate all types of cavities and typologies of buildings, and can be done both from the inside and outside.
Most used injected insulation
Nowadays, there are four great alternatives in injected thermal insulation in the market:
• Polystyrene (extruded or expanded)
• Polyurethane systems
The contour of the hollows, forged fronts or façade intersections are some of the most common special areas in construction and must be analyzed in order to choose the material that best suits the characteristics of each work.
In addition, we should also take into account the characteristics of the product such as the ability to insulate against high and low temperatures (depending on the area in which the house is located), the filling ability of chambers of less than 5 cm, the minimum perforation diameter and the number of perforations required, the behavior against, water resistance and water vapor permeability.
Injection of polyurethane systems for building insulation
There are several types of injected insulation, but polyurethane is the most outstanding one because of its ability to make homes significantly improve their energy efficiency.
Rigid polyurethane foam is a duroplast synthetic material, highly spatially cross-linked and non-fusible. These characteristics mean that, at the usual densities required for correct thermal insulation, the polyurethane contains only a small part of the volume of solid matter (with a density of 30 kg / m 3, only about 3% of the volume is solid matter). This allows high levels of insulation in very narrow and of difficult access air chambers.
The case of injection in chambers requires special attention, both for the valuation of its suitability and for the execution. In order to guarantee the correct execution of the insulation at all times, the injections will be made through spaced holes, with a maximum separation of 1 meter between them, without being placed on the same line. The injection should begin with the holes at the bottom, slowly filling the chamber from bottom to top. This is due to the low density of the polyurethane (between 8 and 12 kg / m3 in free expansion), and with a slow period of, it must saturate the volume of the chamber without creating excessive collateral tensions that could cause cracks.
In addition, polyurethane systems provide structural rigidity to the building, they have great adhesion on different surfaces, they improve the damping of vibrations on surfaces and they do not absorb humidity. For this reason, injected polyurethane is one of the products that has often been used as an insulator during the last years.