Two-layer external walls are characterized by a structure in which we have two layers, i.e. load-bearing and insulation. Each of them is made of a different material with different properties. The first layer is a load-bearing [construction] wall - traditional with the use of brick elements made of ceramic hollow bricks or cellular concrete with a thickness of 24 to 30 cm. The second layer serves as wall insulation, finished with thin-layer plaster, in the case of a traditional method, e.g. with polystyrene or mineral wool. The thickness of such a layer varies from 10-25 cm. However, when using termPIR ETX insulation boards, we can get better thermal parameters by using a thinner layer of insulation - even by half! It is also worth remembering about other aspects of the use of insulation boards - perfect lambda, low water absorption, mechanical and biological resistance, etc. As a result, in the case of the two-layer variant, we can speak of a wall thickness of 30-40 cm.
Heat transfer coefficient
Regardless of the thickness of the walls, how many layers they have and what material they are made of, one of the key issues related to it is the heat transfer coefficient U. Currently, from 2021, according to the guidelines for the amendment of technical conditions, this parameter should not be higher than 0.20 W / (m² · K) for external walls. The lower the U-value, the better the thermal insulation of the walls. Double-layer walls allow you to achieve a very low U-value, because you can easily adjust the thickness of the insulation to the needs of a given structure. By the way, it is worth adding that the use of appropriate material for the construction layer (masonry) is of great importance.
Therefore, Gór-Stal, together with Termo Organika, created the ETICS thermal insulation system that allows to use the advantages of modern PIR insulation in the currently most popular building insulation system: the light-wet method, also known as the seamless thermal insulation system (BSO) or in English External Thermal Insulation Composite System (ETICS).
It consists of termPIR® ETX insulation boards, appropriately selected adhesives, fiberglass mesh, several types of thin-layer plaster and paints with dedicated primers. The system is complemented by a set of accessories necessary for proper thermal insulation.