Insulation is needed in order to protect the thermal insulation materials and the buildings themselves from the penetration of steam and the appearance of condensate. It is worth distinguishing between vapor barrier and waterproofing – the first prevents the penetration of steam, and the second – the penetration of water.
When working with different thermal insulation materials, it is also necessary to calculate the vapor barrier, but there are materials that already have a vapor barrier in their composition, for example, Penofol. In the characteristics of Penofol, and similar heat-insulating materials, it is stated that the installation of the material can be carried out without additional vapor barrier. The page about Penofol (teploizolpenofol) explains that its vapor permeability is almost perfect, so it can be installed without a vapor barrier. If you decide to buy Penafol or any other thermal insulation material, you can contact a specialized company, such as Baustroy, where you can ask for the help of a manager.
Vapor barrier on thermal insulation allows you to buy one material instead of two. The advantage of vapor barrier insulation is that it eliminates the second stage of installation of insulating materials, that is, it allows you to install one layer of insulation, and not two or more. But the disadvantage is that vapor barrier insulation is not used on structures that already have a vapor barrier applied, as the second vapor barrier would then trap the vapor.
In most regions of the world, the application of a vapor barrier is highly recommended. Vapor barrier prevents the penetration of water into the walls, floor, ceiling, which, in turn, prevents the appearance of rot, mold and fungi. As a rule, the vapor barrier faces the interior of the house, as it must keep the room’s moisture from penetrating the walls. In very humid climates, a vapor barrier may be placed on the outside of the house to keep moist air from outside from entering the walls.
Moisture in the walls of the house is a problem, because it forms mold, fungus and the structure begins to rot. In cold climates, vapor barrier is especially important because it also protects the thermal insulation. And if the thermal insulation gets wet, then this not only threatens with mold, but also a decrease in the effectiveness of the thermal insulation layer. In other words, you can use a lot of insulation in a cold climate, but without a vapor barrier, the house will still be cold if the insulation layers get wet from moisture and steam. In addition, if water penetrates into the insulation, and then freezes during cold snaps, and then starts to melt again during warming, this can lead to deformations of the walls and loss of stability of structural elements.
Quite often, a house is built, then a vapor barrier is applied, and then thermal insulation is installed. If a vapor barrier has already been applied and you wish to use vapor barrier insulation, the previously applied vapor barrier can be perforated to allow moisture to pass through.