Which side to lay the vapor barrier for walls

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If the film has a foil coating, then this side should be directed towards the thermal insulation.

In fact, it is quite difficult to give any fusion data on this issue. The thing is that there are many brands of this material on the market. As a rule, detailed information about which side the vapor barrier should be laid is applied to the film.

But nevertheless, there are two generally accepted rules

If the instructions do not provide clear instructions, and this is possible, and the film itself is painted in different tones, then the light side must be directed towards the insulation.


Most materials are rolled into rolls in such a way that the side that ends up on the inside can be immediately laid on the thermal insulation.

Installation of vapor barrier for external insulation of a wooden house
Installation of external vapor barrier.

The vapor barrier for the walls of the house is laid directly on it. Then the lathing is mounted, which can be made of wooden beams or a metal profile. Thermal insulation is laid in the cells of the lathing and only then the finishing material is installed.

If multifunctional materials are used as vapor barriers, which in addition to vapor barriers provide protection for the house from wind and water, they are installed between the insulation and the facade cladding. In this case, it is necessary to arrange an air gap.

When insulating a house made of logs, leaving air gaps does not make sense; their role is played by the gaps that are located between the logs. If the house is built from timber, laying a layer of vapor barrier on the wall is unacceptable. Such an implementation can damage the circulation of steam.