Which side to put the vapor barrier to the insulation on the ceiling, floor, walls and roof?

Thermal insulation will be effective only if this layer remains dry. This can provide a hydro and vapor barrier layer. As a result, the microclimate in the house will always be favorable.

Installation of vapor barrier


  • Which side to lay?
  • Scope and principle of operation
  • What is the difference between vapor barrier and waterproofing?
  • Varieties of vapor barrier
  • Floor insulation
  • Gender
  • Roofs
  • Sten
  • Which side of the heat insulator should be mounted?
  • Recommendations

The most widely used vapor barrier in wooden house building, since the walls of this material are most susceptible to the damaging effects of moisture.

Currently, you can find a variety of vapor barrier materials. The choice is huge, and in order to determine and acquire the right material, it is worth familiarizing yourself with their main types.

Which side to lay?

Wall with internal insulation: 1 - load-bearing wall; 2 - insulation; 3 - vapor barrier; 4 - drywall.
Wall with internal insulation: 1 - load-bearing wall; 2 - insulation; 3 - vapor barrier; 4 - drywall.

To prevent condensation, vapor barrier is used, which is laid under the casing. Laying is carried out from the inside, on the side that faces the living room.

The vapor barrier film is fixed to the wall using a battens. Thus, an air gap is created between the panel of the inner skin and the insulating layer.

At the same time, the joints between the individual films of the film must be absolutely tight. This is ensured by the use of adhesive tape, which is glued to the joints.

In order to avoid collecting condensate on the film, one of its sides is roughened. It is this rough side that must be turned during installation into the inside of the room.

Many beginning masters do not understand which side the vapor barrier film is laid on. It has two sides, front and back. Most often they are the same, but if an anti-condensation film is used, then its fabric side should be in the side of the room.

If applicable foil membrane, then its foil side should be facing the heated room. In the case of the acquisition of a membrane film, it is possible to determine the outer side by color, it is brighter and more saturated.

Scope and principle of operation

Scope of vapor barrierThermal insulation, due to the fact that moisture acts on this layer, becomes useless and loses its properties.

Mineral wool insulation is exposed to negative factors both inside and outside the house. To protect housing from the cold, the creation of a high-quality vapor barrier is required.

Vapor barrier is designed to protect the building from the negative effects of weathering, precipitation, internal vapors and wind, dampness.

There are certain standards according to which insulation should be protected.

For this, a vapor barrier material is placed between the heat insulation layer from the inside of the house and the interior decoration. Work is carried out according to the instructions, since each vapor barrier material has its own characteristics.

There are two main types of materials - films and membranes:

  1. Reinforced films. Used for attic design, ventilation gaps should be created as they do not allow steam to pass through.
  2. Films having microscopic holesare used to create vapor barrier in unheated attics. They perfectly retain moisture.
  3. Anti-condensation film has an extra fleecy layer that allows you to retain water.
  4. Membrane insulation with one or several layers - the material is durable and resistant to various influences.
  5. Foil vapor barrier - has a metallized side, which should be facing toward the premises.

The most commonly used polyethylene, which is widely used. But you need to work with it very carefully so as to prevent excessive tension and damage.

Membrane films have an unusual ability to pass air, while perfectly protecting against moisture. This is a new material that has a specific structure. It provides dry insulation for a long time. However, many membrane materials do not require the creation of an air gap.

What is the difference between vapor barrier and waterproofing?

Roof waterproofing scheme:

Roof waterproofing scheme

The scheme of vapor barrier of the roof:

The scheme of vapor barrier roof

It is worth understanding what is the difference between these two types of isolation. The main difference is that the vapor permeability is significantly different.

Waterproofing materials are responsible for keeping the heat indoors, preventing moisture from entering it. They protect surfaces from direct water.

For example, when creating waterproofing corrugated roofing, it allows you to divert water outside the construction site. In this regard, waterproofing is laid according to special technology.

The vapor barrier has a completely different task - protecting the thermal insulation layer from moisture and vapors that may destroy it. Steam is formed in most cases from the inside, which explains the laying of the material from the inside. For example, from the attic or under the decorative decoration of the sauna room.

Waterproofing materials do not let in water or moisture, while they can easily let steam through. Vapor barrier prevents this.

Varieties of vapor barrier

Floor insulation

Vapor barrier

Floor and ceiling are, in fact, frame structures. Therefore, their vapor barrier is mandatory. The vapor barrier film is placed under the main floor covering and over the skin of the ceiling, creating an air gap.


Vapor barrier

It is carried out in the rooms located on the first floor of the houseif there are basements below or basement floorsin baths and saunas. Laying of the material from the inside is done after the creation of the waterproofing and thermal insulation layers. The material is fastened with double-sided tape or with the help of building brackets, the sheets are overlapped.

Recommendation! The material is laid in two layers, inside and outside the insulation.


Vapor barrier

It is better to use a double-sided diffuse membraneinstallation of which is carried out from the inside and outside of the roof. They are fixed to the insulation layer without leaving gaps. If roll hydro-vapor barrier is used, the edges are also made out with adhesive tape when creating an overlap.

A vapor barrier must be created in any case if a roof tile or metal profile is used as a roofing material.


Vapor barrier walls

Distinguish between internal and external. The material is fixed around the perimeter with the help of a stapler, the joint is overlapped by about 10-15 centimeters, and the joint is glued with tape. From above it is necessary to hammer in wooden slats, which are a crate of thermal insulation.

The frame for thermal insulation can be made of metal profiles or wooden battens, a vapor barrier is created, which is attached to the wall using self-tapping screws.

Which side of the heat insulator should be mounted?

  1. The vapor barrier is mounted, as a rule, from the inside of the thermal insulation. But most often a two-sided composition is created, which allows to provide a reliable barrier between the outside of the building and the room.
  2. When insulating the facade, the film is laid on the outside of the heat insulator. At roof insulation, the film is fixed on top of the mineral wool, as in ventilated facade. When creating a cold roof, a vapor barrier is placed under the rafters.
  3. When warming the top coating, when an attic is created, the barrier is laid at the bottom of the insulating material. With internal wall insulation, the film is fixed on top of the heat insulator, inside the heated room.


Vapor barrier installation
  1. Surfaces before vapor barrier must be properly prepared.
  2. If work is carried out in the cold season, the mastic is diluted with antifreeze.
  3. The ventilation clearance is at least 6 centimeters, which provides protection against condensation. Wall cladding must not come into contact with the film.
  4. When insulating the roof, the creation of a gap is ensured by a crate, which is mounted from racks or horizontal profiles.
  5. The joints of the vapor barrier canvases must be glued. This is done using self-adhesive tapes. Adhesive tape, especially narrow, is not recommended for use.
  6. Installation can be done using a stapler or wide-head nails. But experienced builders recommend using counterrails for these purposes.
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