How to make a vapor barrier walls

During the construction of the house, special attention should be paid to high-quality vapor barrier walls, because dampness, which entails the formation of mold and mildew, can cause structural failure.

Moisture may occur due to the fact that the wall insulation technology has been violated or the formation of condensate at the boundary between heat and cold. Therefore, to get rid of raw air, it is necessary to provide high-quality ventilation. Unfortunately, in the winter season this method is irrational, as it will be too cold in the room (exceptions are houses made of bricks and wood). In all other cases, the provision of a vapor barrier is required.

  How to make a vapor barrier walls

Why do we need vapor barrier walls

Breathable materials that are used for wall insulation may cause the formation of the effect of a moisture condenser. Due to the absorption of moisture by insulants, the disintegration of materials occurs and their further loss of their properties. Over time, these places begin to move away wallpaper, cracked plaster and mold appear.

Multi-layer walls and a ventilated facade also need to provide high-quality vapor barrier. In addition, it is advisable to think in advance about the year-round ventilation system, which is a prerequisite for creating an optimal microclimate in the room.

In the process of vapor barrier used material that can leave moisture outside, but at the same time pass through all the air (due to microscopic pores). Due to this, the vapor barrier system, supplemented by a high-quality ventilation system, can completely relieve the room from moisture.

Attention. Include vapor barrier walls in the list of works should be only in the case when it comes to the construction of housing from breathable materials.

Materials for vapor barrier

Steam insulation materials are divided into several types:

  • plastic film with a thickness of 0.1 millimeters. One of the most budgetary means of vapor barrier, not without its drawbacks. As a result of the use of this material, the advance of air is reduced to nothing, which is why the walls stop breathing. Some people advise to punch the film, which is fundamentally wrong, because in such cases it completely ceases to perform its function;
  • special parisolating mastics. The material that is applied before the final finish, passes air well, but does not allow the pair to get inside;
  • membrane film – one of the latest solutions in construction, fully coping with its task. The air passes in the required volume, steam is not allowed through, thanks to which the insulation is fully protected.

Vapor barrier of the frame house walls

Insulation in its volume occupies about three-quarters of the walls of a frame house, which, in turn, further enhances the need to ensure high-quality vapor barrier of this type of housing. Weak vapor barrier can not only negate the entire effect of insulation, but also, in the end, cause the destruction of the structure.

The wall cake of the frame house should include:

  • external trim of the house;
  • hydro and wind insulation;
  • a layer of insulation width of about 150 millimeters, which is placed between the frame racks;
  • frame;
  • vapor barrier membrane;
  • interior trim.

Using a construction stapler, vapor barrier layers should be securely fastened to the frame risers and piping. Then, using adhesive tape, you must carefully seal the joints.

When fixing the vapor barrier film, it is recommended to follow certain rules that will enhance its effect:

  • to ensure high-quality ventilation of walls and an optimal microclimate, the membrane is installed exclusively on the inside of the heat insulating layer;
  • The vapor barrier must not be fixed on both sides, since the outer layer acts as a protection against moisture, but not against steam. In turn, the vapor barrier and the inner side of the moisture barrier film must pass air, thereby providing ventilation, drying and ventilation of the insulation layer.

Attention. Some experts claim that when using foam and ecowool as a heater, there is no need to provide a vapor barrier, since these materials themselves are resistant to moisture and condensate. In fact, the lack of a vapor barrier can cause problems with the inner lining, as steam stops there, which causes condensation to form.

Vapor barrier of wooden house walls

Wood is a building material that suffers from the negative effects of moisture the most. The only exceptions are those cases when houses are built from glued or rounded timber. Such a timber is already undergoing all the necessary training on the production itself (it is dried and adjusted to a clear, geometric shape), which gives it a high tightness and forms a natural barrier to moisture.

Usually wood that is used in the construction of houses dries for a very long time. The period of complete drying of the material can reach five years, during which (especially in the first year) the most noticeable deformations occur with the tree. These include:

  • gradual shrinkage of the walls;
  • the appearance of cracks in the walls;
  • change of the size of logs;
  • gradual change in the shape of logs.

This natural process is always accompanied by the formation of various defects. This problem can be solved by installing a thermal insulation system, which is divided into external and internal.

Vapor barrier walls. Instruction

Vapor barrier of wooden house walls outside

When external insulation of a wooden house wall cake construction is as follows:

  • To begin with, a vapor barrier is laid on the log, which must be placed overlapping, with edges extending over each other by about 2 centimeters. Joints must be carefully sealed with self-adhesive tape, and the foil must be sealed with metal tape;
  • Then the frame is laid, which is traditionally made from a bar. A heater is attached to this layer, which is carefully protected with waterproofing material;
  • Finally, final finishing is required.

Vapor barrier can be fixed in several ways, which depend on the type of log used:

  • if a round log is used, the vapor barrier is fixed on the tree itself with a simple construction stapler. Ventilation gaps in such cases are not required;
  • in turn, ventilation gaps are needed in those situations if rectangular and square logs are used. To do this, rails should be packed on the tree, the width of which is about 2.5 centimeters, and the step between them is about 1 meter. After that, laying and fixing of the vapor barrier layer takes place.

Vapor barrier walls inside the wooden house

During the internal insulation of the walls of the house, the work will be carried out in the following order:

  • to ensure high-quality ventilation, a crate is needed, the width of which is up to 5 centimeters;
  • A layer of waterproofing film is attached to the crate. The gap formed between the film and the wall will provide high-quality ventilation;
  • metal profiles are attached to the waterproofing film, on which a layer of insulation is then laid;
  • then comes the turn of the vapor barrier film that needs to be overlapped. After that it is required to seal joints carefully;
  • final finishing is carried out.

A wooden house necessarily needs vapor barrier, because this material is good moisture passes. To increase the service life of the walls and the entire building as a whole, it is simply necessary to include a vapor barrier in the wall structure.

Features of vapor barrier walls of a wooden house

  • wooden houses are exposed to the negative effects of steam and condensate much more than houses made of other building materials (for example, from bricks);
  • as mentioned above, the walls of the house, which was used for the construction of logs, begin to dry out during the first five years of operation. Due to the fact that the bars change their size, the grooves begin to collapse. As a result of the fact that getting to the grooves is problematic, the ability to carry out interior decoration of the house disappears. In this case, you need to either pre-vaporize the structural elements of the building, or wait for its final shrinkage;
  • The vapor barrier material must have the same contour as the ceiling and attic floor;

Regardless of why and what the building is being erected, vapor barrier walls should be a mandatory stage of construction work. If you miss this point, then as a result, problems such as the formation of mold and fungus may begin, gradually leading to the destruction of the house.

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Vapor barrier for walls: materials and features of the device

Vapor barrier for walls is a solution to the problem of protecting buildings from the direct action of water vapor. Steam can degrade the characteristics of many building materials. It provokes the appearance of mold on the walls, reduces the life of structures. Therefore, the installation of vapor barrier is an extremely important stage in the construction of various objects.

Vapor barrier is a modern material for effective vapor barrier.

Why vapor barrier is needed

Installation of vapor barrier walls is especially necessary in areas where there is at the same time a fairly warm temperature and high humidity. An example is the baths, as well as basements, which are heated. Inside these structures, steam is formed, that is, warm air with small drops of water. Directions of exit from the room for him are ceilings and walls. Gradually, due to the constant vaporization, the surface of the structures is destroyed, therefore, vapor barrier is a necessary measure during construction.

The principle of the vapor barrier of wall structures

So what is the need for vapor barrier walls in buildings? It is this that creates an obstacle to the penetration of vapor, thereby preventing the destruction of the walls of the object. Vapor barrier may be required not only in basements and baths, but also in many other structures. Its structure is expedient if the object is insulated from the outside with a material that is characterized by low diffusion resistance. It should be understood that there is no universal insulating material, and it is necessary to select a vapor barrier according to the object and the properties of its structures.

Where vapor barrier is required

There are a number of situations in which it is imperative to install a vapor barrier. These include the following:

  • Vapor barrier walls from the inside, especially in situations where wadded materials are used as thermal insulation. Glass wool and mineral wool have excellent insulating properties and are included in the range of materials that are well breathable. Their disadvantage is the fear of high humidity. Under the action of a liquid or steam, wadded materials become wet and lose their performance, and over time, they are completely destroyed. Installing a vapor barrier will help avoid such effects.
  • Multilayer wall structures used in frame houses. Frame construction needs to ensure effective vapor barrier. The procedure for mounting a vapor barrier material in a frame house will be discussed in detail below.
  • Ventilated facades, the surface of the external walls need a vapor barrier to protect against wind. Vapor barrier materials make the airflow softer, turning it into a more metered air. This allows you to protect the outer insulation layer from overload. An example is a brick wall, which is insulated with a cotton-type material, and then sheathed with a siding coating. Thanks to the vapor barrier, a reduction in wall blowing is achieved. Ventilation clearance allows you to remove excess moisture from the windproof surface.

Note! An important factor that allows for an acceptable microclimate in any room except steam, and thermal insulation, is functioning ventilation.

Materials for vapor barrier

Vapor barrier is possible using a variety of materials. The concept of “vapor barrier” does not mean that the barrier should completely block the circulation of steam. Modern vapor barrier membrane provides minimal air flow to prevent the greenhouse effect indoors. The membrane retains excess moisture, and the air, which was part of the steam, does not differ in its ability to damage walls and heat insulating materials. Vapor barrier materials can redirect air flow to the exhaust ventilation system.

Polyethylene used for vapor barrier

The following types of vapor barrier materials can be placed on the walls:

  • Polyethylene. It is a traditional material for creating a vapor barrier layer. This vapor barrier to the wall must be fixed with care, without excessive tension. It is important that the conditions for the breakthrough of the film are not created when the season changes. It should be understood that in the absence of polyethylene perforation, this material limits the entry of both steam and air, which creates obstacles for creating a comfortable microclimate in the room. However, perforation does not provide a good vapor barrier for insulation material and walls. This type of vapor barrier is used less and less in modern construction.
  • Mastic materials. Such material is applied to the wall, passes air and retains excess moisture. Processing walls is carried out before the implementation of finishing finishing manipulations. Mastic materials are relatively inexpensive and convenient to use.
  • Membrane films. This type of vapor barrier is the most modern. The film passes air and stops moisture. The material is characterized by the correct value of vapor permeability to ensure acceptable properties of insulation. Even wadded heat-insulating materials during the operation of membrane films as vapor barrier do not get wet, retain the ability for normal air exchange and do not lose their performance characteristics. Membrane vapor barrier materials are conveniently used for insulation of both frame and wooden walls.

Note! When choosing membrane films, there is often no need for an air gap arrangement.

Advantages of membrane materials

Membrane films are a priority when you need to choose a vapor barrier material. Mastics are in second place in terms of efficiency, and polyethylene films are rarely used in modern construction.

The advantages of membrane films in comparison with other vapor-insulating materials include:

  • high operational efficiency;
  • ease of installation;
  • strength;
  • good moisture repellency;
  • ensuring the resistance of the surface of the wall to the reproduction of mold microorganisms;
  • resistance to rotting processes;
  • environmental friendliness of the material;
  • long term use – the film retains the initial properties for 50 years;
  • wide temperature range of operation (from -60 to +80 degrees Celsius).

Thus, the advantages of choosing precisely vapor-proof membranes are obvious, which determines their growing popularity in the construction market.

Varieties of membrane materials

The range of materials for vapor barrier in the modern construction market is very wide. You should consider the types of membrane materials that have already earned their prestige among consumers.

  • Membranes that can be attached to the outside of the insulation (it is external to the space of the room). These brands include: “Izospan A”, “Megaizol SD”, “Megaizol A”. These membranes are used to protect the exterior of the walls of frame structures, lumber, panel and combined buildings from various atmospheric phenomena: wind, snow, rain.

Important! The membrane should fit snugly to the warming material, be securely fixed on the mounting structure, and have no sagging areas (they provoke claps with sudden gusts of wind).

  • Membranes that can be put on the inside of the walls. These include: “Megaizol B”, “Izospan B”. This kind of membrane materials protects the walls from fungus, condensate, corrosion of structural elements. Also, such membranes prevent the entry of particles of insulating material into the construction space.
  • Membranes incorporating a reflective layer. These include: “Izospan FS”, “Izospan FD”, “Izospan FX”. They are used to vapor barrier such rooms as saunas and baths.

Important! It is necessary to choose the material for the implementation of the vapor barrier strictly according to the purpose of use. This allows you to create optimal conditions for creating a comfortable indoor climate.

Installation of vapor barrier film on the wall

Installation of vapor barrier on the wall is used in cases where mineral materials are used as thermal insulation. It is important to follow the correct procedure for mounting the vapor barrier film. It includes the following stages of work:

  1. Steam insulation film must be placed the right side, then carefully and securely fastened to the crate. It is necessary to work carefully in order not to damage the film.
  2. Then you need to glue well possible gaps, as well as the place of punctures and overlaps.
  3. Next, you need to mount the crate using bars to create acceptable ventilation.
  4. Then the construction is covered with plasterboard, wall panels, and other finishing materials.

Note! Proper installation of the vapor barrier film will ensure a comfortable microclimate in the room.

Recommendations for vapor barrier frame structures

You need to understand how to properly lay a vapor barrier in frame houses. To do this, you must first install the membrane with the required side, and then fix it with a stapler to the racks. Next, you should glue the joints with a special adhesive tape or mastic.

Note! When using ecowool, polyurethane foam, polystyrene foam, and provided an effective ventilating system, a vapor barrier in the frame structure may not be required.

Organization of vapor barrier frame structures

If the need for a vapor barrier is still there, then one of two possible schemes should be applied:

  • The vapor barrier is stitched to the frame racks. How to fix the vapor barrier in this case? First, the film is fixed on the racks, then the walls are cladding with plasterboard, plasterboard or other interior finishing materials. This option can be used in buildings used for the purpose of seasonal stay, which is not necessary during the cold season. These include guest buildings, summer cottages, workshops. This option involves the provision of effective ventilation facilities.
  • It assumes the installation of a layer of lathing (horizontal or vertical plan) above the membrane. The crate is necessary to provide an air gap from 30 to 50 millimeters from the wall surface. This option is advisable to use in homes for permanent residence or buildings that involve intensive use in the cold season.

The choice of a vapor barrier installation scheme in a frame house should be made on the basis of the expected intensity and seasonality of the use of the room.

Vapor barrier walls in wooden houses

Structures made of wooden materials require special vapor protection. Wooden houses are characterized by high vapor permeability of walls in comparison with brick and stone walls. This indicator is determined by the thickness of the timber and logs, the presence of cracks, the impermeability of the slots for moisture and steam.

Glued laminated timber, which is used for building walls, must be dried in production to an acceptable moisture content. Also it should provide sealing grooves, low shrinkage. All this is necessary for the limited flow of steam into the insulation.

Log or log walls with natural moisture indicators are dried directly during use. Due to shrinkage, deformations and cracks appear on the walls for 5 years. Logs and cant change their dimensional characteristics, grooves lose their tightness. Therefore, for 5 years, it is not necessary to carry out interior decoration – this will not allow access to the grooves to return to tightness. In such a situation, two exits are envisaged: either wait until the tree is completely dry, or organize vapor barrier using “Izospan FB”, “Izospan B”, and “Izospan FS” membranes.

Organization of steam insulation of wooden buildings

Important! The vapor barrier should form a single circuit with attic and basement floors of the structure.

The study of the characteristics of the vapor barrier allows you to figure out why it is necessary to organize this phase of construction. The wrong order of activities can lead to a lack of comfortable conditions for living or working indoors. It is for this reason that the choice and installation of vapor-proof materials should be given sufficient amount of time during the construction of various kinds of structures.

Sources:,, sten-materialy.html

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