What is vapor barrier: device, installation technique, manufacturers overview, reviews

What is vapor barrier: device, installation technique, manufacturers overview, reviews
What is vapor barrier: device, installation technique, manufacturers overview, reviews

Insulation reduces heating costs, so it is installed during the construction of a variety of houses. In the process of arranging the insulation, a vapor barrier is used. This material has certain characteristics. There are many varieties of such a film. What is a vapor barrier, what properties does it have, will be discussed further.

General characteristics

What is a vapor barrier? Builders were able to get acquainted with this material relatively recently. Today it is used in the process of repair and installation work. Vapor barrier is used during the arrangement of the thermal insulation layer. In this case, different types of material can be used. It is necessary to choose the right vapor barrier. It depends on the features of the operation of the building, the tasks that pose for thermal insulation. When choosing a vapor barrier, they also take into account the budget that the owners allocate for repair and construction work.

which side of the vapor barrier

Considering what a vapor barrier is, it is worth noting that the final result of the work done depends on the correct installation of this material. If you make a mistake, the heater will not fulfill the duties assigned to it. Therefore, you need to consider how to choose and install a vapor barrier. To understand how to apply the presented material, you need to consider its function.

Indoor humidity levels may vary. This can be influenced by various factors, for example, the presence of a large number of plants, the operation of ventilation, the presence of laundry that is dried on a radiator, etc. Condensation may appear on different surfaces when the temperature changes. Dew also falls in the thermal insulation layer. This phenomenon is explained by a certain ratio of temperature and humidity level. The dew point due to such fluctuations can shift inward. For this reason, condensation may be observed.

It is also worth noting that many building materials have the ability to "breathe". They skip steam. Only glass, metal and some other materials are deprived of this ability. At certain indoor and outdoor temperatures, steam can turn into condensate. This happens more often during the cold season.

Condensation falls inside the walls if certain temperature characteristics are established. In addition to walls, condensate can fall in roofing materials, accumulating in the structure of thermal insulation. The danger of this phenomenon lies in the fact that, having been soaked with water, the thermal insulation ceases to cope with its duties. Heat begins to quickly leave the room. Toto maintain comfortable conditions indoors, it will be necessary to spend more energy resources for heating. The costs in this case increase markedly.

In severe frost, the water in the structure of the material may freeze. This leads to the destruction of the thermal insulation structure. Moreover, this process irrevocably violates the function of the insulation layer. With the onset of heat, the ice will melt, and water will begin to seep through the outer walls of the house. This leads to the destruction of the interior finish, yellow streaks, stains and stains remain on the walls. This will require repairs.

To avoid adverse effects, a vapor barrier is used when arranging the insulation layer. Its main purpose is to prevent steam from entering the thermal insulation from the room. It is important to know which side the vapor barrier is mounted on the base. In this case, the dew point shifts, which helps prevent the destruction of the insulation.

In addition, the materials do not form mold. The fungus will not appear indoors either. This not only prolongs the life of wooden structures, but also allows you to maintain the correct microclimate in the room. The fungus can be dangerous to human he alth. Therefore, the use of vapor barrier is necessary in the process of creating a layer of insulation for buildings and structures of various types.

Vapor barrier and waterproofing

Considering what vapor barrier is, you need to pay attention to its difference from waterproofing. This will allow you to correctly apply both types of films. Waterproofing and vapor barrierdiffer in structure. This determines their scope. The vapor barrier protects buildings and thermal insulation from condensation that can occur due to vapors. They form inside the house. At the same time, the throughput of such a membrane is different.

insulation vapor barrier

Most types of vapor barrier have micropores. In addition, the vapor barrier for insulation is a multilayer material. Each of them performs a number of specific functions. This is a complex system that significantly improves the performance of the insulation. Professional builders have no doubts whether a vapor barrier is needed in the process of arranging thermal insulation.

Waterproofing is a slightly different material. This is a homogeneous film that has no pores. Its surface is airtight, so no water or steam can pass through it. Waterproofing, unlike vapor barrier, is needed to protect rabbits and walls from moisture coming from outside. This may be water that falls on the walls during precipitation. Waterproofing prevents the penetration of moisture from the outside into the insulation layer of the foundation, roof, walls.

Another area of ​​application for waterproofing is to prevent groundwater from reaching the foundation. They seep through the soil, which can eventually lead to the destruction of the foundation. This significantly reduces the life of the house. Therefore, when building a foundation, a waterproofing layer is required. In this case, the foundation of the building will be reliably protected from groundwater, which during the snowmelt season orheavy rainfall may come close to the surface.

Knowing the difference between these materials, you can understand whether vapor barrier is needed and in what construction work it is used. When creating a layer of insulation, both types of films are needed. But the sequence of their installation will be different.

Varieties of vapor barrier

Vapor barrier for the walls of the house can be different. Several types of this material are on sale. The choice depends on the conditions in which the film will be used.

vapor barrier device

Vapor barrier is distinguished by certain parameters that affect not only the scope of its application, but also the principle of its installation. In order not to make a mistake in choosing, you need to consider what vapor barrier options are used today in the course of construction and repair work. The main options are:

  • Adhesive based vapor barrier sheet.
  • Films in rolls that are impregnated with different compositions.
  • Liquid varieties of coating materials.
  • Polyethylene films.
  • Foil layer materials.
  • "Breathable" membranes that allow a certain amount of steam to pass through.

The vapor barrier device of some varieties requires installation on a certain side. It is impossible to confuse the landmarks, since the film in this case will not fulfill the functions assigned to it. Each type of vapor barrier material has a different scope. It is necessary to clearly understand for what purposes it is acquired. Otherwise, during operation, there will bedifficulties of a different nature.

Rolled types of vapor barrier can be impregnated with bitumen or other similar substances in the structure. Such types of vapor barrier are used as a temporary material. At the same time, it is problematic to mount such types of films, since the joints are sealed with a special burner.

Paints that are sold in liquid form are quite expensive. Such types of materials are used to create a floor in a bath or shower room. It is used when finishing the base at the places of communications, at the junctions of different building materials. If you apply the coating to complete the surface treatment of walls, ceilings, the repair budget will increase significantly. At the same time, the procedure for applying a liquid vapor barrier is quite difficult.

Polyethylene film

Vapor barrier for insulation can be made of polyethylene. This type of material is used in rooms with high humidity. However, in some cases it is also used in dry rooms. The advantage of polyethylene vapor barrier is its relatively low cost. Therefore, this type of material is used quite often in the arrangement of thermal insulation. But this type of material is not suitable for all works.

vapor barrier which side to the heater

The sides of the polyethylene vapor barrier are identical. Therefore, for this material, it does not matter how it is deployed during installation. The structure of this material is characterized by certain features. This determines the scope of the material. More often than notused as temporary protection during construction work. The film protects exposed materials from moisture and precipitation. Under certain conditions, condensation may form on such material. It is important to carry out the installation in accordance with existing standards and requirements. Otherwise, the film will not be able to protect structures from decay and premature destruction.

The service life of polyethylene films is quite short. Under the influence of various external factors, the material is rapidly destroyed. If the owners of the house do not want to deal with the installation of a new insulation, you need to choose a different type of vapor barrier. Polyethylene films are a temporary option that is used during construction work. The vapor barrier of the presented type is more often used when arranging a concrete floor.


Which side of the vapor barrier to the insulation is mounted, it is important to know when installing membrane materials. They have perforations of a certain configuration. The shape of such cells, their size determines the speed at which steam will pass through the membrane.

what is vapor barrier

This film is a layered structure that has the important ability to "breathe". In such a vapor barrier, each layer performs a specific function, ensuring the proper functioning of the membrane. Each layer has holes through which the steam passes further. So that it does not come back, the holes have different diameters. In the lowest layer, the pores have a minimum size. They cut off some of the moisture,without passing it inside the insulation layer.

Some varieties of membrane vapor barrier varieties have a reinforcing layer. This ensures a long service life of the film. Reinforcement does not allow the material to deform when the ambient temperature drops. Due to the presence of this layer, the film will last a long time, but its cost will be much higher. It is worth remembering that, despite the high price, this option is preferable in the harsh northern climate. Such a film quickly pays for itself during operation. Insulation in this case will be used longer.

Not all membranes have a reinforcing layer. Therefore, you need to find out if it is present in the vapor barrier for the walls that you plan to buy.

The top layer of the presented membrane-type material also has pores. Their diameter is larger than that of the lower layer. This feature ensures that steam moves in only one direction. This contributes to the appearance of thrust, which moves air masses saturated with moisture at a certain speed. Thanks to this device, water does not stagnate in the structure of the insulation.

The top layer often has a rough texture. It is important to know how to install this material. When installing such membranes, it is important to leave a technological gap between the film and the main finish. Its width should be from 2.5 cm or more. Moisture can accumulate in the rough layer if installed incorrectly. Therefore, for its removal in a natural way, a ventilation gap is laid during the construction process.

Features of combining the membrane with thermal insulation

In some cases, the use of vapor barrier in the process of insulation is not mandatory. The fact is that not all types of thermal insulation use different materials of the presented type. It is necessary to familiarize yourself with the recommendations of experts on when vapor barrier is needed.

house wall vapor barrier

It is worth noting that today in the process of construction work, different types of insulation are used. Such materials may have a porous structure. In this case, they are able to absorb moisture strongly. Because of this, the initial performance of the material is markedly reduced. This is primarily true for mineral wool. This is one of the most common heaters. If it gets wet, the heat easily escapes from the room into the external environment. Therefore, for mineral wool or other types of insulation with a porous structure, it is necessary to use a vapor barrier without fail.

But is a film needed when arranging thermal insulation from polystyrene foam, polystyrene foam, polystyrene foam and other similar materials. These are synthetic insulations that are not able to absorb water. In addition, they do not let steam through. Therefore, many builders believe that vapor barrier is not needed for this material. But it's not.

Although the material does not allow steam to pass through, joints are formed between the plates during installation. Steam is able to penetrate even through the thinnest cracks. It should be noted that polystyrene foam is mounted on glue. Even when using special formulations,a small layer of air remains between the sheets and the base. It is impossible to hermetically attach the material to the base.

In this interval, under some conditions, condensation may appear. This leads to the development of mold and fungus, rotting processes occur. The materials will break down. Steam will also seep through the joints of the insulation. Therefore, even when using materials that repel moisture, a vapor barrier must be used.

Laying a vapor barrier is not required only when using polyurethane foam as a heater. It forms a tight connection with the base, preventing moisture from entering the insulation. There are no gaps in this thermal insulation, which allows you to reliably protect the walls from condensate and steam.

Choosing a film for a balcony

When installing, it is important to understand where it is especially important to apply vapor barrier, which side to the insulation it should be mounted. For different surfaces, the use of such films and membranes is required to a greater or lesser extent. If you plan to carry out insulation on a balcony, loggia, you can’t do without a vapor barrier.

sides of the vapor barrier

Such designs are a barrier between external conditions and the house. There can be a large temperature difference here. Because of this, condensation appears with all the negative consequences. The windows on the balcony have a large area. They have a low temperature during the cold period. Therefore, moisture can spread inside the insulation. To prevent such unpleasant consequences, you need to use it correctly when arranging the insulation.selected vapor barrier.

In this case, you need to use a three-layer membrane. Moreover, the material must have a foil layer. It must be directed to the room. The foil reflects infrared rays back into the room. This allows you to reduce the cost of heating the loggia.


If thermal insulation is installed indoors, vapor barrier is required. It is necessary to put it to the heater with the side not covered with pile. The smooth surface should be directed towards the insulation. The rough side of the vapor barrier should be directed into the room.

When creating thermal insulation outside the room, vapor barrier is not needed. No steam is formed in these layers. If condensate falls here, steam does not penetrate into the structure. Only when creating an external finish for a bath, you need to apply a membrane.


In most cases, a membrane is not needed when arranging the floor. For interfloor floors, waterproofing must be used. But when arranging the floor in the bath, vapor barrier should be used during construction work. There is a lot of steam in such rooms, so it is advisable to use membranes in this case.


When arranging the roof, a vapor barrier is required. How to properly mount such material? The ceiling lets a lot of steam through because it rises up. Even in dry rooms, membranes must be used.

First, the insulation is mounted, and the vapor barrier is already fixed on it. With the rough side, it should be directed into the room. From the side of the attic, a vapor barrier is also mounted. After herinsulation is installed, and waterproofing is laid on top. Next comes the roofing material.

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