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Which side is the vapor barrier film facing? How to lay a vapor barrier on which side, smooth or rough? How to lay a vapor barrier

Like all vapor barrier coatings, the IZOVEC membrane sheet has a smooth coating on one side and a fleecy coating on the other.

Water vapor is picked up by the villi and discharged in a measured volume onto the the opposite side where its evaporation occurs. The glossy base contributes to this to a large extent.

The material is available in several types, designated by letters:

Each model has individual characteristics. That's enough to choose best option for a specific case: insulation of walls, ceilings, protection from moisture, wind.

When protecting the insulation from moisture vapor accumulated in the room, the smooth side of the room places the vapor barrier on the mineral wool. On the outer side, the isovek lays on the insulation with a fleecy surface. It sucks in moisture and removes it outside, where it evaporates. The glossy finish greatly facilitates this process.

When insulating a house, it is important to lay the vapor barrier facing the insulation correctly. After all, if the norms are violated, cold will enter the house, and the heat inside will not be retained. In our article we will take a closer look at all the nuances of installing a vapor barrier.

1. Which side should the vapor barrier be laid towards the insulation?
2. What types of vapor barrier membranes are there?
3. The need to create an air gap near the membrane
4. Rules for attaching vapor barriers

Which side should the vapor barrier be laid against the insulation?

Before determining which side to lay the vapor barrier on, you should consider the locations for laying the vapor barrier membrane:

If your insulation will be installed from the facade, then the vapor barrier should be fixed from the outside. This way you will make waterproofing;
The space under the attic, for example, the ceiling or ceiling, requires laying a vapor barrier membrane underneath the insulation;
When treating the roof and ceiling, it is necessary to use an antioxidant vapor barrier. Diffusion and volumetric coatings are in demand. They should be laid on top of mineral wool;
If your roof and ceiling do not have additional insulation, then in this case the vapor barrier is attached to the rafters from the bottom side;
When thermally insulating the floor and walls from the inside, it is necessary to additionally lay a vapor barrier film on the outside of the mineral wool.

Many builders, even those with extensive experience, do not pay attention to which side to attach the vapor barrier film to the insulation. When choosing a vapor barrier film, it is better to give preference to a material whose front and back sides are the same.

But many people choose options with different sides, and often with an antioxidant insulator. In this case, you need to know that the fabric surface is the wrong side. It is located in inner part rooms. The metal plane of the foil membrane should also be positioned. That is, the shiny side faces the inside of the room.

Regardless of the steam insulating material it is laid with the rough side facing the room and the smooth side facing the insulation.

When purchasing diffusion components, you should carefully study the instructions for use. Various manufacturing companies produce double-sided and single-sided vapor barrier films.

In most cases, the dark side of the film is the outer side.

What types of vapor barrier membranes are there?

Membranes used in construction are:

Vapor permeable.
With vapor barrier properties.

When using mineral wool as insulation, an additional layer of vapor barrier is installed on the inside to protect it from moisture. If the walls are protected from the outside, there should be no pores or perforations in the components.

When choosing, you need to pay attention to the vapor permeability coefficient. It should be as small as possible. A good option would be to buy regular plastic film. The material that is additionally reinforced will be of higher quality. And if the vapor barrier has an aluminum foil coating, then such a film will be of high quality and durable. Using a vapor barrier indoors increases humidity. Therefore, do not forget about the device quality system ventilation.

Special vapor barrier films contain an antioxidant coating. With its help, moisture does not accumulate on the insulation. They are often used in areas that are susceptible to corrosion. For example, in materials such as corrugated sheets, metal tiles and others. The rough back surface helps remove moisture. The fabric side should be facing outward, so that a distance of 2 to 6 cm is maintained from the insulation.

The building membrane is used to insulate the outside of the house. It is able to protect the material from bad weather conditions and carries out evaporation. Usually the vapor barrier has small pores and therefore water is removed from the insulation into the ventilation ducts. Thanks to this, the insulation dries quickly.

There are several types of vapor-permeable films:

Diffusion membranes. The vapor permeability coefficient can be from 300 to 1000 g/m2.
Pseudo-diffusion. They allow no more than 300 g/m2 of vapor to pass through during the day.
Super diffusion membranes. The evaporation coefficient is more than 1000g/m2.

The pseudo-diffusion type of vapor barrier is a high-quality protection against moisture, so it is often laid under the roof as an outer layer. Do not forget about the arrangement of the air gap. The disadvantage of this type is poor vapor conductivity, so this film is not used for facade treatment. Condensation will begin to accumulate on the surface of the insulation, as dust and various debris will clog into the pores of the membrane.

In the other two types, clogging of pores is eliminated. Therefore, you can not leave an air gap and additionally install lathing or counter-battens.

In membranes of diffusion films of volumetric design, a ventilation layer is pre-provided. The structure of such a film is very similar to the antioxidant type. The only difference is the release of moisture from the insulation. If the roof slopes slightly, condensation will not drain through the bottom.

The need for an air gap at the membrane

It is always necessary to leave an air gap. A gap of 5 cm is placed on the underside of the film. This way you can avoid condensation on the floor, walls or insulation. When using diffusion film, it can be attached to moisture-resistant plywood, plinth or thermal insulation. A layer for ventilation is installed on the outside. When using an antioxidant component, an air gap of 4-6 cm should be made on both sides.

When installing a vapor barrier on the roof and ceiling, to create a ventilation gap, you need to install an additional counter-latten made of wooden blocks. When installing horizontal posts and profiles that are positioned perpendicular to the wall and film, a gap should be left for the ventilated façade.

Rules for attaching vapor barriers

You can attach the film to the walls, ceiling or floor using a stapler or wide-headed nails. But the best quality option would be to use counter rails.

The vapor barrier film should be laid with an overlap of at least 10 cm. After attaching the vapor barrier, the joints must be taped with a special tape or tape.

For a qualitative relationship between moisture and temperature building structure, and membranes will also help for a long service life. Without their participation, it is impossible to achieve such qualities. When installing a vapor barrier, all rules must be followed. Many manufacturers indicate on the packaging recommendations for installing vapor barriers.

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What is isolon used for?

A fairly common problem after insulating a house is the lack of the expected effect from the work performed. It would seem that he was chosen traditional material, for example, mineral wool, everything is done according to building laws and canons, but it’s still cold inside the room. The reason for this may be the ignorance of “specialists” about basic standards, including which side of the insulation to lay the vapor barrier. Let's look at this issue in more detail.

Vapor barrier is divided into two types according to the method of application:

liquid paint vapor barrier;
vapor barrier membranes (film).

Painting vapor barrier is applied using brushes and rollers in places where roll vapor barrier is difficult to use, for example, on ventilation and chimneys. This family of vapor barriers is represented by materials such as bitumen, tar and tar.

Vapor barrier membranes

First of all, let's define the types of vapor barrier films according to their purpose. According to their specificity, membranes used in construction are offered in the following versions:

membranes with vapor barrier properties;
membranes are vapor permeable.

To protect the mineral wool from exposure to moisture from the inside, it is necessary to additionally lay a layer of vapor barrier. When insulating a roof, floor or internal space house located directly below it, it is recommended to use an appropriate film. Note that the insulating layer is laid from below, under the laid mineral wool(from the room side).

In cases where it is carried out external protection walls, then the corresponding components must not have perforations or pores.

Always pay attention to the value of the vapor permeability coefficient; the lower it is, the better for you. An excellent option is regular plastic film. The ideal choice would be a material with additional reinforcement. The presence of aluminum foil coating is considered only a plus.

Do not forget that the presence of a vapor barrier finish leads to a multiple increase in humidity in the insulated space, so you should take care of a good ventilation system in advance.

Polyethylene reinforced film

Existing special vapor barrier films are made with an antioxidant coating. Due to this, moisture does not accumulate. As a rule, they are attached under components that are sensitive to rust formation. This is about metal tiles, corrugated sheets, galvanized, etc. The rough fabric layer on the back of the film guarantees effective moisture removal. It is laid with the treated side facing the insulation, and the fabric side facing out, so that there is a distance of 20-60 mm to the mineral wool.

https://youtu.be/xTWpLwH8-QI

Video No. 1. IZOSPAN vapor barrier laying technology

When insulating the walls of a house from the outside, a building membrane is used that can carry out evaporation and protect the material from strong wind gusts. In addition, it is suitable for protecting pitched roofs and facades with a leaky base from moisture. Often vapor barrier film has very small pores and surface perforation, due to which water is effectively removed from the insulation into the ventilation ducts. The more actively the vapor removal occurs, the better the process. This will allow the insulation to dry quickly and efficiently.

The following types of vapor-permeable films are distinguished:

Pseudo-diffusion membranes that transmit no more than 300 grams/m2 of evaporation over 24 hours.
Diffusion membranes, with a vapor permeability coefficient in the range of 300-1000 grams/m2.
Superdiffusion membranes, with an evaporation rate of more than 1000 grams/m2.

Since the first type of insulation is considered good protection against moisture, it is often located under the roof surface as an outer layer. Additionally, it will be necessary to provide an air gap between the insulating layer and the film. At the same time, this component is not suitable for facade processing, since it conducts steam quite poorly. This is explained by the penetration of dust and other debris into the pores of the membrane during dry times, the “breathing” effect disappears and condensation begins to accumulate on the surface of the insulating material.

Superdiffusion membrane IZODACH 115

The two remaining types of membranes have large pores, this eliminates the possibility of their clogging, which is why there is no need to leave an air ventilation layer in the lower part. As a result, there is no need to install sheathing and counter battens.

Three-dimensional diffusion films are available for sale. A ventilation layer is already provided inside the membranes, due to which moisture will not be able to reach metal surfaces. The specifics of the film structure are similar to the antioxidant version. The only difference is the removal of moisture from the insulation. This is beneficial because when the roof is tilted, even at a slight angle of 3-15 degrees, the possibility of condensate draining through the bottom is eliminated. Therefore, corrosion of the galvanized coating will gradually occur, followed by its final destruction.

Which side should the vapor barrier be attached to the insulation?

First you need to figure out in which places you may need to lay a vapor barrier membrane, and then decide on the side of the vapor barrier.

If insulation is installed from the front part of the wall, then the vapor barrier film is fixed from the outside, this will be waterproofing.
Treatment of the ceiling and roof requires the use of an antioxidant vapor barrier. Volume and diffusion coatings are often used. They are laid on top of the mineral wool according to the principle of organizing a ventilation facade.
In the absence of additional insulation of the roof and ceiling, a vapor barrier film is attached to the underside of the rafters.
Thermal insulation of the upper part of the ceiling of rooms, ceilings located under attic space, requires laying a vapor barrier membrane on the underside of the insulation.
When insulating walls and floors from the inside, it is recommended to additionally lay a vapor barrier film on the outside of the mineral wool.

Many “experienced” builders have no idea how to fasten vapor barrier membrane on the walls: front or back.

The best solution would be to use a material with the same back and front sides.

What to do in the case of a one-sided option, in particular with antioxidant insulator? You need to know that the wrong side is the fabric surface located during installation in the inside of the room.

Determining the side of installation of vapor barrier

The metal plane faces in the same direction foil membrane– shiny side towards the inside of the room.

For any film vapor barrier materials The following rule applies: the smooth side is laid against the insulation, while the rough side must face the room.

The same rule applies foam-propylene vapor barriers, which are placed with the smooth side to the insulation.

The vapor barrier is laid with the dark side facing the insulation

It must be borne in mind that when rolling out a roll, for example, on the floor, the inner side should be on the floor.

In addition, most often the darker side is the outer side.

Is there a need for an air gap at the membrane?

You should always leave it on. A special gap up to 50 mm wide is arranged on the bottom side of the films. This will prevent condensation from appearing on the walls, floors and insulation. It is important to avoid contact of surface cladding with the membrane. By using diffusion film for floors, walls or ceilings, you save yourself from many problems, since it can be fixed directly to thermal insulation, OSB or moisture-resistant plywood. A ventilation layer will be required on the outside of the membrane. In the version with an antioxidant component, the air gap should be within 40-60 mm on both sides.

Organization of a ventilation gap when laying vapor barriers

If everything is clear with the walls and floor, then with the roof and ceiling the situation is different. When creating a ventilation gap, additional installation of a counter-lattice based on wooden blocks will be required. When organizing a ventilated façade, a gap is left during the construction of horizontal profiles and racks located perpendicular to the wall and film.

Video No. 2. ONDUTIS vapor barrier laying technology

How is the vapor barrier attached?

The membrane can be fixed to the walls, floor or ceiling using nails with a wide head or a construction stapler. However best choice will be the use of counter rails.

The vapor barrier is laid in an overlap with an overlap of at least 10 cm. After fixing the vapor barrier, the joints are glued with special tape or vapor barrier tape.

Conclusion

In conclusion, we say that membranes will allow any building structure to last for an extremely long time. Unfortunately, it is impossible to achieve a positive ratio of moisture and temperature in other ways. In addition, do not forget about the rules for installing vapor barriers. Most manufacturers also distribute installation instructions along with the product. This is especially true for diffusion and superdiffusion membranes. Therefore, do not be lazy before purchasing to clarify with the sales consultant all the questions that interest you.

Insulation - very important stage during the construction or renovation of a house, which determines whether you will feel comfortable staying in it. Improper implementation of this “procedure” can lead to unpleasant consequences, for example, the release of condensation and increased humidity in the air. But this will not happen if you take care of the vapor barrier and lay it with the correct side to the insulation.

Peculiarities

When insulating a house, you should carefully observe correct sequence actions and use only the most best materials. Unfortunately, often owners who undertake to insulate their home themselves forget about one very important aspect - the vapor barrier. They install only insulation and don’t even think about the fact that it comes into contact with too warm or too cold air inside the room, and that condensation in the form of water droplets will soon begin to form on it.

And this not only does not contribute to insulation, but also spoils the material itself - it moisturizes it, and if the steam does not yet have time to evaporate, mold appears and the insulation structure deteriorates. Moreover, taking into account our climatic conditions, a similar situation occurs at least four times a year - when the seasons change and, accordingly, the temperatures in the room and outside “conflict”, and the insulation becomes the battlefield.

That is why an important stage of insulation is the installation of a “vapor barrier”. The vapor barrier becomes an impenetrable obstacle to steam, preventing it from turning into water, as it “closes” it inside the room and prevents it from coming into contact with excessively warm or excessively cold air.

Materials

Vapor barrier can be made using several materials. From this set, three main types should be distinguished.

Film. A solid vapor barrier that does not allow water vapor to pass through. One of the main advantages is low price. As a rule, it is made from polyethylene or butylene, their derivatives. Vapor-condensate films are two-layer with a smooth inner and rough outer surface. Lingering on the outside, drops of condensate do not flow down, but evaporate over time. In the case of a solid vapor barrier, you also need to take care of the air gap in order to avoid the greenhouse effect, but more on that later.
Diffusion membrane. The main difference from film is that the membrane allows some of the vapor to pass through itself - but only the optimal amount that does not linger inside and evaporates instantly. Therefore, the vapor permeability of membranes is usually considered limited. The diffusion membrane is made of polymer film and polypropylene and has two sides.
Reflective or energy-saving film. The outer layer of this film is metalized, which allows it to withstand high temperatures. Therefore, it is most often used in baths or saunas, reflecting part of the infrared radiation.

As you know, materials such as mineral wool, expanded polystyrene, and ecowool are used to insulate houses in modern conditions. Vapor barrier is also needed in the case of mineral wool insulation.

In fact, vapor barrier is always needed, no matter how expensive or high-quality insulation material you use. Mineral wool or mineral wool is otherwise the cheapest material, but its level of thermal conductivity is low, which reduces the likelihood of heat loss in the room. Rodents, mold, and mildew do not like mineral wool; it has high sound insulation and is easy to install. But it still requires a vapor barrier.

The most commonly used is a vapor-permeable limited diffusion membrane. It is laid against the walls, after which you need to lay mineral wool, and in symbiosis they allow the walls of the house to “breathe”.

The question of vapor barrier also arises when insulating a house with ecowool. In general, ecowool is loose cellulose fibers that have the ability to absorb warm moisture and still remain dry. Fungus and mold do not grow on it, the air in it simply does not get wet (if the change in humidity does not exceed 25% percent). From all of the above it follows that in the case of ecowool, the vapor barrier need not be attached.

Another popular insulation– expanded polystyrene actually has another, easier name: polystyrene foam. It applies to both external and internal surfaces, and in the case of external insulation of loggias, balconies or attic floors, it does not require a vapor barrier - it itself copes well with this if the insulation technology is maintained. But if you are insulating interior spaces with polystyrene foam, vapor barrier and waterproofing are required to avoid the formation of fungus, mold and getting the walls wet.

Device

Purchasing a set quality materials- only a third of success. In fact, these materials need to be installed correctly and arranged in the correct sequence. It is for this purpose that you should find out which side the vapor barrier is laid, how it is fixed, in what order, and what to nail first - a vapor barrier or insulation.

First you need to carry out preparatory work. At this stage, the type of coating that you will insulate, its performance characteristics and requirements for insulation and vapor barrier materials are identified.

So, the surface needs to be carefully prepared. This takes into account the type of material from which it is made. Wooden elements must be treated with compounds against aging, rotting and burning. In the case of concrete and brick, it is possible to use antiseptic compounds deep penetration. From correct processing Half of the success in its operation depends on the surface.

If you are carrying out repairs or reconstruction, then pay attention to the fact that before insulation, all traces of the previous finishing must be removed and a complete cleaning must be carried out. And if we are talking about a log house, then all elements must be treated with fire retardants and antiseptics.

Vapor barrier on the ceiling

In case of roofing structures and interfloor ceilings, the installation of vapor barrier is assumed on an already prepared and properly treated surface. It is best to use a diffusion membrane here.

The main difference between laying a vapor barrier on the ceiling and laying it on other surfaces is that in this case the insulation is laid first, and only then the membrane. This can be mineral or basalt wool in blocks or rolls. It is mounted between the joists and rafters. If the thickness of the insulation is equal to the height of the logs, you will need to additionally install a slatted counter-lattice so that the ceiling is ventilated. After all this, you can work on the vapor barrier.

It should fall slightly onto the walls around the perimeter, the joints should be fastened to the joists - to ensure that moisture does not get into the space between the membrane and the insulation. Pay special attention to the corners - these are problem areas, it is better to seal them additionally. Use reinforced tape or a construction stapler as a fastener.

In the case of insulation flat roof or a concrete ceiling, you can also use a regular vapor barrier film from the inside. It is attached to self-adhesive tape also after the insulation, and then the sheathing is installed - metal or wood.

Vapor barrier on the floor

In the case of laying a vapor barrier on a wooden floor, additional waterproofing must be installed. The floor is also insulated along the joists. Mineral wool or basalt-based wool is installed in the space between the joists. Further without any additional work vapor barrier flooring is being installed.

If we are talking about a rolled vapor barrier, it is laid with an overlap of 12-15 cm with the joints, gaps and cracks glued on both sides with metallized tape as thoroughly as possible. As in the case of ceiling insulation, the overlap on the walls should be within 10 cm.

For a concrete floor you will need sheathing. You will need to lay waterproofing layer into the cells of the sheathing, a heat insulator on top, and after the mineral wool, the third layer is a vapor barrier.

Vapor barrier on walls

The process of insulation and vapor barrier of walls is a little more complicated than performing the same work on the ceiling or floor and implies a little large quantity stages. Let's consider the process of laying a vapor barrier film on the walls.

First of all, a frame is mounted from small cross-section bars. The size of the sheathing is determined by the width of the heat insulator block - the distance between the cells is equal to the width of one slab. Classically, mineral wool is used.

At this stage, you should pay special attention to possible gaps that arise due to the difference in the width of the insulation, frame and vapor barrier. The cracks are sealed with reinforced tape, and the sheets of film are glued horizontally with a 15 cm overlap.

Installation subtleties

When installing a vapor barrier, special attention should be paid to important issues.

Which side should the vapor barrier be laid?

Very often masters find it difficult to answer this question, but everything is not so complicated. Ordinary film has the same front and back sides - and then it doesn’t matter which side it is laid on. But in the case of single-sided films, the situation is a little more complicated.

For example, antioxidant films have a fabric backing, and according to installation requirements, it must face the inside of the room. Vapor condensate films must be laid with the smooth side facing the insulation, and the rough side facing outwards. But with diffusion films, you should look directly at the instructions, since such films can be either one-sided or double-sided. Energy-saving films are laid with the foil side, on the contrary, outward - after all, they should reflect and not absorb heat. The same applies to metal coatings.

How to distinguish the outside from the inside?

This information should be indicated in the instructions or on the manufacturer’s website; you can ask a consultant or technician about this. However, if none of the above suits you, you will have to learn to determine the sides of the vapor barrier yourself.

So, remember: if the vapor barrier has two-color sides, then the light side will always fit against the insulation.

But also pay attention to how the vapor barrier roll is rolled out - the side facing the floor will be the inner side, and it should be placed against the insulation. In the case of a vapor barrier with a different surface, the smooth layer will always be the inner one, and the fleecy or rough one will always be the outer layer.

What kind of fastener should I use?

This can be either a regular construction stapler or nails with a wide head, but counter-battens are considered to be the best option.

Is an air gap necessary near the membrane?

It is believed that this is a mandatory point - it is absolutely forbidden for the wall to come into close contact with the membrane; a gap of about five centimeters should be left for ventilation. Condensation will not accumulate this way. In the case of a diffusion vapor barrier, the air gap is made with outer side, and the film itself is laid directly on the insulation.

Do I need to tape the joints?

This is also mandatory - the individual parts of the vapor barrier should be hermetically connected to each other without forming gaps, the same applies to the places where the vapor barrier is attached to windows or doors. For this, self-adhesive tapes are used - double-sided or single-sided - usually made of polyethylene or butylene, propylene. These tapes not only perfectly hold membranes together, but are also used in their repair - they can be used to seal holes and cracks.

Do not use tape for this under any circumstances; it is better to contact a sales consultant in the store. building materials or go to the website of the company from which you purchased the vapor barrier - as a rule, companies produce materials for repairing their products.

The main purpose of a vapor barrier is to prevent water pores from leaving the room through the insulation and surfaces. This means that the vapors, one way or another, remain in the room, and in order to prevent the humidity from increasing and the microclimate from being disturbed, it is necessary to carry out natural or forced ventilation in a timely manner.

If you are interested in the question of what kind of overlap to make if parts of the membrane overlap each other, then we advise you to pay attention to the films themselves. There are markings along their edges - they indicate how exactly the overlap of the films should be. Depending on the type and company, the value indicated there is no less than 10 cm and no more than 20.

And also pay attention to the angle of the roof slope. If it is less than 30 degrees, the overlap cannot be more than 10 cm. If it is less than 20 degrees, the overlap cannot be less than 20 cm.

For information on installing a roof vapor barrier and which side to lay the vapor barrier against the insulation, see the following video.

Almost every living space needs a vapor barrier. What it is? What type of material is best for a vapor barrier? And which side should it be placed against the insulation? These and other questions regarding vapor barrier and its installation are answered by our specialists in this article.

What functions does a vapor barrier perform? The fact is that insulation is usually installed on the inside of the room, and when it comes into contact with warm air may become covered with water droplets. Where does moisture come from? The explanation is simple: steam settles on the walls of the room and, when cooled, changes from a vaporous state to a liquid one. To prevent this situation, you need to install a vapor barrier.

Experts identify several main functions of a vapor barrier:

increasing the service life of thermal insulation materials;
protecting the room from excess humidity.

Vapor barriers must be installed in rooms such as:

The vapor barrier is installed mainly on ceilings, where a large amount of vapor settles. Walls that are not insulated from the outside also need it, but in this case the vapor barrier will be installed on the outside of the building.

Which ones are best to use? The use of a certain type of vapor barrier material depends on intended purpose vapor barrier - indoors or outdoors. Therefore, experts name the following main types of materials with which vapor barriers are installed:

painting (bitumen, tar, mixtures of rubber bitumen, etc.) - applied directly to uninsulated surfaces (these can be roofs, ventilation pipes and the like);
film (films made of polyethylene, polypropylene, diffuse membranes, antioxidant films) - these types of vapor barrier materials are excellent for equipping private houses, both as the main vapor barrier layer and for installing an additional layer that acts as protection against roof leaks.

Which side should the vapor barrier be laid on? When laying vapor barrier film materials, it is necessary to take into account the basic rule: the smooth side is located directly to the insulation layer, and the rough side should face the inside of the room itself.

If the vapor barrier material is equipped with an aluminum layer, installation should be carried out as follows:

the rough side is applied to the insulation;
the shiny smooth side should face the inside of the room.

On the contrary, they act when laying foam-propylene vapor barrier materials:

the smooth side must be attached to the insulation;
turn the rough side inward.

But these material features are taken into account in the presence of a layer of insulation that has already been mounted previously on the insulated surface. If there is no insulation layer on the surface (for example, the outer sides of the walls of buildings), then the vapor barrier is attached directly to the frame:

the smooth side must be facing the wall;
The rough side directs the material towards the street.

It is not difficult to determine the smoothness or roughness of a vapor barrier material: just run your fingertips along its surface. Please note that the plastic film is the same on both sides - smooth. Therefore, installation is simplified; such a film is laid with either side facing the insulation.

Are there rules for installing vapor barriers? Experts say that such rules really exist. There are several of them:

the sheet of insulating material must be overlapped;
the sizing of the canvases is carried out with a special fixer - construction tape (the only condition is to prevent air from entering);
monitor the integrity of all layers of vapor barrier materials.

Be sure to check for defects - they should be absent from the vapor barrier material in principle. Since any crack, tear or hole can cause moisture condensation, which will constantly accumulate on the interior surfaces of the room (especially the ceiling).

Experts advise that before installing vapor barrier materials, carefully read the instructions that come with them. This instruction necessarily states the main point, which side of the material for the vapor barrier layer should be considered external and which side should be considered internal. Although, as already mentioned, this can be determined by eye and touch by certain signs:

different colors of the sides (the light side is placed next to the insulation);
texture (laying depends on the characteristics of the material itself, as discussed above in this article);
free rolling of the roll (the side of the material facing the floor is usually considered internal and is laid against the insulation);
the smooth layer is usually considered internal, and the fleecy layer is considered external.

When installing a vapor barrier, the main thing is to correctly lay it against the insulation (if any). This will help keep it thermal insulation properties and extend service life. If a vapor barrier is not installed, then the insulating materials will gradually begin to deteriorate due to constant exposure to moisture, which will lead to rapid wear and tear of the main structural elements of the building itself. This is especially true for private residential buildings: it becomes cold inside the premises, and additional costs will be required for heating or heating them.

Which side should the vapor barrier be placed against the insulation?

Which side should the vapor barrier be placed against the insulation? Almost every living space needs a vapor barrier. What it is? What type of material is best suited for vapor barrier

Which side should the vapor barrier be placed on the insulation?

When insulating a roof or room with a heat insulator (mineral wool, glass wool, loose polystyrene) capable of transmitting and accumulating moisture, it is necessary to install a vapor barrier layer. Moisture that gets into the thermal insulation significantly worsens its performance properties, increasing thermal conductivity. In addition, due to the humid environment, wooden structures with which the insulation comes into contact quickly begin to rot and collapse. At the stage of preparation for insulating a roof or house, it is important to figure out which side to lay the vapor barrier against the insulation - a violation of the technology will lead to steam from the room penetrating into the thermal insulation layer.

What kind of vapor protection is needed?

Types of vapor barrier materials

The primary issue is the choice of material that will protect the insulation from moisture. Classic roofing felt and glassine, which were used for water vapor barrier, have given way to modern polymer films with different performance parameters. Membranes used in construction are divided according to vapor permeability into completely impermeable films and partially permeable (diffusion) films.

Manufacturers offer the following types of vapor barrier membranes::

polyethylene film (can be used to insulate a roof or floor, the barrier is vapor and waterproof);
reinforced polyethylene film (higher strength);
aluminum foil film (used for internal insulation, mounted with the reflective side facing the room - additionally helps to retain heat, primarily designed for use in saunas and baths);
film with anti-condensation coating (prevents moisture condensation, intended for installation in structures with metal elements, prone to corrosion - corrugated sheets, metal tiles, etc., the film is mounted with the treated side facing the heat insulator).

Reinforced polyethylene film If, when insulating rooms in a house, a completely impermeable film is used to create a vapor barrier, it is necessary to provide effective ventilation of the rooms that can remove excess moisture outside.

Vapor barrier films with a porous structure differ in their ability to diffuse. Due to the pores in the barrier, moisture from the insulation leaves to the outside, due to which the heat insulator retains its operational properties, and those in contact with it metal constructions do not rust, wooden ones do not rot. Among vapor-permeable membranes there are differences:

Pseudo-diffusion. During the day, up to 300 g/m2 of vapor is passed through.
Diffusion. The amount of evaporation passed per day ranges from 300 to 1000 g/m2.
Superdiffusive. The evaporation rate exceeds 1000 g/m2.

The vapor barrier film of the first type is classified as effective protection from moisture and are used for internal insulation of structures (from the room side). If a pseudo-diffusion membrane is mounted on top of a fiber insulation on an external wall, the vapor barrier will trap moisture in the insulation. For facade insulation diffusion and superdiffusion membranes are suitable, which simultaneously serve as a wind barrier.

Superdiffusion membrane

Principles for installing a vapor barrier

Laying a vapor barrier is an important stage in the work on insulating structures fibrous materials, capable of accumulating moisture. The work is carried out as part of the repair or reconstruction of the house or at the stage of preparation for finishing new construction. You need to know how to properly fasten membrane sheets together to ensure a continuous layer that protects against moisture penetration, and how to attach the film to structures. Before laying the vapor barrier film, it is also necessary to determine which side it needs to be placed on the insulating material.

Preparatory stage

For insulation of block or wooden house, arranging a bathhouse, heat-insulating materials are used that need to be protected from moisture accumulation. For this purpose, on the walls inside the house, on the ceiling or floor, on the inside roofing pie install material that does not allow evaporation to pass through. Or a diffusion membrane for facade insulation.

On preparatory stage you should choose a vapor barrier option taking into account the installation features and requirements for the characteristics of the film. Popular options include Izospan (and its analogue Megaizol), a membrane material with high performance parameters. The manufacturer offers a line of membranes with various technical indicators, which allows you to choose a material depending on its purpose - vapor barrier for the roof, floors, wall structures made of wood or concrete.

Those who plan to build a bathhouse, not without reason, believe that foil film will reliably protect the mineral wool insulation from getting wet and will help maintain a high temperature in the room by reflecting thermal radiation. Along with the classic “insulation + vapor barrier” scheme, today ready-made non-combustible heat-insulating mats with a foil-coated vapor-proof surface are used.

Correctly attaching reflective vapor barrier

Before laying a vapor barrier, it is necessary to properly prepare the surfaces of the structures. The preparation technology depends on the material from which the walls, floor, ceiling or roof are made. It also takes into account what kind of work is being carried out at the site - construction or repair:

When building a wooden house, all wooden structural elements must be treated with compounds against rotting, pest damage and fire.
During repair work First, dismantle the finish, clean the surfaces, and:
- wooden structures are treated with an antiseptic and fire retardant.
- Concrete and block structures are treated with an antiseptic if they are damp and there is a risk of mold, as well as in wet rooms.

Due to improper preparation of structures, walls, ceilings or rafter systems can become unusable over time or become a source of fungal spores that can provoke allergies, asthma attacks, and exacerbation of respiratory diseases.

How to install a vapor barrier on a ceiling

Installation of a vapor barrier layer on the ceiling is required when insulating flat or pitched roof in a house without an attic, with thermal insulation of the basement, as well as residential premises above which is located cold attic. The ceiling in the bathhouse is also insulated and vapor-insulated. Before installing a vapor barrier on a roof made of concrete slab, on reinforced concrete or wooden floor from the inside, the surface of the structure should be prepared.

The fabric made of film or pseudo-diffusion membrane must be solid so that there are no joints through which moisture can penetrate into the insulation. If width roll material not enough, the strips will have to be joined together. The recommended overlap of the canvases is from 10 to 20 cm, while the joints on both sides are carefully taped with reinforced construction tape.

Fastening the vapor barrier membrane The foil film sheets are laid without overlap - end-to-end, and the seam is taped with aluminum tape.

If the roof base or ceiling is a wooden structure, you must first lay waterproofing membrane(solid sheet) and attach it to the base (you can use a vapor barrier material).

Then, in the spaces between the floor joists or rafters, a heat insulator is placed in the form of mats or rolled material made of mineral (basalt) wool. After this, you can lay a vapor barrier on the ceiling. If the thickness of the heat insulator corresponds to the thickness of the logs, you should nail a counter-lattice made of slats to create a ventilation gap.

The vapor barrier should be placed on the ceiling in such a way that the fabric extends along the entire perimeter of the walls and that all corners are closed. The joints of the canvases should be on the floor joists - this will allow them to be securely fixed. To properly install a vapor barrier on the ceiling, monitor the tension of the canvas, it should not sag.

Ceiling installation

We will also consider how to lay a vapor barrier on concrete floor. To insulate a ceiling from the inside or flat roof, made of a concrete slab, you need to attach a waterproofing coating (vapor barrier film) to it using self-adhesive tape, and then install a sheathing made of bars or a metal profile.

The correct height of the sheathing should be selected taking into account the thickness of the insulation and the ventilation gap, the installation step should be 1-2 cm less than the width of the insulation, so that mats made of insulating materials fit into the cells at odds. How to attach a vapor barrier to the sheathing will be described in detail below.

How to lay a vapor barrier on the floor

Installation of a vapor barrier membrane on the floor is similar in technology to how vapor barriers are installed for walls and ceilings. After preparing the base of a wooden floor when insulating along the joists, before laying the vapor barrier on the floor, a waterproofing carpet is installed, which should go around the joists. Then a thermal insulator made of mineral wool is inserted between the joists. After which the vapor barrier is laid, it is important to know how to lay the film correctly.

The overlap of the sheets of rolled material should be at least 10 cm, with the joint taped on each side. The resulting canvas is secured in such a way that the overlaps lie on the floor joists, and along the entire perimeter the evenly stretched canvas extends 5-10 cm onto the walls.

Insulated floor with air gap

Before laying a vapor barrier on a concrete floor, it is necessary to install a sheathing, between the elements of which the waterproofing and insulation will be placed. Further work is carried out according to the standard scheme.

Fastening principles

If they are insulated concrete structures or wooden walls, it is necessary to install a sheathing of bars. To the resulting sheathing, to the ceiling or rafter system It is convenient to attach the film using staples and a construction stapler. You can also secure the vapor barrier material with nails with wide heads or pads under the heads. It is advisable to use galvanized nails - they do not rust. Films and membranes are placed on concrete structures using a special connecting tape.

Overlap when installing vapor barrier

In order to properly fasten the vapor barrier, the canvas should be carefully pulled, and the fastening elements should be placed in small increments - no more than 30 cm. Installation rules require careful attention to the fastening of the canvas around the perimeter - it is spread and fixed in such a way as to exclude the possibility of moisture penetrating into the insulation.

Before attaching the vapor barrier, make sure that the sheet is positioned with the correct side to the thermal insulation.

Which side to install the vapor barrier material

Let's consider which side of the film or membrane is laid to the insulation:

polyethylene film (simple or reinforced) can be attached to either side - this does not affect the functionality of the barrier;
the foil film is placed with the shiny side facing the room so that the barrier reflects heat;
the anti-condensation film is attached with the treated side to the structures, the fabric side to the room;
the membrane should be facing the smooth side towards the heat-insulating material, and the rough side towards the room.

Rule for laying vapor barrier to insulation If the front side of the membrane looks similar to the back side, and it is difficult to determine how to properly lay the material, you can conduct an experiment. Cover the bowl of boiling water with a small piece of membrane - whichever side the condensation appears on is the side that is waterproof; it should be facing the insulation.

It is important to know which side to lay the vapor barrier against the insulation if the membrane is used to install a waterproofing barrier - front or back. Thermal insulation “pie” with internal insulation it is mounted in such a way that the smooth side of the membrane faces the insulation on both sides. That is, the rough layer of vapor barrier should be facing towards the room, and when installing a waterproofing carpet - towards the structure that is being insulated.

Installation features

It is important not only to install the vapor barrier correctly, but also to ensure ventilation gap between the vapor-tight layer and the cladding of the structure for finishing, for which counter battens are placed along the sheathing. Moisture settling on the rough side of the laid vapor barrier sheets will evaporate naturally without damaging the finish.

Diagram of an insulated roof with a ventilation gap

If the vapor barrier is installed correctly, the insulation is reliably protected from moisture. Almost half of the problems associated with freezing and damage to structures are associated with defects in the installation of the vapor barrier.

Which side to lay the vapor barrier to the insulation, how to attach it correctly

Which side is correct to put it on? thermal insulation material to the insulation. Varieties of vapor barrier films with stages of installation on the roof, ceiling and floor.

Which side to lay the vapor barrier against the insulation. Types of vapor barrier materials. Installation of vapor barrier

Very often there is a need to insulate rooms from the inside. If you plan to do the work yourself, many questions immediately arise about how to do it correctly. And one of them concerns the need to use vapor barrier films and their place in the thermal insulation “pie”.

Let’s answer right away: vapor barrier is necessary when using any moisture-absorbing types of insulation. Read on for more details.

Why do you need a vapor barrier?

The insulation installed on the inside, even in the presence of external cladding, is in contact with the warm air of the room, which always contains water vapor. But under certain conditions they pass from a vapor state into a liquid state, that is, into drops of water.

What are these conditions?

Excessive vapor concentration for a given air temperature. The higher the temperature, the more water vapor the air holds.
Decrease in air temperature.

If the concentration of water vapor and the temperature inside and outside the room are approximately equal, vapor barrier is not needed - the steam will not turn into water. But as soon as these parameters inside the room become higher, the steam tends to escape outside through any obstacles.

As you understand, in our climatic conditions this happens throughout heating season which lasts more than six months. It is also clear that the coldest surfaces in the house are those in contact with the outside air: walls, ceilings above unheated basements, ceilings top floors and so on. That is why they are insulated.

Installation of heat and vapor insulation of walls

In the absence of a vapor barrier, steam penetrates into the layer of thermal insulation adjacent to cold walls or other structures, where it condenses, turning into droplets of water and moistening the insulation.

As a result, the thermal insulation properties of the material decrease, and it begins to perform its functions worse. And if the water does not have time to evaporate, then more serious problems are possible: damage to structural elements in contact with the insulation, the appearance of mold.

If a vapor barrier is laid under the insulation, then it becomes an impassable (or partially passable) obstacle to steam. It remains in a warm room without cooling and remains in a gaseous state.

Therefore, the installation of internal thermal insulation clearly requires the installation of a vapor barrier between the insulation and the warm air of the room.

It doesn’t matter what you are insulating: the walls in the room, the ceiling, the floors or the roof. Without high-quality vapor barrier, you will not achieve the desired effect and may even harm the microclimate in the room.

Types of vapor barrier materials

Film

Izolon insulation is a multifunctional material).

Attention! Because reliable vapor barrier does not allow water vapor to escape from the room through the insulation and walls, then it is necessary to ensure good forced or natural ventilation. Its absence can lead to an excessive increase in air humidity and, as a result, disruption of a comfortable microclimate and damage to the finish.

Rules for vapor barrier installation

It would seem that there is nothing complicated: attach the film over the insulation and the vapor barrier is ready (Read also the article Shelter Insulation - a new technology). However, there are some nuances in this matter that you need to know about.

Types of vapor barrier materials

Among those presented at construction market There are three main types of vapor barrier materials:

Film. It is a type of blind vapor barrier that absolutely does not allow water vapor contained in the air to pass through. Its main advantage is its low price.

In addition to regular polyethylene film, special steam-condensate films are also produced. They are two-layer, with a smooth inner side and a rough outer side. Drops of condensation are retained by the rough surface and evaporate instead of flowing down.

Vapor barrier membrane

Reflective (energy saving) film. Features a metallized outer layer that is heat resistant and reflective most infrared radiation.

This material is most often used in baths and saunas.

Installation of vapor barrier

From all that has been said above, we can conclude that the vapor barrier material is attached on top of the insulation on the room side. But it is very important to take into account two more points: which side of the vapor barrier is laid to the insulation and what are the features of its installation.

This is where you need to look at the type of film used.

Ordinary polyethylene film is laid on either side. However, they are no different from each other.
The vapor condensate film is laid smooth inside on the insulation, and the fleecy side faces outward.
Diffusion membranes are installed in exactly the same way - with the smooth side facing the insulation.
Energy-saving vapor barrier materials are attached with the foil side facing outward, since it is this side that reflects the heat penetrating back to it.

Note! It should be remembered that laying blind vapor-tight materials requires a ventilated gap.

The fact is that with excess air humidity, blind vapor barriers contribute to the creation of a greenhouse effect. If the internal lining is installed without a gap, close to the vapor barrier, then it will be constantly exposed to the harmful effects of moisture settling on the film. If there is such a gap, the movement of air in it will contribute to the evaporation of condensate.

Insulation of a loggia using a vapor barrier membrane - no ventilated gap required

Which side to lay the vapor barrier to the insulation: video instructions for DIY installation, photos and price

Which side should the vapor barrier be laid to the insulation?

In the process of thermal insulation of buildings, you have to not just lay insulation, but create a whole “pie” consisting of layers that perform various functions. To protect insulating materials and the structure itself from steam penetration and condensation, a film or a special membrane is used. For it to work, it is important to know which side to lay the insulation correctly against the insulation being used. Improper installation will negate all efforts at thermal insulation, allowing the insulation to get wet. In addition, humidity will negatively affect the material. structural elements building.

Purpose of vapor barrier

Steam and condensate have a significant impact on the condition of the structural elements of the roof, walls, and floors. Excess moisture promotes the growth of fungus and mold, causes metal corrosion and rotting wooden parts. Wet insulation, especially mineral wool, sharply reduces its insulating properties, allowing the penetration of cold. The vapor barrier fabric serves as a protective barrier that does not allow wet steam to pass inside the “pie”, but does not prevent it from escaping outside.

The appearance of condensation is caused by the temperature difference in the heated room and in the cold street. The steam trying to leave the building cools and turns into droplets of water. The vapor barrier film, installed on the correct side, prevents moisture from getting to the insulation. Condensation flows down the surface of the canvas without getting on the structural elements, or dries on it. Some products designed to protect against steam do not require you to choose which side to turn them towards the insulation. These versatile films are especially convenient for novice builders.

Types of vapor barrier materials

A wide range of vapor barrier materials allows you to choose a canvas for any area of the building. The following are used as special protection:

Rules for installing vapor barrier film

To determine which side you need to turn the fabric towards the insulation, it is often enough to read the manufacturer's instructions. If there are no instructions in it, then the texture of the product will help you choose the right side. The smooth side of the vapor barrier is laid on the insulation, this ensures a tight fit, and the fleecy side serves to retain steam. Manufacturers of diffuse membranes always provide detailed instructions for their use, and the outer part is painted in a brighter color.

The production of vapor barrier products in rolls facilitates installation and allows it to be completed in a short time. Standard width the canvases are 1.5 meters and the length is 50,100 meters. To calculate required amount material, find the total area of the insulated surface, and then add 15% for overlaps and trimming. The fastening method is selected depending on the material used; it is better to fix the plastic film with wooden strips into which staples are driven. This will eliminate the possibility of damage to the polyethylene.

It is convenient to use a stapler to attach the vapor barrier sheet

Installation of paintings on walls is always carried out from the bottom up. In difficult places - corners, protrusions, slopes, the tight fit of the material is ensured by gluing with tape. To work you will need a set of simple tools:

construction knife;
tape measure and pencil;
scissors;
stapler with staples or hammer and galvanized nails.

Ceiling mounting

Due to the rise of heated air, including steam, the ceiling turns out to be one of the most vulnerabilities premises. An effective option for protecting it is a special membrane. Such canvases are offered in two types:

one-sided - for operation it is not necessary to choose how to correctly install the insulation in relation to the insulation;
double-sided - the membrane must be mounted with the side indicated in the instructions.

Such material does not require leaving a gap for ventilation, eliminating the need to create a counter-lattice. Installation costs will be reduced, and ceiling heights will change slightly. The membranes are quite strong; to secure them you need to use small nails or staples from a construction stapler.

The vapor barrier must be installed after laying the insulation. The canvas should not be stretched too much, because during operation it contracts and stretches as the temperature changes. Excessive tension can lead to rupture, this is especially true for products installed in unheated room. You don’t need a lot of sagging either, 1-2 cm is enough. When spreading the material, part of it is placed on the walls to connect with their vapor barrier.

We isolate the roof from steam

When installing a vapor barrier for roof insulation, you can use a film material made of two layers of polyethylene reinforced in the middle metal mesh. It will also be a good waterproofer. Installing the film requires leaving an air gap of at least 5 cm, so there must be free space between the insulation and the edge of the rafters. If the angle of inclination of the slope is less than normal, it is worth using the film on adhesive based. This will greatly facilitate installation and increase the tightness of complex joints. For reinforced concrete roof slabs, liquid bitumen mastic is used as a vapor barrier.

For guard wooden structures special vapor barrier films or membranes are used

Working with insulated facades

Placing a vapor barrier product on the outside of the walls has its own nuances. They are due to the change temperature conditions, presence of precipitation, wind load. Let's figure out how to install vapor barriers for facades. The panel fits tightly to the insulation (if necessary on both sides), and a gap is left between it and the lining for ventilation. The material must be carefully secured so that the wind does not blow it away. Usually a membrane is used, in which it does not matter which side it is laid on the insulation. Horizontal and vertical stripes overlap each other by at least 10 cm, this will ensure the tightness of the joints. Bonding the parts with butyl rubber-based tape ensures high joint strength. Condensate flowing down the vapor barrier film is removed through drain holes in the lower part of the wall.

Installing film on an insulated floor

When vapor barrier of floor insulation placed between the joists, strips of material are stretched across wooden joists. Fastening is done with staples. The junctions with the wall and overlaps of adjacent panels are sealed with double-sided adhesive tape. Steam from the room penetrates from above, so the film is laid with the rough side up.

Features of installation of reflective vapor barrier

Fabrics with a layer aluminum foil necessary in rooms requiring maximum heat retention. When installing them, the reflective layer is always directed into the room. Between isolation and finishing a gap is left, it will enhance the effect of the foil and prevent damage to the cladding due to condensation. Adjacent panels are installed end-to-end and glued with special metallized tape. If the tightness of the surface of the product is broken during fastening, then the hole is sealed with tape.

Which side to lay the vapor barrier towards the insulation?

How to properly install a vapor barrier to protect the ceiling, roof, walls, and floor. What material is better to use and which side should it be laid against the insulation.

Steam and condensate have a significant impact on the condition of the structural elements of the roof, walls, and floors. Excess moisture promotes the growth of fungus and mold, causing corrosion of metal parts and rotting of wooden parts. Wet insulation, especially mineral wool, sharply reduces its insulating properties, allowing the penetration of cold. The vapor barrier fabric serves as a protective barrier that does not allow wet steam to pass inside the “pie”, but does not prevent it from escaping outside.

Types of vapor barrier materials

A wide range of vapor barrier materials allows you to choose a canvas for any area of the building. The following are used as special protection:

Polyethylene film is a standard, affordable, but not durable option. Low strength requires careful handling during installation; it is important not to break the tightness of the canvas. To strengthen it, it is subjected to reinforcement. Models are offered with and without perforation; the presence of micro-holes allows for better moisture removal. The polyethylene is fastened with staples. Places where the panels overlap are sealed with adhesive tape. During installation, an air gap is left between the insulation and the film.
Polypropylene film – resistant to low and high temperatures, tensile strength. The material has two layers, the outer one is covered with viscose and cellulose. It has a rough and loose structure to retain condensation. Laying vapor barriers made of polypropylene involves placing the smooth side towards the insulation. If there is an anti-condensation layer, it is necessary to leave a ventilation gap, which will ensure the evaporation of collected moisture. Polypropylene can be used to protect roofs, ceilings, and walls.
Membranes are modern, effective and expensive protective materials. When installed the correct way, they provide full protection from moisture, steam, wind. There are diffuse and superdiffuse types of canvases. The first option is characterized by a vapor permeability coefficient in the range of 300-1000 g/sq.m. m, the second has an indicator of more than 1000 g/sq. m. A huge number of tiny holes in the form of funnels allows steam to pass freely and retain water. Construction multilayer membranes are used to insulate roofs and the outside of facades. The basis of the material is a non-woven polymer.
Vapor barrier with a foil layer is a durable material with a reflective effect. Used indoors high humidity– kitchens, balconies, saunas, baths. This group includes various materials (foamed polyethylene, kraft paper) laminated with aluminum foil. Determining which side to install reflective insulation correctly is quite simple - the aluminum layer should be directed into the room. To perform the installation correctly, you do not need to place parts of the canvases on top of each other, as when laying film. It is necessary to join the strips and glue them with metallized tape.

Rules for installing vapor barrier film

The production of vapor barrier products in rolls facilitates installation and allows it to be completed in a short time. The standard width of the canvas is 1.5 meters and the length is 50,100 meters. To calculate the required amount of material, find the total area of the insulated surface, and then add 15% for overlaps and trimming. The fastening method is selected depending on the material used; it is better to fix the plastic film with wooden strips into which staples are driven. This will eliminate the possibility of damage to the polyethylene.

It is convenient to use a stapler to attach the vapor barrier sheet

construction knife;
tape measure and pencil;
scissors;
stapler with staples or hammer and galvanized nails.

Ceiling mounting

Due to the rise of heated air, including steam, the ceiling turns out to be one of the most vulnerable places in the room. An effective option for protecting it is a special membrane. Such canvases are offered in two types:

one-sided - for operation it is not necessary to choose how to correctly install the insulation in relation to the insulation;
double-sided - the membrane must be mounted with the side indicated in the instructions.

The vapor barrier must be installed after laying the insulation. The canvas should not be stretched too much, because during operation it contracts and stretches as the temperature changes. Excessive tension can lead to rupture, this is especially true for products installed in an unheated room. You don’t need a lot of sagging either, 1-2 cm is enough. When spreading the material, part of it is placed on the walls to connect with their vapor barrier.

We isolate the roof from steam

When installing a vapor barrier for roof insulation, you can use a film material made of two layers of polyethylene, reinforced in the middle with a metal mesh. It will also be a good waterproofer. Installing the film requires leaving an air gap of at least 5 cm, so there must be free space between the insulation and the edge of the rafters. If the angle of inclination of the slope is less than normal, it is worth using an adhesive-based film. This will greatly facilitate installation and increase the tightness of complex joints. For reinforced concrete roof slabs, liquid bitumen mastic is used as a vapor barrier.

To protect wooden structures, special vapor barrier films or membranes are used

Working with insulated facades

Placing a vapor barrier product on the outside of the walls has its own nuances. They are caused by changes in temperature conditions, the presence of precipitation, and wind load. Let's figure out how to install vapor barriers for facades. The panel fits tightly to the insulation (if necessary on both sides), and a gap is left between it and the lining for ventilation. The material must be carefully secured so that the wind does not blow it away. Usually a membrane is used, in which it does not matter which side it is laid on the insulation. Horizontal and vertical stripes overlap each other by at least 10 cm, this will ensure the tightness of the joints. Bonding the parts with butyl rubber-based tape ensures high joint strength. Condensate flowing down the vapor barrier film is removed through drain holes in the lower part of the wall.

Installing film on an insulated floor

When vapor barrier is applied to floor insulation placed between joists, strips of material are stretched across the wooden joists. Fastening is done with staples. The junctions with the wall and overlaps of adjacent panels are sealed with double-sided adhesive tape. Steam from the room penetrates from above, so the film is laid with the rough side up.

Features of installation of reflective vapor barrier

Canvases with a layer of aluminum foil are necessary in rooms that require maximum heat retention. When installing them, the reflective layer is always directed into the room. A gap is left between the insulation and the finishing; it will enhance the effect of the foil and prevent damage to the cladding due to condensation. Adjacent panels are installed end-to-end and glued with special metallized tape. If the tightness of the surface of the product is broken during fastening, then the hole is sealed with tape.

In contact with

A fairly common problem after insulating a house is the lack of the expected effect from the work performed. It would seem that a traditional material was chosen, for example, mineral wool, everything was done according to building laws and canons, but it was still cold inside the room. The reason for this may be the ignorance of “specialists” about basic standards, including which side to lay the vapor barrier against the insulation. Let's look at this issue in more detail.

Vapor barrier is divided into two types according to the method of application:

liquid paint vapor barrier;
vapor barrier membranes (film).

Painting vapor barrier is applied using brushes and rollers in places where roll vapor barrier is difficult to use, for example, on ventilation and stove pipes. This family of vapor barriers is represented by materials such as bitumen, tar and tar.

Vapor barrier membranes

First of all, let's define the types of vapor barrier films according to their purpose. According to their specificity, membranes used in construction are offered in the following versions:

membranes with vapor barrier properties;
membranes are vapor permeable.

To protect the mineral wool from exposure to moisture from the inside, it is necessary to additionally lay a layer of vapor barrier. When insulating the roof, floor or interior space of the house located directly below it, it is recommended to use the appropriate film. Note that the insulating layer is laid from below, under the laid mineral wool (from the side of the room).

If external wall protection is provided, the corresponding components must not have perforations or porosities.

Always pay attention to the value of the vapor permeability coefficient - the lower it is, the better. An excellent option is regular plastic film. The ideal choice would be a material with additional reinforcement. The presence of aluminum foil coating will only be a plus.

Do not forget that the presence of a vapor barrier finish leads to a multiple increase in humidity in the insulated space, so you should take care of a good ventilation system in advance.

Special vapor barrier films are made with an antioxidant coating. Due to this, moisture does not accumulate. As a rule, they are attached under components that are sensitive to rust formation. We are talking about metal tiles, corrugated sheets, galvanization, etc. The rough fabric layer on the back of the film guarantees effective moisture removal. It is laid with the treated side facing the insulation, and the fabric side facing out, so that there is a distance of 20-60 mm to the mineral wool.

When insulating the walls of a house from the outside, a building membrane is used that can carry out evaporation and protect the material from strong wind gusts. In addition, it is suitable for protecting pitched roofs and facades with a leaky base from moisture. Often, the vapor barrier film has very small pores and surface perforations, due to which water is effectively removed from the insulation into the ventilation ducts. The more actively the vapor removal occurs, the better the process. This will allow the insulation to dry quickly and efficiently.

The following types of vapor-permeable films are distinguished:

Pseudo-diffusion membranes that transmit no more than 300 grams/m2 of evaporation over 24 hours.
Diffusion membranes, with a vapor permeability coefficient in the range of 300-1000 grams/m2.
Superdiffusion membranes, with an evaporation rate of more than 1000 grams/m2.

Which side to attach the vapor barrier to the insulation

First you need to figure out in which places you may need to lay a vapor barrier membrane, and then decide on the side of the vapor barrier.

If insulation is installed from the front part of the wall, then the vapor barrier film is fixed from the outside, this will be waterproofing.
Treatment of the ceiling and roof requires the use of an antioxidant vapor barrier. Volume and diffusion coatings are often used. They are laid on top of the mineral wool according to the principle of organizing a ventilation facade.
In the absence of additional insulation of the roof and ceiling, a vapor barrier film is attached to the underside of the rafters.
Thermal insulation of the upper part of the ceiling of rooms and ceilings located under the attic space requires laying a vapor barrier membrane on the underside of the insulation.
When insulating walls and floors from the inside, it is recommended to additionally lay a vapor barrier film on the outside of the mineral wool.

Many “experienced” builders have no idea how the vapor barrier membrane should be attached to the walls: front side or back side.

The best solution would be to use a material with the same back and front sides.

The metal plane faces in the same direction foil membrane- shiny side towards the inside of the room.

For any film vapor barrier materials The following rule applies: the smooth side is laid against the insulation, while the rough side must face the room.

The same rule applies foam-propylene vapor barriers, which are placed with the smooth side to the insulation.

The vapor barrier is laid with the dark side facing the insulation

It must be borne in mind that when rolling out a roll, for example, on the floor, the inner side should be on the floor.

In addition, most often the darker side is the outer side.

Is there a need for an air gap at the membrane?

Organization of a ventilation gap when laying vapor barriers

Video: ONDUTIS vapor barrier installation technology

How is the vapor barrier attached?

The membrane can be fixed to the walls, floor or ceiling using nails with a wide head or a construction stapler. However, the best choice would be to use counter rails.

The vapor barrier is laid in an overlap with an overlap of at least 10 cm. After fixing the vapor barrier, the joints are glued with special tape or vapor barrier tape.

Conclusion

“Izospan B” (which side to lay it towards the insulation, you will learn from the article) is a material that acts as a vapor barrier when there is a need to protect thermal insulation or other structural elements that can become saturated with moisture vapor during operation. The vapor barrier can be used in buildings for any purpose. Its structure consists of two layers, one of which is smooth, while the other is rough. Last layer allows the material to retain drops of moisture, which then evaporate.

Need for use

The use of vapor barrier material "Izospan V" allows you to preserve for a long time performance thermal insulation. The material prevents the formation of excess moisture, protecting building components from corrosion and damage by microorganisms. As another additional function vapor barrier is that it protects the room from penetration of insulation fibers.

Which side to cover

Quite often, Izospan B has recently been used as a vapor barrier. You should ask which side to lay it towards the insulation before starting installation. At the first stage, the consumer should decide where the smooth and rough surfaces are located. According to the instructions, the smooth side should be facing the surface of the insulation; this advice must be followed strictly. The membrane is installed on the load-bearing elements of the frame or on the rough sheathing. It is necessary to use a stapler as fastener.

If the room will have finishing material or linings, then “Izospan V” is strengthened along the frame wooden slats with a section of 4x5 cm. Installation work provide for tight joining of thermal insulation with the film. If the material is used as a material, then the horizontal strips must be overlapped, and this work must begin from the bottom. Horizontally and vertically, the overlap should be approximately 15 cm.

Used to conduct interior work material "Izospan B". You now know which side to lay it towards the insulation. However, during installation there are many nuances that must be observed. For example, vapor barrier can be used in the construction of floors. In this case, the canvases must be laid along the ceiling joists. The material must be placed between the subfloor and the finishing floor. Between the thermal insulation and top layer membrane, as well as between the membrane and the finished floor, a gap of up to 5 cm should be left.

If you also decide to use Izospan V when carrying out repair work, which side should be placed towards the insulation, it is important to ask before the start of manipulations. For example, if working surface is represented by plasterboard, the membrane must be fixed to the galvanized profile. It should be tightly mounted with the smooth side facing the thermal insulation. All resulting joints and places where the membrane will be connected to other materials must be glued with connecting tape from the same manufacturer. Do not forget to leave a ventilation gap of 3 cm, which is necessary to prevent displacement and reduce the likelihood of excess moisture accumulation.

Quite often, people wonder which side to place the vapor barrier against the insulation, if the latter is reinforced on the outside of the wall. In this case, “Izospan B” should be installed indoors, and its rough part should face inward. To fasten the material in all cases, you can use a stapler or slats, the latter of which are nailed. Both solutions are good, the main thing is to purchase galvanized fasteners, which will last a long time and will not cause rust spots.

Overlapping

After you have figured out which side to place Izospan on the insulation, you need to pay attention to one more point, which is the need to form an overlap of 20 cm wide between the sheets, which will prevent air from penetrating under the material. If fixation is carried out to vertical profiles, then the material should be tensioned to prevent it from sagging. A slight weakening is possible, but its fluctuations should not exceed 50 mm.

Specifications

Izospan vapor barrier is quite common today. Which side to lay it towards the insulation was mentioned above. However, you may also be interested in specifications, as well as purpose. For example, the areas of use in this case are as follows:

insulated sloping roofs;
internal walls;
frame walls;
basement floors.

The material is produced in widths that can be 1.4 or 1.6 m. The area of one roll is 35 or 70 m2. The composition contains 100% polypropylene, its breaking load (transverse and longitudinal) is 107 and 130 N/cm, respectively. Resistance to vapor permeation square meter is 7 Pa/mg. The water resistance of the material is 1000 mm water. Art. Within 4 months, the surface of “Izospan B” will be able to undergo impacts ultraviolet radiation. It can be operated in a temperature range from -60 to +80 °C.

Technology for performing vapor barrier work

If you also decide to use Izospan V, which side to lay it towards the insulation, you need to decide before starting work. This was discussed in more detail above. However, not only correct location material in relation to thermal insulation is a guarantee of a successful procedure. It is also important to follow all the rules of technology. Thus, it should be taken into account that the vapor barrier coating is laid according to the principle that is used when installing a waterproofing layer. The coating must be laid in its entirety, with a minimum number of gaps. In those places where the covering is adjacent to the wall, it is important to place it on a vertical surface by about 15 cm to prevent the thermal insulation from getting wet. The vapor barrier should also not be moistened during work.

Adjacent sheets should be laid overlapping, and it is important to prevent the formation of voids and holes. “Izospan B” is becoming more and more common today. It is important to understand for yourself which side to lay it towards the insulation. But it is also necessary to remember that in winter such work should be carried out in warm places. The surface where the vapor barrier will be installed must be prepared, cleaned of dirt, dried and heated. If the rolls were stored in the cold, then they must first be kept warm for at least a day. The material should not be transported from place to place in the cold.

Which side should Izospan A be placed on?

You may be interested in the question of which side to lay Izospan A to the insulation. This material is located on the outside of the wall or roof, after facing material walls or roofing. The rough surface should be adjacent to the thermal insulation, while the smooth surface should be on the side roofing material or external cladding walls.

Conclusion

Floors can be vapor-insulated using the Izospan material. Which side to lay the material towards the insulation in this case was mentioned above. Using this vapor barrier, you can carry out work inside and outside buildings, the main thing is to figure out which type of membrane to choose.

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