Vapor barrier in the attic which side to lay. Which side to lay the vapor barrier to the insulation? Arrangement of individual places

The vapor barrier is laid according to the manufacturer's instructions, where it is necessarily indicated which side it should lay. If there is no instruction, or if it does not contain recommendations for choosing sides, you can be guided by the general principles of laying.

Which side are placed different types of vapor barrier:

1. Glassine. As a vapor barrier, it is laid on the inside of the insulation, with a black (bitumen-coated) surface inside the room.
2. Single layer polyethylene films. They are attached from the inside to the insulation by any side, since they do not have additional properties, but only perform the function of a vapor barrier.
3. Polyethylene films reinforced with polymer mesh. They also do not have specific instructions for laying, it is convenient to lay them in the course of unwinding the roll.
4. Two-layer vapor barrier films (fluffy on one side and smooth on the other). You need to put them with the pile out, close to the insulation with the smooth side.
5. Foil vapor barrier. It is attached with a shiny side inside the room, as it is also a heat reflector.

Superdiffusion membranes should not be used as a vapor barrier - their function is to remove steam from the insulation, and not to prevent its penetration.

Which side to lay the vapor barrier on the floor

You can lay a two-layer vapor barrier on the floor with the fleecy side on the floor beams. This option is suitable for brick houses with wooden floors so that the beams can "breathe". If the film is fixed to the ceiling under the beams, the tree can “rot”, which will lead to the formation of mold.

Which side to lay on the roof

By laying a foil vapor barrier on the inside of the roof with the shiny side into the room, you can reduce the cost of heating the room. If you use glassine under the roof, you will have to lay it in several layers with the black side inward - because of its rather high vapor permeability.

Which side to lay on the walls

Reinforced polyethylene films are attached inside on the walls with either side to the insulation. They are preferable to ordinary polyethylene, as they are much stronger and, accordingly, they are easier to attach. Outside the walls, vapor barrier is not used; instead, vapor-permeable wind insulation (waterproofing) is used.

Until recently, glassine served as the only type of vapor barrier. Cut, attached, fixed - that's all! And only a few decades ago, a more convenient polyethylene film appeared, and more complex and reliable materials began to be made on its basis. Yes, modern options please not only with strength characteristics, but also with resistance to temperature and ultraviolet changes, and with their versatility. But, at the same time, they are upset by the more complicated instructions for their use: they should be connected along a clearly defined line, and only special tape should be used, and - most importantly! - the laying side must be chosen correctly.

Therefore, it is not surprising how often panic questions can be found on the Internet, such as how and which side to put the vapor barrier to the insulation, and what to do if the parties are still mixed up? Is it really necessary to disassemble the entire structure? We can assure you: you don't have to. And with the definition of which side is "correct", let's take a closer look - you will be very surprised!

What is the essence of roof vapor barrier?

Moisture protection of the insulation is one of the most important problems of thermal insulation, and we will now tell you why.

By itself, water is an excellent conductor of heat, because it is not without reason that it is used in heating and cooling systems. And, if the roof insulation is not sufficiently protected from the steam from the room, then this will not end well. Even in the warm season, you will not know about the problem, because. such steam will be easily vented due to heat and good ventilation. And in hot countries, where there is no sub-zero temperature, they don’t think about the vapor barrier of the insulation at all, because the problem is imperceptibly solved by itself. But in the Russian latitudes, due to the temperature difference in the cold season, the steam rises and penetrates the insulation, concentrating in the form of water when it meets the so-called "dew point".

At the same time, the top layer of insulation in the roofing cake freezes and creates one more condition for getting wet from the inside. The efficiency of the insulation itself is significantly reduced, and the changed structure contributes to the development of fungus and corrosion. Moreover, with a large amount of moisture, it can even seep back into the room and damage, thereby, the interior finish. This is exactly what a vapor barrier is for.

And in order to understand how to properly mount the vapor barrier, you first need to understand the design itself. So, the insulation is protected from two sides by completely different films that perform opposite tasks. From below, from the side of the living room, a vapor barrier is installed that will not allow steam to pass through, and from above - a vapor-permeable membrane, which, on the contrary, will release excess steam from the insulation, if it is “cotton-wool”, and protect it from roof leaks:

But where is the logic, you ask? How can steam get into the insulation if there is a vapor barrier in front of it? In fact, not a single film or membrane protects 100%, and there are still poorly glued joints and other construction errors. And therefore, some minimum amount of steam will still be in the heater, and it is important to competently bring the steam out without harm:

Look carefully at the diagram: do you see where the condensate appears in a well-equipped roof? That's right, not from the side of the room, but quite a bit from the side of the roof, on the other side of the insulation, and it is easily removed by a windproof anti-condensate film or membrane. But condensation should not appear on the vapor barrier, and none of its rough side can cope with it, because. it has a different structure, and we will prove it to you now.

Types of vapor barrier materials: A, B, C and D

To understand, after all, which side of the vapor barrier should be laid and why, for example, both sides of it suddenly turned out to be smooth, you must first determine its type. After all, not every species generally has two different sides!

Type A insulation: only for steam outlet on the other side

For example, type A cannot be used as a roof vapor barrier because in the end all the vapors will end up in the insulation. After all, the main task of such isolation is precisely to provide them with unhindered passage, but not to let rainwater through from the other side.

Such insulation is used in roofs with a slope angle of 35 °, so that water drops can easily roll off and evaporate (and the ventilation gap between such insulation and insulation helps them evaporate).

Vapor barrier B: classic double-sided installation

But B is a real vapor barrier material. Vapor barrier B has a two-layer structure, which avoids condensation, due to the fact that moisture is absorbed into its villi in the morning and ventilated during the day.

That is why type B vapor barrier is always placed with the smooth side towards the insulation (film side), and the rough side outward. Vapor barrier B is used only in insulated roofs, because for non-insulated, it has too little strength.

Type C membrane: for enhanced water vapor protection

Vapor barrier type C is a two-layer membrane of increased density. It differs significantly from type B in the thickness of the vapor barrier film layer. It is used in the same place as type B vapor barrier, but in itself is more durable.

Additionally, such a vapor barrier is used in non-insulated roofs to protect the wooden elements of the attic floor and in flat roofs to enhance the protection of thermal insulation. Vapor barrier C must also be laid with the rough side inside the room.

Polypropylene insulation D: for heavy loads

The newfangled type D vapor barrier is a particularly durable polypropylene fabric, in which one of the sides is a laminating coating. This can withstand significant mechanical stress. It is used not only to insulate the attic floor as a waterproofing layer, but in the insulated roof to protect it from leaks. Moreover, type D vapor barrier is indispensable for rooms with especially high humidity.

Here are the cases and where all these types of insulation are needed:

Does vapor permeability change when changing sides?

All of the above modern barriers are divided into the following types:

• for one-sided installation, which need to be rolled out only on a certain side, and it is recommended not to confuse them;
• and for double-sided use, usually with membranes that can be laid on either side.

You will be interested to know that for the first time membranes, which already had such properties as modern roofing, were used in astronautics! And from there they began to be used in construction and in many areas of the national economy. And until recently, there were not as many problems with their installation as they are today.

And now there is a strong opinion among the townsfolk: if you lay the vapor barrier to the roof insulation on the “wrong side”, then the whole structure will not last long. In fact, the right choice of side affects only the service life of the interior finish of the roofing cake, because the rough side has the same abilities as the smooth one and has exactly the same vapor permeability. But how much it retains droplets of condensate there is a little-studied question.

Let's deal with such concepts as condensate - this is important. There is a catch here: for some reason, most ordinary people are sure that if high-quality vapor barrier is used, then there will be no condensate at all. Or vice versa, it will quickly evaporate on its own. In fact, condensate is formed from the moisture that rises in the vapor state.

There is such a thing as a “temperature limit”, i.e. that specific condition under which the air temperature and humidity are sufficient for the vapor to come out in the form of droplets. For example, at a temperature of 15 ° C and an air humidity of about 65%, condensation will already begin to form. But if the air humidity reaches 80%, then the condensate will appear already at a temperature of 17 ° C.

In other words, the entire process of water vapor formation appears as a result of the so-called "partial pressure" difference. All the water vapor that is contained in the air is trying to go outside - to a colder street through the enclosing structures of the roof, but on its way they encounter a barrier in the form of a vapor barrier. If the air in the house warms up faster than the surface of the vapor barrier, then the moisture from the air will fall on it in the form of condensate. Here, the difference between an insulated roof and an uninsulated one is clearly visible: any vapor barrier that is laid on a heater will warm up much faster than something that is in direct contact with the cold elements of the roof.

If there is no vapor barrier layer at all, or it is not enough, then water vapor penetrates into the roofing pie and meets a “cold front” there, which turns steam into condensate, and under special circumstances also into ice. And it all happens inside the roof! This ice will not bother you until spring comes and the outside air warms up, thereby warming the roofing elements. Then the accumulated ice will melt and form whole smudges on the slopes inside the house.

But with a properly equipped roof, condensate should not appear at all, and therefore, in fact, the difference between a smooth and rough side is not significant, at least in this aspect.

What is the difference between an anti-condensation film and an "anti-condensation side"?

As we have already said, most modern manufacturers emphasize that their vapor barrier films have a so-called “anti-condensation side”:

The “anti-condensation” side differs from the usual “anti-condensation” side by the presence of a fleecy layer that absorbs a small amount of condensate and holds it until it evaporates.

Due to this, the risk of wetting the surface of the film is much lower, which prolongs the life of the interior finish of the roofing cake. That is why the rough side should always be directed inside the living room or attic, and the smooth side should be leaned against the insulation. But is it really so?

Practice shows that if condensation forms inside the roofing cake, then the fleecy side of the film cannot help in this regard, and there is not much difference whether these drops stick to the film or flow down. The fact that they exist at all is bad in itself. The anti-condensation side of the vapor barrier and the anti-condensation waterproofing film on the other side of the insulation are two completely different things!

Therefore, let's summarize: the "correct" side of the vapor barrier is not equivalent in terms of the properties of the anti-condensation film: it does not remove water vapor, does not destroy moisture drops and does not solve the problem with condensate.

But, if you are still in the process of building a roof, then for the sake of peace of mind, do as the manufacturer instructed in the attached instructions. If you have already laid the vapor barrier and doubt whether it is correct - forget it and do not worry anymore. But if you hope that the “correct” side of the vapor barrier will take on all the future shortcomings of the roofing pie, do not believe it.

Experienced roofers often state that they generally consider the epic about which side to attach the vapor barrier to, some kind of shamanism. Allegedly complicating the product, they increase its positioning in the market. But in fact, as we have already said, with a well-arranged vapor barrier, there should not be any droplets on the walls, otherwise even the lining on the walls will swell, and the wallpaper will fall off, since everything is so serious.

After all, this happens only with serious errors during the construction of the roof. In addition, if the vapor barrier itself will be between drywall and mineral wool, then there is no point in messing around with such a complex structure at all. By itself, drywall absorbs moisture well, and steam can hardly reach the internal vapor barrier. In this design, even a simple glassine is quite acceptable!

For example, some curious roofers even run their own vapor barrier tests to determine if the "wrong" side works or doesn't work:

And those who are especially quick-witted even say that with a rough side, polyethylene vapor barrier is obtained simply in the factory, when polyethylene is combined with non-woven material: the film is glued with a rough layer, and the finished product really has two different sides. And it makes no sense to modify the second side so that it also becomes smooth by connecting with another layer of polyethylene: the vapor barrier properties will not change, and the manufacturing process becomes more expensive.

And therefore it is easier to give this meaning to the product itself. And in fact, quite a lot of people have already become convinced that, even if they mix up the sides of the vapor barrier, nothing like this happens, and the film works the same way on both sides, fully fulfilling its functions.

Therefore, in any case, just strive to implement the roof protection from steam correctly, think through all the necessary details and not save on quality!

Vapor barrier is a layer that protects the insulation or building structures from the penetration of wet steam, which in turn leads to the accumulation of condensate on them, the loss of useful properties and rotting under the influence of moisture. To create a vapor barrier, completely impervious double-sided or having one regular working surface films and sheets can be used. It is extremely important to determine exactly which side to put the vapor barrier on the insulation, a mistake at this stage provokes an accelerated destruction of building materials and significant financial costs. The main guideline is the manufacturer's instructions, but often this document is not available when buying, the choice is made taking into account the type of vapor barrier film and installation conditions.

1. How is the vapor barrier installed?
2. Technology Violations
3. Tips & Tricks

For ordinary or double-sided reinforced polyethylene, this problem is not relevant; in other cases, the working surface is impervious to vapor. Most often, the vapor barrier is laid with a smooth side to the insulation, and protected - it turns to the source of steam penetration. Depending on the type of material, these are:

• Laminate on cardboard (do not recommend laying on critical objects).
• Reflective side of foil and aluminum roll coatings.
• Hairy or rough flatness in antioxidant films coated with viscose or cellulose.
• The vapor-tight side of the membranes is usually brighter.

1. Laying vapor barrier on the floor.

Protection from steam and moisture is required when insulating floors or horizontal planes, assembling structures from timber. Reflective films that return heat to the house are considered optimal for the floor. During the construction or repair of the first floors, the insulation is protected by a layer of waterproofing, and from above - by rolled vapor barrier materials, overlapped (from 10 cm and above) with gluing with metallized tape. The situation is slightly different when arranging attic floors and interfloor ceilings: the films are turned with the impermeable side down to protect against steam penetrating through the logs or slabs.

2. Vapor barrier of ceiling structures.

Most often, the need to close the ceiling occurs in baths, saunas, kitchens, showers and other facilities with high humidity. The larger the volume of vapors emitted and the higher their temperature, the more reliable the vapor barrier is required from them. To protect the ceilings of the steam room, dense aluminum, lavsan and antioxidant vapor barrier materials are well suited, for living rooms - the same, plus ordinary penofol. A prerequisite is an overlap of at least 10-15 cm and sealing of the joints; for reliability, the vapor barrier is fixed on the ceiling with a grate or brackets. In this case, the reflective or vapor-tight side is directed exclusively to the inside of the room.

3. Vertical structures.

Installation of a vapor barrier during wall insulation is necessary when: using fibrous and cotton wool insulation, erecting frame wall panels, arranging ventilated facades, in the latter case, in addition, it performs the functions of wind protection. In all the points mentioned, it is not recommended to choose completely impermeable films, the insulation must breathe, diffusion and superdiffusion membranes that allow air to pass through, but not moisture and steam are considered the best option. For outdoor work, the vapor barrier is laid with a smooth side to the mineral wool or other insulation on the walls, rough - towards the street. The film or webs should not sag, but excessive tension is also unacceptable. On internal vertical walls, they are held by staples or upholstery with thin strips, with the vapor-tight side towards the room.

4. Roof vapor barrier.

The vapor barrier is an obligatory layer when laying a roofing cake. It prevents the accumulation of condensate in the inner insulation layer and protects the rafters from fungus. The highest possible tightness is required from the vapor barrier, preference is given to antioxidant and reflective types, the vapor-tight side is directed into the attic. Overlap - from 15 cm, as well as gluing joints and seams. An important condition is the need to seal vapor barrier materials adjacent to vertical structures.

5. Other applications.

A vapor barrier is also needed when insulating basements and balconies (areas in contact with cold outdoor surfaces. For basement and underground areas, membrane films are considered the best, the walls and ceiling of the basement must breathe, the floors are insulated from the ground. For the installation of vapor barrier when insulating balconies and loggias, preference is given to foamed polyethylene with a reflective side directed into the apartment.This is almost the only case when materials are placed end-to-end, and not overlapping, but sealing adjacent areas is still required.

Possible mistakes

In addition to choosing the wrong side, technology violations include:

1. Lack of overlaps or insufficient insulation of joints.

2. Stretching thin films, especially on structures subject to temperature changes, this leads to their rupture. But excessive sagging is also not required.

3. Lack of ventilation gaps for evaporation of condensate from the vapor-tight side of the film (a vivid example of an error is the installation of the inner cladding directly on the bottom layer of the roofing pie).

Before laying the vapor barrier, it is necessary to calculate its required amount. The use of different types is undesirable, although there are no clear standards in this case. A common mistake is to buy rolls strictly according to the area of ​​​​working surfaces without a margin of 15% overlap and banal damage.

There is only one option when it is not necessary to put a vapor barrier - when building a house from a wooden beam, but this exception does not apply to absorbent insulation materials and floors, they always need to be protected. Works are carried out in a warm and, if possible, dry season, the films are protected in every possible way from getting wet. An important condition is the tight fit of the vapor barrier to the insulation (ventilation gaps remain on the outer, reflective and impenetrable side), voids and sagging are unacceptable. All surfaces must be clean, free of grease and dry.

In case of doubt about the correctness of the decision, which side the vapor barrier is laid to the insulation, you should read the instructions again. Reflective and rough planes are easily determined, with membranes it is more difficult. Generally, the side facing down when the roll is unrolled is considered to be the inside. Experts advise paying attention to coloring: lighter shades are observed at the sides adjacent to the insulation. But there is a variety in which the matte (most often fabric) surface is vapor-tight. If this is not enough to reveal the desired properties, then the canvas or film rolls a little on the floor, the tightly fitting side of the material will be the inside.

When building a country house or a private bath, an important step is the thermal insulation of various surfaces. In addition, the insulation itself needs high-quality and reliable vapor barrier protection. To prevent the negative impact of external factors and the formation of condensation on the thermal insulator, any homeowner should have a general idea of ​​\u200b\u200bhow to properly install the vapor barrier in order to ensure the long life of the entire building.

Membrane structure and principle of operation

The most popular in terms of their performance characteristics are breathable multilayer membranes, which are designed to create a reliable vapor barrier.

They consist of three layers, each of which performs an important function. The first layer prevents the penetration of steam into the insulation, the second provides the necessary strength of the base, the third protects against moisture from the outside.

Each individual layer has the necessary perforation for good air exchange. The first layer removes excess moisture, allowing the penetration of dried air. The reinforcing layer keeps warm air masses inside thanks to a special weaving of threads. The third layer provides a sufficient level of traction within the structure.

Some types of membranes have an additional anti-condensation layer on a viscose or cellulose basis. It retains excess moisture deposited on the paper fibers. For the natural removal of moisture from the membrane, a technological gap of 2.5 cm is provided between the vapor barrier and the surface finish.

Features of the installation of vapor barrier

An important stage in the protection of insulating materials is the laying of a reliable vapor barrier layer. All work is carried out in the process of repairing or reconstructing a finished building or during the construction of a new building. In order to correctly install the vapor barrier, it is necessary to understand how to connect the membrane sheets and which side to fix them to the insulating base.

Preparatory work

At this stage, work is underway to select the appropriate type of vapor barrier, taking into account the features of the installation process, performance characteristics and material requirements.

Before laying the vapor barrier, careful surface preparation will be required. Here it is important to consider the type of material used in the construction of floors, walls, ceilings and roof structures.

1. During the construction of a log house, all structural elements are treated with protective antiseptics and flame retardants.
2. When carrying out repair and reconstruction work, a complete dismantling of the finishing, cleaning and preparation of surfaces is carried out:

Wooden elements are treated with compositions against aging, rotting and burning. Concrete, block and brick surfaces are treated with deep penetration antiseptic compounds.

Proper surface preparation will ensure a long service life of the insulation material and the entire structure.

Technology for laying vapor barrier on the ceiling

If the roof structure and interfloor flooring are made of wood, then the installation of the waterproofing membrane is carried out on a prepared base.

A roll or block insulation is mounted in the space between the rafters and lags, the best option is mineral or basalt wool. Next, you can lay the vapor barrier on the ceiling surface.

When the thickness of the insulation is equal to the height of the log, an additional lath counter-lattice is installed to maintain natural ventilation.

It is necessary to mount the vapor barrier on the ceiling with a slight overlap on the walls along the perimeter, with special attention to be paid to the corners. Joints are best placed on logs and glued on both sides with tape on a reinforced basis.

Important! When installing a vapor barrier, sagging and deformation of the sheets should be avoided.

For thermal insulation of a flat roof or concrete ceiling, a waterproofing film is mounted on a self-adhesive tape from the inside, then a crate made of wood or metal is installed.

The height of the crate is determined based on the thickness of the heat-insulating material and the minimum technological gap for ventilation. The installation step is 3 cm narrower than the width of the heat insulator, which makes it possible to ensure high-quality laying of the insulator in the prepared cells of the crate.

Technology of laying vapor barrier on the floor

The scheme of installation of vapor barrier protection on the floor is similar to how the material is laid on wall and ceiling surfaces.

The wooden floor is insulated along the logs, which are covered with hydroprotection. Further, a heater is laid in the space between them - cotton wool on a mineral or basalt basis. After that, the vapor barrier material is laid.

The roll material must be laid with an overlap of 12 cm with careful gluing of the joints with metallized tape on both sides. A properly installed vapor barrier should completely cover the floor surface with an overlap of up to 10 cm on the walls.

To equip the vapor barrier protection on a concrete base, it will be necessary to install a crate, in the cells of which a waterproofing layer and a heat insulator will be laid.

Choosing a side for installing a vapor barrier

After the material for the vapor barrier has been selected, an important question should be considered - which side to attach the vapor barrier to the insulation. Such materials can be fixed as follows:

• Polyethylene films (reinforced and plain) are laid on either side, which does not impair the protective properties of the material.
• Foil films are installed with the reflective side inside the room to effectively reflect heat.
• Anti-condensation films are mounted with a fabric surface inside the room, processed - to a heat-insulating base.
• Membranes of any type are attached with a smooth surface to the heat insulator, and with a rough surface - inside the room.
• Foam-based insulators are laid similarly to membrane materials.

Important! Before laying the vapor barrier to the insulation, it is recommended to spread the prepared material on a flat surface to correctly determine the inside and outside.

Face or underside of the vapor barrier?

If a breathable membrane is used to create a protective barrier, the main thing is to determine which side to put the vapor barrier on - the front or the wrong side.

The vapor barrier cake must be laid so that the protection is directed to the heat insulator on both sides with a smooth wrong side, and with a rough front side - inside the room.

The rough surface provides protection against moisture penetration to the insulation, and the smooth surface contributes to maximum heat accumulation.

Determining the width of the lap when installing the membrane

Along the edge of the insulating membrane there is a special marking for determining the width of the overlap of the sheets, which ranges from 8 to 20 cm.

The vapor barrier strips on the roof should be laid in a horizontal plane from bottom to top overlapping each other 15 cm wide. In the ridge, the overlap is 18 cm, in the valley - 25 cm.

On walls, ceilings and floors, the canvases are mounted with an overlap of 10-15 cm.

Is ventilation required?

At the bottom of the membrane vapor barrier there is a 5 cm ventilation gap, which helps prevent condensation on surfaces and the heat insulator.

Diffusion membranes can be attached to insulation, plywood sheets or OSB. In a membrane with an anti-condensation layer, gaps up to 6 cm wide are located on both sides.

To create a gap for ventilation when insulating the roof structure, a counter-lattice is used. In the process of fastening a ventilated facade, a technological gap is created during the installation of racks located perpendicular to the vapor barrier.

Elements for fixing the vapor barrier

To securely fasten a membrane or film vapor barrier, wide-head nails or metal construction staples are used. The most practical fastener option is counter rails.

To increase the tightness of the structure, individual elements of the vapor barrier are additionally glued with double-sided adhesive tape or wide metallized tape.

To ensure the long service life of modern heaters, high-quality vapor barrier protection is required. Otherwise, it will be difficult to obtain the optimal ratio of temperature and humidity indicators in the premises. The main thing in this matter is to choose the right material and know how and which side to lay to the heat insulator.

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

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

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

Paint vapor barrier is applied with brushes and rollers in places where rolled vapor barrier is difficult to apply, such as ventilation and chimneys. This family of vapor barriers is represented by materials such as bitumen, tar and tar.

Vapor barrier membranes

First of all, we will determine 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 moisture from the inside, it is necessary to additionally lay a layer of vapor barrier. When insulating the roof, floor or interior 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).

In cases where external wall protection is carried out, then the corresponding components should not have perforations or pores.

Always pay attention to the value of the vapor permeability coefficient, the smaller it is, the better for you. An excellent option is the usual plastic film. The ideal choice would be a material with additional reinforcement. The presence of a foil-coated aluminum 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 it, moisture accumulation does not occur. As a rule, they are attached under components that are sensitive to rust formation. We are talking about metal tiles, corrugated board, galvanization, etc. The rough fabric layer on the underside of the film guarantees effective moisture removal. It is laid with the treated side to the insulation, and the fabric side out, so that a distance of 20-60 mm remains to the mineral wool.

https://youtu.be/xTWpLwH8-QI

Video #1. IZOSPAN vapor barrier laying technology

When insulating the walls of the house from the outside, a building membrane is used that is capable of evaporating and protecting the material from strong wind gusts. In addition, it is suitable for protecting pitched roofs, facades with a non-hermetic 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 process is better, the more actively the evaporation takes place. This will allow the insulation to dry quickly and efficiently.

There are the following types of vapor-permeable films:

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

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

Super diffusion membrane IZODACH 115

The two remaining types of membranes have large pores, which eliminates the possibility of their blockage, which is why there is no need to leave an air ventilation layer in the lower part. As a result, it is not necessary to mount the crate and counter-rails.

Bulk diffusion films are commercially available. A ventilation layer is already provided inside the membranes, due to which moisture cannot reach the metal surfaces. The specifics of the film device are similar to the antioxidant version. The difference lies only in the removal of moisture from the insulation. This is beneficial, because when the roof is tilted, even at a small angle of 3-15 degrees, the possibility of condensate draining through the bottom is excluded. Therefore, corrosion of the galvanized coating will gradually occur, followed by its final destruction.

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 laid from the front of the wall, then the vapor barrier film is fixed from the outside, this will be a waterproofing.
• The processing of the ceiling and roof requires the use of an antioxidant vapor barrier. Bulk 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, the vapor barrier film is attached to the underside of the rafters.
• Thermal insulation of the upper part of the ceiling of rooms, the ceiling located under the attic space, requires the installation of a vapor barrier membrane on the underside of the insulation.
• When performing thermal insulation of 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 do not even have a clue how the vapor barrier membrane should be attached to the walls: front or wrong side.

The best solution would be to use a material with the same wrong side and front side.

And 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 a fabric surface, which is located during laying in the inside of the room.

Determination of the laying side of the vapor barrier

A metal plane circulates in the same direction foil membrane- shiny side inside the room.

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

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

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

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

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

Do you need an air gap at the membrane?

You should always leave it. A special gap up to 50 mm wide is arranged on the underside of the films. This will avoid the appearance of condensation on the walls, floor and insulation. It is important to avoid contact between the facing surfaces and the membrane. Using diffusion film for floors, walls or ceilings, you save yourself from many problems, since it can be fixed directly on a heat insulator, 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.

Arrangement of a ventilation gap when laying a vapor barrier

If everything is clear with the walls and floor, then with the roof and ceiling the situation is kept apart. When making a ventilation gap, additional installation of a counter-lattice based on wooden bars will be required. When organizing a ventilated facade, a gap is left when erecting horizontal profiles and racks located perpendicular to the wall and the film.

Video #2. Vapor barrier laying technology ONDUTIS

How is the vapor barrier attached?

Fixing the membrane to the walls, floor or ceiling can be done with wide-head nails or a construction stapler. However, the best choice would be the use of counter rails.

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

Conclusion

In conclusion, we say that the membranes will allow any building structure to last 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 laying vapor barrier. Most manufacturers also distribute installation instructions along with the product. This is especially true for diffusion and superdiffusion membranes. Therefore, do not be too lazy to clarify with the sales assistant all the questions you are interested in before purchasing.

Insulation is a very important stage in the construction or repair of a house, which determines whether you will be comfortable in it. Improper implementation of this "procedure" can lead to unpleasant consequences, for example, condensation, increased humidity in the air. But this will not happen if you take care of the vapor barrier and lay it with the right side to the insulation.

Peculiarities

During the insulation of the house, you should carefully follow the correct sequence of actions and use only the best materials. Unfortunately, often the owners, who undertake to insulate their homes on their own, forget about one very important aspect - the vapor barrier. They install only a heater and do not even think that it is in contact with too warm or too cold air inside the room, and that soon condensation will form on it in the form of water droplets.

And this not only does not contribute to insulation, but also spoils the material itself - it moisturizes it, and if the steam still does not have time to evaporate, mold appears, and the design of the insulation 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 temperature in the room and outside it “conflict”, and it is the heater that becomes the battlefield.

That is why an important stage of insulation is the fastening of the "vapor barrier". The vapor barrier becomes an impenetrable obstacle for steam, prevents it from turning into water, as it "closes" it inside the room and does not allow it to come 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 deaf vapor barrier that does not allow water vapor to pass through. One of the main advantages is the low price. As a rule, it is made from polyethylene or butylene, their derivatives. Steam 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 deaf 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 the film is that the membrane passes part of the steam through itself - but only that optimal amount of it that does not linger inside and instantly evaporates. Therefore, the vapor permeability of membranes is usually referred to as limited. The diffusion membrane is made of a polymer film and polypropylene and has two sides.
• Reflective or energy saving film. The outer layer of such a film is metallized, which allows it to withstand high temperatures. Therefore, most often it is used in baths or saunas, reflecting part of the infrared radiation.

As you know, for the insulation of houses in modern conditions, materials such as mineral wool, expanded polystyrene, ecowool are used. 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 thermal conductivity is low, which reduces the likelihood of heat loss in the room. Mineral wool is not liked by rodents, mold, fungus, it has high sound insulation and is easy to install. But it still requires a vapor barrier for itself.

The most commonly used vapor-permeable limited diffusion membrane. It fits to the walls, after it 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 the house is insulated with ecowool. In general, ecowool is loose cellulose fibers that have the ability to absorb warm moisture and at the same time remain dry. It does not start fungus, mold, 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 just in the case of ecowool, the vapor barrier can not be fixed.

Another popular insulation - polystyrene foam actually has another more easily called polystyrene. It lies both on external surfaces and on internal ones, and in the case of external insulation of loggias, balconies or attic floors, it does not require vapor barrier - he himself copes well with this when the insulation technology is maintained. But if you insulate the interior with foam, vapor barrier and waterproofing are required to prevent the formation of fungus, mold and wetting the walls.

Device

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

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 the material of the insulation and vapor barrier are revealed.

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

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

Vapor barrier on the ceiling

In the case of roof structures and interfloor floors, the installation of a vapor barrier is supposed to be on an already prepared and properly processed surface. It is best to use a diffusion membrane here.

The main difference between laying 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. It can be mineral or basalt wool in blocks or rolls. It is mounted between the lags and rafters. If the thickness of the insulation is equal to the height of the log, you will additionally need to perform a rack counter-lattice so that the ceiling is ventilated. After all this, you can do the vapor barrier.

It should fall a little on the walls around the perimeter, the joints should be fastened on the logs - 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 glue them additionally. Use reinforced tape or a construction stapler as a fixative.

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

Vapor barrier on the floor

In the case of laying a vapor barrier on a wooden floor, additional waterproofing should be installed. The floor is also insulated along the lags. Mineral wool or cotton wool on a basalt basis is installed in the space between the lags. Further, without any additional work, a vapor barrier flooring is performed.

If we are talking about a rolled vapor barrier, but it is overlapped by 12-15 cm with the most thorough gluing of joints, gaps and cracks on both sides with metallized tape. As in the case of ceiling insulation, the overlap on the walls should be within 10 cm.

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

Vapor barrier on walls

The process of wall insulation and vapor barrier is a little more complicated than doing the same work on the ceiling or floor and implies a slightly larger number of stages. Consider the process of laying a vapor barrier film on the walls.

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

At this stage, special attention should be paid to possible gaps arising from 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 an overlap of 15 cm.

Installation subtleties

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

Which side to install the vapor barrier?

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

For example, antioxidant films have a fabric underside, and according to the installation requirements, it should look inside the room. Steam condensate films should be laid with a smooth side to the insulation, rough - out. But with diffusion films, you should look directly at the instructions, since such films can be either one-sided or two-sided. Energy-saving films are laid with the foil side, on the contrary, outward - after all, they should reflect, 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 master about this. However, if none of the above suits you, you will have to learn how 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 to the insulation.

But also pay attention to how the vapor barrier roll rolls out - the side that faces the floor will be the inside, and it should be placed against the insulation. In the case of a vapor barrier with different surfaces, a smooth layer will always be internal, and a fleecy or rough layer will always be external.

What fastener should be used?

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

Is an air gap necessary near the membrane?

It is believed that this is a mandatory moment - it is absolutely impossible for the wall to come into close contact with the membrane, you should leave a gap for ventilation of about five centimeters. Condensate will not accumulate in this way. In the case of a diffusion vapor barrier, the air gap is made on the outside, and the film itself is laid directly on the insulation.

Do joints need to be glued?

This is also mandatory - the individual parts of the vapor barriers should be hermetically attached to each other without the formation of 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 fasten the membranes together, but are also used in their repair - they can close up holes and cracks.

In no case do not use adhesive tape for this, it is better to contact a sales assistant in a building materials store 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 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 for the humidity not to increase and the microclimate not to be disturbed, it is necessary to carry out natural or forced ventilation in time.

If you are interested in the question of how to overlap if parts of the membrane overlap each other, then we advise you to pay attention to the films themselves. There are markings along their edge - it tells you exactly how the overlap of the films should be. Depending on the type and company, the value indicated there is not less than 10 cm and not 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.

About the installation of the roof vapor barrier and which side to lay the vapor barrier to 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 what side to put it to the heater? These and other questions regarding vapor barrier and its installation are answered by our experts in this article.

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

Experts identify several main functions of a vapor barrier:

• increase the service life of thermal insulation materials;
• protection of the room from excessive humidity.

Vapor barrier must be installed in such premises as:

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

1. Which are the best to use? The use of a certain type of vapor barrier material depends on the intended purpose of the vapor barrier - inside the room or from its outside. Therefore, experts call the following main types of materials with which to mount the vapor barrier:

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

1. Which side should the vapor barrier be placed 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 be turned inside the room itself.

In the case where the vapor barrier material is equipped with an aluminum layer, laying 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 inside the room.

But these features of the materials are taken into account in the presence of a layer of insulation, already mounted earlier 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 turned to the wall;
• the rough side guides the material to the street.

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

1. Are there any rules for laying vapor barrier? Experts say that such rules really exist. There are several of them:

• a 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 on the vapor barrier material in principle. Since any crack, tear or hole can cause moisture condensation, which will constantly accumulate on the interior finish of the surfaces of the room (especially the ceiling).

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

• different coloring of the sides (the light side is laid to the insulation);
• texture (laying depends on the characteristics of the material itself, as discussed in this article above);
• free rolling of the roll (the side that the material faces the floor is usually considered internal and is laid against the insulation);
• the smooth layer is usually considered the inner layer, and the fleecy outer layer.

When installing a vapor barrier, the main thing is to correctly lay it to the insulation (if any). This will help to maintain its thermal insulation properties and extend the service life. If the vapor barrier is not equipped, then the insulation materials, due to the constant exposure to moisture, will gradually become unusable, which will lead to the rapid wear 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 for their heating or heating will be required.

Which side to put the vapor barrier to the insulation?

Which side to put the vapor barrier to the insulation? Almost every living space needs a vapor barrier. What it is? What type of material is best for vapor barrier

Which side to put the vapor barrier to the insulation

When insulating a roof or a room with a heat insulator (mineral wool, glass wool, loose foam plastic), capable of passing and accumulating moisture, it is necessary to install a vapor barrier layer. Moisture that has entered the thermal insulation noticeably worsens its operational properties, increasing thermal conductivity. In addition, due to the humid environment, the wooden structures with which the insulation is in contact quickly begin to rot and collapse. At the stage of preparing for the insulation of a roof or house, it is important to figure out which side to lay the vapor barrier to the insulation - a violation of the technology will lead to the fact that steam from the room will penetrate into the heat-insulating layer.

What steam protection is needed

Varieties of vapor barrier materials

The primary issue is the choice of material that will protect the insulation from moisture. The classic roofing felt and glassine, which were used for waterproofing, gave way to modern polymer films with different operational parameters. The membranes used in construction are divided by vapor permeability into completely impermeable films and partially permeable (diffusion) ones.

Manufacturers offer vapor barrier membranes of the following types:

• polyethylene film (can be used to insulate the roof or floor, the barrier is vapor and hydro-tight);
• reinforced film made of polyethylene (characterized by increased strength);
• aluminum foil film (used for internal insulation, mounted with a reflective side to the room - additionally helps to retain heat, primarily designed for use in saunas and baths);
• a film with an anti-condensation coating (prevents moisture condensation, is intended for installation as part of structures with metal elements prone to corrosion - corrugated board, metal tiles, etc., the film is mounted with the treated side to the heat insulator).

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

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

1. Pseudo-diffusion. During the day, up to 300 g / m 2 of evaporation is passed.
2. Diffusion. The amount of vapors passed per day is from 300 to 1000 g/m 2 .
3. Superdiffusion. The evaporation rate exceeds 1000 g/m 2 .

The vapor barrier film of the first type is classified as an effective protection against moisture and is used for internal insulation of structures (from the side of the room). If a pseudo-diffusion membrane is mounted over a fibrous heat insulator on an outer wall, the vapor barrier will retain moisture in the insulation. Diffusion and superdiffusion membranes are suitable for facade insulation, which at the same time serve as a wind barrier.

Super diffusion membrane

Principles of installing a vapor barrier

Laying a vapor barrier is an important stage in the insulation of structures with fibrous materials that can accumulate moisture. The work is carried out as part of the repair or reconstruction of the house or at the stage of preparation for finishing a new building. It is necessary to know how to properly fasten the membrane sheets to each other in order to provide a continuous layer that protects against moisture penetration, 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 to the insulating material.

Preparatory stage

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

At the preparatory stage, you should choose a vapor barrier option, taking into account the installation features and the requirements for film characteristics. 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 the material depending on the purpose - vapor barrier for roofs, ceilings, wall structures made of wood or concrete.

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

Correctly fasten the reflective vapor barrier

Before laying the vapor barrier, it is necessary to correctly 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 work is being carried out at the facility - construction or repair:

1. When building a wooden house, all elements of the wood structure must be treated with compounds against decay, damage by pests and fire.
2. During the repair work, the finishes are preliminarily dismantled, the surfaces are cleaned, while:
   • wooden structures are treated with an antiseptic and flame 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 wall structures, ceilings or rafter systems, they can eventually become unusable or become a source of fungal spores that can provoke allergies, an asthma attack, and exacerbation of respiratory diseases.

How to install vapor barrier on the ceiling

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

The canvas of the film or pseudo-diffusion membrane must be solid so that there are no joints through which moisture can penetrate into the insulation. If the width of the roll material is 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 glued with reinforced construction tape.

Fastening the vapor barrier membrane Sheets of foil film are laid without overlap - end-to-end, and the seam is glued with aluminum tape.

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

Then, in the gaps 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 that, you can lay the vapor barrier on the ceiling. If the thickness of the heat insulator corresponds to the thickness of the log, a counter-lattice of rails should be nailed to create a ventilation gap.

Lay the vapor barrier on the ceiling in such a way that the canvas along the entire perimeter goes onto the walls, and that all corners are closed. The joints of the canvases should fall on the overlap logs - this will allow them to be securely fixed. In order to qualitatively lay the vapor barrier on the ceiling, follow the tension of the canvas, it should not sag.

Ceiling installation

We will also consider how to lay a vapor barrier on a concrete floor. In order to insulate a ceiling or a flat roof made of a concrete slab from the inside, it is required to attach a waterproofing coating (vapor barrier film) to it with a self-adhesive tape, and then mount a crate of bars or a metal profile.

The correct height of the crate should be selected taking into account the thickness of the insulation and the ventilation gap, the installation step is 1-2 cm less than the width of the insulation, so that the mats of insulation materials fit into the cells by surprise. How to fix the vapor barrier to the crate will be described in detail below.

How to install vapor barrier on the floor

The installation of a vapor barrier membrane on the floor is similar in technology to how vapor barrier is performed for walls and ceilings. After preparing the base of the wooden floor for insulation along the logs, before laying the vapor barrier on the floor, a waterproofing carpet is installed, which should go around the logs. Then a mineral wool heat insulator is inserted between the lags. After that, the vapor barrier is laid, and it is important to know how to properly lay the film.

The overlap of the sheets of rolled material should be at least 10 cm, while on each side the joint is glued with adhesive tape. The resulting canvas is fixed in such a way that the overlaps lie on the floor logs, and along the entire perimeter the evenly stretched canvas goes onto the walls by 5-10 cm.

Insulated floor with air gap

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

Fastening principles

If concrete structures or wooden walls are insulated, it is necessary to install a crate of bars. It is convenient to attach the film to the resulting crate, to the ceiling or truss system using brackets and a construction stapler. It is also possible to fix the vapor barrier material with nails with wide heads or linings under the hats. 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 during installation of vapor barrier

In order to properly fix the vapor barrier, the canvas should be carefully stretched, and the fasteners should be placed in small increments - no more than 30 cm. The installation rules prescribe to carefully consider the fastening of the canvas around the perimeter - it spreads and is fixed so as to exclude the possibility of moisture penetration into the insulation.

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

Which side to mount the vapor barrier material

Consider which side the film or membrane is laid to the insulation:

• polyethylene film (plain 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 towards the room so that the barrier reflects heat;
• the anti-condensate film is fixed with the treated side to the structures, the fabric side to the room;
• the membrane should be turned with a smooth side towards the heat-insulating material, and a rough side towards the room.

The rule of laying the vapor barrier to the insulation If the front side of the membrane looks similar to the wrong side, and it is difficult to determine how to properly lay the material, you can conduct an experiment. A small piece of the membrane covers a bowl of boiling water - which side condensate appears on, that side is waterproof, it should be facing the heater.

It is important to know which side to put the vapor barrier to the insulation, if the membrane is used to install a waterproofing barrier - front or back. The heat-insulating "pie" with internal insulation 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 turned towards the room, and when installing a waterproofing carpet - towards the structure that is being insulated.

Mounting Features

It is important not only to properly lay the vapor barrier, but also to provide a ventilation gap between the vapor barrier layer and the sheathing of the structure for finishing, for which counter rails are stuffed along the crate. 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 flaws in the installation of the vapor barrier.

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

Which side is correct to put the heat-insulating material to the insulation. Varieties of vapor barrier films with stages of work on mounting on the roof, ceiling and floor.

Which side to lay the vapor barrier to the insulation. Types of vapor barrier materials. Vapor barrier installation

Very often there is a need for thermal insulation of premises from the inside. If you plan to do the work yourself, many questions immediately arise about how to do it right. And one of them concerns the need to use vapor barrier films and their place in the heat-insulating "pie".

We will answer right away: vapor barrier is necessary in case of using any moisture-absorbing types of insulation. Read on for more details.

Why 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 vaporous state to 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 in the room and outside 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 go outside through any obstacles.

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

The device of heat and vapor barrier of walls

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

As a result, the thermal insulation properties of the material are reduced, 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 the 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 being cooled and remaining in a gaseous state.

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

It does not matter what you insulate: 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 can even harm the microclimate in the room.

Types of vapor barrier materials

• Film

Isolon insulation is a multifunctional material).

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

Vapor barrier device rules

It would seem that nothing complicated: fix the film on top of the insulation and the vapor barrier is ready (See also the article Insulation Shelter - the technology of the new time). However, there are some nuances in this matter that you need to be aware of.

Types of vapor barrier materials

Among the materials for vapor barrier presented on the construction market, three main types can be distinguished:

• Film. It belongs to the type of deaf vapor barriers, which absolutely do not let water vapor contained in the air pass through them. Its main advantage is its low price.

In addition to the usual polyethylene film, special, vapor condensate films are also produced. They are two-layer, with a smooth inside and a rough outside. Droplets of condensate are held by the rough surface and evaporate instead of dripping down.

Vapor barrier membrane

• Reflective (energy saving) film. It has a metallized outer layer that is resistant to high temperatures and reflects most of the infrared radiation.

This material is most often used in baths and saunas.

Vapor barrier installation

From all of the above, we can conclude that the vapor barrier material is attached over the insulation from the side of the room. But it is very important to take into account two more points: which side 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 do not differ from each other.
• The vapor condensate film is laid with a smooth inner side on the insulation, and the fleecy side looks out.
• In the same way - with the smooth side to the insulation - diffusion membranes are also mounted.
• Energy-saving vapor barrier materials are attached with the foil side outward, since it is this side that reflects the heat penetrating to it back.

Note! It should be remembered that the installation of deaf vapor-tight materials requires a ventilated gap.

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

Loggia insulation using a vapor barrier membrane - a ventilated gap is not required

Which side to lay the vapor barrier to the insulation: do-it-yourself video installation instructions, photo and price

Which side to lay the vapor barrier to the insulation: do-it-yourself video installation instructions, photo and price

Which side should the vapor barrier be laid to the insulation

In the process of thermal insulation of buildings, it is necessary not only to lay insulation, but to create a whole “pie” consisting of layers that perform various functions. To protect the insulation materials and the structure itself from the penetration of steam and condensation, a film or a special membrane is used. For it to work, it is important to know which side to properly lay the insulation to the insulation used. Incorrect installation will nullify all efforts for thermal insulation, allowing the insulation to get wet. In addition, moisture will adversely affect the material of the structural elements of the building.

The purpose of the vapor barrier

Steam and condensate have a significant impact on the condition of the structural elements of the roof, walls, floor. Excess moisture promotes the growth of fungus and mold, causes corrosion of metal 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 enter the “pie”, but does not prevent it from escaping to the outside.

The appearance of condensate provokes a temperature difference in a heated room and on a cold street. The steam tending to leave the building cools and turns into water droplets. The vapor barrier film, installed on the correct side, prevents moisture from getting to the insulation. The condensate flows down on the surface of the canvas, without falling 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 to the insulation. These versatile films are especially suitable for beginner builders.

Types of vapor barrier materials

A wide range of vapor barrier materials allows you to choose a canvas for any part of the building. As a special protection are used:

Rules for installing a vapor barrier film

To determine which side you need to turn the canvas to 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 snug fit, and the fleecy side serves to trap steam. Manufacturers of diffuse membranes always give detailed instructions for their use, and the outer part is painted in a brighter color.

The release of vapor barrier products in rolls facilitates installation and allows it to be completed in a short time. The standard width of the paintings 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 undercuts. The fastening method is selected depending on the material used, it is better to fix the plastic film with wooden planks into which the staples are hammered. This will eliminate the possibility of damage to the polyethylene.

It is convenient to use a stapler to fasten the vapor barrier web

Installation of paintings on the walls is always carried out from the bottom up. In difficult places - corners, ledges, slopes, the tightness of the fit of the material is ensured by gluing with adhesive tape. To work, you 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 is one of the most vulnerable places in the room. An effective option to protect it is a special membrane. These canvases are offered in two types:

• one-sided - for operation it is not required to choose how to properly install the insulation in relation to the insulation;
• double-sided - the membrane must be mounted on 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 the height of the ceilings will change slightly. The membranes are strong enough; for their fastening, you need to use small nails or staples of a construction stapler.

Vapor barrier must be installed after laying the insulation. The canvas should not be stretched too much, because during operation it shrinks and stretches with temperature changes. Excessive tension can lead to rupture, this is especially true for products installed in an unheated room. Large sagging is also not needed, 1-2 cm is enough. When spreading the material, part of it is brought onto the walls in order to dock 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 become a good waterproofing. 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 the norm, it is worth using an adhesive-based film. This will greatly facilitate installation, increase the tightness of complex joints. For reinforced concrete roof slabs, liquid bituminous 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 regimes, the presence of precipitation, wind load. We will figure out how to lay vapor barrier for facades. The panel fits snugly against the insulation (if necessary, on both sides), a gap is left between it and the cladding for ventilation. The material must be carefully fixed so that it is not blown away by the wind. A membrane is usually used, in which it does not matter which side it is laid on the insulation. Horizontal and vertical strips overlap each other by at least 10 cm, this will ensure the tightness of the joints. The bonding of the parts with butyl rubber tape provides a high bonding strength. Condensate flowing down the vapor barrier film is drained through the drain holes in the lower part of the wall.

Installing a film on an insulated floor

During the vapor barrier of the floor insulation placed between the logs, the strips of material are stretched across the wooden logs. Fastening is carried out with brackets. Places of adjunction to 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 the installation of reflective vapor barrier

Cloths with a layer of aluminum foil are necessary in rooms that require maximum heat retention. When they are installed, the reflective layer is always directed into the room. A gap is left between the insulation and the finish, it will enhance the effect of the foil and prevent damage to the lining by the resulting condensate. Neighboring canvases are installed end-to-end and glued with a special metallized adhesive tape. If the tightness of the surface of the product is broken during fastening, then the hole is sealed with adhesive tape.

Which side to the insulation to lay the vapor barrier

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

Types of vapor barrier used to protect the walls of the house from moisture. Why is this needed? Proper laying and fixation of the material. Tips, features when installing a vapor barrier with your own hands.

Wall vapor barrier

Vapor barrier of walls during the construction and decoration of the house is one of the first tasks. Fencing from moisture will protect the building from destruction, bring warmth and comfort to the house. As well as protection against fungus, which negatively affects the health of all households.

Vapor barrier is carried out using various materials both outside and inside the room. The installation technology requires compliance with the phased work, as well as the implementation of the rules on which the quality of the work performed depends.

Why you need to install a vapor barrier inside and outside the house

When decorating the walls of a house inside and out, heaters are often used that absorb moisture like breathable materials. As a result, a condensate collection point appears. This leads to the destruction of the insulation, the appearance of fungus, deformation and damage to finishing materials (detachment of wallpaper, falling off tiles, deformation of drywall sheets).

To create the desired microclimate in the room, a vapor barrier is used that can not let moisture through to the insulation. At the same time, many of these composites are breathable, which is necessary for both walls and finishing materials. This feature allows you to make ventilation, which is necessary for all elements on the walls.

Cases when vapor barrier is required:

1. When the walls inside the room are insulated with mineral wool. It is breathable and breaks down when wet.
2. Walls sheathed with plasterboard and other cladding. Basically, condensation is created between the draft wall and the cladding, which negatively affects the finish.
3. Outside, a vapor barrier layer is mounted to protect the walls from external influences of moisture. This is done when insulating the facade of the building.

To create the necessary climate in a room with a vapor barrier, a ventilation system is necessary.

Types of vapor barrier material: which is better

The construction market is full of types of vapor barrier. It can be both liquid and in rolls. Each material has its purpose, composition. Some are used for walls outside the house, others only indoors.

Mastic

Mastic has a bitumen-polymer base. It is applied to the surface, creating a layer that protects against moisture and allows the rough base to “breathe”. Mastic is applied to clean, dry walls from various components (wood, brick, concrete) with a brush in 2 layers. The second time the bitumen is applied to the dried first layer. The advantage is that the mixture is already sold ready-made and does not require additional preparatory work for cutting or cooking. Service life of mastic is more than 25 years.

membranes

Membrane materials have a large selection in the construction market. They have the following properties:

• laying on the outside of the insulation. The membrane protects the outer wall from precipitation, winds. Install siding, lining from above;

The membrane should fit snugly against the insulation and be firmly fixed. Because it can break due to strong winds.

• for vapor barrier for walls inside the house, "Megaizol V" is used - a polypropylene film in 2 layers with an "anti-condensate" surface. The film protects the walls from the appearance of a dew collection point, which leads to the development of fungus, dampness;
• Izospan FD, FS, FX - reflective surfaces used in bathrooms, baths, saunas.

With a wide choice of membranes, you need to pay attention to what purpose they are intended for - for the street, baths or vapor barrier inside the house.

Vapor barrier film

For vapor barrier, a film with a thickness of less than 0.1 mm is used. It is the most widely used of all. Has no perforation, does not let air through. However, a breathable film has recently been produced.

The vapor barrier film is applicable due to solutions to such problems:

1. There is microventilation of walls and insulation.
2. Partially, condensate is removed, which is collected when the temperature outside changes.
3. In saunas and baths, where there is high humidity and high temperatures that other vapor barriers cannot withstand.

The vapor barrier film does not allow small drops of water to pass through, at the same time it “breathes”, which allows solving problems.

Liquid rubber

This material is sold in the form of a bitumen-polymer liquid agent. After application, a “rubber” covering appears on the surface, which repeats all the recesses on the wall. The rubber surface does not allow moisture to penetrate, it makes the protection of hydro, - thermal insulation.

Types of liquid rubber:

1. Emulsion - applied by machine. Applicable on the floor for vapor barrier.
2. Emulsion applied to the floor by hand.

Liquid rubber is also applicable to protect the foundation from the street side.

Installation of vapor barrier material for insulation inside a brick house

Vapor barrier of brick walls is produced using several types of materials to choose from. Indoors - these are films and membranes.

And also applicable materials, the basis of which is foil. They have reflective properties. In this case, the foil side is placed inside the room.

If a brick wall is insulated from the inside with mineral wool, then it must be protected from both sides. From the side of the wall from condensate, and from the side of the room from vapors penetrating into the insulation.

Of the protective materials, alufom, penotherm, penofol are used.

The first step is to prepare the wall: it is cleaned of sharp protrusions, dust.

After that, the vapor barrier is fixed, the insulation is in the created crate and the vapor barrier is again on top. In this way, the mineral wool is protected from both sides.

Which side to put to the insulation inside the building: how to put

Depending on where the installation of the material takes place, it is determined which side to lay it:

1. When laying the insulation from the street side, the vapor barrier is fixed to the insulation - from the street side.
2. When processing the ceiling, roofing, antioxidant materials are used. They are fixed on a heater.
3. If there is no additional fastening of the ceiling and roof insulation, then the material is fixed from below the rafters.
4. If there is thermal insulation from the inside of the walls, then fixation is carried out from the outside of the insulation.

Many materials are used that have the same surface on both sides. Therefore, it does not matter which side the vapor barrier is attached to.

Which side to fasten and nail

If the question arises, which side the vapor barrier is fixed on, nuances arise:

1. There are materials that have the same sides. Their use does not affect the protective functions.
2. The antioxidant insulator is placed with the smooth side to the insulation.
3. Foil membrane - fixed with a shiny surface inside the room.
4. Film materials - smooth side to the insulation.
5. When choosing a diffuse component, you need to study the instructions, since they can be double-sided.

The dark side of the material is external.

How to stick

The vapor barrier is fixed in several ways:

• use nails with wide hats;
• the use of a construction stapler;
• on top of the layer, after a certain distance, wooden planks are fixed.

The joints are glued with adhesive tape for vapor barrier.

Features of vapor barrier frame and wooden buildings

To protect the wooden walls of the house, a vapor barrier is made both outside and inside. This is necessary first of all, to protect the wooden beams, since after wetting there is a slow drying. During the drying time, the tree deforms and rots.

In a wooden house, it is imperative to fix the vapor barrier layer, because there is the possibility of temperature fluctuations, the appearance of humidity. Especially in the autumn-spring period.

Vapor barrier of walls in frame houses is carried out by a different method.

How to properly lay

The vapor barrier of the walls of a wooden house from the street is produced in the following sequence:

1. Overlapping layers are fixed on wooden beams. All joints are sealed with tape or foil tape.
2. Next, the installation of the frame base for the insulation is carried out.
3. After fixing the mineral wool, a hydrobarrier is attached to the bars from above.
4. The last step is finishing the house.

If the bars create a flat surface, then the vapor barrier must be mounted on wooden slats. This will create ventilation.

Vapor barrier inside the house:

• a gap should be made using rails for ventilation;
• material is attached to the rails;
• the next step is the construction of the frame base for the insulation.
• after laying the insulation, a hydrobarrier is fixed;
• The last step is finishing.

When laying the vapor barrier material of a frame house, you must be guided by the following rules:

• use membranes, create a layer of ventilation;
• installation of vapor barrier on both sides is not done.

The material is fixed with a stapler, the borders are sewn up with tape.

Is additional protection needed?

In a wooden house, additional protection is not required. But in frame structures, materials such as hydro-, wind protection are applicable. It is fixed to the exterior. After that, OSB, thermal insulation, vapor barrier and finishing are applied.

Is it possible to lay multiple layers

This is not necessary, because the vapor barrier material is designed in such a way that it fully performs its functions. In addition, in some cases, in addition to vapor barrier, additional materials are used to protect the insulation and walls (wind protection, waterproofing).

Attention. Some types of membranes are made up of several layers. Applying this material, there will be additional protection of walls in wet rooms.

How difficult is it to make a vapor barrier with your own hands

Despite the fact that the vapor barrier of the walls in the house is an important point for protecting the building from destruction, it can be done independently. To do this, you must follow the rules:

1. You need to know how to properly install in specific cases (high humidity, wooden walls).
2. Before carrying out installation work, you should familiarize yourself with the technical characteristics of the selected material.
3. It is necessary to cut the roll accurately by measuring the correct length. The fewer joints, the better for the building.
4. Fixing the layer cannot be done simply with nails to the surface. Over time, the vapor barrier will break and weaken. Be sure to use either wooden slats or a stapler.

Peculiarities

Before installing the vapor barrier, the following features must be taken into account:

1. material. Having studied the technical characteristics of the material, you can understand how suitable it is for indoor or outdoor use.
2. The correctness of the work. In addition to the fact that the roll material is laid with an overlap of at least 20 cm, you need to know which side and which method: vertically, horizontally.
3. The joints of the material must be glued to avoid moisture getting on the insulation.
4. Fixation of the material is carried out every 60 cm.

For a quality work done, the masters recommend purchasing a vapor barrier and its components from the same company. For example, adhesive tape for joints should be of the same company as the material itself.

Vapor barrier of the walls of the house can be carried out not only when a new building is being erected, but also during repair work. The walls of the house are destroyed under the influence of moisture, therefore, for their safety, the material is mounted on the street and in the house. Only in some cases, work is carried out on one side (frame house). Having studied all the nuances of installation, the vapor barrier will last a long time, and the microclimate in the house will not be disturbed by moisture.

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