How to properly lay vapor barrier. How to lay a vapor barrier on which side, smooth or rough? To lay the vapor barrier material you need

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

Peculiarities

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

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

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

Materials

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

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

As is known, to insulate houses in modern conditions materials such as mineral wool, polystyrene foam, and 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 level of thermal conductivity is low, which reduces the likelihood of heat loss in the room. Rodents, mold, and mildew do not like mineral wool; it has high sound insulation and is easy to install. But it still requires a vapor barrier.

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

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

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

Device

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

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

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

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

Vapor barrier on the ceiling

In case of roofing structures And interfloor covering The installation of a vapor barrier is supposed to be on an already prepared and properly treated surface. It is best to use a diffusion membrane here.

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

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

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

Vapor barrier on the floor

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

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

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

Vapor barrier on walls

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

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

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

Installation subtleties

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

Which side should the vapor barrier be laid?

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

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

How to distinguish the outside from the inside?

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

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

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

What kind of fastener should I use?

Is an air gap necessary near the membrane?

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

When settling in protective layers insulation, the use of vapor barriers is necessary in any case. The range of products is large, it is difficult to understand the purpose, scope, and characteristics. In addition, you should know which type of materials is suitable for a wooden base, and which one is needed for concrete slabs ceilings Let’s look at the questions in more detail, let’s figure out how to install a vapor barrier on the ceiling and whether it’s possible to do the work yourself.

If the room is located so that one side of the ceiling is constantly warm, and the second plane faces outward, where the temperature drops to sub-zero levels, for example, a room under an unheated attic or roof, then condensation will collect in a certain area of ​​the structure. This area is called the dew point and it is important to move this point beyond the insulation layers. Otherwise, the overlap bearing structures and the thermal insulation will begin to get wet, rot and through a short time will fall into disrepair.

Vapor barrier material protects the main structural units, floors, load-bearing beams from damage, prevents rot, and increases the energy efficiency of the house. A correctly laid insulator layer will release moisture out, but will not let it back in - this is due to the special structure of the material.

Advice! In rooms with variable humidity, laying out a vapor barrier is a necessary condition. The suspended water rises to the top; it is necessary to ensure timely release of steam so that mold does not form in the room.

Types of vapor barrier materials

The product range is large:

1. Reinforced polyethylene films. They have zero moisture absorption and cope well with protective functions. For areas of high humidity, it is better to use films with perforations, and for rooms with normal moisture levels, non-perforated products are suitable. The availability and versatility of the material are advantages, but the ability to collect condensation on the surface is a disadvantage.
2. Polypropylene tapes with viscose coating - an option that is suitable for all types of rooms. Viscose absorbs moisture without forming condensation. Increased strength and ease of installation are advantages; the high cost of the material can be a disadvantage.
3. Foil-coated insulation It is made of foamed polyethylene or thick cardboard, covered with foil (on one or both sides). High quality, reliability, durability and the ability to display heat are advantages. In addition, the products are small in thickness and are indicated for installation in baths and saunas.
4. Vapor barrier membranes. Modern material consisting of several layers: perforated fabric, polymer film, polypropylene. The main quality is 100% vapor barrier. The membrane collects all the moisture without giving it back. Particularly effective are 2-sided insulators, which successfully remove all moisture to the outside. For processing concrete surfaces Varnishes and mastics with a membrane effect are offered.
5. Glassine is a durable cardboard impregnated with bitumen. It is distinguished by its plasticity, light weight and is used to protect wooden buildings.

When choosing a vapor barrier, you should pay attention not only to the cost of the material, but also the purpose, scope, protective characteristics and base materials for which the product is best suited.

Operating principle of vapor barrier products

Regardless of the type of product, all insulation has one purpose - to prevent the accumulation of condensation on the insulating materials. But the principle of operation of the products differs. For example, the film does not allow moisture into the insulation, and the membrane allows steam to pass into the layers of thermal insulation, helping to evaporate excess moisture. And this is the main difference.

Important! When purchasing membrane sheets, you need to know how to properly install a vapor barrier on the ceiling - unlike film products, membrane rolls installed incorrectly will release moisture inside without allowing it to pass out.

What materials are better to choose

The type of insulation is selected depending on the base material, the level of humidity in the room, the evenness of the base ceiling and many other factors.

For wooden ceilings

Basic requirements: to protect the wood from moisture and to ensure ventilation of the structure and the “insulation pie”.

Suitable:

• films of polyethylene, polypropylene;
• foil-type insulators;
• glassine;
• membrane vapor barriers.

To eliminate condensation on films, it is necessary to provide ventilation gaps - this way the moisture will gradually evaporate without damaging the wood structures.

For concrete ceilings

You should choose products that are attached directly to the base: varnishes, mastics, paints, insulators with a foil layer. The latter are mounted both on floor slabs and on a wooden frame - this is convenient for forming a suspended, suspended ceiling.

Features of vapor barrier installation and fastening technology

Before starting work, the ceiling is cleaned of old coating, dirt and dust. Then like this: if used rolled materials, the surface needs to be puttied, eliminating defects, unevenness, and filling cracks, but before covering with liquid paints and bitumen materials, it is enough to level the concrete floor slabs with a ready-made repair compound. After puttying and leveling, the base surface is primed in 2-3 layers with preliminary drying of the previous layer before applying the next one.

On a note! Wooden ceiling need to be treated with an antiseptic, fire impregnation, and only then prime it.

On a wooden ceiling base

Rolled sheets are attached to the prepared base with a stapler and staples. When laying out film products, in order not to deform the sheets, it is better to place small pieces of cardboard or thick paper under the bracket.

Lay the strips overlapping each other by about 15-20 cm, and glue the joints with reinforced construction tape. In the areas of junction with the walls, the film is not cut, but is lowered 10-25 cm onto the wall panel.

Important! When using a vapor barrier membrane, first consider the material and determine which side to place the vapor barrier on the ceiling. The smooth side is laid out towards the ceiling, and the rough surface is “turned” towards the room.

After installing the insulation, a lathing is formed so that the sheets are held tighter; in addition, the structure will create the necessary ventilation gap so that drops do not collect on the ceiling vapor barrier, and will serve as the basis for finishing ceiling. Attach the sheathing with self-tapping screws, sewing it to the base base.

On concrete ceiling bases

Preliminary preparation of concrete slabs will reduce the risk of the thermal insulation layers getting wet. Most often, the sheets become moistened due to cracks at the junction of the plates, so it is important to properly seal all the seams, inspect the areas where the ceiling meets the walls - putty and prime the surface.

Once the base has dried, vapor barrier materials can be applied. Polymer mastic is considered a good solution - the mixture protects well from moisture vapor, and also does not allow water to pass through from above if there is a gap left somewhere in the ceilings. The mastic is applied according to the manufacturer's instructions; all information is written on the packaging; it should be carefully studied.

When using rolled or sheet materials, a lathing is formed on the base from wooden beam or metal profile. The size of the cells must correspond to the size of the insulation sheets. Many craftsmen prefer to measure insulation rather than vapor barrier materials - first the insulation elements are laid out in the cells, and then the membrane or film.

How to attach a vapor barrier to the ceiling:

• on wooden sheathing staples (a construction stapler will come in handy);
• on metal structure with tape.

On a note! Foil materials are laid out only end-to-end, membrane and film with the sheets overlapping each other by 15-20 cm. However, in both cases the seams are secured with tape.

After the installation of the ceiling vapor barrier is completed, the sheets are pressed against another sheathing frame so that the necessary ventilation gap remains. If the ceiling is then covered with a tension fabric, then to form the second frame of the sheathing it is permissible to take thin dies so as not to burden the entire structure. And in the case of forming a suspended ceiling or lining the surface with plywood, gypsum plasterboard, the timber must be strong enough, otherwise the suspended ceiling will collapse.

Why does condensation appear on vapor barriers?

Having figured out how to properly install a vapor barrier on the ceiling, many owners are still faced with the formation of drops on the surface of the materials.

There are several reasons:

1. Sheets of foil products are laid overlapping one another. This is not true. Lack of clearance and ventilation leads to moisture accumulation on the surface of the insulator.
2. Wrong product selection. In rooms with high humidity film insulators will collect all the moisture on the surface, which will then flow down. To avoid this phenomenon, replace regular film with materials with a viscose layer - this will eliminate the appearance of condensation.

And the main mistake is that the vapor barrier membrane is laid on the wrong side. Let us remind you: to ceiling surface(to the rough ceiling) the smooth side is turned, and the rough side “looks” into the room. If you are afraid of making a mistake, take a 2-sided foil insulator; in addition to protection from moisture, the product has the ability to retain heat, which is an additional advantage of the insulator.

Any homeowner spends a lot of effort to create for his family comfortable conditions accommodation.

This is maintaining a constant temperature in the home, ensuring a flow of fresh air, and humidity within normal limits. All life activity of any living creature is accompanied by the release of heat and steam.

Wet cleaning and washing, showering and cooking, boiling water, and even breathing - all this is a source of accumulation in the room. Increased humidity leads to the formation of condensation on various surfaces indoors.

Moisture penetrating deep into the structure in wooden house influences them negative impact, and contributes to their deterioration and even destruction. The materials used for construction are covered, and pockets of rotting form on them. Besides, high humidity does not have the best effect on the well-being and health of people living in the premises.

To avoid damage and deterioration of individual floor elements, use a special one. His functional purpose– prevent the harmful effects of moisture. At the same time, it does not interfere with air circulation; it calmly goes outside. This technique allows floor coverings not to lose their working qualities and ensures their long service life.

Almost until the end of the second millennium, the role of vapor barrier material was usually played by roofing material, glassine and roofing felt.

Today we can see the widest range insulating materials different types and parties, some of which can also protect from water.

For wooden buildings, various breathable films and membranes are most often used as a vapor barrier layer.

In addition to them, there is another type of insulation - bitumen-polymer mastic, liquid rubber, etc. But these materials are more suitable for protecting and not the foundation of the building.

Polyethylene film

Perhaps the most affordable and common type of vapor barrier material for installation. Trade presents two types of synthetic films - perforated and non-perforated.

It is believed that the first is more suitable for, and the second for insulating from steam. Their difference lies in the presence or absence of microscopic holes in the material, and, accordingly, in the level of permeability.

Thanks to innovative technologies Improved versions of familiar materials are appearing on the market. These are, for example, films with a layer of aluminum applied to them. They have much better performance characteristics and high vapor barrier properties.

They are preferably used where extremely high levels of humidity and temperature are possible. These are kitchen areas, saunas, and so on.

Like any material, film is not without its drawbacks. The main and most significant thing is that it is very easy to tear, which should be taken into account when using and installing. Even if you use a reinforced type of material (reinforced with a special mesh), its strength and durability will not be particularly high.

Polypropylene film

A material such as polypropylene, compared to polyethylene, has better resistance to the effects of precipitation and has a more high strength. At first this type The vapor barrier material was made strictly from polypropylene. Later it was discovered that condensation was accumulating on the film on the insulation side. It has a negative impact on the quality of the insulation and provokes its premature failure.

This drawback was eliminated as follows. A special viscose-cellulose layer is applied to the reinforced polypropylene film. It prevents the formation of drops, perfectly absorbing and retaining moisture. During installation, such material is placed with the anti-condensation layer down. The ventilation gap is usually made between the layer of this film and.

Diffuse membrane

Breathable diffuse membranes can easily be classified as the most expensive and high-quality vapor barrier materials. This material has an extremely high vapor permeability rate, which is ensured by the special microstructure of the material. It is a non-woven fabric made from synthetic fibers.

They are used not only to protect against excess moisture, but also to control its required level. This ability is provided to them by a special quality - the ability to pass air on one side or both. According to this quality, membranes are divided into double- and single-sided. The specific installation method used for each type depends on this. When using single-sided film, you need to make sure which side is facing the layer.

Breathable membranes are also divided according to the number of layers that make them up: there may be one, two or three.

In the manufacture of membranes, a special anti-condensation layer is used, which has the ability to absorb excess moisture and then gradually evaporate it.

A unique representative of diffuse multilayer membranes is a special intelligent membrane. It successfully combines steam, hydro and heat insulating properties. This material is able to independently regulate the microclimate in the room (by changing vapor exchange), based on the level of moisture and temperature present there.

Another invaluable quality of a diffuse membrane is the absence of the need for arrangement between it and. Well, and of course, there are shortcomings, where would we be without them. There is only one, but it is quite sensitive - the high price of such a vapor barrier for the floor covering. But positive properties and the advantages of the material more than compensate for it.

Liquid rubber

Liquid rubber today is a fairly actively used material for arranging vapor barriers. What does this name even hide?

This is a bitumen-polymer cold emulsion prepared at water based. It is convenient to spray it on the working surface. This simple application makes it easy to apply even on surfaces with complex terrain. After final hardening, the mass forms a monolithic rubber carpet that has no seams.

It poses an insurmountable threat to liquids and gases, and is also characterized by sound, hydro- and heat-insulating qualities.

Today's liquid rubber There are different types:

• A special emulsion applied to the surface manually. The working area for application should be no more than several tens of meters.
• An emulsion for which special coatings are used. automated systems. It is used in cases where we are talking about vapor barrier of large floor surfaces: hundreds and thousands of squares in size.

Floor: proper vapor barrier

If you need to install a high-quality vapor barrier system in a house under construction, then there won’t be much hassle with it. All floorboards must be treated with specialized products that protect the wood from pests and insects.

This especially applies to lags and subfloor, which are closest to, in close proximity to it. It is this that will become the basis on which the vapor barrier layer will lie.

If you need to equip an already erected structure with a vapor barrier, then the hassle will increase, and the technology will be different. If you need to carry out major renovation, or replace the vapor barrier layer, you will have to lift and remove the floor covering, remove and remove the heat and vapor barrier.

The screed is thoroughly cleaned with a broom or even a vacuum cleaner. A careful inspection is carried out to check for possible defects. They can be unevenness, chips, small and large cracks.

Dampness without vapor barrier

If there are a lot of them, then repairs should be carried out. If necessary, the screed must be leveled to prevent possible moisture from entering through the cracks from the outside. You can install an additional one to protect against water penetration from the ground.

If a roll is used for this waterproofing material, then it must be overlapped. All resulting joints are sealed with simple adhesive tape or tape.

The level of each of them must be strictly adjusted so that the surface is perfectly horizontal. All elements and parts made of wood are impregnated with protective. The surface is cleaned of debris and dust, and only then you can begin laying the vapor barrier layer.

Laying vapor barrier

To properly install a vapor barrier layer, you do not need any special knowledge. Usually, widely used film materials are used to create a vapor barrier with your own hands. Their worthy representatives are the Izospan B floor vapor barrier and the Izospan membrane. A layer of vapor barrier is carefully laid on load-bearing frame, making sure that the sheets of material overlap strictly. Its width must be at least 20 centimeters.

Secure the laid layer using a construction stapler or special galvanized nails. Often, the material manufacturers themselves recommend using a special adhesive tape, which provides a virtually monolithic coating, without holes or cracks.

So that during work there are no questions regarding possible ways fastenings, it is better to clarify this issue in advance when purchasing the material.

All kinds of junctions, parapets, relief areas and others hard to reach places convenient to protect with bitumen-based coating materials. Laying film vapor barriers in them can be very difficult.

After placing the vapor barrier layer, insulation is mounted on top of it. It could be , or . The insulation is laid in such a way that it fits snugly, without cracks or gaps, against the joists.

Another vapor barrier layer should be placed on top of it, which will become an obstacle to moisture escaping from the room. You should carefully monitor the location of the membrane - strictly overlapping.

Then the joints are glued, and you can begin laying the main floor. When laying boards, keep in mind that there should be a gap of one to two centimeters between the floor and the vapor barrier.

How to install vapor barrier correctly

How to determine which way to lay a vapor barrier membrane: which side?

Tape the seams with foil tape

If a two-layer film is used in the process, then, according to the instructions, it should be laid with the rough side, capable of retaining moisture, in the direction of the room, and smooth surface, preventing moisture from entering the layer

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

Water vapor is picked up by the villi and in a dosed volume is discharged to the opposite side, where it evaporates. The glossy base contributes to this to a large extent.

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

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

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

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

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

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

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

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

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

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

Regardless of the vapor barrier material, it is laid with the rough side facing the room and the smooth side facing the insulation.

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

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

What types of vapor barrier membranes are there?

Membranes used in construction are:

1. Vapor permeable.
2. With vapor barrier properties.

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

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

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

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

There are several types of vapor-permeable films:

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

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

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

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

The need for an air gap at the membrane

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

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

Rules for attaching vapor barriers

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

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

Membranes will help ensure a high-quality relationship between moisture and temperature of the building structure, as well as a long service life. Without their participation, it is impossible to achieve such qualities. When installing a vapor barrier, all rules must be followed. Many manufacturers indicate on the packaging recommendations for installing vapor barriers.

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

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

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

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

Vapor barrier membranes

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

• membranes with vapor barrier properties;
• membranes are vapor permeable.

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

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

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

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

Polyethylene reinforced film

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

https://youtu.be/xTWpLwH8-QI

Video No. 1. IZOSPAN vapor barrier laying technology

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

Distinguish the following types vapor-permeable films:

1. Pseudo-diffusion membranes that transmit no more than 300 grams/m2 of evaporation over 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 good protection against moisture, it is often located under the roof surface as an outer layer. Additionally, it will be necessary to provide an air gap between the insulating layer and the film. At the same time, this component is not suitable for facade processing, since it conducts steam quite poorly. This is explained by the penetration of dust and other debris into the pores of the membrane during dry times, the “breathing” effect disappears and condensation begins to accumulate on the surface of the insulating material.

Superdiffusion membrane IZODACH 115

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

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

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

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

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

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

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

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

Determining the side of installation of vapor barrier

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

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

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

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

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

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

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

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

Organization of a ventilation gap when laying vapor barrier

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

Video No. 2. ONDUTIS vapor barrier laying technology

How is the vapor barrier attached?

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

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

Conclusion

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

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

Peculiarities

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

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

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

Materials

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

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

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

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

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

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

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

Device

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

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

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

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

Vapor barrier on the ceiling

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

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

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

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

Vapor barrier on the floor

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

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

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

Vapor barrier on walls

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

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

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

Installation subtleties

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

Which side should the vapor barrier be laid?

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

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

How to distinguish outside from internal?

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

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

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

What kind of fastener should I use?

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

Is an air gap necessary near the membrane?

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

Do I need to tape the joints?

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

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

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

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

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

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

Knowing which side to lay the vapor barrier against the insulation on the ceiling, wall or floor is very important when working on insulation. It only at first glance seems that which side to lay the vapor barrier against the wall insulation does not matter, but in reality this is not the case. In this material we will tell you why a vapor barrier is needed and its purpose. Watch the video - which side to lay the vapor barrier on, how to distinguish the inside of the vapor barrier film from the outside.

The need for high-quality thermal insulation of premises arises very often. If you plan to insulate wooden house with your own hands, then many questions arise on how to do it correctly. And one of the important questions concerns the need to use a vapor barrier, the place of the film in the thermal insulation “pie” and which side to lay the vapor barrier against the insulation on the wall.

Vapor barrier is always necessary when using moisture-absorbing insulation. The fact is that the characteristics of mineral wool are such that the material installed on the inside of the wall comes into contact with warm air, which contains water vapor. In the absence of a water barrier, moisture penetrates into the thermal insulation layer on the floor, where it condenses, turning into water.

As a result of moistening, the thermal insulation properties of mineral wool material are reduced; in addition, mold and mildew may appear in a humid environment. If the vapor barrier under the insulation on the wall is correctly laid, then it becomes an obstacle to moisture. Therefore, thermal insulation requires the installation of a vapor barrier between the warm air of the room and the insulation.

Types of vapor barriers for insulation

Among those presented on the construction market today modern materials For hydro- and vapor barriers, three main types can be distinguished:

Film refers to blind vapor barriers that do not allow moisture to pass through. The main advantage of polyethylene film is its low price. Two-layer vapor condensate films are also produced - these are smooth on the inside and rough on the outside. Drops of water do not pass through the film, but are retained.

Diffusion membrane– a vapor barrier with limited vapor permeability, consisting of non-woven polypropylene and polymer film. It has an outer and inner side (see video), which allows steam to pass through optimal quantity. Water vapor does not linger in the insulation, but quickly evaporates.

Vapor barrier membrane(energy saving) film has a metallized outer layer, resistant to high temperatures. The material is more often used when insulating the walls of baths and saunas, because the material additionally reflects infrared radiation(works like ).

If glass wool is not protected with a vapor barrier during installation, then as moisture is absorbed, the thermal conductivity of the material will increase.

Roll waterproofing- used for protection building structures from moisture. When using this material, it does not depend on which side the waterproofing is laid to the insulation, since the rolled and coating material does not allow moisture to pass in both directions.

At first glance, it seems that there is nothing complicated - attach the waterproofing film over the insulation from the side warm room and everything is ready. However, there are some important nuances, which you need to know about. It is also important to take into account which side the vapor barrier is laid to the insulation on the ceiling and what the installation features are. This is where previously acquired knowledge about the types of film used comes in handy.

How to distinguish the inside from the outside

If the manufacturer’s instructions are missing or do not contain the necessary information about which side of the film is considered internal, then you should independently determine this by external factors. Please pay attention to the following points:

1 . If the waterproofing film has different colors on both sides, then bright side isospan fits to the insulation;
2 . Side waterproofing, which when rolled out facing the floor, considered internal and should look towards the insulation;
3 . External side made fleecy so as not to allow moisture to pass through, and the inner side is smooth and is placed towards the insulation.

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

The polyethylene film is laid on either side, because they are no different from each other. The diffusion membrane (vapour-condensate film) is correctly laid with the smooth side on the insulation, and the rough side towards the warm room. Thus, it prevents the insulation on the ceiling or wall from getting wet, and excess moisture from the material can freely pass through the smooth side.

Also, diffusion membranes are mounted on the floor or wall with the smooth side facing the insulation. Vapor barriers with a foil side are attached with the reflective side facing outwards, as it reflects heat back towards the warm room. And it should be remembered that laying vapor-tight materials, for example, isospan, requires the installation of a ventilation gap to remove excess moisture.

If the internal cladding (false wall) is made closely without a gap, then it will be exposed to the influence of moisture settling on the film. If there is a gap, air movement will facilitate the unhindered evaporation of excess condensate from the surface of the film. It is important not only to know which side to put the isospan towards the insulation, but also to maintain the integrity of the vapor barrier itself.

Video. Which side to lay Izospan on?