How to install vapor barrier when insulating walls from the inside. How to lay the vapor barrier which side is smooth or rough? Membrane structure and principle of operation

The roof structure is a complex system. It consists of several layers of dissimilar materials, each of which performs its own unique function.

To provide comprehensive protection buildings from influence environment quality performance is required for all installation work, as well as the correct choice of base and insulating materials. This whole process is briefly called.

Standard Composition roofing cake includes:

Inner finishing layer;
The design of the crate;
Counter-breech;
(does not apply to a cold attic);
(about);
ventilation shafts or gaps;
Roof covering.

Why do you need a roof vapor barrier? Vapor barrier layer protects the roof from the penetration of water vapor into the thermal insulation. The fact is that insulating materials for the most part have porous structure, since the air contained in them performs the function heat insulator. When in contact with a colder environment, the vapor turns into condensate, which lingers in voids.

This can lead to a violation of the functionality of the heat-insulating material, as well as the occurrence of decomposition and decay processes in the summer. In winter, freezing water expands, thereby breaking bonds between cellular elements.

The main characteristic of a vapor barrier material is vapor permeability, depending on the density of the material. The values of this indicator can be found in the passport of the packaged building material.

Release form of vapor barrier films - roll. Vapor barrier can be made from various materials. Some of them have additional positive properties that increase the efficiency of the operation of the interior of the building. Installing a vapor barrier on the roof is not as difficult as it seems at first glance, but it requires a careful approach and accuracy.

Types of vapor barrier

Single layer polyethylene films

They are made of low-density polyethylene, which provides an increased degree of steam penetration. This material often has defects associated with the ingress of foreign particles during manufacture. The cheapest type of insulating material.

Reinforced polyethylene films

Compared to single-layer polyethylene, reinforced vapor barrier has little greater thickness, as it includes a reinforcing frame. It is made up of polymer twisted threads located in mutually perpendicular directions. The mesh is fastened to the polyethylene base by warm pressing.

This technique does not affect the waterproofing and mechanical properties of the material, but may reduce the degree of vapor barrier.

Anti-condensation film

Made from two layers: smooth and hairy. The smooth layer is attached to the surface to be insulated. The fleecy layer is created from cellulose fibers. Steam, falling on such a surface, clings to the fibrous structure, thereby preventing moisture from dripping onto the underlying structures. pitched roofs. Excess water is removed together with air through the ventilated space.

Polymers with a foil layer

They are made of penofol or foamed polypropylene, covered with a thin layer of metal. Due to the reflective properties of metal surfaces, such a vapor barrier performs an additional function protection against heat loss.

Membranes (film for roof vapor barrier)

Membrane vapor barrier materials are divided into five main classes:

Type A. It has increased resistance to moisture and wind. Fits between roofing and thermal insulation layer. Manufacturing technology - spunbond. Such a vapor barrier does not allow moisture to flow through the cracks. roofing material, as well as from the resulting condensate. The absence of a laminating layer allows the use of such membranes in roof structures with a slope. over 35 degrees. To remove excess moisture, it is necessary to arrange ventilation holes from a double crate located between the membrane and the insulation.
Type AM. Unlike Type A has a multilayer structure. It is located between the insulation and the roof, to provide adequate protection from negative atmospheric influences. The most common is a three-layer construction, consisting of two layers of spunbond with a diffuse film located between them. It acts as a waterproofing, as it allows steam to pass through, but retains water. Laying is carried out directly on the heat-insulating layer, which reduces labor costs for the device of the ventilation gap.
Type B. Double layer material. It consists of a layer of vapor barrier film and spunbond. It is used to protect the insulation from the internal vapors of the building. Applies only in insulated roof structures.
Type C. It is made similarly to type B membranes. It has a stronger and thicker spunbond layer, which provides better protection of the insulation from moisture. Used in insulated and non-insulated, pitched and flat roofs.
Type D. Consists of polypropylene fabric, protected on one side with a laminating polymer coated. The structure of the material allows it withstand significant mechanical stress. This causes it to be laid between the insulation and the attic floor screed, as well as in non-insulated roof structures.

Which side is the vapor barrier for the roof?

The principle of installation of vapor barrier materials depends on which side is the layer responsible for the repulsion of water vapor:

We figured out which side to lay the vapor barrier on the roof, now we will analyze in detail how to properly lay the vapor barrier on the roof.

Vapor barrier for the roof: how to properly install using special technology

Laying the vapor barrier on the roof is carried out as follows:

Laying can be done vertically and horizontally. In the second option, the installation of the roof vapor barrier is carried out starting from ridge part roofs. Each subsequent strip is superimposed on the previous layer. with an overlap, the value of which should not exceed 10 cm.

CAREFULLY!

When joining elements, a mandatory seam sealing, which provides optimal protection against moisture ingress into the gap between them. Most often, gluing is done with one- or two-sided adhesive tape or adhesive tape. In roofs with a slope of up to 3o degrees, additional fixation with wooden planks.

The vapor barrier is attached to the wooden truss elements with the help of galvanized nails or a construction stapler.
When installing films and membranes near roof hatches, you need to use a special vapor barrier apron which is included as standard.
At the joints with ventilation pipes, film and membrane structures are wrapped down, wrapped around the pipe and tightly fixed with construction tape.
After laying the vapor barrier layer, it is necessary to nail wooden blocks. The rules for laying vapor barrier on the roof dictate the following rule - the step between the bars of the crate should be 500 mm. In this case, a ventilation gap is formed, and additional fastening of the vapor barrier layer is carried out. Now you know how to lay a vapor barrier on the roof, you can move on to the issue of waterproofing.
If the vapor barrier for the roof was damaged, then small cuts or holes can be stick with special tape for vapor barrier membranes.

Roofing pie scheme

Gluing joints with adhesive tape

The final version of the vapor barrier

NOTE!

A tightly stretched film is the key to good vapor barrier.

Hydro and vapor barrier of the roof - what's the difference?

Useful video

And now we invite you to familiarize yourself with the video instruction on the vapor barrier of the roof:

Conclusion

Vapor barrier is the lightest and thinnest layer of the roof. But neglect of its structure can nullify all material and physical efforts to create quality roof. So don't neglect it important element, it will significantly increase the life of the entire building.

In contact with

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 lack of knowledge by the "specialists" of elementary norms, including which side to lay the vapor barrier to the insulation. Let's look at this issue in more detail.

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

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

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).

If external wall protection is carried out, the respective components must not have perforations or pores.

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

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

Special vapor barrier films are made with an antioxidant coating. Due to 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.

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 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:

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

Since the first type of insulation is considered 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.

The two remaining types of membranes have large pores, which eliminates the possibility of 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.

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: ONDUTIS vapor barrier laying technology

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. but the best choice will 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, let us say that membranes will allow any building structure 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.

Foreword. During the construction of a private house Special attention should be given to the vapor barrier of the ceiling, floor, walls and roof. If this important step is skipped, the structural elements of the building will not last long. We will talk further about why it is important to arrange a vapor barrier in a private house and how to do it correctly.

Why do you need a vapor barrier insulation

A special film that protects the heat-insulating material from moisture must be included in the "pie" of walls or roofs. The fact is that due to the temperature difference, especially in winter, condensate settles on the walls and ceilings on the street and in the house, indoors. As a result, the heat insulator gets wet and stops performing its functions. The house is getting cold. In addition, moisture leads to damage to the structural elements of the building.

Depending on the variety, the cost of the material may be different. For example, an ordinary vapor barrier polyethylene film costs about 500 rubles per roll. The foil version will cost about 1400-1800 rubles. A three-layer diffusion membrane will cost about 4000-5000 rubles. The popular Izospan vapor barrier will cost about 800-1000 rubles. per roll.

Types of vapor barrier materials

Vapor barrier in frame wall. A photo

There are only three main types of films designed to protect mineral wool or expanded polystyrene from moisture:

Standard. The cheapest and not particularly durable type of vapor barrier. In most cases, this is an ordinary thick plastic film.

foil. It costs more than polyethylene, but at the same time, in addition to the actual vapor barrier, it performs another function - it reflects heat back into the room. Owners country houses very often they are interested in which side to lay the vapor barrier on the walls and ceiling. This question usually arises in relation to this variety. How such a film is actually mounted, we will consider a little lower.

Membrane. Differs in limited vapor barrier. This allows you to control the removal of moisture from the room.

Basic rules for laying vapor barrier

Of course, before you go to the store to buy film, you need to do everything necessary calculations. It is quite easy to carry out this procedure. All that needs to be done is to calculate the area of all structural elements of the house that require protection. The calculation is made taking into account the width of the vapor barrier film and the necessary overlaps.

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 the inside, then you should independently determine this by external factors. You should pay attention to the following:

1 . If waterproofing film has a different color on both sides, then the light side of the isospan is laid to the insulation.

2 . The side of the waterproofing, which, when rolled out, faces the floor, is considered internal and should look towards the insulation.

3 . The outer side is made fleecy so as not to let moisture through, and the inner side is smooth and fits in the direction of the insulation.

Which side to put the vapor barrier on the insulation

Which side to lay the vapor barrier on the floor
Of course, it is also worth knowing how to lay this type of vapor barrier. In this case, as in all others, the crate is initially installed. Sheets are mounted on it and fixed with self-tapping screws. The joints are sealed with adhesive tape.

One of the main criteria for a comfortable life in the house is the optimal temperature level, as well as a suitable humidity indicator. Correctly mounted layers of heat, moisture and vapor barrier will help to ensure good performance. Moreover, properly laid layers not only improve the microclimate in the house, but also protect the floors from the effects of various factors, including humidity. How to put the vapor barrier on the floor?

Each house has its own specific microclimate. Here a person prepares food, takes a shower or bath, and does wet cleaning. Thanks to all these processes, enough a large number of a couple who are trying to find a way out of the walls of the rooms. It has a strong enough effect on all elements of the structure, and drops of moisture settle on the surface of the walls, ceiling, inside the floor pie. The resulting condensate, willy-nilly, begins to penetrate into the structure of the materials used to build the house - it is absorbed into the wood, penetrates into the insulation layer, reducing the performance of the materials, destroying them.

In rooms located on the first floors directly above the ground or basement, the floors also experience increased exposure to moisture. Here, moisture also acts on the materials from below. And the vapor barrier is laid just in order to reduce the level of impact on the floors, while this type of material does not interfere with air circulation at all - its flows can easily go outside, the rooms will “breathe”.

On a note! Vapor barrier is especially necessary when building houses made of wood. However, it will not be superfluous in the construction of concrete structures, as it will reduce the level of humidity in the building.

Prices for vapor barrier film "Izospan"

vapor barrier film isospan

What is the difference between hydro and vapor barrier

Vapor barrier is a thin film that is mounted inside the floor pie. However, quite often it is confused with waterproofing, but this is completely different materials. So, the waterproofing layer is designed to keep moisture out of the room from the outside. If water still gets to the insulation, then its characteristics will deteriorate significantly - it will no longer retain heat. This will be especially felt in winter, when the water inside the insulation layer will turn into ice crystals. The floor will become colder, and in general it will not be so comfortable to be in the room. To prevent this from happening, it is necessary to lay a layer of waterproofing. In general, it does not pass precipitation through itself, ground water and fit outside the floor cake.

The vapor barrier is laid inside the floor pie. And it will protect the materials included in the structure of the base, no longer from moisture from the outside, but from the condensate coming from inside the room, which is formed due to breathing, cooking and other processes, accompanied by the release of steam and moisture.

The main difference between these two types of materials lies in their structure. Waterproofing coatings do not allow moisture to pass through, but they are quite capable of passing evaporation through themselves. But vapor barriers retain both moisture and steam, thereby protecting the insulation. Thus, the vapor barrier does not have a membrane structure as such.

On a note! Not all types of waterproofing materials are vapor permeable.

Types of vapor barrier materials

Several basic types of materials can be used to create a vapor barrier layer. This is a polyethylene or polypropylene film, the so-called diffuse membrane or liquid rubber. Previously, only roofing felt, roofing material and other similar materials were used.

Polyethylene film is the cheapest and easiest material used to create a vapor barrier layer. It is quite thin, and therefore during installation it is important to be careful not to tear it. The film may or may not have fine perforations.

On a note! There is an opinion that a perforated film is used for arranging waterproofing, and without it - for vapor barrier. This is due to the presence of small holes in the material.

Vapor barrier film "Yutafol H 110"

However, in any case, whatever the film, when using it, you will have to equip the ventilation gap. And since you still have to do it, many do not think about the presence of perforation and simply buy the material that is cheaper.

Now another subspecies of films made of polyethylene has appeared - it has a reflective layer coated with aluminum. This material has more high rates vapor barrier and is usually used in rooms where high levels of humidity and air temperature are noted.

The film polypropylene differs in high rates of quality and durability. It is easy to install and can last for years. Polypropylene film is made not only from polypropylene - it also has an additional cellulose-viscose layer, which is able to absorb a lot of moisture and retain it. At the same time, during the decrease in the level of humidity, the layer dries up and is again ready to absorb it into itself.

When laying this type of film, it is worth remembering that the anti-condensate absorbent layer must be turned away from the insulation. And between the vapor barrier layer itself and the insulating material, a small gap is left for ventilation.

Diffuse membranes are perhaps the most expensive vapor barrier option. They are considered the highest quality, are called "breathable" and are able not only to protect building materials from excess moisture, but also to regulate the moisture index. The membranes are divided into one- and two-sided, and the materials are mounted differently - if when laying a one-sided version of the membrane it is important to observe which side it will be turned to the insulation, then the two-sided one can be laid as you like.

Such membranes are characterized by significant vapor permeability. They are made from a special non-woven artificial material and may have multiple layers. When installing, leave a gap for ventilation is not necessary.

On a note! Among the membranes there are those that are called "intelligent". They combine several properties at once - they are able to work as a vapor barrier layer, provide waterproofing and are also a heat-insulating material. This type of membrane is able to regulate the level of steam depending on the levels of indicators such as ambient temperature and humidity in the room.

Liquid rubber, when creating a wooden floor cake, is used extremely rarely for vapor barrier; it is more suitable for concrete bases. However, it is still a fairly common option to talk about it. Such rubber is a polymer-bitumen composition prepared on the basis of water. It is applied very simply - it is sprayed on the base, moreover, it forms a seamless and durable coating - a kind of rubber carpet. When the polymerization process is completed, the material will not be able to pass any substances through itself.

Liquid rubber can be applied automatically and used to process spacious structures, or manually - this option is suitable for small rooms.

Brands of materials for creating a vapor barrier

There is a wide variety of various brands of vapor barrier materials on the materials market. They have a lot of differences and may differ in price, quality and other factors.

Table. Material brands.

brand	Information	Manufacturer	Price
Tyvek	Good protection against steam and moisture	Denmark	5500 rub./50 sq.m.
Izospan	Protects from moisture, wind, steam	Russia	13 rub./sq.m.
Brane		Russia	1100 rub./70 sq.m.
Domizol	Excellent protection against steam, moisture, wind	Russia	13 rub./sq.m.
Polyethylene	Tears, but protects well from steam	Russia	No more than 10 rubles / sq. m.

Isospan is especially popular. There are several subspecies of it, and it is recommended to purchase Izospan V for floors. It is a two-layer version of the membrane. It is smooth on one side and slightly rough on the other. The rough side holds capillary moisture well, absorbing it.

Mounting Features

The floor cake is made of several layers, including logs, a layer of waterproofing material, a subfloor, a layer of insulation, a vapor barrier layer, a layer of soundproof material and a finishing coating. Before installing the vapor barrier, it is imperative to prepare the surface. If the building is being built from scratch, then there will be no problems with the installation of this layer. The boards of the subfloor are simply treated with antiseptic preparations, leveled, and vapor barrier material spreads over them. It is also recommended to cover the logs with protective compounds.

If the house has already been built, it is carried out overhaul, then for starters it is important to remove the old flooring and other previously used materials. Next, it is important to check the strength of the logs, the rough base - if they bend or rot, they will have to be dismantled and replaced with new ones. All debris is removed before further work, the smallest specks are removed with a vacuum cleaner.

The vapor barrier layer must be laid on a flat base without protruding nails. Otherwise, it may be damaged. Immediately before installation, it is important to determine which side the vapor barrier material will be mounted on. As for a conventional polyethylene film, there is no need to determine the side. If Isospan is used, then it is important to look at its color on both sides. It is laid with the bright side to the insulation. If the material has a pile, then this side is mounted in the direction of the room - the pile will absorb excess moisture.

Laying vapor barrier "Izospan"

On a note! To work with a vapor barrier, a material such as adhesive tape is useful. With its help, the joints of the individual strips of the coating are connected. This is necessary to improve the tightness of the vapor barrier layer. In this case, individual strips of material are overlapped by 15-20 cm on top of each other.

Installation of vapor barrier does not require special knowledge. The material is rolled out on the surface of the prepared floor and fixed on it with the help of small nails, a construction stapler. However, the easiest way is to use a special adhesive tape.

Hard-to-reach or unusually shaped places are best treated with a bitumen-based coating agent. The reason for these actions is that in such places it will be quite problematic to lay and properly fix the vapor barrier material.

The process of laying "Izospan"

The insulation itself will be laid directly on top of the vapor barrier if the material is used to protect it from moisture not only from the inside, but also from the outside. Styrofoam, mineral wool or expanded polystyrene can be used as an insulating layer. It must fit very tightly. wooden lags so that cold bridges do not form.

On top of the insulation layer, another layer of vapor barrier is mounted. He will no longer allow the moisture coming from inside the room to get to the insulation and soak into it.

On a note! Foil film perfectly reflects infrared radiation. Therefore, it is laid with the shiny side in the direction of the room.

How to install vapor barrier

Vapor barrier must be laid in compliance with the technology, although in general this process is quite simple and understandable to everyone.

Step 1. Windproof material is spread over the subfloor.

Step 2 The film is laid so that its edges go over the wooden logs.

Step 3 The fixation of the material is carried out using a construction stapler along the logs.

Step 4 After that, insulation boards are laid on the laid material. They should cover all the space between the lags.

Step 5 Adhesive tape is glued along the perimeter of the wall in its lower part before installing the vapor barrier layer.

Step 6 A vapor barrier layer is laid. pieces the right sizes laid across the log with a slight overlap on the walls. The film is laid so that in the middle it sags a little.

Step 7 Fixing the film is carried out using a construction stapler on the logs.

Step 8 The edge of the vapor barrier film, wound onto the wall, is glued to it on the adhesive tape installed earlier.

Step 9 The junction of the next layer of film is sealed with adhesive tape, which is glued along the edge of the previously laid layer.

Step 10 A new piece of material is laid so that an overlap is obtained at the location of the adhesive tape. The rest of it is again fixed on the logs with the help of a construction stapler.

Floor installation

Prices for liquid rubber for waterproofing

liquid rubber for waterproofing

Video - Laying vapor barrier

Video - Vapor barrier films for the floor "Ondutis"

Vapor barrier is a layer in the floor cake, which should not be neglected, and even more so - replace it with a waterproofing material. It is thanks to the vapor barrier that it will be possible to create a microclimate favorable for life in the house.

Vapor barrier is a layer that protects insulation or building structures from the penetration of wet steam, which in turn leads to the accumulation of condensate on them, loss useful properties and rot when exposed to moisture. To create a vapor barrier, completely impermeable double-sided or having one correct work surface films and canvases. It is extremely important to determine exactly which side to put the vapor barrier on the insulation, an error at this stage provokes accelerated destruction of building materials and significant financial expenses. The main guideline is the manufacturer's instructions, but often this document is not available when buying, the choice is made based on the type of vapor barrier film and installation conditions.

How is the vapor barrier installed?
Technology Violations
Tips & Tricks

For ordinary or double-sided reinforced polyethylene, this problem is not relevant; in other cases, the working surface is impervious to steam. 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 when insulating walls is necessary when: using fibrous and cotton wool insulation, erecting frame wall panels, arrangement of 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 impervious films, the insulation must breathe, the best option Diffusion and superdiffusion membranes are considered to allow air to pass through, but not moisture and steam. 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 domestic vertical walls they are held on 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. Usage different types 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 the only option when it is not necessary to put a vapor barrier - when building a house from wooden beam, but this exception does not apply to absorbent insulation materials and floors, they always need protection. 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 junction 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.

During construction country house or private bath milestone is thermal insulation 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.

During the construction of the log house, everything structural elements treated with protective antiseptics and flame retardants.
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 around 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 flat roof or a 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 thermal insulation 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

Once a vapor barrier material has been selected, consideration should be given to important question- 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 the bottom up 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. Most practical option fasteners - 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 suitable 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:

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

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.

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:

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

Super diffusion membrane IZODACH 115

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.

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?

Arrangement of a ventilation gap when laying a vapor barrier

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 most best materials. Unfortunately, often the owners, who undertake to insulate their home on their own, forget about one very important thing. important aspect- about 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 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 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, polystyrene foam, 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 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 vapor barrier flooring is being carried out.

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 stacked 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 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 surface a smooth layer will always be internal, and a fleecy or rough layer will always be external.

What fastener should be used?

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

Is an air gap necessary near the membrane?

It is believed that this obligatory 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 the sales assistant 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 the repair of 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.