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.
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 the vapor barrier is attached to the rafters from the bottom;
- 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 steam insulating 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 people choose options with different sides, and often with an antioxidant insulator. In this case, you need to know that the fabric surface is the wrong side. It is placed in the inner part of the room. 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:
- Vapor permeable.
- With vapor barrier properties.
When using mineral wool as insulation, an additional layer of vapor barrier is installed on the inside to protect it from moisture. If the walls are protected from the outside, there should be no pores or perforations in the components.
When choosing, you need to pay attention to the vapor permeability coefficient. It should be as small as possible. A good option There will be a purchase of ordinary plastic film. The material that is additionally reinforced will be of higher quality. And if the vapor barrier has an aluminum foil coating, then such a film will be of high quality and durable. Using a vapor barrier indoors increases humidity. Therefore, do not forget about 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:
- Diffusion membranes. The vapor permeability coefficient can be from 300 to 1000 g/m2.
- Pseudo-diffusion. They allow no more than 300 g/m2 of vapor to pass through during the day.
- Superdiffusion membranes. The evaporation coefficient is more than 1000g/m2.
The pseudo-diffusion type of vapor barrier is a high-quality protection against moisture, so it is often laid under the roof as an outer layer. Do not forget about the arrangement of the air gap. The disadvantage of this type is poor vapor conductivity, so this film is not used for facade treatment. Condensation will begin to accumulate on the surface of the insulation, as dust and various debris will clog into the pores of the membrane.
In the other two types, clogging of pores is eliminated. So you don't have to leave air gap and additionally arrange 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. And the layer for ventilation is arranged with outside. When using an antioxidant component, an air gap of 4-6 cm should be made on both sides.
When installing a vapor barrier on the roof and ceiling, to create a ventilation gap, you need to install an additional counter-latten made of wooden blocks. When installing horizontal posts and profiles that are positioned perpendicular to the wall and film, a gap should be left for the ventilated façade.
Rules for attaching vapor barriers
You can attach the film to the walls, ceiling or floor using a stapler or wide-headed nails. But 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.
For the qualitative relationship between moisture and temperature of the building structure, as well as for long term services will help membranes. 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.
Although the vapor barrier is not the best important element buildings, however, the performance characteristics of the roof, attic floors and floors above an uninsulated basement, the enclosing structures of the attic and the multi-layer walls of the building largely depend on it. How to carry out installation correctly and which side to lay the vapor barrier film on?
What is it for?
Vapor barrier is designed to prevent the formation of condensation on the internal surfaces of the roof, walls and ceilings, which can lead to soaking of the insulation and, accordingly, to a decrease in its thermal characteristics. The occurrence of condensation is explained by the contact of warm water vapor obtained as a result of human activity on the cold surface of the wall or by the condensation of moisture on it. The material retains water vapor and reflects its entry into the room, eliminating the possibility of condensation.
For correct installation vapor barrier, one should understand the physical nature of the phenomenon from which it protects the insulation and building structures.
Moisture vapor always tends to move from the area with high pressure(warm room) to the area of low pressure ( environment), while passing through the insulation. Therefore protect the heat insulating material it is possible by laying the film in the path of vapor movement, i.e. between the heated room and the insulation layer. This rule applies to all structures without exception, both for ceilings and for walls and ceilings.
Which side should the vapor barrier film be laid: correct installation
The domestic building materials market today offers a considerable selection of film vapor barriers from various domestic and foreign manufacturers. At the same time, her individual species may have surfaces of different textures, so please read the manufacturer's instructions before installation.
And although it is easy to determine that when using films with one-sided coating with aluminum foil to insulate rooms with high humidity (steam rooms, bathrooms, etc.), the metallized surface should be directed into the room, for example, for the material “Izospan B” not everything is so clear. This film has a two-layer structure - smooth and rough surfaces. The manufacturer's instructions indicate that a rough surface, made with such a texture to retain drops of condensation and their subsequent evaporation, should be directed into the room, and a smooth surface should fit tightly to the insulation.
If the installation of the vapor barrier was carried out correctly, there will be no condensation inside
Features of attic insulation
- the film is attached to the rafters from the inside of the attic with galvanized nails or a construction stapler, covering the insulation;
- strips of material are laid horizontally, from bottom to top, with an overlap of one strip over another of at least 15 cm;
- in rooms with high humidity the strips are fastened to each other with a special connecting tape;
- fixation is carried out by attaching a frame to the rafters, intended for fastening decorative panels or sheets of plasterboard.
In all cases, there must remain between the cladding and the vapor barrier. ventilation gap 4 – 5 cm in size!
How to attach a vapor barrier to the ceiling, floor and ceilings
When located under pitched roof unheated attic, thermal insulation must be covered underneath. In this case, the film is attached from below, to the load-bearing floor beams, and is secured using elements draft ceiling or a finished frame. Here it is also necessary to create a ventilation gap between the insulating layer and the finished ceiling to remove humid air.
When insulating a floor above a cold basement, a vapor barrier is placed on the floor beams on top, protecting the insulation from warm water vapor rushing into the basement, where the partial pressure is lower. To create a ventilation gap, the film is not stretched, but is placed between the beams on insulation, the thickness of which is less than the height of the beams. Logs are nailed on top, and flooring is laid on them - boards or a base for linoleum, carpet or other material.
Below are a few rules to consider during installation:
- vapor barrier is carried out in enclosing structures separating heated rooms and the external environment;
- always fits between the insulation and the cladding under the inner finishing;
- vapor barrier and cladding for internal finishing must be separated by a ventilation gap to remove water vapor.
Compliance with these rules will minimize the possibility of condensation!
Installation of vapor barrier and insulation on the roof
Video: laying vapor barrier film
A wide range of vapor barrier films and membranes produced by domestic and foreign manufacturers, allows you to select the material that best suits the temperature and humidity conditions of the room and climatic conditions construction area. The correct choice of insulating material will make it possible to obtain the desired effect at minimal cost.
Vapor barrier for walls is a solution to the problem of protecting a structure from the direct action of water vapor. Steam can degrade the performance of many building materials. It provokes the appearance and reduces the service life of structures. Therefore, laying a vapor barrier is an extremely important stage in the construction of various facilities.
Installation of a vapor barrier on walls is especially necessary in rooms where there are quite a lot of warm temperature and high humidity. An example would be basements that are heated. Inside these structures, steam is formed, that is, warm air with small drops of water.
The directions of exit from the room for him are the ceilings and walls. Gradually, due to constant vapor formation, the surface of structures is destroyed, so vapor barrier is a necessary measure during construction.
So why do you need vapor barrier for walls in buildings? It is this that creates an obstacle to the penetration of vapors, thereby preventing the destruction of the walls of the facility. Vapor barrier may be required not only in basements and bathhouses, but also in many other structures.
Its device is advisable if the outside of the object is insulated with a material characterized by low diffusion resistance. It is worth understanding that there is no universal insulating material, and it is necessary to select a vapor barrier according to the object and the properties of its structures.
Where vapor barrier is required
There are a number of situations in which it is necessary to install a vapor barrier.
These include the following:
- Vapor barrier, especially in situations where cotton wool materials are used as thermal insulation. Glass wool and mineral wool have excellent thermal insulation properties and are part of the range of materials that allow air to pass through well. Their disadvantage is fear high humidity. When exposed to liquid or steam, cotton materials become wet and lose their performance characteristics, and over time they completely collapse. Installing a vapor barrier will help avoid such consequences.
- Multi-layer wall structures used in . Frame structures need to provide effective vapor barrier. The procedure for installing vapor barrier material in frame house will be discussed in detail below.
- , the surface of the external walls requires a vapor barrier to provide protection from the wind. Vapor barrier materials make the air flow softer and make it more metered. This allows you to protect the outer insulating layer from overload. An example is brick wall, which is insulated with cotton-type material and then covered with siding. Thanks to the vapor barrier, a reduction in wall blowing is achieved. The ventilation gap allows you to remove excess moisture from the windproof surface.
An important factor that allows you to ensure an acceptable microclimate in any room, except for steam and thermal insulation, is functioning ventilation.
Vapor barrier materials
It is possible to install a vapor barrier using a variety of materials. The very concept of “vapor barrier” does not mean that the barrier should completely block the circulation of steam. A modern vapor barrier membrane ensures a minimum air flow to prevent the greenhouse effect indoors.
The membrane retains excess moisture, and the air that was part of the steam is not capable of damaging walls and heat-insulating materials. Vapor barrier materials can redirect air flow to the system exhaust ventilation.
The following types can be installed on walls: vapor barrier materials:
- Polyethylene. It is a traditional material for creating a vapor barrier layer. Such a vapor barrier must be attached to the wall with care, without excessive tension. It is important that conditions are not created for the film to break through when the season changes. You need to understand that in the absence of perforation of polyethylene, this material limits the flow of both steam and air, which creates obstacles to creating a comfortable microclimate in the room. However, perforation no longer provides good vapor barrier for insulating material and walls. This type of vapor barrier is increasingly used in modern construction.
- Mastic materials. This material is applied to the wall, allows air to pass through and retains excess moisture. Wall treatment is carried out before finishing finishing manipulations are carried out. Mastic materials are relatively inexpensive and easy to use.
- Membrane films. This type of vapor barrier is the most modern. The film allows air to pass through and stops moisture. The material is characterized by the correct value of vapor permeability to ensure acceptable insulation properties. Even cotton insulation materials do not get wet when using membrane films as vapor barriers, retain the ability for normal air exchange and do not lose their properties. performance characteristics. Membrane vapor barrier materials are convenient to use for insulating both frame and wooden walls.
When choosing membrane films, there is often no need to install air gaps.
Advantages of membrane materials
Membrane films are a priority when it comes to choosing a vapor barrier material. Mastics are in second place in terms of efficiency, and polyethylene films are used relatively rarely in modern construction.
The advantages of membrane films compared to other vapor barrier materials include:
- high operating efficiency;
- ease of installation;
- strength;
- good ability to repel moisture;
- ensuring the resistance of the wall surface to the proliferation of mold microorganisms;
- resistance to decay processes;
- environmental friendliness of the material;
- long service life - the film retains its original properties for 50 years;
- wide temperature Range operation (from -60 to +80 degrees Celsius).
Thus, the advantages of choosing vapor barrier membranes are obvious, which determines their increasing popularity in the construction market.
Types of membrane materials
The range of materials for vapor barriers on the modern construction market is very wide. You should consider the types of membrane materials that have already earned their authority among consumers:
- Membranes that can be attached to the outside of the thermal insulation (it is external to the space of the room). These include the following brands: “Izospan A”, “Megaizol SD”, “Megaizol A”. These membranes are used to protect the outside of walls frame structures, timber, panel and combined structures from various atmospheric phenomena: wind, snow, rain.
The membrane must fit tightly to the insulating material, be securely fixed to the mounting structure, and have no sagging areas (they provoke popping noises during sudden gusts of wind).
- Membranes that can be placed on the inside of walls. These include: “Megaizol V”, “Izospan V”. This type of membrane materials protects walls from fungus, condensation, and corrosion of structural elements. Also, such membranes prevent particles of insulating material from entering the space of the structure.
- Membranes including a reflective layer. These include: “Izospan FS”, “Izospan FD”, “Izospan FX”. They are used for the purpose of vapor barrier in premises such as saunas and baths.
It is necessary to select a material for vapor barrier strictly according to the purpose of use. This allows you to create optimal conditions to create a comfortable indoor climate.
Installation of vapor barrier film on walls
Installation of vapor barrier on walls is used in cases where mineral materials are used as thermal insulation. It is important to follow the correct installation procedure for the vapor barrier film.
It includes the following stages of work:
- The vapor barrier film must be positioned on the desired side, and then carefully and securely fastened to the sheathing. In this case, you need to work carefully so as not to damage the film.
- Then you need to carefully glue any possible cracks, as well as punctures and overlaps.
- Next, you need to install the sheathing using beams to create acceptable ventilation.
- Then the structure is covered with plasterboard, wall panels, others finishing materials.
Correct installation of the vapor barrier film will ensure a comfortable microclimate in the room.
You need to understand how to properly install vapor barrier in frame houses. To do this, you must first install the membrane on the required side, and then secure it to the racks with a stapler. Next, you should glue the joints using special tape or mastic.
When using ecowool, polyurethane foam, polystyrene foam as insulating material and provided there is an effective ventilation system, a vapor barrier layer in the frame structure may not be required.
If there is still a need for vapor barrier, then one of two possible schemes should be used:
- The vapor barrier is sewn onto the frame posts. How to attach a vapor barrier in this case? First, the film is fixed on the racks, after which the walls are lined with clapboard, plasterboard or other interior finishing materials. This option can be used in buildings used for seasonal purposes, which are not needed during the cold season. These include guest buildings, country houses, and workshops. This option involves ensuring effective ventilation of the structure.
- It involves installing a layer of sheathing (horizontal or vertical) above the membrane. Lathing is necessary to ensure air gap from 30 to 50 millimeters from the wall surface. This option is advisable to use in permanent homes or buildings that require intensive use during the cold season.
The choice of installation scheme for vapor barrier in a frame house should be made based on the expected intensity and seasonality of use of the room.
Vapor barrier of walls in wooden houses
Designs from wooden materials require special vapor protection. Wooden houses characterized by high vapor permeability of walls in comparison with brick and stone walls. This indicator is determined by the thickness of the timber and logs, the presence of cracks, and the impermeability of the grooves to moisture and steam.
Glued laminated timber, which is used to build walls, must be dried in production to an acceptable humidity level. It should also have sealing grooves and low shrinkage. All this is necessary to limit the flow of steam into the insulation.
Timber or log walls with natural humidity levels are dried directly during use. Due to shrinkage within 5 years, deformations and cracks appear on the walls. Logs and beams change their dimensional characteristics, the grooves lose their tightness.
Therefore, you should not carry out interior finishing for 5 years - this will not allow access to the grooves to restore the tightness. In such a situation, there are two options: either wait for the wood to dry completely, or organize a vapor barrier using membranes such as “Izospan FB”, “Izospan B”, “Izospan FS”.
The vapor barrier must form a single contour with the attic and basement floors structures.
Video
Studying the features of vapor barrier allows you to understand why the organization of this stage of construction is necessary. An incorrect order of activities can lead to a lack of comfortable conditions for living or working indoors.
It is for this reason that a sufficient amount of time should be devoted to the selection and installation of vapor barrier materials during the construction of various types of structures.
Until recently, the only type of vapor barrier was glassine. We cut it, attached it, secured it – that’s all! It was only a few decades ago that a more convenient polyethylene film appeared, and more complex and reliable materials began to be made on its basis. Yes, modern options They please not only with their strength characteristics, but also with their resistance to changes in temperature and ultraviolet radiation, and with their versatility. But, at the same time, they are upset by the complicated instructions for their use: they should be connected along a clearly defined line, and only special tape should be used, and - most importantly! – the installation side must be chosen correctly.
Therefore, it is not surprising how often you can find panicky questions on the Internet about how and which side to lay the vapor barrier to the insulation, and what to do if the sides are mixed up? Will it really be necessary to disassemble the entire structure? We can assure you: you won’t have to. Let’s take a closer look at determining which side is “correct” - you will be very surprised!
What is the essence of roof vapor barrier?
Protecting insulation from moisture is one of the most important problems of thermal insulation, and we will now tell you why.
Water itself is an excellent conductor of heat, because it is used in heating and cooling systems for a reason. And, if the roof insulation is not sufficiently protected from steam from the room, then this will not end well. Even in the warm season, you will not know about the presence of a problem, because... such steam will easily disappear due to heat and good ventilation. And in hot countries where there is no subzero temperature, they don’t think about vapor barrier of insulation at all, because the problem is quietly solved on its own. But in Russian latitudes, due to temperature differences in the cold season, steam rises and penetrates the insulation, concentrating in the form of water when it meets the so-called “dew point”.
At the same time, the top layer of insulation in the roofing pie freezes and creates yet another condition for getting wet from the inside. The effectiveness of the insulation itself is significantly reduced, and the changed structure contributes to the development of fungus and corrosion. Moreover, when large quantities moisture can even seep back into the room and thereby damage the interior decoration. This is exactly what a vapor barrier is for.
And in order to understand how to properly install a vapor barrier, you first need to understand the structure itself. Thus, the insulation is protected on both sides by completely different films that perform opposite tasks. Below, on the side of the living room, a vapor barrier is installed that will not allow steam to pass through, and on top - a vapor-permeable membrane, which, on the contrary, will release excess steam from the insulation, if it is “wadded”, and will protect it from roof leaks:
But where is the logic, you ask? How can steam get into the insulation if there is a vapor barrier in front of it? In fact, no film or membrane protects 100%, and there are still poorly glued joints and other construction errors. Therefore, some minimal amount of steam will still be in the insulation, and it is important to properly remove the steam outside without harm:
Look carefully at the diagram: do you see where condensation appears in a well-designed roof? That's right, not from the side of the room, but quite a bit from the side of the roof, on that side of the insulation, and it is easily removed by a windproof anti-condensation film or membrane. But condensation should not appear on the vapor barrier, and no rough side of it can cope with it, because... it has a different structure, and we will now prove it to you.
Types of vapor barriers: A, B, C and D
To understand which side the vapor barrier should be laid and why, for example, both sides suddenly turned out to be smooth, you must first determine its type. After all, not every species has two different sides!
Type A insulation: only for steam outlet on the other side
For example, type A cannot be used as a roof vapor barrier because eventually all the vapors will end up in the insulation. After all, the main task of such insulation is precisely to provide them with unhindered passage, but not to allow rainwater to pass through from the other side.
Such insulation is used in roofs with an inclination angle of 35° or more, so that water droplets can easily roll off and evaporate (and the ventilation gap between such insulation and the insulation helps them evaporate).
Vapor barrier B: classic double-sided installation
But B is a real vapor barrier material. Vapor barrier B has a two-layer structure that allows you to avoid condensation, due to the fact that moisture is absorbed into its fibers in the morning and disappears during the day.
That is why type B vapor barriers are always placed with the smooth side facing the insulation (film side), and the rough side facing outwards. Vapor barrier B is used only in insulated roofs, because For an uninsulated one, its strength is too low.
Type C membrane: for enhanced protection against water vapor
Type C vapor barrier is a two-layer membrane of high density. It differs significantly from type B in the thickness of the vapor barrier film layer. It is used in the same place as type B vapor barrier, but in itself is more durable.
Additionally, such a vapor barrier is used in non-insulated roofs to protect wooden elements attic floor and in flat roofs to enhance thermal insulation protection. Vapor barrier C should also be installed with the rough side facing the inside of the room.
Polypropylene insulation D: for heavy loads
The new-fashioned vapor barrier type D is an especially durable polypropylene fabric, one of which has a laminate coating on one side. This can withstand significant mechanical loads. It is used not only for insulating attic floors as a waterproofing layer, but also in insulated roofing to protect it from leaks. Moreover, type D vapor barrier is indispensable for rooms with particularly high humidity.
Here are the cases and where all these types of insulation are needed:
Does vapor permeability change when changing sides?
All of the above modern barriers are divided into the following types:
- For single-sided installation, which need to be rolled out only on a certain side, and it is recommended not to confuse them;
- and for double-sided use, usually with membranes that can be laid on either side.
You will be interested to know that for the first time, membranes that already had such properties as modern roofing membranes were used in astronautics! And from there they began to be used in construction and in many areas of the national economy. And until recently, there were not as many problems with their installation as there are today.
But now there is a strong opinion among ordinary people: if you lay the vapor barrier to the roof insulation “on the wrong side,” then the entire structure will not last long. In fact, the correct choice of side affects only the service life interior decoration roofing cake, because the rough side has the same abilities as the smooth side and has absolutely the same vapor permeability. But how much it will retain droplets of condensate there is a little-studied question.
Let's understand such concepts as condensation - this is important. There is a catch here: for some reason, most ordinary people are sure that if high-quality vapor barrier is used, then there will be no condensation at all. Or, on the contrary, it will quickly evaporate on its own. In fact, condensation is formed from moisture that rises upward in a vaporous state.
There is such a thing as a “temperature limit”, i.e. that specific condition under which the air temperature and humidity are sufficient for steam to appear in the form of droplets. For example, at a temperature of 15°C and air humidity of about 65%, condensation will already begin to form. But if the air humidity reaches 80%, then condensation will appear at a temperature of 17°C.
In other words, the entire process of water vapor formation occurs as a result of the difference in the so-called “partial pressure”. All the water vapor contained in the air tries to escape out into the colder street through the roof enclosing structures, but on its way they encounter a barrier in the form of a vapor barrier. If the air in the house warms up faster than the surface of the vapor barrier, then moisture from the air will fall on it in the form of condensation. Here the difference between an insulated roof and a non-insulated one is clearly visible: any vapor barrier that is laid on the insulation will warm up much faster than something that is in direct contact with the cold elements of the roof.
If there is no vapor barrier layer at all, or there is not enough of it, then water vapor penetrates inside the roofing pie and encounters a “cold front” there, which turns the vapor into condensate, and under special circumstances, also into ice. And all this happens inside the roof! This ice will not bother you until spring comes and the outside air warms up, thereby warming the roofing elements. Then the accumulated ice will melt and form entire smudges on the slopes inside the house.
But with a properly equipped roof, condensation should not appear at all, and therefore, in fact, the difference between the smooth and rough side is not significant at least in this aspect.
What is the difference between anti-condensation film and “anti-condensation side”?
As we have already said, the majority modern manufacturers They emphasize that their vapor barrier films have a so-called “anti-condensation side”:
The “anti-condensation” side differs from the usual one in the presence of a fleecy layer that absorbs a small amount of condensation and holds it until it evaporates.
Thanks to this, the risk of the film surface getting wet is much lower, which extends the service life of the interior finishing of the roofing cake. That is why the rough side should always be directed inside the living room or attic, and the smooth side should be leaned against the insulation. But is this really so?
Practice shows that if condensation forms inside the roofing pie, then the fleecy side of the film cannot help in this regard, and there is not much difference whether these drops adhere to the film or flow down. The fact that they exist at all is bad in itself. The anti-condensation side of the vapor barrier and the anti-condensation waterproof film on the other side of the insulation are completely two different things!
Therefore, let's summarize: the “correct” side of the vapor barrier is not equivalent in terms of the properties of the anti-condensation film: it does not remove water vapor, does not destroy drops of moisture and does not solve the problem with condensation.
But, if you are still in the process of building a roof, then for the sake of peace of mind, do as the manufacturer instructed in the attached instructions. If you have already installed a vapor barrier and are in doubt whether it is correct, forget it and don’t worry anymore. But if you hope that the “right” side of the vapor barrier will take care of all the future shortcomings of the roofing pie, don’t believe it.
Experienced roofers often declare that they consider the whole epic about which side to attach the vapor barrier to be a kind of shamanism. Allegedly, by complicating the product, they increase its positioning in the market. But in fact, as we have already said, with a well-equipped vapor barrier, there shouldn’t be any droplets on the walls, otherwise even the lining on the walls will swell and the wallpaper will fall off, since everything is so serious.
After all, this only happens when there are serious mistakes during roof construction. In addition, if your vapor barrier itself is located between drywall and mineral wool, then with such complex design there's no point in messing around at all. Drywall itself absorbs moisture well, and steam will practically not be able to reach the internal vapor barrier. In this design, even simple glassine is quite acceptable!
For example, some curious roofers even conduct their own vapor barrier tests to determine whether the “wrong” side is working or not:
And especially the shrewd ones even say that with rough side polyethylene vapor barrier is obtained simply in the factory, when polyethylene is combined with non-woven material: the film is glued to a rough layer, and the finished product actually has two different sides. And there is no point in modifying the second side so that it also becomes smooth by connecting it to another layer of polyethylene: the vapor barrier properties will not change, and the manufacturing process will become more expensive.
And therefore it is easier to give this meaning to the product itself. And in fact, quite a lot of people have already become convinced that, even if they mix up the sides of the vapor barrier, nothing like that happens, and the film works the same on both sides, fully performing its functions.
Therefore, in any case, just strive to implement roof steam protection correctly, think through all the necessary details and not skimp on quality!
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Construction work, regardless of purpose, cannot be done without an insulating layer, due to which the quality and service life of the building significantly increases. The most important insulating material is vapor barrier, which ensures the correct microclimate in the under-roof space, as well as in wall structures. Working with it does not cause any particular difficulties, however, every developer should know how to properly attach a vapor barrier.
Types of insulating materials and technology for their construction
There are several types of vapor barrier, and in each specific case it is necessary to take into account the presence certain features material.
The most common materials for vapor barrier include:
- pasting, for installation of which an adhesive composition is used. The integrity of the insulating layer is ensured by the tight fit of the material to the surface of the structure;
- painting;
- grouting materials.
When working with film, it does not matter how the vapor barrier is attached, that is, it can be turned with either side to the base and nailed with small nails or staples. Facial and inner side This type of insulation fiber is absent, which greatly simplifies working with it.
Installation of film depending on its type
It should be remembered that the film is attached depending on a certain gap and its maximum tension level. Since the material has an impenetrable structure, air freely penetrates through the gap into the insulated space. This type of material has a slightly modified copy - with a rough front side, which serves for the timely release of steam to the outside. If necessary, it is permissible to lay two layers of film, with the glossy side facing each other.
As a more modern insulation, manufacturers offer wide possibilities applications. When laying it, the front side must face outward to allow air to flow to the structural elements and release moisture from them.
To determine the correct placement of the material, just look carefully at its canvas - there is a special mark there. Such films are available in two types: single-sided and double-sided, which are used depending on the characteristics of the work being performed.
Vapor barrier films are offered with reflective properties, and they are also called penofol. On one side of this material a foil layer is applied, due to which the film is widely used in baths and steam rooms. In addition, it is necessary during the construction frame houses, where the main construction material– these are galvanized metal profiles. This insulation is fastened quite quickly and simply, but when working with structures endowed with special properties and characteristics, some difficulties may arise.
Preparation of the primary base for vapor barrier material
Developers who do not have sufficient experience in performing construction work often wonder which side to lay the vapor barrier so that it reliably protects the roof from negative factors. To answer this, you should take the time to Special attention completely to the whole stage.
Initially, a primary base must be prepared, where the insulation layer will be attached. In most cases, this will require ordinary lumber that has been cleaned, dried and primed.
This type of insulation does not require special tension, but the film should not sag in the spaces between the elements of the main structure. Under no circumstances should you use staples, nails or other fasteners that could perforate the material or compromise the integrity of the canvas. Experts recommend attaching such insulation to a strong adhesive tape, which ensures a high-quality connection of the film with the primary base.
The material is supplied to the market in rolls, so it is very convenient to work with it, cutting strips of the required length. To form a complete layer of material, a slight overlap should be made when placing the cut pieces.
Thanks to this type of insulation, a number of actions are carried out that have a positive effect on the building as a whole:
- evaporation of residual and excess moisture without the formation of condensation in the under-roof or inter-wall space;
- microclimate is regulated as in interior spaces, and in the roofing structure;
- increases the service life of individual building elements and the whole house, cottage.
Installation of vapor barrier materials directly on top of the roof is allowed. In this case, solutions made from bitumen, special varnish and mastic are more suitable. This installation is relevant in the case of arranging some roof structures, most often used for the construction of high-rise buildings and those covered with soft roofing material. Grout insulation materials can be used as a base for cement mortar, poured according to construction requirements.
Self-installation of insulation film
So, initially, you need to determine how much film will be needed to complete the work. If you skip this stage, it may turn out that there is not enough material, or too much, which is fraught with additional material costs. To correctly calculate material consumption, you need to have a clear understanding of total area, and to the resulting value add about 15% for the reserve, which will be used to overlap the material, as well as replace damaged pieces (read also: " "). It is impossible to complete the work without special tools, so you also need to take care of their preparation in advance. Stock up on a pencil, tape measure, utility knife, adhesive tape, stapler and other equipment necessary for construction.
It is better to secure the canvas before insulation of the room begins. In order for the insulation system to function effectively, experts recommend checking the correct location of the film in relation to the structure. The material needs to be slightly stretched. Make sure there are no wrinkles on it.
Regardless of which side the vapor barrier is laid on, it is imperative to maintain an overlap of at least 50 mm between the two slabs of material - this is the only way to guarantee the integrity of the insulating layer. To connect each strip, you need to use adhesive tape, the structure of which allows you to securely fasten the insulation without damaging it. To completely prevent damage to the interlayer during subsequent operation, carefully inspect the strips of material - if there are even small defects, it is better to replace the damaged material with a whole sheet. The highest quality insulating layer will be obtained if the strips are laid with a slight overlap not only among themselves, but also on the walls (150 mm is enough), as shown in the photo.
Now we will dwell in detail on how to correctly place the selected insulating film on the base.
Despite the fact that all insulating materials perform the same function, the requirements for their placement do not provide for a single pattern. This fact is explained by the fact that each type of insulation requires a special fastening that ensures reliable fixation of the material to the structure.
When choosing special types of films that are produced without the inner and front sides, the work is greatly simplified. In other cases, if the material is placed incorrectly, the opposite protective effect will be created.
An example is the function of a membrane film - it is to allow wet vapors to pass out and prevent moisture from penetrating inside. If the developer confuses which side to attach the vapor barrier, then a reverse reaction will result, which is fraught with rapid destruction of the wooden elements. Thus, moist air from the street will be drawn into the room, in which additional fumes will accumulate that have not gained access to the outside. In a word, such a system will lead to a significant reduction in the service life of the building.
Features of installation of roofing and wall vapor barriers
Performance insulation works can be placed at the basis of the entire construction, since in the absence of such a protective layer the frame structure or rafter roofing system will not be able to fully perform its functions, which means it will be subject to rapid wear and tear.
Depending on the availability and use of thermal insulation, the installation of vapor barrier materials will be determined. If there is no insulation in the under-roof pie, attention should be paid to how to lay a vapor barrier: it is laid as a layer between the sheathing and the rafter system. Thus, the rafters are protected from the accumulation of moisture, due to which fungus and mold will appear over time.
Using attic space like a second residential floor, roof structure must be installed with high-quality insulation using mineral wool or foam boards. Latest material dangerous due to the release of chemical particles as a result of strong heating.
So, when performing thermal insulation, a double vapor barrier layer is installed, which will protect not only rafter system, but also the insulation itself. According to special requirements, we pre-check correct location sides of the film - this is the only way to be sure of the complete safety of the building material during operation.
If the installation of insulating material is carried out to wall structures, then the installation requirements are completely different. In this case, you need to determine the purpose of the walls in the building, and also pay attention to what they are made of. The most popular are interior partitions, with the help of which a living space is delimited into several zones. Such walls are usually erected from frame structures with double-sided cladding.
For filling interior partitions you will need insulation and soundproofing materials, necessary for a high-quality and comfortable microclimate in the house. This design does not require insulation equipment, only if it does not border the kitchen or bathroom, where steam is constantly generated and moisture settles on the walls.
How to properly attach a vapor barrier, more details in the video:
Let's look at how to properly install a vapor barrier in this case.
Inside the partition itself, where the insulation material, it is necessary to build a protective layer that would prevent the penetration of moist air. The function of such protection is assigned to a vapor barrier film laid on both sides of the thermal insulation so that there are no gaps. To make the canvas complete, you need to connect it individual elements adhesive tape - it does an excellent job not only with two, but also with several insulation elements. The insulating material itself of the required amount is carefully cut from the roll, even if minor damage you need to replace it with a new one.
So, installing a vapor barrier is a mandatory stage of any construction work, which will result in a high-quality structure that is ready to last a long period of time.