Modern construction cannot be imagined without thermal insulation. At the same time, even the highest quality insulation material will not be able to function effectively enough if it is not protected by properly installed roofing and wall vapor barriers.
Vapor barrier of the roof is necessary in order to prevent the appearance of condensation on the materials that serve as roof insulation. The production of this type of work is very important stage for the construction of warm and cozy home, especially in the case frequent changes outside temperatures. Proper vapor barrier reliably protects the roof. If errors were made during the installation, the thermal insulation quickly loses its properties. functional characteristics, the house becomes damp, mold and mildew may develop. That is why, when repairing a roof, it is advisable to carry out thermal insulation of the roof and vapor barrier of the roof simultaneously.
Equally important is the vapor barrier of walls: after all, any building very quickly loses heat through the walls. If the installation work was carried out efficiently and professionally, the house will always be cozy and warm, and the walls will be reliably protected from getting wet as a result of diffusion. When carrying out work, a layer of material with a fairly high degree of diffusion resistance is most often used. Usually materials such as roofing felt, glassine, aluminum foil, polyethylene. If selected sheet material, the seams must be carefully sealed.
Vapor barrier of walls
It can be external and internal. Before you choose best option, take into account the area of the walls and the material that was used to build the house. If the building is supplemented with a veranda, it plays the role of a kind of air cushion that prevents heat loss. In this case, work costs will be kept to a minimum. It is somewhat more difficult to perform a vapor barrier on concrete and brick houses: such structures have high thermal conductivity and are characterized by high heat transfer. External vapor barrier of walls can be done in one of three ways:
- “sandwich” - wall + thermal insulation + external panel;
- fastening the insulation to the wall using a special adhesive composition;
- ventilated facade.
Advantages of the method: you can carry out work at any time of the year, insulate only the coldest areas, corners, joints; the architectural appearance of the house is not disturbed.
Roof vapor barrier
The material used as roof insulation must remain moisture resistant for a long time and meet all requirements fire safety, and also be environmentally friendly and not emit toxic substances during operation. Heat loss is significantly reduced if the roof is supplemented with an attic, as well as in the case pitched roof. For such roofs, the requirements for roofing material somewhat softer: the main thing is that it should not shrink - this can lead to the formation of “cold bridges”.
Vapor barrier materials
There is simply no universal vapor barrier material that could be used to cover the entire building, from the roof to the foundation. The choice of material largely depends on the goals you set for yourself. However, in any case, when choosing a material, pay attention special attention on its properties such as reliability, fire resistance and reliability. In addition, thermal conductivity is very important: the lower it is, the less material you will need for laying vapor barrier layers.
Is vapor barrier of walls and roof always necessary? There is no need for work if the walls of the building are insulated from the outside with a material that has low diffusion resistance; when the walls of the building are constructed from a homogeneous material, as well as in the case of “breathing” walls.
If you decide to organize thermal insulation protection, you need to seek the services of specialists - only a professional organization will provide a warm and dry home.
Materials for vapor barrier.
VAPOR PROOF, OR HOW TO “KILL” VAPTOR PERMEABILITY.
The reason for writing this article was the numerous requests from our clients, who used it at their facilities as the main construction material for masonry walls gas silicate blocks, also called aerated concrete blocks
. Within the framework of this article, there is no need to once again list all the main properties of this material, but one indicator of aerated concrete is one of the defining ones. And this indicator is the coefficient of vapor permeability.
So what is the vapor permeability of a material and in what units is it measured? By definition, the vapor permeability of a material is the ability to transmit or retain water vapor as a result of the difference in partial pressures of water vapor at the same atmospheric pressure on both sides of the layer of material. This ability is characterized by the value of the coefficient of vapor permeability or the inverse value - the resistance to water vapor permeability. Typically, vapor permeability is indicated in milligrams of water vapor passing through a layer with a thickness expressed in meters in 1 hour with a difference in partial pressure of water vapor of 1 Pa. Vapor permeability coefficients for various materials can be found in table SNIP II-3-79. For gas silicate, this value, depending on the density, is in the range of 0.17 – 0.25. For comparison, for ordinary concrete or reinforced concrete it is only 0.03, for cement-concrete sand mortar– 0.09, for cement-lime sand mortar – 0.12. So, as we see, the vapor permeability of gas silicate is very high. To determine the vapor permeability resistance of a specific wall made of a homogeneous material, it is necessary to divide the thickness of the material layer (in meters) by the coefficient corresponding to the material from the SNIP II-3-79 table. The vapor permeability resistance of a multilayer enclosing structure is determined by the sum of the vapor permeability resistances of its constituent layers. It should be noted that mainly when modern construction Multi-layer enclosing structures are used, with one layer of the “pie” being insulation (most often the cheapest is mineral wool). To avoid the accumulation of moisture in the enclosing structure, which can lead not only to loss of heat-saving properties (especially if the insulation is mineral wool), but also to destruction of the enclosing structure itself, the thickness of all layers should be calculated so that the dew point is carried into the insulation layer. This case is generally accepted as optimal. In this regard, when designing a building envelope, it is necessary to pay attention not only to calculating the thermal conductivity of the structure, but also to calculate its vapor permeability in accordance with SNIP II-3-79.
So, many consumers suddenly make the following discovery for themselves: gas silicate 7 (!) times more permeable to water vapor than ordinary concrete. And since correct design wall “pie” is considered to be one in which the vapor permeability of each subsequent layer is greater than the previous one in the direction from inside the room to the street, they come to the absolutely correct conclusion that in the area, as mathematicians say, real numbers of such a design simply cannot exist - there are no such materials. And then they decide simply “ kill vapor permeability”, rightly believing that if even ordinary concrete roofs with a coefficient of 0.03 are supposed to be vapor-insulated before laying insulation, then gas silicate with its average of 0.20 is God’s order.
Vapor barrier performs the function of a vapor barrier and serves to reduce the flow of diffusing water vapor from inside the room to the outside, and also reduces the risk of condensation in the insulated structure. Meanwhile, no recommendations on how remove vapor permeability Manufacturers of gas silicate blocks do not provide their favorite products. And then clients call us.
There is no need to reinvent the wheel for the coating to become a vapor barrier. There are many methods of partial or complete vapor barrier. The simplest vapor barrier method- this is to lay under one of the internal finishing coatings, for example, under drywall, simple ordinary polyethylene film. However this method is fraught with possible accumulation of condensation and subsequent inevitable swelling of the wall. Note that even simple vinyl wallpaper reduces vapor mass transfer by 8-10 times.
One of the common methods of reliable vapor barrier is to use as plaster a thick layer of the most common mixture based only on sand and cement (the so-called “Armenian” version) without additives dolomite flour or lime with a thickness of at least 2.5 - 3.5 cm. Such a coating already reduces steam transfer by 5-6 times, which is sometimes quite sufficient. However, we do not recommend using such a vapor barrier, since sometimes peeling and even crumbling of the plaster is observed due to the high water absorption capacity of aerated concrete, although the main choice remains with the customer. But we offer three options for vapor barrier finishing using our products.
According to the first option, we suggest before carrying out any internal plastering works on gas silicate, carry out priming of the walls three to four times with a special composition “”. With a composition consumption of 1.2 kg per 1 sq. m. the vapor permeability of the wall is reduced by 5-6 times. Further, the addition of this concentrate when mixing the plaster into water in an amount of only 15% makes it possible to reduce the vapor permeability of conventional gypsum plaster another 3 - 4 times, and cement - 2-2.5 times (less water is used for cement) with a thickness of the plaster layer of only 10 -15 mm. As a result, we get the desired effect. If you then paint the wall with a special paint with low vapor permeability (this can be ordinary oil paint), or paste it over vinyl wallpaper, then “killing” the vapor permeability of the wall can be considered a solved problem. As a result, we achieve the desired result - this reliable vapor barrier.
According to the second option, we propose to carry out pre-treatment interior walls special composition "", diluted with water in a ratio of 1:2 - 1:3 and with a flow rate of 1.0 to 1.5 kg per 1 square meter, which leads to a decrease in the vapor permeability of the wall by 6-8 times. The composition works similarly if you use this composition instead of water when mixing plasters.
Finally, according to the third option, we propose to cover the inside of walls made of gas silicate with a thin - 3-4 mm thick - layer of a composition unique in its properties. This treatment completely blocks the flow of air and steam through the walls. As a result, the presented material can be used as vapor barrier mixture. Then any leveling layer of plaster and/or putty can be applied to the resulting vapor barrier (and at the same time waterproofing!) coating, or attached facing tiles, but the type of coverage no longer matters.
Vapor barrier serves to protect the roof structure from the penetration of condensation, water vapor and moisture. If you perform a vapor barrier correctly, it is quite possible to provide it inside the house comfortable atmosphere and extend the life of the roofing covering. Vapor barrier for the roof is one of the most important structural elements of the house, which to a small extent determines the efficiency of work roofing pie and roof service life.
For various types For roofs, the number of layers may vary, but three of them are thermal insulation, waterproofing and vapor barrier of the roof, as a rule, are unchanged. It is very important to understand that roofing vapor barrier and waterproofing function differently: the first prevents steam from escaping from interior spaces into the roof pie, and the second prevents moisture from penetrating into the building.
Vapor barrier - what is it?
Living quarters, one might say, are always warm. Water vapor, which is always present there, warms up and rushes upward into the under-roof space. Due to the temperature difference, steam condenses and settles on the thermal insulation.
With the onset of cold weather, the vapor lingering in the insulation layer gradually begins to freeze, and eventually the entire layer freezes completely. As the temperature rises, it begins to thaw. The resulting water flows down and moistens the upper sections of the walls and ceilings. Wet insulation thus worsens its protective characteristics.
And after several such cycles it will become completely unusable. For example, soft insulation based on mineral wool will collapse in one cycle, but polystyrene foam will last longer.
Moreover, in wet areas of the structure favorable conditions are created for the formation of fungus, mold and rot, which does not in the best possible way is reflected in the living conditions.
Avoid these and others negative impacts couple on roof structure Roof vapor barrier, which is performed using special materials, will help.
Attention!
For those who want to save on roof vapor barrier installation, we specifically note that it will cost much less than installing repair work and eliminating the consequences of biocontamination.
The main task of the vapor barrier layer, which is laid under the thermal insulation layer, is to protect it from moisture that comes from the room. This becomes especially important if the humidity inside the building exceeds 60%.
To emphasize the importance of a vapor barrier device, just one simple example. Quite often, stone or mineral wool is used as insulation. As is known, this material easily adsorbs moisture contained in the air, which is extremely undesirable - mineral wool, when moistened by 5%, saves only 50% of heat.
Note
If the humidity of the insulation increases by only 1%, it loses its ability to retain heat by 32%, but if the humidity increases by 5%, then its characteristics deteriorate by 50%.
How to choose the right vapor barrier material
The construction market today is distinguished by a wide range of materials for roof vapor barrier. They are designed to solve the same problems, but at the same time differ in their physical and operational characteristics.
Let's try to figure out which vapor barrier is better for the roof. Let's start with the main criteria that this insulating material:
- Vapor permeability. It characterizes the speed at which steam pressure equalizes between adjacent parts of the under-roof space into which the roof vapor barrier divides it. This indicator is determined by the structure and thickness of the vapor barrier. The greater the thickness, the lower the vapor permeability of the material.
- Strength. Rather, it is an installation characteristic that determines the reliability of the coating. The best vapor barrier for roofing does not tear during installation and can withstand maximum loads. Obviously, the greater the safety margin of the material, the more reliable the coating will be.
- Water resistance. Water should be well retained on the surface of the vapor barrier on the roof should be well retained by water. Only then will moisture not be able to penetrate the insulation and inside the house.
- Fire safety. The insulation must be fire resistant.
- Environmental friendliness. The raw materials used in production must be safe, and the process itself must be technologically pure.
- Sustainability. This indicator indicates the ability of the material to retain its quality characteristics for a long time.
- Durability. This important indicator, since the service life of the roofing pie depends on it.
Types of material
Conventionally, materials can be classified into the following types: anti-condensation films and diffuse membranes.
Anti-condensation films are used for additional protection, in particular, from rain flowing into ventilation inlets or roof leaks, etc. This material is installed under the roofing. The films prevent drops of moisture from flowing down, and the moisture dries out.
Diffuse membranes are an exceptional material capable of transmitting water vapor, which, having formed in the premises, rises under the roof due to convection processes. They are installed on inside insulation.
- Polyethylene film for roof vapor barrier is considered to be quite a popular material today. She is one of the universal materials, which can be used for both steam and waterproofing. This type polyethylene film, as a rule, is made of reinforced mesh or fabric. This allows you to significantly increase the strength indicators compared to conventional ones.
The surface on which the paint vapor barrier is applied is thoroughly cleaned of dirt and dust and dried. All irregularities must be eliminated using grout. After that, mastic is applied in an even layer, without missing a single section.
Vertical surfaces on the roof, such as the walls of attic exits, chimneys or exits ventilation ducts They are also covered with mastic to a height of approximately 20 cm. When applied, mastics must be heated:
- bitumen – up to 180°C,
- tar - up to 160°C,
- Gudrokam - up to 70°C,
- rubber-bitumen – up to 200°C.
Pasting
According to the instructions, vapor barrier of the roof in both pitched and flat roof laid after installing the heat-insulating layer. A roof vapor barrier using a film is called adhesive film.. It is arranged according to the following principle: if the air humidity inside the building is up to 75%, one layer of film is laid, and above this value - two.
Carrying out this process yourself is quite simple:
- roll material easy to cut;
- fixed on wooden structures using galvanized nails or staples;
- for the reliability of the vapor barrier, laid with a slight overlap, the joints are glued with connecting tapes;
- On top of the resulting layer, bars pre-treated with antiseptics are stuffed in half-meter increments. This creates ventilation gap, through which the condensate evaporates.
Note
When using some types of membranes, a counter-lattice is not necessary. Although, the resulting air corridor can be used for various communications.
Pasted vapor barrier is laid according to the principle. Protective layer sealed using construction tape, as well as soldering the edges.
Some important nuances of technology
- The direction of laying the insulation sheets can be either vertical or horizontal. When installed vertically installation work start from the top of the structure.
- The minimum overlap is 100 mm.
- To seal the joints, use tape at least 100 mm wide. Connecting adhesive tapes manufactured at different bases. It is not recommended to use products based on butyl rubber or polyurethane for sealing due to insufficient adhesiveness - after time they will simply move away from the surface.
- If the connecting tape is double-sided, first it is glued inside the overlap, securing it to the bottom sheet, after which the top sheet is fixed with an overlap. Accordingly, the protective coating is removed from each side of the tape before gluing.
- When the film is laid along the rafters and the rough sheathing of the insulation is not carried out, the overlap of the sheets and their fastening should be on the rafters.
Attention!
It is unacceptable for the vapor barrier film to envelop the rafters, otherwise the roof will begin to rot due to condensation getting on the wood.
- For roofs with a slope greater than 30° or when between sheets thermal insulation material There remains a small gap; it is recommended to use special clamping strips for additional fixation of the vapor barrier.
- Finishing adjoining passages or areas around window openings has its own characteristics. In these places it is necessary to provide an overlap of the fabric in the form of folds 20–30 mm wide. Such a deformation margin will avoid possible damage films that may appear over time as a result of subsidence of the building.
- Insulation laid around during installation dormer window, protected with a special apron.
- Ventilation pipes in places where they pass through the roof, they are wrapped in a vapor barrier film, turning the material down, and securely secured with construction tape.
- In areas where the insulation is adjacent to the supporting wall, chimneys, ventilation openings and other roofing elements, you need to pay attention to the type of surface to which the vapor barrier is fixed. If it is uneven or lumpy, such as the surface of untreated wood, brick and other films, the film is glued to a special adhesive composition on an acrylic or rubber base.
- When installing foil vapor barrier film It is recommended to use aluminum-coated products as connecting tapes.
Roof vapor barrier: video
A little about ventilation gaps
Usage vapor barrier materials having a very low coefficient of vapor permeability, of course, protects the thermal insulation from the effects of vapors from the interior, however, the natural air exchange of the attic is disrupted, humidity increases there, which can contribute to the formation of condensation. Condensation can also form due to the temperature difference between inside and outside the building.
Due to condensation, mold may develop and decrease thermal insulation properties insulation - having been saturated with moisture, it begins to conduct the cold better.
Therefore, two ventilation gaps are created under the roof using sheathing.
Condensation, which forms when the temperature changes inside and outside the room, renders thermal insulation unusable and causes fungus and mold. To combat it, use a vapor barrier, which is a mandatory part of the work when insulating and waterproofing.
Bitumen-polymer compositions have proven themselves to be excellent for these purposes. They are viscous homogeneous mixtures that do not require preheating - unlike conventional bitumen mastics. They're not afraid low temperatures, easy to use, applied quickly, which is important for builders. When hardened, bitumen-polymer mastics form a reliable vapor barrier membrane.
Practical advantages:
- Excellent adhesion to any surfaces;
- Elasticity and strength;
- Wide area applications;
- Ease of application;
- Environmental friendliness;
- Long term services.
Coating vapor barrier from the company "Giz-Technologies"
The company "Giz-Technologies" offers a unique mastic "GizElast", which traditionally performs the functions of 100% waterproofing, as well as 100% vapor barrier, while affordable prices. The composition is widely used in both industrial and private construction.In order to work with mastic, you do not need to have special professional skills. It is enough just to stir the one-component solution and cover the surface to be treated with it. The material is applied in one, or better yet, in two layers. Consumption is 1-2 kg per 1 m².
The composition is also suitable for application to smooth surfaces- such as walls and ceilings, and for use in sealing seams and joints. This allows you to quickly and easily treat surfaces, making them completely vapor-tight. In order to achieve maximum effect from the work performed, when choosing materials, you should first of all pay attention to their quality.
We offer only the highest quality products.
GizElast mastic is always in stock. You can buy it and order delivery right here on the website, or by calling: +7 495 231-9661
Price:
The Technoprok company offers 2 alternative materials for vapor barrier of walls.
- emulsions and mastic compositions (made in Israel), known in Russia as liquid rubber.
- Eurovent roofing films (made in Germany), also known as roofing membranes.
Despite the fact that films are “under-roofing”, they are a traditional material for vapor barrier of walls. Most builders know only this material and for many it is a revelation that vapor barrier of walls can be done with liquid or paste waterproofing materials.
Vapor barrier of walls with films
If someone prefers to make a vapor barrier on the walls the old fashioned way or has those 2 restrictions mentioned above, then the Technoprok company offers wide choice various diffusion films trademark Eurovent.
Eurovent diffusion membranes with high vapor permeability are used as an under-roof covering for pitched insulated roofs, as well as for vapor barrier of walls.
Eurovent vapor barrier films are products characterized by high mechanical strength, which is one of them key properties for high-quality vapor barrier.
High UV stability (4 months) does not limit the time it takes to complete the work before installing the roof. This is not so important for vapor barrier of walls from the inside, but is a significant factor when installing vapor barrier of walls from the outside or when installing roof vapor barrier.
The advantage of Eurovent brand products is, undoubtedly, their durability, confirmed by wear tests carried out in one of the leading laboratories in Germany, Institut für textile Bau und Umwelttechnik GmbH w Greven.
Testing products using simulated wear conditions is one of the requirements of the European standard EN13859-1. This standard applies to materials used as underlayment for pitched roofs.
The Technoprok company presents single-layer and multilayer membranes and films from the German company “EVROSYSTEM”, among which you can choose the optimal one for each task. Vapor barrier membranes designed to protect not only the roof, but also the wall and floor from exposure to vapors, preventing the appearance of fungi, mold and rot in the wood..
Areas of application of vapor barrier LLC Technoprok
Besides vapor barrier of walls, liquid rubbers, both emulsions and mastics, are the most convenient and reliable materials when proper hydro- and vapor barrier of the floor is required. This is especially true for the first floor located above the basement or in wooden house or in damp room(shower room, bathhouse, laundry room, swimming pool, etc.).
In order for the building to be dry and warm in any weather, it is necessary to carry out competent and high-quality roofing work, one of the conditions of which is a properly implemented roof vapor barrier. Using liquid rubber for flat roof It is also convenient because it allows you to quickly and efficiently install a vapor barrier layer over a large area.
In order for the vapor barrier of a house to be effective, protect the building from the penetration of moisture from the outside and protect the insulation from exposure to moist air, it is necessary to understand what steam, condensation and dew point are.
Technoprok company specialists will advise you on the use of vapor barriers and wind barriers. In addition, we have very affordable prices for the entire range. In our warehouse we always have liquid rubber and waterproofing mastics, geotextiles and drainage membranes - in short, everything that is necessary for installing a vapor barrier and.
