To create a favorable indoor microclimate, it is necessary to take into account the properties building materials. Today we will look at one property - vapor permeability of materials.
Vapor permeability is the ability of a material to allow vapors contained in the air to pass through. Water vapor penetrates the material due to pressure.
Tables that cover almost all materials used for construction will help you understand the issue. Having studied this material, you will know how to build a warm and reliable home.
Equipment
If we're talking about about prof. construction, it uses special equipment to determine vapor permeability. This is how the table that appears in this article appeared.
The following equipment is used today:
- Scales with minimal error - analytical type model.
- Vessels or bowls for conducting experiments.
- Tools with high level accuracy for determining the thickness of layers of building materials.
Understanding the property
There is an opinion that “breathing walls” are beneficial for the house and its inhabitants. But all builders think about this concept. “Breathable” is a material that, in addition to air, also allows steam to pass through - this is the water permeability of building materials. Foam concrete and expanded clay wood have a high rate of vapor permeability. Walls made of brick or concrete also have this property, but the indicator is much less than that of expanded clay or wood materials. 
Steam is released when taking a hot shower or cooking. Because of this, increased humidity is created in the house - a hood can correct the situation. You can find out that the vapors are not escaping anywhere by looking at the condensation on the pipes and sometimes on the windows. Some builders believe that if a house is built of brick or concrete, then it is “hard” to breathe in the house.
In reality, the situation is better - in a modern home, about 95% of the steam escapes through the window and hood. And if the walls are made of “breathing” building materials, then 5% of the steam escapes through them. So residents of houses made of concrete or brick do not particularly suffer from this parameter. Also, the walls, regardless of the material, will not allow moisture to pass through due to vinyl wallpaper. “Breathing” walls also have a significant drawback - in windy weather, heat leaves the home.
The table will help you compare materials and find out their vapor permeability indicator:
The higher the vapor permeability index, the more moisture the wall can absorb, which means that the material has low frost resistance. If you are going to build walls from foam concrete or aerated block, then you should know that manufacturers are often cunning in the description where vapor permeability is indicated. The property is indicated for dry material - in this state it really has high thermal conductivity, but if the gas block gets wet, the indicator will increase 5 times. But we are interested in another parameter: the liquid tends to expand when it freezes, and as a result, the walls collapse.
Vapor permeability in multilayer construction
The sequence of layers and the type of insulation are what primarily affect vapor permeability. In the diagram below you can see that if the insulation material is located on the facade side, then the indicator of pressure on moisture saturation is lower. 
If the insulation is located with inside at home, then between load-bearing structure and this construction will cause condensation. It negatively affects the entire microclimate in the house, while the destruction of building materials occurs much faster.
Understanding the coefficient
The coefficient in this indicator determines the amount of vapor, measured in grams, that passes through materials 1 meter thick and a layer of 1 m² within one hour. The ability to transmit or retain moisture characterizes the resistance to vapor permeability, which is indicated in the table by the symbol “µ”.
In simple words, coefficient is the resistance of building materials, comparable to the permeability of air. Let's look at a simple example: mineral wool has the following vapor permeability coefficient: µ=1. This means that the material allows moisture to pass through as well as air. And if you take aerated concrete, then its µ will be equal to 10, that is, its vapor conductivity is ten times worse than that of air.
Peculiarities
On the one hand, vapor permeability has a good effect on the microclimate, and on the other hand, it destroys the materials from which the house is built. For example, “cotton wool” perfectly allows moisture to pass through, but in the end, due to excess steam on windows and pipes, cold water Condensation may form, as indicated in the table. Because of this, the insulation loses its quality. Professionals recommend installing a vapor barrier layer with outside Houses. After this, the insulation will not allow steam to pass through. 
If the material has a low vapor permeability rate, then this is only a plus, because the owners do not have to spend money on insulating layers. And get rid of the steam generated from cooking and hot water, a hood and a window will help - this is enough to maintain a normal microclimate in the house. When a house is built from wood, it is impossible to do without additional insulation, and wood materials require a special varnish.
The table, graph and diagram will help you understand the principle of operation of this property, after which you can already make your choice suitable material. Also, do not forget about climatic conditions outside the window, because if you live in an area with high humidity, then you should completely forget about materials with a high vapor permeability rate.
We supply building materials to the cities: Moscow, St. Petersburg, Novosibirsk, Nizhny Novgorod, Kazan, Samara, Omsk, Chelyabinsk, Rostov-on-Don, Ufa, Perm, Volgograd, Krasnoyarsk, Voronezh, Saratov, Krasnodar, Togliatti, Izhevsk, Yaroslavl, Ulyanovsk, Barnaul, Irkutsk, Khabarovsk, Tyumen, Vladivostok, Novokuznetsk, Orenburg , Kemerovo, Naberezhnye Chelny, Ryazan, Tomsk, Penza, Astrakhan, Lipetsk, Tula, Kirov, Cheboksary, Kursk, Tver, Magnitogorsk, Bryansk, Ivanovo, Ulan-Ude, Nizhny Tagil, Stavropol, Surgut, Kamensk-Uralsky, Serov, Pervouralsk , Revda, Komsomolsk-on-Amur, Abakan, etc.
08-03-2013
30-10-2012
World wine production is expected to fall by 6.1 percent in 2012 due to poor harvests in several countries of the world,
What is vapor permeability
10-02-2013Vapor permeability, according to the set of rules for design and construction 23-101-2000, is the property of a material to transmit air moisture under the influence of a difference (difference) in the partial pressures of water vapor in the air on the inner and outer surfaces of the material layer. The air pressure on both sides of the material layer is the same. The density of a stationary flow of water vapor G n (mg/m 2 h), passing under isothermal conditions through a layer of material 5 (m) thick in the direction of decreasing absolute air humidity is equal to G n = cLr p / 5, where c (mg/m h Pa ) - coefficient of vapor permeability, Ar p (Pa) - difference in partial pressures of water vapor in the air at opposite surfaces of the material layer. The inverse value of c is called vapor permeation resistance R n = 5/c and refers not to the material, but to a layer of material with a thickness of 5.
Unlike air permeability, the term “vapor permeability” is an abstract property, and not a specific amount of water vapor flow, which is a terminological shortcoming of SP 23-101-2000. It would be more correct to call vapor permeability the value of the density of the stationary flow of water vapor G n through a layer of material.
If, in the presence of air pressure differences, the spatial transfer of water vapor is carried out by mass movements of the entire air together with water vapor (wind) and is assessed using the concept of air permeability, then in the absence of air pressure differences there is no mass movement of air, and the spatial transfer of water vapor occurs through chaotic movement water molecules in still air in through channels in a porous material, that is, not convective, but diffusion.
Air is a mixture of molecules of nitrogen, oxygen, carbon dioxide, argon, water and other components with approximately the same average speeds, equal to the speed of sound. Therefore, all air molecules diffuse (chaotically move from one zone of gas to another, continuously colliding with other molecules) at approximately the same speeds. So the speed of movement of water molecules is comparable to the speed of movement of molecules of both nitrogen and oxygen. As a result, the European standard EN12086 uses, instead of the concept of vapor permeability coefficient μ, the more precise term diffusion coefficient (which is numerically equal to 1.39 μ) or diffusion resistance coefficient 0.72/μ.
Rice. 20. The principle of measuring the vapor permeability of building materials. 1 - glass cup with distilled water, 2 - glass cup with a drying composition (concentrated solution of magnesium nitrate), 3 - material to be studied, 4 - sealant (plasticine or paraffin mixture with rosin), 5 - sealed thermostated cabinet, 6 - thermometer, 7 - hygrometer.
The essence of the concept of vapor permeability is explained by the method for determining the numerical values of the vapor permeability coefficient GOST 25898-83. A glass cup with distilled water is hermetically covered with the sheet material being tested, weighed and placed in a sealed cabinet located in a thermostated room (Fig. 20). An air dehumidifier (a concentrated solution of magnesium nitrate, providing a relative air humidity of 54%) and instruments for monitoring temperature and relative air humidity (a thermograph and a hygrograph that continuously records are desirable) are placed in the cabinet.
After a week of exposure, the cup of water is weighed, and the vapor permeability coefficient is calculated from the amount of water that has evaporated (passed through the test material). The calculations take into account that the vapor permeability of the air itself (between the surface of the water and the sample) is 1 mg/m hour Pa. The partial pressures of water vapor are taken equal to p p = cppo, where p is the saturated vapor pressure at a given temperature, cp is the relative air humidity, equal to one(100%) inside the cup above the water and 0.54 (54%) in the cabinet above the material.
Data on vapor permeability are given in tables 4 and 5. Recall that the partial pressure of water vapor is the ratio of the number of water molecules in the air to total number molecules (nitrogen, oxygen, carbon dioxide, water, etc.) in the air, i.e., the relative countable number of water molecules in the air. The given values of the heat absorption coefficient (with a period of 24 hours) of the material in the structure are calculated using the formula s = 0.27(A,poCo) 0 "5, where A, po and Co are the tabulated values of the thermal conductivity coefficient, density and specific heat capacity.
Table 5 Vapor permeation resistance sheet materials and thin layers of vapor barrier (Appendix 11 to SNiP P-3-79*)
|
Material |
Layer thickness |
Resistance to vapor permeation, m/hour Pa/mg |
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Ordinary cardboard |
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Asbestos-cement sheets |
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Gypsum cladding sheets (dry plaster) |
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Wood fiber sheets |
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Wood fiber sheets |
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Roofing glassine |
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Ruberoid |
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Roofing felt |
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Polyethylene film |
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Three-layer plywood |
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Hot bitumen painting at once |
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Hot bitumen painting in two times |
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Oil painting twice with pre-putty and primer |
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Painting with enamel paint |
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Coating with insulating mastic for |
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Coating of butum-kukersol mastic at one time |
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Coating of butum-kukersol mastic twice |
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Conversion of pressure from atmospheres (atm) to pascals (Pa) and kilopascals (1 kPa = 1000 Pa) is carried out taking into account the ratio 1 atm = 100,000 Pa. In bath practice, it is much more convenient to characterize the content of water vapor in the air by the concept of absolute air humidity (equal to the mass of moisture in 1 m 3 of air), since it clearly shows how much water needs to be added to the heater (or evaporated in a steam generator). Absolute air humidity is equal to the product of relative humidity and saturated vapor density:
|
Temperature °C 0 |
||||||||||
|
Density saturated steam do, kg/m 3 0.005 |
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|
Pressure rich para rho, atm 0.006 |
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Pressure saturated steam rho, kPa 0.6 |
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Since the characteristic level of absolute air humidity in baths of 0.05 kg/m 3 corresponds to a partial pressure of water vapor of 7300 Pa, and the characteristic values of partial pressure of water vapor in the atmosphere (outdoors) are at 50% relative air humidity 1200 Pa in the summer (20 °C) and 130 Pa in winter (-10 °C), then the characteristic differences in partial pressures of water vapor on the walls of the baths reach values of 6000-7000 Pa. It follows that the typical levels of water vapor flows through the timber walls of bathhouses 10 cm thick are (3-4) g/m 2 hour in complete calm conditions, and based on 20 m 2 walls - (60-80) g/hour.
This is not so much, considering that a bath with a volume of 10 m 3 contains about 500 g of water vapor. In any case, if the walls are air permeable, during strong (10 m/sec) gusts of wind (1-10) kg/m 2 hour, the transfer of water vapor by the wind through timber walls can reach (50-500) g/m 2 hour. All this means that the vapor permeability of timber walls and ceilings of bathhouses does not significantly reduce the moisture content of wood wetted with hot dew during supply, so that the ceiling in a steam bath can actually get wet and work as a steam generator, mainly humidifying only the air in the bathhouse, but only when carefully protecting the ceiling from gusts of wind.
If the bathhouse is cold, then the differences in water vapor pressure on the walls of the bathhouse cannot exceed 1000 Pa in the summer (at 100% humidity inside the wall and 60% air humidity outside at 20°C). Therefore, the characteristic drying rate of timber walls in summer due to vapor permeation is at the level of 0.5 g/m 2 hour, and due to air permeability in a light wind of 1 m/sec - (0.2-2) g/m 2 hour and with gusts of wind 10 m/sec - (20-200) g/m 2 hour (although inside the walls the movements of air masses occur at speeds less than 1 mm/sec). It is clear that vapor permeation processes become significant in the moisture balance only with good wind protection of the building walls.
Thus, for quick drying of building walls (for example, after emergency roof leaks), it is better to provide vents (ventilated façade channels) inside the walls. So, if in a closed bath you wet the inner surface of a timber wall with water in the amount of 1 kg/m2, then such a wall, allowing water vapor to pass through it to the outside, will dry out in the wind in a few days, but if timber wall plastered on the outside (that is, windproofed), it will dry out without heating in only a few months. Fortunately, wood is saturated with water very slowly, so drops of water on the wall do not have time to penetrate deep into the wood, and it is not typical for walls to dry out for such a long time.
But if the crown of the log house lies in a puddle on the base or on wet (and even damp) ground for weeks, then subsequent drying is only possible by the wind through the cracks.
In everyday life (and even in professional construction), it is in the field of vapor barrier that there is greatest number misunderstandings, sometimes the most unexpected. For example, it is often believed that hot bath air supposedly “dries out” a cold floor, and cold dank air from the underground is “absorbed” and supposedly “moisturizes” the floor, although everything happens just the opposite.
Or, for example, they seriously believe that thermal insulation (glass wool, expanded clay, etc.) “sucks” moisture and thereby “dries out” the walls, without asking the question about future fate this supposedly endlessly “absorbed” moisture. It is useless to refute such everyday considerations and images in everyday life, if only because in the general public no one is seriously interested (and even more so during “bathroom chatter”) in the nature of the phenomenon of vapor permeability.
But if a summer resident, having the appropriate technical education, actually wants to figure out how and where water vapor penetrates the walls and how they exit from there, then he will have, first of all, to assess the real moisture content in the air in all areas of interest (inside and outside the bathhouse ), and objectively expressed in mass units or partial pressure, and then, using the given data on air permeability and vapor permeability, determine how and where water vapor flows move and whether they can condense in certain zones, taking into account real temperatures.
We will get acquainted with these questions in the following sections. We emphasize that for approximate estimates the following characteristic values of pressure drops can be used:
Air pressure differences (to assess the transfer of water vapor along with air masses - by wind) range from (1-10) Pa (for one-story bathhouses or weak winds of 1 m/sec), (10-100) Pa (for multi-story buildings or moderate winds 10 m/sec), more than 700 Pa during hurricanes;
Changes in partial pressure of water vapor in the air from 1000 Pa (in residential premises) to 10,000 Pa (in baths).
In conclusion, we note that people often confuse the concepts of hygroscopicity and vapor permeability, although they have completely different physical meanings. Hygroscopic (“breathing”) walls absorb water vapor from the air, converting water vapor into compact water in very small capillaries (pores), even though the partial pressure of water vapor may be lower than the saturated vapor pressure.
Vapor-permeable walls simply allow water vapor to pass through without condensation, but if in some part of the wall there is a cold zone in which the partial pressure of water vapor becomes higher than the pressure of saturated vapor, then condensation, of course, is possible in the same way as on any surfaces. At the same time, vapor-permeable hygroscopic walls are moistened more than vapor-permeable non-hygroscopic walls.
First of all, it must be said that I will not talk about vapor-permeable (breathable) and vapor-impermeable (non-breathable) walls in terms of good/bad, but will consider them as two alternative options. Each of these options is completely correct if fulfilled with all the required requirements. That is, I do not answer the question “are vapor-permeable walls necessary,” but consider both options.
So, vapor-permeable walls breathe and allow air (steam) to pass through them, but vapor-impermeable walls do not breathe and do not allow air (steam) to pass through them. Vapor-permeable walls are made only from vapor-permeable materials. Vapor-impermeable walls contain in their design at least one layer of vapor-impermeable material (this is enough for the entire wall to become vapor-impermeable). All materials are divided into vapor-permeable and non-vapor-permeable, this is not good, not bad - this is such a given :-).
Now let's see what all this means when these walls are included in a real house (apartment). We do not consider the constructive capabilities of vapor-permeable and vapor-impermeable walls in this matter. Both such and such a wall can be made strong, rigid, etc. The main differences arise in these two questions:
Heat loss. Naturally, additional heat loss occurs through vapor-permeable walls (heat also leaves along with the air). It must be said that these heat losses are very small (5-7% of the total). Their size affects the thickness of the thermal insulation and heating power. When calculating the thickness (of the wall, if it is without insulation, or the insulation itself), the vapor permeability coefficient is taken into account. When calculating heat loss for heating selection, heat loss due to the vapor permeability of the walls is also taken into account. That is, these losses are not lost anywhere, they are taken into account when calculating what they affect. And, moreover, we have already made enough such calculations (based on the thickness of the insulation and heat loss to calculate the heating power), and this is what can be seen: there is a difference in the numbers, but it is so small that it really cannot affect either the thickness of the insulation or the power heating device. Let me explain: if with a vapor-permeable wall you need, for example, 43 mm of insulation, and with a non-vapor-permeable wall, 42 mm, then it is still 50 mm, in both versions. The same is with the boiler power, if based on the overall heat loss, it is clear that a 24 kW boiler is needed, for example, then just because of the vapor permeability of the walls, the next most powerful boiler will not work.
Ventilation. Vapor-permeable walls participate in air exchange in the room, but vapor-permeable walls do not. The room must have inflow and exhaust, they must correspond to the norm and be approximately equal. In order to understand how much supply and exhaust there should be in a house/apartment (in m3 per hour), a ventilation calculation is made. It takes into account all the possibilities of supply and exhaust, considers the norm for this house/apartment, compares the realities and the norm, and recommends methods for bringing the power of supply and exhaust to the norm. So this is what comes out as a result of these calculations (we have already done a lot of them): as a rule, in modern houses there is not enough inflow. This happens because modern windows vapor-tight. Previously, no one considered this ventilation for private housing, since the influx was normally provided by old wooden windows, leaky doors, walls with cracks, etc. And now, if we take new construction, almost all houses with plastic windows, and at least half with vapor-impermeable walls. And there is practically no (constant) air flow in such houses. Here you can see examples of ventilation calculations in the topics:
It is clear from these houses that the inflow through the walls (if they are vapor-permeable) will be only about 1/5 of the required inflow. That is, ventilation must be designed (calculated) normally no matter what the walls and windows are. Only vapor-permeable walls, and everything - necessary the influx is still not provided.
Sometimes the question of vapor permeability of walls becomes relevant in such a situation. In an old house/apartment that lived normally with vapor-permeable walls, old wooden windows, and one exhaust duct in the kitchen, they begin to change the windows (to plastic ones), then, for example, the walls are insulated with foam plastic (from the outside, as expected). Begin wet walls, mold, etc. The ventilation stopped working. There is no inflow, without inflow the hood does not work. From here, it seems to me, arose the myth about the “terrible polystyrene foam”, which as soon as you insulate a wall, mold will immediately begin to grow. And the point here is a set of issues regarding ventilation and insulation, and not the “horror” of this or that material.
Regarding what you write, “it is impossible to make airtight walls.” This is not entirely true. It is quite possible to make them (with a certain approximation to tightness), and they are made. We are currently preparing an article about such houses, where windows/walls/doors are completely sealed, all air is supplied through a recovery system, etc. This is the principle of so-called “passive” houses, we will talk about this soon.
Thus, here is the conclusion: you can choose either a vapor-permeable wall or a non-vapor-permeable one. The main thing is to competently resolve all related issues: proper thermal insulation and compensation for heat loss, and ventilation.
There is a legend about a “breathing wall”, and tales about the “healthy breathing of a cinder block, which creates a unique atmosphere in the house.” In fact, the vapor permeability of the wall is not large, the amount of steam passing through it is insignificant, and much less than the amount of steam carried by air when it is exchanged in the room.
Vapor permeability is one of the most important parameters, used in calculating insulation. We can say that the vapor permeability of materials determines the entire insulation design.
What is vapor permeability
The movement of steam through the wall occurs when there is a difference in partial pressure on the sides of the wall ( different humidity). In this case, there may not be a difference in atmospheric pressure.
Vapor permeability is the ability of a material to pass steam through itself. According to the domestic classification, it is determined by the vapor permeability coefficient m, mg/(m*hour*Pa).
The resistance of a layer of material will depend on its thickness.
Determined by dividing the thickness by the vapor permeability coefficient. Measured in (m sq.*hour*Pa)/mg.
For example, the vapor permeability coefficient brickwork accepted as 0.11 mg/(m*hour*Pa). With a brick wall thickness of 0.36 m, its resistance to steam movement will be 0.36/0.11=3.3 (m sq.*hour*Pa)/mg.
What is the vapor permeability of building materials?
Below are the values of the vapor permeability coefficient for several building materials (according to normative document), which are most widely used, mg/(m*hour*Pa).
Bitumen 0.008
Heavy concrete 0.03
Autoclaved aerated concrete 0.12
Expanded clay concrete 0.075 - 0.09
Slag concrete 0.075 - 0.14
Burnt clay (brick) 0.11 - 0.15 (in the form of masonry with cement mortar)
Mortar 0,12
Drywall, gypsum 0.075
Cement-sand plaster 0.09
Limestone (depending on density) 0.06 - 0.11
Metals 0
Chipboard 0.12 0.24
Linoleum 0.002
Foam plastic 0.05-0.23
Polyurethane solid, polyurethane foam
0,05
Mineral wool 0.3-0.6
Foam glass 0.02 -0.03
Vermiculite 0.23 - 0.3
Expanded clay 0.21-0.26
Wood across the grain 0.06
Wood along the grain 0.32
Brickwork made of sand-lime brick on cement mortar 0.11
Data on the vapor permeability of layers must be taken into account when designing any insulation.
How to design insulation - based on vapor barrier qualities
The basic rule of insulation is that the vapor transparency of layers should increase towards the outside. Then, during the cold season, it is more likely that water will not accumulate in the layers when condensation occurs at the dew point.
The basic principle helps to make a decision in any case. Even when everything is “turned upside down,” they insulate from the inside, despite persistent recommendations to do insulation only from the outside.
To avoid a catastrophe with the walls getting wet, it is enough to remember that the inner layer should most stubbornly resist steam, and based on this, for internal insulation apply extruded polystyrene foam in a thick layer - a material with very low vapor permeability.
Or don’t forget to use even more “airy” mineral wool on the outside for very “breathable” aerated concrete.
Separation of layers with a vapor barrier
Another option for applying the principle of vapor transparency of materials in multilayer construction— separation of the most significant layers with a vapor barrier. Or the use of a significant layer, which is an absolute vapor barrier.
For example, insulating a brick wall with foam glass. It would seem that this contradicts the above principle, since it is possible for moisture to accumulate in the brick?
But this does not happen, due to the fact that the directional movement of steam is completely interrupted (when sub-zero temperatures from the room to the outside). After all, foam glass is a complete vapor barrier or close to it.
Therefore, in this case, the brick will enter into a state of equilibrium with the internal atmosphere of the house, and will serve as an accumulator of humidity during sudden changes indoors, making the internal climate more pleasant.
The principle of layer separation is also used when using mineral wool - an insulation material that is especially dangerous due to moisture accumulation. For example, in a three-layer construction, when mineral wool is located inside a wall without ventilation, it is recommended to place a vapor barrier under the wool, and thus leave it in the outside atmosphere.
International classification of vapor barrier qualities of materials
The international classification of materials based on vapor barrier properties differs from the domestic one.
According to the international standard ISO/FDIS 10456:2007(E), materials are characterized by a coefficient of resistance to vapor movement. This coefficient indicates how many times more the material resists the movement of steam compared to air. Those. for air, the coefficient of resistance to steam movement is 1, and for extruded polystyrene foam it is already 150, i.e. Expanded polystyrene is 150 times less permeable to steam than air.
It is also customary in international standards to determine vapor permeability for dry and moistened materials. The internal humidity of the material is 70% as the boundary between the concepts of “dry” and “moistened”.
Below are the values of the steam resistance coefficient for various materials according to international standards.
Steam resistance coefficient
Data are given first for dry material, and separated by commas for moistened material (more than 70% humidity).
Air 1, 1
Bitumen 50,000, 50,000
Plastics, rubber, silicone - >5,000, >5,000
Heavy concrete 130, 80
Medium density concrete 100, 60
Polystyrene concrete 120, 60
Autoclaved aerated concrete 10, 6
Lightweight concrete 15, 10
Fake diamond 150, 120
Expanded clay concrete 6-8, 4
Slag concrete 30, 20
Fired clay (brick) 16, 10
Lime mortar 20, 10
Drywall, gypsum 10, 4
Gypsum plaster 10, 6
Cement-sand plaster 10, 6
Clay, sand, gravel 50, 50
Sandstone 40, 30
Limestone (depending on density) 30-250, 20-200
Ceramic tile?, ?
Metals?, ?
OSB-2 (DIN 52612) 50, 30
OSB-3 (DIN 52612) 107, 64
OSB-4 (DIN 52612) 300, 135
Chipboard 50, 10-20
Linoleum 1000, 800
Underlay for plastic laminate 10,000, 10,000
Underlay for laminate cork 20, 10
Foam plastic 60, 60
EPPS 150, 150
Solid polyurethane, polyurethane foam 50, 50
Mineral wool 1, 1
Foam glass?, ?
Perlite panels 5, 5
Perlite 2, 2
Vermiculite 3, 2
Ecowool 2, 2
Expanded clay 2, 2
Wood across the grain 50-200, 20-50
It should be noted that the data on resistance to steam movement here and “there” are very different. For example, foam glass is standardized in our country, and the international standard says that it is an absolute vapor barrier.
Where did the legend of the breathing wall come from?
A lot of companies produce mineral wool. This is the most vapor-permeable insulation. According to international standards, its vapor permeability resistance coefficient (not to be confused with the domestic vapor permeability coefficient) is 1.0. Those. in fact, mineral wool is no different in this respect from air.
Indeed, this is a “breathable” insulation. What to sell mineral wool as much as possible is needed beautiful fairy tale. For example, that if you insulate a brick wall from the outside with mineral wool, it will not lose anything in terms of vapor permeability. And this is the absolute truth!
The insidious lie is hidden in the fact that through brick walls 36 centimeters thick, with a humidity difference of 20% (on the street 50%, in the house - 70%) about a liter of water will leave the house per day. While with the exchange of air, about 10 times more should come out so that the humidity in the house does not increase.
And if the wall is insulated from the outside or inside, for example with a layer of paint, vinyl wallpaper, dense cement plaster (which is generally “the most common thing”), then the vapor permeability of the wall will decrease several times, and with complete insulation - tens and hundreds of times.
Therefore always brick wall and it will be absolutely the same for household members whether the house is covered with mineral wool with “raging breath”, or with “sadly sniffling” polystyrene foam.
When making decisions on insulating houses and apartments, it is worth proceeding from the basic principle - the outer layer should be more vapor permeable, preferably by several times.
If for some reason it is not possible to withstand this, then you can separate the layers with a continuous vapor barrier (use a completely vapor-proof layer) and stop the movement of steam in the structure, which will lead to a state of dynamic equilibrium of the layers with the environment in which they will be located.
Table of vapor permeability of building materials
I collected information on vapor permeability by combining several sources. The same sign with the same materials is circulating around the sites, but I expanded it and added modern meanings vapor permeability from the websites of building materials manufacturers. I also checked the values with data from the document “Code of Rules SP 50.13330.2012” (Appendix T), and added those that were not there. So on this moment This is the most complete table.
| Material | Vapor permeability coefficient, mg/(m*h*Pa) |
| Reinforced concrete | 0,03 |
| Concrete | 0,03 |
| Cement-sand mortar (or plaster) | 0,09 |
| Cement-sand-lime mortar (or plaster) | 0,098 |
| Lime-sand mortar with lime (or plaster) | 0,12 |
| Expanded clay concrete, density 1800 kg/m3 | 0,09 |
| Expanded clay concrete, density 1000 kg/m3 | 0,14 |
| Expanded clay concrete, density 800 kg/m3 | 0,19 |
| Expanded clay concrete, density 500 kg/m3 | 0,30 |
| Clay brick, masonry | 0,11 |
| Brick, silicate, masonry | 0,11 |
| Hollow ceramic brick (1400 kg/m3 gross) | 0,14 |
| Hollow ceramic brick (1000 kg/m3 gross) | 0,17 |
| Large format ceramic block(warm ceramics) | 0,14 |
| Foam concrete and aerated concrete, density 1000 kg/m3 | 0,11 |
| Foam concrete and aerated concrete, density 800 kg/m3 | 0,14 |
| Foam concrete and aerated concrete, density 600 kg/m3 | 0,17 |
| Foam concrete and aerated concrete, density 400 kg/m3 | 0,23 |
| Fiberboard and wood concrete slabs, 500-450 kg/m3 | 0.11 (SP) |
| Fiberboard and wood concrete slabs, 400 kg/m3 | 0.26 (SP) |
| Arbolit, 800 kg/m3 | 0,11 |
| Arbolit, 600 kg/m3 | 0,18 |
| Arbolit, 300 kg/m3 | 0,30 |
| Granite, gneiss, basalt | 0,008 |
| Marble | 0,008 |
| Limestone, 2000 kg/m3 | 0,06 |
| Limestone, 1800 kg/m3 | 0,075 |
| Limestone, 1600 kg/m3 | 0,09 |
| Limestone, 1400 kg/m3 | 0,11 |
| Pine, spruce across the grain | 0,06 |
| Pine, spruce along the grain | 0,32 |
| Oak across the grain | 0,05 |
| Oak along the grain | 0,30 |
| Plywood | 0,02 |
| Chipboard and fibreboard, 1000-800 kg/m3 | 0,12 |
| Chipboard and fibreboard, 600 kg/m3 | 0,13 |
| Chipboard and fibreboard, 400 kg/m3 | 0,19 |
| Chipboard and fibreboard, 200 kg/m3 | 0,24 |
| Tow | 0,49 |
| Drywall | 0,075 |
| Gypsum slabs (gypsum slabs), 1350 kg/m3 | 0,098 |
| Gypsum slabs (gypsum slabs), 1100 kg/m3 | 0,11 |
| Mineral wool, stone, 180 kg/m3 | 0,3 |
| Mineral wool, stone, 140-175 kg/m3 | 0,32 |
| Mineral wool, stone, 40-60 kg/m3 | 0,35 |
| Mineral wool, stone, 25-50 kg/m3 | 0,37 |
| Mineral wool, glass, 85-75 kg/m3 | 0,5 |
| Mineral wool, glass, 60-45 kg/m3 | 0,51 |
| Mineral wool, glass, 35-30 kg/m3 | 0,52 |
| Mineral wool, glass, 20 kg/m3 | 0,53 |
| Mineral wool, glass, 17-15 kg/m3 | 0,54 |
| Extruded polystyrene foam (EPS, XPS) | 0.005 (SP); 0.013; 0.004 (???) |
| Expanded polystyrene (foam), plate, density from 10 to 38 kg/m3 | 0.05 (SP) |
| Expanded polystyrene, plate | 0,023 (???) |
| Cellulose ecowool | 0,30; 0,67 |
| Polyurethane foam, density 80 kg/m3 | 0,05 |
| Polyurethane foam, density 60 kg/m3 | 0,05 |
| Polyurethane foam, density 40 kg/m3 | 0,05 |
| Polyurethane foam, density 32 kg/m3 | 0,05 |
| Expanded clay (bulk, i.e. gravel), 800 kg/m3 | 0,21 |
| Expanded clay (bulk, i.e. gravel), 600 kg/m3 | 0,23 |
| Expanded clay (bulk, i.e. gravel), 500 kg/m3 | 0,23 |
| Expanded clay (bulk, i.e. gravel), 450 kg/m3 | 0,235 |
| Expanded clay (bulk, i.e. gravel), 400 kg/m3 | 0,24 |
| Expanded clay (bulk, i.e. gravel), 350 kg/m3 | 0,245 |
| Expanded clay (bulk, i.e. gravel), 300 kg/m3 | 0,25 |
| Expanded clay (bulk, i.e. gravel), 250 kg/m3 | 0,26 |
| Expanded clay (bulk, i.e. gravel), 200 kg/m3 | 0.26; 0.27 (SP) |
| Sand | 0,17 |
| Bitumen | 0,008 |
| Polyurethane mastic | 0,00023 |
| Polyurea | 0,00023 |
| Foamed synthetic rubber | 0,003 |
| Ruberoid, glassine | 0 - 0,001 |
| Polyethylene | 0,00002 |
| Asphalt concrete | 0,008 |
| Linoleum (PVC, i.e. unnatural) | 0,002 |
| Steel | 0 |
| Aluminum | 0 |
| Copper | 0 |
| Glass | 0 |
| Block foam glass | 0 (rarely 0.02) |
| Bulk foam glass, density 400 kg/m3 | 0,02 |
| Bulk foam glass, density 200 kg/m3 | 0,03 |
| Glazed ceramic tiles | ≈ 0 (???) |
| Clinker tiles | low (???); 0.018 (???) |
| Porcelain tiles | low (???) |
| OSB (OSB-3, OSB-4) | 0,0033-0,0040 (???) |
It is difficult to find out and indicate in this table the vapor permeability of all types of materials; manufacturers have created great amount various plasters, finishing materials. And, unfortunately, many manufacturers do not indicate this on their products. important characteristic like vapor permeability.
For example, defining a value for warm ceramics(position “Large-format ceramic block”), I studied almost all the websites of manufacturers of this type of brick, and only some of them listed vapor permeability in the characteristics of the stone.
Also different manufacturers different meanings vapor permeability. For example, for most foam glass blocks it is zero, but some manufacturers have the value “0 - 0.02”.
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