The table shows the values ​​​​of vapor permeability of materials and thin layers of vapor barrier for common ones. Resistance to vapor permeability of materials Rp can be defined as the quotient of the material thickness divided by its vapor permeability coefficient μ.

It should be noted that vapor permeation resistance can only be specified for a material of a given thickness, in contrast to , which is not tied to the thickness of the material and is determined only by the structure of the material. For multilayer sheet materials the total resistance to vapor permeability will be equal to the sum of the resistances of the material of the layers.

What is the vapor permeability resistance? For example, consider the value of resistance to vapor permeability of an ordinary thickness of 1.3 mm. According to the table, this value is 0.016 m 2 ·h·Pa/mg. What does this value mean? It means the following: square meter the area of ​​such a cardboard in 1 hour will pass 1 mg with a difference in its partial pressures at opposite sides of the cardboard equal to 0.016 Pa (at the same temperature and air pressure on both sides of the material).

Thus, vapor permeation resistance indicates the required difference in partial pressures of water vapor, sufficient for the passage of 1 mg of water vapor through 1 m 2 of the area of ​​the sheet material of the specified thickness in 1 hour. According to GOST 25898-83, vapor permeability resistance is determined for sheet materials and thin layers of vapor barrier having a thickness of not more than 10 mm. It should be noted that the vapor barrier with the highest vapor permeability in the table is.

Vapor resistance table

Material	layer thickness, mm	Rp resistance, m 2 h Pa / mg
Cardboard ordinary	1,3	0,016
Asbestos-cement sheets	6	0,3
Gypsum sheathing sheets (dry plaster)	10	0,12
Rigid wood fiber sheets	10	0,11
Soft wood fiber sheets	12,5	0,05
Painting with hot bitumen in one go	2	0,3
Painting with hot bitumen for two times	4	0,48
Oil painting for two times with preliminary putty and primer	—	0,64
Enamel paint	—	0,48
Coating with insulating mastic in one go	2	0,6
Coating with bitumen-cookersalt mastic at a time	1	0,64
Coating with bitumen-cookersalt mastic for two times	2	1,1
Roofing glassine	0,4	0,33
Polyethylene film	0,16	7,3
Ruberoid	1,5	1,1
Tol roofing	1,9	0,4
Three-layer plywood	3	0,15

Sources:
1. building codes and rules. Construction heat engineering. SNiP II-3-79. Ministry of Construction of Russia - Moscow 1995.
2. GOST 25898-83 Construction materials and products. Methods for determining the resistance to vapor permeation.

To create favorable microclimate indoors, it is necessary to take into account the properties building materials. Today we will analyze one property - vapor permeability of materials.

Vapor permeability is the ability of a material to pass vapors contained in the air. Water vapor penetrates the material due to pressure.

They will help to understand the issue of the table, which cover almost all the materials used for construction. After studying this material, you will know how to build a warm and reliable home.

Equipment

When it comes to Prof. construction, then it uses specially equipped equipment to determine vapor permeability. Thus, the table that is in this article appeared.

Today the following equipment is used:

• Scales with a minimum error - an analytical type model.
• Vessels or bowls for experiments.
• Tools with high level accuracy for determining the thickness of layers of building materials.

Dealing with property

There is an opinion that "breathing walls" are useful for the house and its inhabitants. But all builders think about this concept. “Breathable” is the material that, in addition to air, also allows steam to pass through - this is the water permeability of building materials. Foam concrete, 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 - an extractor hood can correct the situation. You can find out that the vapors do not go anywhere by the condensate on the pipes, and sometimes on the windows. Some builders believe that if the house is built of brick or concrete, then the house is "hard" to breathe.

In fact, the situation is better - in a modern home, about 95% of the steam leaves through the window and the hood. And if the walls are made of breathable 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 let moisture through due to vinyl wallpaper. The "breathing" walls also have a significant drawback - in windy weather, heat leaves the dwelling.

The table will help you compare materials and find out their vapor permeability index:

The higher the vapor permeability index, the more moisture the wall can contain, which means that the material has low frost resistance. If you are going to build walls from foam concrete or aerated concrete, 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, then the indicator will increase by 5 times. But we are interested in another parameter: the liquid tends to expand when it freezes, as a result, the walls collapse.

Vapor permeability in a multi-layer construction

The sequence of layers and the type of insulation - this is what primarily affects the vapor permeability. In the diagram below, you can see that if the insulation material is located on the front side, then the pressure on moisture saturation is lower.

If the insulation is located on the inside of the house, then between load-bearing structure and this building will appear condensate. It negatively affects the entire microclimate in the house, while the destruction of building materials occurs much faster.

Dealing with the ratio

The coefficient in this indicator determines the amount of vapor, measured in grams, that pass through materials with a thickness of 1 meter and a layer of 1 m² within one hour. The ability to pass or retain moisture characterizes the resistance to vapor permeability, which is indicated in the table by the symbol "µ".

In simple words, the coefficient is the resistance of building materials, comparable to air permeability. Let's take a simple example, mineral wool has the following vapor permeability coefficient: µ=1. This means that the material does not allow moisture to pass through. worse than air. And if we 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 houses are built. For example, “cotton wool” perfectly passes moisture, but in the end, due to excess steam on windows and pipes with cold water condensation may form, as indicated in the table. Because of this, the insulation loses its qualities. Professionals recommend installing a vapor barrier layer with outside Houses. After that, the insulation will not let steam through.

If the material has a low vapor permeability, 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, the hood and the window will help - this is enough to maintain a normal microclimate in the house. In the case when the house is built of wood, it is impossible to do without additional insulation, while wood materials require a special varnish.

A table, graph and diagram will help you understand the principle of this property, after which you can already make a 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 forget about materials with a high vapor permeability.

1. Only a heater with the lowest coefficient of thermal conductivity can minimize the selection of internal space

2. Unfortunately, the storage heat capacity of the array outer wall we lose forever. But there is a win here:

A) there is no need to spend energy on heating these walls

B) when you turn on even the smallest heater in the room, it will almost immediately become warm.

3. At the junction of the wall and the ceiling, "cold bridges" can be removed if the insulation is applied partially on the floor slabs with subsequent decoration of these junctions.

4. If you still believe in the "breathing of the walls", then please read THIS article. If not, then the obvious conclusion is: thermal insulation material should be very tightly pressed against the wall. It is even better if the insulation becomes one with the wall. Those. there will be no gaps and cracks between the insulation and the wall. Thus, moisture from the room will not be able to get into the dew point zone. The wall will always remain dry. Seasonal temperature fluctuations without access to moisture will not have negative impact on the walls, which will increase their durability.

All these tasks can be solved only by sprayed polyurethane foam.

Possessing the lowest coefficient of thermal conductivity of all existing thermal insulation materials, polyurethane foam will take up a minimum of internal space.

The ability of polyurethane foam to adhere reliably to any surface makes it easy to apply it to the ceiling to reduce "cold bridges".

When applied to walls, polyurethane foam, being in a liquid state for some time, fills all the cracks and microcavities. Foaming and polymerizing directly at the point of application, polyurethane foam becomes one with the wall, blocking access to destructive moisture.

VAPOR PERMEABILITY OF WALLS
Supporters of the false concept of “healthy breathing of walls”, in addition to sinning against the truth of physical laws and deliberately misleading designers, builders and consumers, based on a mercantile urge to sell their goods by any means, slander and slander thermal insulation materials with low vapor permeability (polyurethane foam) or heat-insulating material and completely vapor-tight (foam glass).

The essence of this malicious insinuation boils down to the following. It seems like if there is no notorious “healthy breathing of the walls”, then in this case the interior will definitely become damp, and the walls will ooze moisture. In order to debunk this fiction, let's take a closer look at the physical processes that will occur in the case of lining under the plaster layer or using inside the masonry, for example, a material such as foam glass, the vapor permeability of which is zero.

So, due to the heat-insulating and sealing properties inherent in foam glass, the outer layer of plaster or masonry will come into an equilibrium temperature and humidity state with the outside atmosphere. Also, the inner layer of masonry will enter into a certain balance with the microclimate. interior spaces. Water diffusion processes, both in the outer layer of the wall and in the inner one; will have the character of a harmonic function. This function will be determined, for the outer layer, by daily changes in temperature and humidity, as well as seasonal changes.

Particularly interesting in this respect is the behavior of the inner layer of the wall. In fact, the inside of the wall will act as an inertial buffer, the role of which is to smooth out sudden changes in humidity in the room. In the event of a sharp humidification of the room, the inner part of the wall will adsorb the excess moisture contained in the air, preventing the air humidity from reaching the limit value. At the same time, in the absence of moisture release into the air in the room, the inner part of the wall begins to dry out, preventing the air from “drying out” and becoming like a desert one.

As a favorable result of such an insulation system using polyurethane foam, the harmonics of fluctuations in air humidity in the room are smoothed out and thus guarantee a stable value (with minor fluctuations) of humidity acceptable for a healthy microclimate. Physics this process well studied by the developed construction and architectural schools of the world and to achieve a similar effect when using fiber inorganic materials as a heater in closed systems insulation, it is highly recommended to have a reliable vapor-permeable layer on inside insulation systems. So much for "healthy breathing walls"!

Table of vapor permeability of building materials

I collected information on vapor permeability by linking several sources. The same sign with the same materials walks around the sites, but I expanded it, added modern meanings vapor permeability from the websites of manufacturers of building materials. I also checked the values ​​with the data from the document "Code of Rules SP 50.13330.2012" (Appendix T), added those that were not there. So at the 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 fiberboard, 1000-800 kg/m3	0,12
Chipboard and fiberboard, 600 kg/m3	0,13
Chipboard and fiberboard, 400 kg/m3	0,19
Chipboard and fiberboard, 200 kg/m3	0,24
Tow	0,49
Drywall	0,075
Gypsum slabs (gypsum boards), 1350 kg/m3	0,098
Gypsum slabs (gypsum boards), 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
Expanded polystyrene extruded (EPPS, XPS)	0.005 (SP); 0.013; 0.004 (???)
Expanded polystyrene (foam plastic), plate, density from 10 to 38 kg/m3	0.05 (SP)
Styrofoam, plate	0,023 (???)
Ecowool cellulose	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. not natural)	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 tile (tile)	≈ 0 (???)
Clinker tiles	low (???); 0.018 (???)
Porcelain stoneware	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 a huge variety of plasters, finishing materials. And, unfortunately, many manufacturers do not indicate this on their products. important characteristic as vapor permeability.

For example, defining a value for warm ceramics(position "Large-format ceramic block"), I studied almost all the sites of manufacturers of this type of brick, and only some of them had vapor permeability indicated in the characteristics of the stone.

Also at different manufacturers different meanings vapor permeability. For example, for most foam glass blocks it is zero, but for some manufacturers the value is "0 - 0.02".

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There is a legend about the "breathing wall", and legends about the "healthy breathing of the 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.

Permeability is one of the most important parameters used in the calculation of insulation. We can say that the vapor permeability of materials determines the entire design of insulation.

What is vapor permeability

The movement of steam through the wall occurs with 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 - 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 * h * Pa).

The resistance of a layer of material will depend on its thickness.
It is determined by dividing the thickness by the vapor permeability coefficient. It is measured in (m sq. * hour * Pa) / mg.

For example, the vapor permeability coefficient brickwork taken as 0.11 mg/(m*h*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. * h * Pa) / mg.

What is the vapor permeability of building materials

Below are the values ​​​​of the coefficient of vapor permeability for several building materials (according to the regulatory document), which are most widely used, mg / (m * h * 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 on 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
Polyfoam 0.05-0.23
Polyurethane hard, 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 fibers 0.06
Wood along the fibers 0.32
brickwork from silicate brick on cement mortar 0.11

Data on the vapor permeability of the layers must be taken into account when designing any insulation.

How to design insulation - according to vapor barrier qualities

The basic rule of insulation is that the vapor transparency of the layers should increase outward. Then in the cold season, with a greater probability, there will be no accumulation of water in the layers, when condensation occurs at the dew point.

The basic principle helps to decide in any cases. Even when everything is "turned upside down" - they insulate from the inside, despite the insistent recommendations to make insulation only from the outside.

In order to avoid a catastrophe with wetting the walls, 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 do not forget to use even more “airy” mineral wool for a very “breathing” aerated concrete from the outside.

Separation of layers with a vapor barrier

Another way to apply the principle of vapor transmission 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, - insulation of a brick wall with foam glass. It would seem that this contradicts the above principle, because it is possible to accumulate moisture in a brick?

But this does not happen, due to the fact that the directional movement of steam is completely interrupted (at 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 an equilibrium state with inner atmosphere at home, and will serve as an accumulator of humidity during its sharp jumps indoors, making the indoor climate more pleasant.

The principle of separation of layers is also used when using mineral wool - a heater that is especially dangerous for moisture accumulation. For example, in a three-layer construction, when mineral wool is inside a wall without ventilation, it is recommended to put 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 for 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 steam 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. Styrofoam is 150 times less vapor permeable than air.

Also in international standards it is customary to determine the vapor permeability for dry and moist materials. The boundary between the concepts of “dry” and “moistened” is the internal moisture content of the material of 70%.
Below are the values ​​of the coefficient of resistance to steam movement for various materials according to international standards.

Steam resistance coefficient

First, data are given for dry material, and separated by commas for moist (more than 70% moisture).
Air 1, 1
Bitumen 50,000, 50,000
Plastics, rubber, silicone — >5,000, >5,000
Heavy concrete 130, 80
Concrete medium density 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
Burnt clay (brick) 16, 10
Lime mortar 20, 10
Drywall, plaster 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
Substrate for plastic laminate 10 000, 10 000
Substrate for laminate cork 20, 10
Polyfoam 60, 60
EPPS 150, 150
Polyurethane hard, 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 grain 50-200, 20-50

It should be noted that the data on the resistance to the movement of steam 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 does not differ in this respect from air.

Indeed, it is a "breathing" insulation. To sell mineral wool as much as possible, you need a beautiful fairy tale. For example, that if you insulate a brick wall from the outside mineral wool, then she will not lose anything in terms of vapor permeability. And this is absolutely true!

An insidious lie is hidden in the fact that through brick walls 36 centimeters thick, with a humidity difference of 20% (outside 50%, in the house - 70%), about a liter of water will leave the house per day. While with air exchange, 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 from the inside, for example with a layer of paint, vinyl wallpaper, dense cement plaster, (which, in general, is “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 households will be absolutely the same whether the house is covered with mineral wool with “raging breath”, or “dull-sniffling” foam plastic.

When making decisions on the insulation of houses and apartments, it is worth proceeding from the basic principle - the outer layer should be more vapor-permeable, preferably at times.

If for some reason it is not possible to withstand this, then it is possible to separate the layers with a continuous vapor barrier (use a completely vapor-tight 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.