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

It should be noted that vapor permeation resistance can only be specified for the material 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 permeation will be equal to the sum of the resistances of the layer material.

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

Thus, vapor permeation resistance shows the required difference in partial pressure of water vapor, sufficient for the passage of 1 mg of water vapor through 1 m 2 of sheet material of the specified thickness in 1 hour. According to GOST 25898-83, vapor permeation resistance is determined for sheet materials and thin layers of vapor barrier having a thickness of no more than 10 mm. It should be noted that the vapor barrier with the highest resistance to vapor permeation in the table is.

Vapor permeation resistance table

Material	Layer thickness, mm	Resistance Rп, m 2 h Pa/mg
Ordinary cardboard	1,3	0,016
Asbestos cement sheets	6	0,3
Gypsum cladding sheets (dry plaster)	10	0,12
Hard wood fiber sheets	10	0,11
Soft wood fiber sheets	12,5	0,05
Hot bitumen painting in one go	2	0,3
Painting with hot bitumen in two times	4	0,48
Oil painting in two times with preliminary putty and primer	—	0,64
Painting with enamel paint	—	0,48
Coating with insulating mastic at one time	2	0,6
Coating with bitumen-kukersol mastic at one time	1	0,64
Coating with bitumen-kukersol mastic in two times	2	1,1
Roofing glassine	0,4	0,33
Polyethylene film	0,16	7,3
Ruberoid	1,5	1,1
Roofing felt	1,9	0,4
Three-layer plywood	3	0,15

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

The concept of “breathing walls” is considered positive characteristic the materials from which they are made. But few people think about the reasons that allow this breathing. Materials that can pass both air and steam are vapor permeable.

A good example building materials with high vapor permeability:

• wood;
• expanded clay slabs;
• foam concrete.

Concrete or brick walls are less permeable to steam than wood or expanded clay.

Indoor steam sources

Human breathing, cooking, water vapor from the bathroom and many other sources of steam in the absence exhaust device create high level indoor humidity. You can often observe the formation of perspiration on window glass in winter time, or on cold water pipes. These are examples of water vapor forming inside a home.

What is vapor permeability

The design and construction rules give the following definition of the term: vapor permeability of materials is the ability to pass through droplets of moisture contained in the air due to different values ​​of partial vapor pressures on opposite sides at identical values air pressure. It is also defined as the density of the steam flow passing through a certain thickness of the material.

The table, which has a vapor permeability coefficient compiled for building materials, is conditional in nature, since the specified calculated values ​​of humidity and atmospheric conditions do not always correspond to real conditions. The dew point can be calculated based on approximate data.

Wall design taking into account vapor permeability

Even if the walls are built from a material that has high vapor permeability, this cannot be a guarantee that it will not turn into water within the thickness of the wall. To prevent this from happening, you need to protect the material from the difference in partial vapor pressure from inside and outside. Protection against the formation of steam condensate is carried out using OSB boards, insulating materials such as penoplex and vapor-proof films or membranes that prevent steam from penetrating into the insulation.

The walls are insulated so that closer to the outer edge there is a layer of insulation that is unable to form moisture condensation and pushes back the dew point (water formation). In parallel with protective layers V roofing pie it is necessary to ensure the correct ventilation gap.

Destructive effects of steam

If the wall cake has a weak ability to absorb steam, it is not in danger of destruction due to the expansion of moisture from frost. The main condition is to prevent moisture from accumulating in the thickness of the wall, but to ensure its free passage and weathering. It is equally important to arrange forced exhaust excess moisture and steam from the room, connect a powerful ventilation system. Observing listed conditions, you can protect the walls from cracking and increase the service life of the entire house. The constant passage of moisture through building materials accelerates their destruction.

Use of conductive qualities

Taking into account the peculiarities of building operation, it is used next principle insulation: the most vapor-conducting insulating materials are located outside. Thanks to this arrangement of layers, the likelihood of water accumulating when the outside temperature drops is reduced. To prevent the walls from getting wet from the inside, inner layer insulated with a material that has low vapor permeability, for example, a thick layer of extruded polystyrene foam.

The opposite method of using the vapor-conducting effects of building materials has been successfully used. It consists in the fact that brick wall covered with a vapor barrier layer of foam glass, which interrupts the moving flow of steam from the house to the street during low temperatures. The brick begins to accumulate moisture in the rooms, creating a pleasant indoor climate thanks to a reliable vapor barrier.

Compliance with the basic principle when constructing walls

Walls must have a minimum ability to conduct steam and heat, but at the same time be heat-intensive and heat-resistant. When using one type of material, the required effects cannot be achieved. The outer wall part must retain cold masses and prevent their impact on internal heat-intensive materials that maintain a comfortable thermal regime inside the room.

Reinforced concrete is ideal for the inner layer; its heat capacity, density and strength are at their maximum. Concrete successfully smoothes out the difference between night and day temperature changes.

When conducting construction work wall pies are made taking into account the basic principle: the vapor permeability of each layer should increase in the direction from the inner layers to the outer ones.

Rules for the location of vapor barrier layers

To ensure better performance characteristics of multilayer structures, the rule is applied: on the side with more high temperature, materials with increased resistance to steam penetration and increased thermal conductivity are used. Layers located on the outside must have high vapor conductivity. For the normal functioning of the enclosing structure, it is necessary that the coefficient of the outer layer is five times higher than that of the layer located inside.

When this rule is followed, water vapor trapped in warm layer walls, it will not be difficult to quickly exit through more porous materials.

If this condition is not met, the inner layers of building materials harden and become more thermally conductive.

Introduction to the table of vapor permeability of materials

When designing a house, the characteristics of building materials are taken into account. The Code of Rules contains a table with information about what coefficient of vapor permeability building materials have under normal conditions. atmospheric pressure and average air temperature.

Material	Vapor permeability coefficient mg/(m h Pa)
extruded polystyrene foam
polyurethane foam
mineral wool
reinforced concrete, concrete
pine or spruce
expanded clay
foam concrete, aerated concrete
granite, marble
drywall
chipboard, osp, fibreboard
foam glass
roofing felt
polyethylene
linoleum

The table refutes misconceptions about breathing walls. The amount of steam escaping through the walls is negligible. The main steam is carried out with air currents during ventilation or with the help of ventilation.

The importance of the table of vapor permeability of materials

The vapor permeability coefficient is important parameter, which is used to calculate the layer thickness insulation materials. The quality of insulation of the entire structure depends on the correctness of the results obtained.

Sergey Novozhilov - expert on roofing materials with 9 years experience practical work in the field of engineering solutions in construction.

Vapor permeability table- this is a complete summary table with data on the vapor permeability of all possible materials, used in construction. The word “vapor permeability” itself means the ability of layers of building material to either pass or retain water vapor due to different meanings pressure on both sides of the material at the same atmospheric pressure. This ability is also called the resistance coefficient and is determined by special values.

The higher the vapor permeability index, the more wall can contain moisture, which means that the material has low frost resistance.

Vapor permeability table indicates the following indicators:

1. Thermal conductivity is a kind of indicator of the energetic transfer of heat from more heated particles to less heated particles. Consequently, equilibrium is established in temperature conditions. If the apartment has high thermal conductivity, then this is the most comfortable conditions.
2. Thermal capacity. Using it, you can calculate the amount of heat supplied and heat contained in the room. It is imperative to bring it to a real volume. Thanks to this, temperature changes can be recorded.
3. Thermal absorption is the enclosing structural alignment during temperature fluctuations. In other words, thermal absorption is the degree to which wall surfaces absorb moisture.
4. Thermal stability is the ability to protect structures from sudden fluctuations in heat flow.

Completely all the comfort in the room will depend on these thermal conditions, which is why during construction it is so necessary vapor permeability table, as it helps to effectively compare different types of vapor permeability.

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. In such cases, it is recommended to install a vapor barrier layer on the outside of the house. After this, the insulation will not allow steam to pass through.

Vapor barriers are materials that are used from negative impact air vapor to protect the insulation.

There are three classes of vapor barrier. They differ in mechanical strength and resistance to vapor permeability. The first class of vapor barrier is rigid materials based on foil. The second class includes materials based on polypropylene or polyethylene. And the third class consists of soft materials.

Table of vapor permeability of materials.

Table of vapor permeability of materials- these are construction standards for international and domestic standards for vapor permeability of building materials.

Table of vapor permeability of materials.

Material	Vapor permeability coefficient, mg/(m*h*Pa)
Aluminum
Arbolit, 300 kg/m3
Arbolit, 600 kg/m3
Arbolit, 800 kg/m3
Asphalt concrete
Foamed synthetic rubber
Drywall
Granite, gneiss, basalt
Chipboard and fibreboard, 1000-800 kg/m3
Chipboard and fibreboard, 200 kg/m3
Chipboard and fibreboard, 400 kg/m3
Chipboard and fibreboard, 600 kg/m3
Oak along the grain
Oak across the grain
Reinforced concrete
Limestone, 1400 kg/m3
Limestone, 1600 kg/m3
Limestone, 1800 kg/m3
Limestone, 2000 kg/m3
Expanded clay (bulk, i.e. gravel), 200 kg/m3	0.26; 0.27 (SP)
Expanded clay (bulk, i.e. gravel), 250 kg/m3
Expanded clay (bulk, i.e. gravel), 300 kg/m3
Expanded clay (bulk, i.e. gravel), 350 kg/m3
Expanded clay (bulk, i.e. gravel), 400 kg/m3
Expanded clay (bulk, i.e. gravel), 450 kg/m3
Expanded clay (bulk, i.e. gravel), 500 kg/m3
Expanded clay (bulk, i.e. gravel), 600 kg/m3
Expanded clay (bulk, i.e. gravel), 800 kg/m3
Expanded clay concrete, density 1000 kg/m3
Expanded clay concrete, density 1800 kg/m3
Expanded clay concrete, density 500 kg/m3
Expanded clay concrete, density 800 kg/m3
Porcelain tiles
Clay brick, masonry
Hollow ceramic brick (1000 kg/m3 gross)
Hollow ceramic brick (1400 kg/m3 gross)
Brick, silicate, masonry
Large format ceramic block(warm ceramics)
Linoleum (PVC, i.e. unnatural)
Mineral wool, stone, 140-175 kg/m3
Mineral wool, stone, 180 kg/m3
Mineral wool, stone, 25-50 kg/m3
Mineral wool, stone, 40-60 kg/m3
Mineral wool, glass, 17-15 kg/m3
Mineral wool, glass, 20 kg/m3
Mineral wool, glass, 35-30 kg/m3
Mineral wool, glass, 60-45 kg/m3
Mineral wool, glass, 85-75 kg/m3
OSB (OSB-3, OSB-4)
Foam concrete and aerated concrete, density 1000 kg/m3
Foam concrete and aerated concrete, density 400 kg/m3
Foam concrete and aerated concrete, density 600 kg/m3
Foam concrete and aerated concrete, density 800 kg/m3
Expanded polystyrene (foam), plate, density from 10 to 38 kg/m3
Extruded polystyrene foam (EPS, XPS)	0.005 (SP); 0.013; 0.004
Expanded polystyrene, plate
Polyurethane foam, density 32 kg/m3
Polyurethane foam, density 40 kg/m3
Polyurethane foam, density 60 kg/m3
Polyurethane foam, density 80 kg/m3
Block foam glass	0 (rarely 0.02)
Bulk foam glass, density 200 kg/m3
Bulk foam glass, density 400 kg/m3
Glazed ceramic tiles
Clinker tiles	low; 0.018
Gypsum slabs (gypsum slabs), 1100 kg/m3
Gypsum slabs (gypsum slabs), 1350 kg/m3
Fiberboard and wood concrete slabs, 400 kg/m3
Fiberboard and wood concrete slabs, 500-450 kg/m3
Polyurea
Polyurethane mastic
Polyethylene
Lime-sand mortar with lime (or plaster)
Cement-sand-lime mortar (or plaster)
Cement-sand mortar (or plaster)
Ruberoid, glassine
Pine, spruce along the grain
Pine, spruce across the grain
Plywood
Cellulose ecowool

According to SP 50.13330.2012 "Thermal Protection of Buildings", Appendix T, Table T1 "Calculated Thermal Indicators of Building Materials and Products", the vapor permeability coefficient of galvanized covering (mu, (mg/(m*h*Pa))) will be equal to:

Conclusion: internal galvanized stripping (see Figure 1) in translucent structures can be installed without vapor barrier.

To install a vapor barrier circuit, it is recommended:

Vapor barrier for fastening points of galvanized sheets, this can be achieved with mastic

Vapor barrier of joints of galvanized sheets

Vapor barrier of joints of elements (galvanized sheet and stained glass crossbar or stand)

Ensure that there is no vapor transmission through fasteners (hollow rivets)

Terms and Definitions

Vapor permeability- the ability of materials to transmit water vapor through their thickness.

Water vapor is the gaseous state of water.

Dew point - The dew point characterizes the amount of humidity in the air (water vapor content in the air). Dew point temperature is defined as the ambient temperature to which the air must cool before the vapor it contains reaches saturation and begins to condense into dew. Table 1.

Table 1 - Dew point

Vapor permeability- measured by the amount of water vapor passing through 1 m2 of area, 1 meter thick, within 1 hour, at a pressure difference of 1 Pa. (according to SNiP 02/23/2003). The lower the vapor permeability, the better the thermal insulation material.

Vapor permeability coefficient (DIN 52615) (mu, (mg/(m*h*Pa)) is the ratio of the vapor permeability of a layer of air 1 meter thick to the vapor permeability of a material of the same thickness

Air vapor permeability can be considered as a constant equal to

0.625 (mg/(m*h*Pa)

The resistance of a layer of material depends on its thickness. The resistance of a layer of material is determined by dividing the thickness by the vapor permeability coefficient. Measured in (m2*h*Pa) / mg

According to SP 50.13330.2012 "Thermal protection of buildings", Appendix T, Table T1 "Calculated thermal performance indicators of building materials and products" the vapor permeability coefficient (mu, (mg/(m*h*Pa)) will be equal to:

Rod steel, reinforcing steel (7850 kg/m3), coefficient. vapor permeability mu = 0;

Aluminum(2600) = 0; Copper(8500) = 0; Window glass (2500) = 0; Cast iron (7200) = 0;

Reinforced concrete (2500) = 0.03; Cement-sand mortar (1800) = 0.09;

Brickwork from hollow brick(ceramic hollow core with a density of 1400 kg/m3 on cement sand solution) (1600) = 0,14;

Brickwork made of hollow bricks (ceramic hollow brick with a density of 1300 kg/m3 on cement sand mortar) (1400) = 0.16;

Brickwork made of solid brick (slag on cement sand mortar) (1500) = 0.11;

Brickwork made of solid brick (ordinary clay on cement sand mortar) (1800) = 0.11;

Expanded polystyrene boards with a density of up to 10 - 38 kg/m3 = 0.05;

Ruberoid, parchment, roofing felt (600) = 0.001;

Pine and spruce across the grain (500) = 0.06

Pine and spruce along the grain (500) = 0.32

Oak across the grain (700) = 0.05

Oak along the grain (700) = 0.3

Glued plywood (600) = 0.02

Sand for construction work (GOST 8736) (1600) = 0.17

Mineral wool, stone (25-50 kg/m3) = 0.37; Mineral wool, stone (40-60 kg/m3) = 0.35

Mineral wool, stone (140-175 kg/m3) = 0.32; Mineral wool, stone (180 kg/m3) = 0.3

Drywall 0.075; Concrete 0.03

The article is given for informational purposes

Often in construction articles there is an expression - vapor permeability concrete walls. It means the ability of a material to allow water vapor to pass through, or, in popular parlance, to “breathe.” This parameter has great importance, since waste products are constantly formed in the living room, which must be constantly removed outside.

General information

If you do not create normal ventilation in the room, dampness will be created in it, which will lead to the appearance of fungus and mold. Their secretions can be harmful to our health.

On the other hand, vapor permeability affects the ability of a material to accumulate moisture. This is also a bad indicator, since the more it can retain it, the higher the likelihood of fungus, putrefactive manifestations, and damage due to freezing.

Vapor permeability means Latin letterμ and measured in mg/(m*h*Pa). The value indicates the amount of water vapor that can pass through wall material on an area of ​​1 m2 and with a thickness of 1 m in 1 hour, as well as a difference in external and internal pressure of 1 Pa.

High ability to conduct water vapor in:

• foam concrete;
• aerated concrete;
• perlite concrete;
• expanded clay concrete.

Rounding out the table is heavy concrete.

Advice: if you need to make a technological channel in the foundation, diamond drilling of holes in concrete will help you.

Aerated concrete

1. Using the material as an enclosing structure makes it possible to avoid the accumulation of unnecessary moisture inside the walls and preserve its heat-saving properties, which will prevent possible destruction.
2. Any aerated concrete and foam concrete block contains ≈ 60% air, due to which the vapor permeability of aerated concrete is recognized to be at a good level, the walls in this case can “breathe”.
3. Water vapor seeps freely through the material, but does not condense in it.

The vapor permeability of aerated concrete, as well as foam concrete, significantly exceeds heavy concrete - for the first it is 0.18-0.23, for the second - (0.11-0.26), for the third - 0.03 mg/m*h* Pa.

I would especially like to emphasize that the structure of the material provides it with effective removal moisture in environment, so that even when the material freezes, it does not collapse - it is forced out through open pores. Therefore, when preparing, you should consider this feature and select appropriate plasters, putties and paints.

The instructions strictly regulate that their vapor permeability parameters are not lower than aerated concrete blocks used for construction.

Tip: do not forget that vapor permeability parameters depend on the density of aerated concrete and may differ by half.

For example, if you use D400, their coefficient is 0.23 mg/m h Pa, and for D500 it is already lower - 0.20 mg/m h Pa. In the first case, the numbers indicate that the walls will have a higher “breathing” ability. So when selecting finishing materials for walls made of aerated concrete D400, make sure that their vapor permeability coefficient is the same or higher.

Otherwise, this will lead to poor drainage of moisture from the walls, which will affect the level of living comfort in the house. Please also note that if you have used it for exterior finishing vapor-permeable paint for aerated concrete, and for the interior - non-vapor-permeable materials, steam will simply accumulate inside the room, making it damp.

Expanded clay concrete

The vapor permeability of expanded clay concrete blocks depends on the amount of filler in its composition, namely expanded clay - foamed baked clay. In Europe, such products are called eco- or bioblocks.

Advice: if you cannot cut the expanded clay block with a regular circle and grinder, use a diamond one.
For example, cutting reinforced concrete diamond wheels makes it possible to quickly solve the problem.

Polystyrene concrete

The material is another representative cellular concrete. The vapor permeability of polystyrene concrete is usually equal to that of wood. You can make it yourself.

Today more attention begins to pay attention not only to the thermal properties of wall structures, but also to the comfort of living in the structure. In terms of thermal inertness and vapor permeability, polystyrene concrete resembles wooden materials, and heat transfer resistance can be achieved by changing its thickness. Therefore, poured monolithic polystyrene concrete is usually used, which is cheaper than ready-made slabs.

Conclusion

From the article you learned that building materials have such a parameter as vapor permeability. It makes it possible to remove moisture outside the walls of the building, improving their strength and characteristics. The vapor permeability of foam concrete and aerated concrete, as well as heavy concrete, differs in its characteristics, which must be taken into account when choosing finishing materials. The video in this article will help you find additional information on this topic.