Vapor-permeable walls, are they needed? Vapor-permeable insulation (not extruded) Neopor expanded polystyrene (Neopor) from BASF Bulk density of insulation

Extruded or extruded polystyrene foam (EPS, EPPS, XPS), styrofoam (PSV / EPS) and foam plastic (PSB-S, expanded polystyrene, styrofoam) are widely used in Russia as thermal insulation material(insulation). Unfortunately, manufacturers are often silent about the fact that due to the lack of vapor permeability, these materials can lead to the appearance of fungi and mold. This is especially true of non-vapor-permeable extruded polystyrene foam, which, for this reason, is used to insulate brick and concrete walls Not recommended.

But recently I caught the eye of a premium cottage village near St. Petersburg, which used imported materials, including Belgian brick and Neopor expanded polystyrene insulation. I was shocked that such houses were called eco-houses. Passive house when using 400 mm brickwork, as well as 350 mm of Neopor insulation (Neopor) on the walls, 300 mm of extruded polystyrene foam under foundation slab, 400 mm of Neopor insulation (Neopor) on floor slabs in a run - this is of course excellent. Moreover, a very small number of houses correspond to the German Passive House standard in Russia. But Ecohouse...

In addition, the choice of expanded polystyrene, albeit from the German manufacturer BASF, as a heater seemed strange. It is possible that this is a desire to make everything according to Western tracing paper and Western materials. But it seems to me much more reasonable to use brick (foam glass chips) or.

It turned out that Neopor (Neopor) is a new generation of expanding polystyrene foam (EPS) from BASF. In the Russian-language brochures "Neopor Wall Insulation (BASF)" and "Neopor. Expanding Polystyrene (EPS). Innovative AI Insulation.", unfortunately, information on the vapor transmission of this material is completely missing. The entire emphasis is on black graphite granules, which make it possible to reduce the thickness of the insulation by 15 percent, while maintaining the coefficient of thermal conductivity.

Information about Neopor on the BASF website in Russian is generally scarce. But in English you can find more interesting things. For example, the following:

Water and Neopor are good friends.

Neopor Rigid Thermal Insulation is a closed-cell foam, but not all closed-cell foams are created equally. Neopor Rigid Thermal has a Class III Vapor Permeability rating of between 2.5 and 5.5 depending on thickness and density. This means walls constructed with Neopor as Continuous Insulation can more easily transport water vapor, reducing the likelihood of mold, mildew and structural damage. And, Neopor Rigid Thermal Insulation has low water absorption relative to traditional insulation materials.

I'll try to translate:

Water and Neopor are good friends.

Neopor solid insulation is a closed cell foam, but not all closed cells are made the same. Neopor Rigid Thermal has a class 3 vapor permeability ranging from 2.5 to 5.5, depending on thickness and density. This means that walls built with Neopor as continuous insulation can easily carry steam, reducing the chance of mold, false powdery mildew as well as structural damage. Solid Neopor insulation has less water absorption than traditional insulation materials.

In Russian sources, I came across information that the vapor permeability of Neopor is at least 0.05 mg / (m.h.Pa). But I'm not sure that these data can be trusted. Concrete has less vapor permeability. But the brick already has more, and it differs greatly from what kind of brick. So everything is correctly indicated about reducing the likelihood of fungi and mold. If you already use extruded polystyrene foam, styrofoam or polystyrene foam for insulation stone walls, then it is precisely a similar vapor-permeable (i.e., extruded polystyrene foam immediately disappears). Although environmentally friendly, non-flammable and durable - foam glass chips and vermiculite - even with vapor permeability, everything is much better. In any case, in addition to environmental friendliness, pay attention to the fact that the durability of the insulation corresponds to the durability of the walls of the house, and the vapor permeability of the insulation is at the level of the vapor permeability of the walls or higher.

Of course, the problem with heaters that do not remove steam can be solved with the help of forced ventilation, as well as with the help of interior decoration that blocks the passage of steam. But is it worth it to do so, you decide. Moreover, with such a struggle with the cause, there is always a chance that something will go wrong, including due to the mistake of finishers or equipment breakdown.

In general, be careful when you read marketing brochures, even if it's in the premium segment. Beautiful pictures and imported materials are not yet a guarantee of quality and environmental friendliness. Of course, for 60 million rubles in the case of Wright Park, the cottage turns out to be very interesting solutions and quality materials. But for that kind of money, I would still avoid solutions like this one from Active House LLC.

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 a building material to either pass or retain water vapor due to different pressures 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 moisture the wall can contain, which means that the material has low frost resistance.

Vapor permeability table indicated by the following indicators:

1. Thermal conductivity is, in a way, an indicator of the energy transfer of heat from more heated particles to less heated particles. Therefore, an equilibrium is established in temperature conditions. If the apartment has a high thermal conductivity, then this is the most comfortable conditions.
2. thermal capacity. It can be used to calculate the amount of heat supplied and the amount of heat contained in the room. It is necessary to bring it to a real volume. Thanks to this, it is possible to fix the temperature change.
3. Thermal absorption is an enclosing structural alignment during temperature fluctuations. In other words, thermal absorption is the degree of absorption of moisture by the surfaces of the walls.
4. Thermal stability is the ability to protect structures from sharp fluctuations in heat flows.

Completely all the comfort in the room will depend on these thermal conditions, which is why it is so necessary during construction 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 houses are built. In such cases, it is recommended to install a vapor barrier layer with outside Houses. After that, the insulation will not let steam through.

Vapor barrier 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 is made up of soft materials.

Table of vapor permeability of materials.

Table of vapor permeability of materials- these are building codes of international and domestic vapor permeability standards 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 fiberboard, 1000-800 kg/m3
Chipboard and fiberboard, 200 kg/m3
Chipboard and fiberboard, 400 kg/m3
Chipboard and fiberboard, 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 stoneware
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. not natural)
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 plastic), plate, density from 10 to 38 kg/m3
Expanded polystyrene extruded (EPPS, XPS)	0.005 (SP); 0.013; 0.004
Styrofoam, 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 tile (tile)
Clinker tiles	low; 0.018
Gypsum slabs (gypsum boards), 1100 kg/m3
Gypsum slabs (gypsum boards), 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
Ecowool cellulose

Vapor permeability - the ability of a material to pass or retain steam as a result of the difference in the partial pressure of water vapor at the same atmospheric pressure on both sides of the material. Vapor permeability is characterized by the value of the coefficient of vapor permeability or the value of the permeability resistance coefficient when exposed to water vapor. The vapor permeability coefficient is measured in mg/(m h Pa).

Air always contains some amount of water vapor, and warm air always has more than cold air. At an internal air temperature of 20 °C and a relative humidity of 55%, the air contains 8 g of water vapor per 1 kg of dry air, which create a partial pressure of 1238 Pa. At a temperature of -10°C and a relative humidity of 83%, the air contains about 1 g of steam per 1 kg of dry air, which creates a partial pressure of 216 Pa. Due to the difference in partial pressures between indoor and outdoor air, a constant diffusion of water vapor from the wall occurs through the wall. warm room out. As a result, in real conditions During operation, the material in the structures is in a slightly moistened state. The degree of moisture content of the material depends on the temperature and humidity conditions outside and inside the fence. The change in the thermal conductivity coefficient of the material in the structures in operation is taken into account by the thermal conductivity coefficients λ(A) and λ(B), which depend on the humidity zone of the local climate and the humidity regime of the room.
As a result of the diffusion of water vapor in the thickness of the structure, moist air moves from interior spaces. Passing through the vapor-permeable structures of the fence, moisture evaporates to the outside. But if a layer of material is located near the outer surface of the wall that does not pass or poorly passes water vapor, then moisture begins to accumulate at the border of the vapor-tight layer, causing the structure to become damp. As a result, the thermal protection of a wet structure drops sharply, and it begins to freeze. in this case, it becomes necessary to install a vapor barrier layer on the warm side of the structure.

Everything seems to be relatively simple, but vapor permeability is often remembered only in the context of the "breathability" of the walls. However, this is the cornerstone in choosing a heater! It must be approached very, very carefully! It is not uncommon for a homeowner to insulate a house based only on the heat resistance index, for example, a wooden house with foam plastic. As a result, he gets rotting walls, mold in all corners and blames the "non-environmental" insulation for this. As for foam, due to its low vapor permeability, it must be used wisely and think very carefully whether it suits you. It is for this indicator that often wadded or any other porous heaters are better suited for insulating walls from the outside. In addition, with cotton wool heaters it is more difficult to make a mistake. However, concrete or brick houses you can safely insulate with polystyrene - in this case, the foam "breathes" better than the wall!

The table below shows materials from the TCH list, the vapor permeability index is the last column μ.

How to understand what vapor permeability is, and why it is needed. Many have heard, and some actively use the term "breathable walls" - and so, such walls are called "breathable" because they are able to pass air and water vapor through themselves. Some materials (for example, expanded clay, wood, all wool insulation) pass steam well, and some very poorly (brick, foam plastics, concrete). The steam exhaled by a person, released during cooking or taking a bath, if there is no exhaust hood in the house, creates increased humidity. A sign of this is the appearance of condensation on windows or pipes with cold water. It is believed that if the wall has a high vapor permeability, then it is easy to breathe in the house. In fact, this is not entirely true!

In a modern house, even if the walls are made of "breathable" material, 96% of the steam is removed from the premises through the hood and window, and only 4% through the walls. If vinyl or non-woven wallpaper is pasted on the walls, then the walls do not let moisture through. And if the walls are really "breathing", that is, without wallpaper and other vapor barrier, in windy weather heat blows out of the house. The higher the vapor permeability of a structural material (foam concrete, aerated concrete and other warm concrete), the more moisture it can absorb, and as a result, it has a lower frost resistance. Steam, leaving the house through the wall, at the "dew point" turns into water. The thermal conductivity of a damp gas block increases many times, that is, it will be very cold in the house, to put it mildly. But the worst thing is that when the temperature drops at night, the dew point shifts inside the wall, and the condensate in the wall freezes. When water freezes, it expands and partially destroys the structure of the material. Several hundred such cycles lead to the complete destruction of the material. Therefore, the vapor permeability of building materials can do you a disservice.

About the harm of increased vapor permeability on the Internet walks from site to site. I will not publish its content on my website due to some disagreement with the authors, but I would like to voice selected points. So, for example, a well-known manufacturer of mineral insulation, Isover, on its English site outlined the "golden rules of insulation" ( What are the golden rules of insulation?) from 4 points:

Effective isolation. Use materials with high thermal resistance (low thermal conductivity). A self-evident point that does not require special comments.

Tightness. Good tightness is necessary condition for an efficient thermal insulation system! Leaky thermal insulation, regardless of its coefficient of thermal insulation, can increase energy consumption from 7 to 11% for heating a building. Therefore, the tightness of the building should be considered at the design stage. And at the end of the work, check the building for tightness.

Controlled ventilation. The task of removing excess moisture and steam is assigned to ventilation. Ventilation should not and cannot be carried out due to a violation of the tightness of the enclosing structures!

Quality installation. On this point, I think, too, there is no need to speak.

It is important to note that Isover does not produce any foam insulation, they deal exclusively with mineral wool insulation, i.e. products with the highest vapor permeability! This really makes you think: how is it, it seems that vapor permeability is necessary to remove moisture, and manufacturers recommend complete tightness!

The point here is the misunderstanding of this term. The vapor permeability of materials is not designed to remove moisture from the living space - vapor permeability is needed to remove moisture from the insulation! The fact is that any porous insulation is not, in fact, the insulation itself, it only creates a structure that holds the true insulation - air - in a closed volume and, if possible, motionless. If such an unfavorable condition suddenly forms that the dew point is in a vapor-permeable insulation, then moisture will condense in it. This moisture in the heater is not taken from the room! The air itself always contains some amount of moisture, and it is this natural moisture that poses a threat to the insulation. Here, in order to remove this moisture to the outside, it is necessary that after the insulation there are layers with no less vapor permeability.

A family of four per day on average releases steam equal to 12 liters of water! This moisture from the indoor air must not get into the insulation in any way! What to do with this moisture - this should not bother the insulation in any way at all - its task is only to insulate!

Example 1

Let's look at the above with an example. Take two walls frame house of the same thickness and the same composition (from the inside to the outer layer), they will differ only in the type of insulation:

Drywall sheet (10mm) - OSB-3 (12mm) - Insulation (150mm) - OSB-3 (12mm) - ventilation gap (30mm) - wind protection - facade.

We will choose a heater with absolutely the same thermal conductivity - 0.043 W / (m ° C), the main, tenfold difference between them is only in vapor permeability:

Expanded polystyrene PSB-S-25.

Density ρ= 12 kg/m³.

Vapor permeability coefficient μ= 0.035 mg/(m h Pa)

Coef. thermal conductivity in climatic conditions B (the worst indicator) λ (B) \u003d 0.043 W / (m ° C).

Density ρ= 35 kg/m³.

Vapor permeability coefficient μ= 0.3 mg/(m h Pa)

Of course, I also use exactly the same calculation conditions: inside temperature +18°C, humidity 55%, outside temperature -10°C, humidity 84%.

I did the calculation in thermotechnical calculator By clicking on the photo, you will go directly to the calculation page:

As can be seen from the calculation, the thermal resistance of both walls is exactly the same (R = 3.89), and even their dew point is almost the same in the thickness of the insulation, however, due to the high vapor permeability, moisture will condense in the wall with ecowool, greatly moistening the insulation. No matter how good dry ecowool is, raw ecowool keeps heat much worse. And if we assume that the temperature outside drops to -25 ° C, then the condensation zone will be almost 2/3 of the insulation. Such a wall does not meet the standards for protection against waterlogging! With polystyrene foam, the situation is fundamentally different because the air in it is in closed cells, it simply has nowhere to get enough moisture for dew.

In fairness, it must be said that ecowool is not laid without vapor barrier films! And if you add to the "wall pie" vapor barrier film between OSB and ecowool on the inside of the room, then the condensation zone will practically leave the insulation and the structure will fully meet the requirements for moisture (see picture on the left). However, the vaporization device practically makes it meaningless to think about the benefits of the “wall breathing” effect for the microclimate of the room. Vapor barrier membrane has a vapor permeability coefficient of about 0.1 mg / (m h Pa), and sometimes vapor barrier polyethylene films or insulation with a foil side - their vapor permeability coefficient tends to zero.

But low vapor permeability is also far from always good! When insulating fairly well vapor-permeable walls made of gas-foam concrete with extruded polystyrene foam without vapor barrier, mold will certainly settle in the house from the inside, the walls will be damp, and the air will not be fresh at all. And even regular airing will not be able to dry such a house! Let's simulate a situation opposite to the previous one!

Example 2

The wall this time will consist of the following elements:

Aerated concrete brand D500 (200mm) - Insulation (100mm) - ventilation gap (30mm) - wind protection - facade.

We will choose the insulation exactly the same, and moreover, we will make the wall with exactly the same heat resistance (R = 3.89).

As we can see, with absolutely equal thermal characteristics we can get radically opposite results from insulation with the same materials!!! It should be noted that in the second example, both designs meet the standards for protection against waterlogging, despite the fact that the condensation zone enters the gas silicate. This effect is due to the fact that the plane of maximum moisture enters the expanded polystyrene, and due to its low vapor permeability, moisture does not condense in it.

The issue of vapor permeability needs to be thoroughly understood even before you decide how and with what you will insulate your house!

puff walls

In a modern house, the requirements for thermal insulation of walls are so high that a homogeneous wall is no longer able to meet them. Agree, with the requirement for heat resistance R = 3, making a homogeneous brick wall with a thickness of 135 cm is not an option! modern walls- these are multilayer structures, where there are layers that act as thermal insulation, structural layers, a layer exterior finish, a layer of interior decoration, layers of steam-hydro-wind-insulations. Due to the different characteristics of each layer, it is very important to position them correctly! The basic rule in the arrangement of the layers of the wall structure is as follows:

The vapor permeability of the inner layer must be lower than the outer one, for free steam to escape the walls of the house. With this solution, the "dew point" moves to outside bearing wall and does not destroy the walls of the building. To prevent condensation inside the building envelope, the heat transfer resistance in the wall should decrease, and the vapor permeability resistance should increase from outside to inside.

I think this needs to be illustrated for better understanding.