What is the difference between vapor barrier a and v. Vapor barrier and wind insulation: purpose, application, which side to lay

Izospan is a non-woven building material used for insulation of residential and non-residential premises. In addition, it is necessary to protect against moisture and water. This is especially important when creating a house plan with an attic and a garage, which must be insulated with high quality water and heat.

The reader will learn in this article what types of isospan exist, what advantages this material has.

Izospan: material characteristics

Isospan film is now very common on construction market. It is used as the first barrier layer during the installation of insulation: it prevents moisture from entering the main thermal insulation layer polystyrene foam or other insulation. The material consists of pure polypropylene, fully synthetic, therefore it does not completely absorb water. When creating an insulation plan, isospan should be taken into account in the work.

Attention! Izospan is recognized as a very effective material for insulating attics, garages, one-story buildings.

An attic is an attic space that can be used for storage or as living space. The roof itself becomes the walls of this room, which should be well insulated. Izospan insulates and protects against moisture and wind, maintaining a comfortable temperature inside the attic and the whole house.

Similarly, isospan coating is used to insulate garages and other one-story non-residential premises:

protects metal from corrosion, wood from decay;
prevents the occurrence of condensate and moistening of the insulation, which reduces the thermal insulation properties;
reflects air currents, protecting the room from cooling and drafts;
maintains a stable temperature inside the room, does not release heat.

The following advantages of isospan can be distinguished:

waterproof;
durable and environmentally friendly (does not emit harmful impurities);
has high elasticity;
protects from ultraviolet radiation;
protects from the wind;
does not release, reflects heat;
withstands high pressure;
durable (serves about 50 years);
retains its properties in the range from minus 60 to plus 80 degrees Celsius.

In terms of creating comfortable conditions inside residential premises, isospan plays an important role, especially when arranging a house with an attic, a garage and other one-story outbuildings in the Russian climate.

Varieties of material, their technical features

Now high-quality manufacturers create pure polypropylene and a film from it using high-tech equipment, controlling the quality of production. In Russia, domestic companies are opening that offer building materials similar to foreign companies in quality and more favorable in price.

When choosing products, you need to focus on the presence of isospan quality and safety certificates. Well-known manufacturers coordinate their production plans with legal requirements.

Now, when decorating houses and non-residential premises, 4 main modifications of isospan are used, which have their own characteristics.

Isospan A

This is a film (membrane), which perfectly waterproofs and helps to eliminate moisture, its vapors, from the insulation. This modification is used to protect against wind and water, increases the life of the insulation. It is applied to isolation of private houses, penthouses, garages and any other rooms.

This isospan is resistant to mechanical stress and pressure, completely neutral to bio-impact (mold, bacteria, etc.). Can stretch:

longitudinally by 190 mm;
transversely by 140 mm.

The material is fixed from the outside of the insulation as an additional barrier. For example, when insulating an attic, it is mounted on the roof with an overlap in wide strips.

Important! The smooth surface should remain outside, the film itself should not come into contact with the insulation material. Otherwise, isospan will not be able to qualitatively waterproof the room and the insulation.

It is necessary that the membrane lies flat, does not protrude, swell or sag. Izospan A is fixed with wooden slats and nails.

Izospan A can be seen in the photo:

Izospan V

This modification perfectly blocks the way for water vapor, which eliminates the impregnation of the insulation with steam.

Important! When creating a garage plan, this can be very important to keep the room where the car is stored from getting damp.

Izospan B is two-layer, used:

On pitched roofs.
On the walls: external and internal.
To save floors in the basement, attic (attic).
In garages and other non-residential premises.

The vapor permeability index is 7, the material can also be stretched: in the longitudinal direction by 130 mm, in the transverse direction - at least 107 mm.

Each layer of this material has its own functions:

fleecy layer retains moisture and condensate;
the smooth part allows you to firmly fix the film with insulation.

Unlike the previous modification, isospan B is attached to the inside of the insulation. Fastened from the bottom up and overlapped. In order for the film to capture vapors, condensate, there must be a free space of at least 5 cm above the fleecy layer.

The appearance of the packaging of isospan B can be seen in the photo:

Izospan C

It also consists of two layers, but is used to protect an uninsulated roof, floors between floors, floor insulation. Has high strength.

The film is used for steam and water insulation:

uninsulated pitched or flat roof;
frame, load-bearing walls;
wooden floors located parallel to the floor;
concrete floor.

Installation of non-insulated roofs (slopes) is carried out with an overlap (with a depth of about 15 cm), also fastened with wooden slats. When arranging the attic at home, this material perfectly isolates the room from moisture from the environment.
If we talk about wooden floors, then here the film is attached directly to the insulation with a small free space from the floor (4-5 cm).
When insulating a concrete floor, isospan C is placed directly on the floor and pulled together on it.

Izospan C can be seen in the photo:

Izospan D

This modification is very durable, able to withstand great pressure and loads. It is used in roofing. In terms of waterproofing and protection against condensation, it perfectly withstands even a large crust of snow on itself.

Great for arranging the attic of a house or garage in regions with heavy snowfall. Material protects wooden structures and uninsulated roofs. Isospan D is insulated:

flat and pitched roofs;
concrete floors and ceilings at the basement level of the house.

The high strength of the film allows you to protect living space from wind and moisture, even in cases where the roof passes moisture.

It is also mounted with an overlap horizontally in strips, fixed on the rafters of the roof of the house with the help of rails. Installation on a concrete floor is similar to the previous modification of isospan, because in many respects isospan C and D are similar in their characteristics.

Izospan D can be seen in the photo:

The main modifications of the building material are described above, there are also varieties of these modifications that have different densities or additional qualities, for example, flame retardant additives, which give greater fire safety and protect against fire.

Also, manufacturers took care of the creation of additional consumables in time, which allow isolating seams and minor damage. We are talking about isospan adhesive tapes - these adhesive tapes allow you to isolate seam lines, uneven surfaces. Enough to working surface was dry and cleaned - isospan FL, SL adhesive tape will provide good impermeability of such places. There is even a metallized tape that has a high resistance index.

Important points for installing isospan

In the instructions for the use of isospan, the following points can be distinguished:

The laying of this insulating material does not require any special knowledge, it can be done by hand, taking into account individual features membranes.
The sales kit is always accompanied by instructions, which must be read carefully and acted according to the instructions. For example, if you fix isospan with the reverse side, then all the work will be meaningless - no isolation will occur.
Fastening to the tree occurs with the help of a stapler, one should not forget about sealing the seams, possible cracks with the help of isospan adhesive tape.
When a heat-insulating film is mounted, the metallized part should look inside the room, and the laying work itself is carried out butt-to-butt, without overlap. The seams are also sealed.

Izospan allows you to make life in your home comfortable and warm. The use of this film in the plinth or in the attic extends the service life truss system, wooden floors, creates a stable microclimate in residential premises. Isolation of the garage from moisture and condensate, allows you to make the room dry and safe for the metal coating of the car and other equipment.

Modern technologies greatly simplify the arrangement of your home. Approaching the issue responsibly, each person will be able to not know the problems in his home for a long time!

With the rise in the cost of energy carriers, it becomes necessary to make heat loss through the walls / floor / ceiling to a minimum. To solve this problem, a layer is laid (its thickness depends on the purpose of the room, climatic conditions and characteristics of the selected type of material). But this raises another problem: with the inevitable temperature difference between the outer and inner surfaces, condensation forms. If it is formed in the insulation layer, this entails a decrease in its characteristics. It has been established that with an increase in the moisture content of thermal insulation by 5%, the thermal insulation properties decrease by 50%. After drying, the properties are partially restored, the thermal insulation gradually becomes worse, the heat loss is more significant. Since the humidity in the room is almost always higher (and even more so in the bath), the steam tends to go outside, along the way “getting stuck” in the heater. To prevent the penetration of steam, a vapor barrier is laid from the side of the room.

Usually the vapor barrier is laid from the side of the room. This is due to the fact that usually indoor humidity is higher. This is especially true for kitchens, bathrooms, as well as baths and saunas. For baths or saunas built from wood, the penetration of moisture into the wood is also fraught with the formation of mold and the gradual destruction of the tree. This problem is especially relevant for Russian baths with their high level humidity.

In traditional baths made of rounded logs without additional thermal insulation, the removal of vapors, the regulation of humidity and the drying of the room occur due to natural processes. Even with perfectly fitted logs and caulked intervention joints, vapor removal and intake fresh air occurs due to micropores of wood, small cracks in the logs. This is exactly how our ancestors steamed: they warmed up the bathhouse for a long time - six to eight hours, did not rush anywhere and did not save firewood.

We also need the bath to be ready for a maximum of an hour, while energy costs should be minimal. This is achieved through a multilayer "pie" of various materials to keep warm and steam. A vapor barrier layer in such a “sandwich” is required, otherwise all the “layers” will have to be changed in a year or two, and the wood will be “treated” for a long time and hard from mold and fungi.

Waterproofing and vapor barrier: what's the difference?

The main difference between waterproofing and vapor barrier is the vapor permeability of materials. Waterproofing does not allow moisture to pass through, but collects it on the surface. Therefore, this type of material is laid in places where moisture enters in the form of drops, for example, under corrugated board on the roof. Condensate from the corrugated board in the form of water drops falls on the waterproofing, flows down it and is discharged outside the roof (because the edges of the waterproofing are wrapped in the form of an envelope).

The task of vapor barrier is different: it should prevent the penetration of water vapor into the insulation. Since the couples more are on the warmer side, then membranes or films are laid more often on the “warm” side. If we talk about the roof, then the vapor barrier materials are placed from the side of the attic, if we talk about the vapor barrier of the walls of the steam room or other bath rooms, then membranes / films are placed behind the decorative sheathing.

Summing up: the waterproofing does not conduct water (but it can conduct steam, releasing one that has penetrated into the insulation), the vapor barrier does not allow steam to pass through.

About how vapor barrier differs from waterproofing is described in detail in the video.

In order to minimize damage, it is advisable to use wooden planks that press the film against the guides, and already hammer staples / nails into the plank. Membrane can be fixed in the same way. They are not as torn as films made of polyethylene or polypropylene, it is easier to work with them.

Vapor barrier fastening

Cloths of rolled materials are stacked one on top of the other With with an overlap of at least 10-15 cm, gluing the joints with adhesive tape. You can use specialized, foil or regular adhesive tape.

Foil tape must be used at the joints of foil materials, otherwise much of their effectiveness is lost. When gluing joints of other materials, manufacturers recommend using their own adhesive tapes, but they do not explain what their differences and advantages are.

Please note that during installation, the vapor barrier webs should not be stretched: they tend to stretch / shrink when temperatures change. To avoid breaks during tension, you need to leave a small margin. It is considered normal to “sag” the canvas during installation by 1-2 cm. This is especially true when laying a vapor barrier on a roof or in an unheated room.

When installing a vapor barrier in places with a difficult terrain (protrusions, corners, etc.), it is advisable to glue the adjacent surfaces with adhesive tape: it is difficult to achieve perfect tightness in such places, and this is the main condition for effective protection. Therefore, any auxiliary means will be superfluous. It is also necessary to glue the edges of the vapor barrier along the perimeter of the door and window openings to ensure tightness. In general, tightness is the basis of high-quality vapor barrier for a bath, roof or any other room. Therefore, when carrying out work, pay maximum attention to this aspect.

I was led to this article by total illiteracy both on the part of builders and on the part of buyers, as well as more and more often flashing in commercial offers the phrase on "steam hydro insulation" - because of which then all the pandemonium begins, lost money, problematic structures, etc.

So, you have probably heard about waterproofing, wind protection and vapor barrier - that is, about films that are placed in insulated roofs and frame walls to protect them. But here further, often begins a complete "steam-hydrodisgrace".

I will try to write in a very simple and accessible way, without diving into formulas and physics. The main thing is to understand the principles.

Steam or hydro?

Start with the fact that main mistake, is to mix in one concept of steam and moisture. Steam and moisture are completely different things!

Formally, steam and moisture are water, but in different states of aggregation, respectively, having a different set of properties.

Water, it is also moisture, it is also “hydra” (hydro from ancient Greek ὕδωρ “water”) - this is what we see with our eyes and can feel. Tap water, rain, river, dew, condensate. In other words, it's a liquid. It is in this state that the term "water" is commonly used.

Steam is the gaseous state of water, water dissolved in air .

When an ordinary person talks about steam, for some reason he thinks that it is necessarily something visible and tangible. Steam from the nose of a kettle, in a bathhouse, in a bathroom, etc. But actually it is not.

Vapor is present in the air always and everywhere. Even as you read this article, there is steam in the air around you. It underlies the very humidity of the air, which you have probably heard about and complained more than once that the humidity is too high or too low. Although no one saw this moisture with their eyes.

In a situation where there is no steam in the air, a person will not live long.

Taking advantage of the different physical properties of water in liquid and gaseous states, science and industry have received the ability to create materials that allow steam to pass through, but do not allow water to pass through.

That is, this is a kind of sieve that can pass steam, but will not let water through. liquid state.

At the same time, especially smart scientists, and then manufacturers, figured out how to make a material that will conduct water in only one direction. How exactly this is done is not important to us. There are few such membranes on the market.

Vapor permeable membrane - allows steam to pass through in both directions, but does not allow moisture to pass through

So, a construction film that is impervious to water, but passes steam equally in both directions - is called waterproofing paro permeable membrane. That is, it passes steam freely in both directions, but does not pass water (hydra) at all or only in one direction.

Paro insulation - this is a material that does not let anything through, neither steam nor water. Moreover, at the moment, vapor barrier membranes- that is, materials that have one-sided vapor permeability have not yet been invented.

Remember as "Our Father" - there is no universal "parohydro membrane". There is a vapor barrier and vapor permeable waterproofing. These are fundamentally different materials. different purpose. The use of these films in the wrong place and in the wrong place can lead to extremely sad consequences for your home!

Formally, vapor barrier can be called vapor barrier, since it does not let water or steam through. But using the term is a path to dangerous mistakes.

Therefore, once again, in frame construction, as well as in insulated roofs, two types of films are used

Paro insulating- which do not let steam or water through and are not membranes
Waterproofing steam permeable membranes (also called windproof, due to extremely low air permeability or superdiffusion)

These materials have different properties and using them for other purposes is almost guaranteed to lead to problems with your home.

Why do you need films in the roof or frame wall?

To understand this, you need to add a little theory.

Let me remind you that the purpose of this article is to explain “on the fingers” what is happening, without delving into physical processes, partial pressure, molecular physics, etc. So I apologize in advance to those who had five in physics 🙂 In addition, I will immediately make a reservation that in reality all the processes described below are much more complicated and have a lot of nuances. But we need to understand the essence.

Nature has already ordered that in the house the steam always goes in the direction from warm to cold. Russia, a country with a cold climate, has an average heating period of 210-220 days out of 365 a year. If you add to it the days and nights when it is colder outside than in the house, then even more.

Therefore, we can say that most of the time, the steam movement vector is directed from the inside of the house, to the outside. It doesn't matter what in question- Walls, roof or underfloor. Let's call all these things in one word - enclosing structures

In homogeneous designs, the problem usually does not occur. Because the vapor permeability of a homogeneous wall is the same. The vapor easily passes through the wall and out into the atmosphere. But as soon as we have a multilayer structure consisting of materials with different vapor permeability, everything becomes not so simple.

Moreover, if we talk about walls, then we are not necessarily talking about frame wall. Any multi-layer wall, even brick or aerated concrete with external insulation, will already make you think.

Surely you have heard that in a multi-layer construction, the vapor permeability of the layers should increase as the steam moves.

What will happen then? Steam enters the structure and moves in it from layer to layer. At the same time, the vapor permeability of each subsequent layer is higher and higher. That is, from each subsequent layer, steam will come out faster than from previous.

Thus, we do not form an area where the vapor saturation reaches the value when, at a certain temperature, it can condense into real moisture (dew point).

In this case, we will not have any problems. The difficulty is that to achieve this in a real situation is not easy enough.

Vapor barrier of roof and walls. Where is it placed and why is it needed?

Let's consider another situation. Steam got into the structure, moves outward through the layers. Passed the first layer, the second ... and then it turned out that the third layer is no longer as vapor-permeable as the previous one.

As a result, the steam that got into the wall or roof does not have time to leave it, and a new “portion” is already supporting it from behind. As a result, before the third layer, the vapor concentration (more precisely, saturation) begins to grow.

Remember what I said before? Steam moves from warm to cold. Therefore, in the region of the third layer, when the vapor saturation reaches a critical value, then at a certain temperature at this point, the vapor will begin to condense into real water. That is, we got the "dew point" inside the wall. For example, on the border of the second and third layers.

This is exactly what people often observe, whose house is sewn up from the outside with something that has poor vapor permeability, such as plywood or OSB or DSP, but there is no vapor barrier inside or it is made of poor quality. By inside outer skin rivers of condensate flow, and the cotton wool adjacent to it is all wet.

Steam easily enters the wall or roof and "skips" the insulation, which usually has excellent vapor permeability. But then he "rests" in outer material with poor permeability, and as a result, the dew point is formed inside the wall, just in front of the obstruction to the vapor path.

There are two ways out of this situation.

It is long and painful to select the materials of the “pie” so that the dew point does not under any circumstances end up inside the wall. The task is possible, but difficult, given that in reality, the processes are not as simple as I describe now.
Put a vapor barrier on the inside and make it as airtight as possible.

It is along the second path that they go to the west, they make an airtight obstacle in the way of steam. After all, if you do not let steam into the wall at all, then it will never reach the saturation that will lead to condensation. And then you don’t have to puzzle over what materials to use in the “pie” itself, in terms of the vapor permeability of the layers.

In other words, the installation of a vapor barrier is a guarantee of the absence of condensation and dampness inside the wall. At the same time, the vapor barrier is always placed on the inner, “warm” side of the wall or roof and is made as tight as possible.

Moreover, the most popular material for this "they" is ordinary polyethylene 200 microns. Which is inexpensive and has the highest vapor permeability, after aluminum foil. Foil would be even better, but it's hard to work with.

In addition, I draw Special attention for the word sealed. In the west, when installing a vapor barrier, all joints of the film are carefully glued. All openings from the wiring of communications - pipes, wires through the vapor barrier, are also carefully sealed. The overlapping vapor barrier installation, which is popular in Russia, without gluing the joints, can give insufficient tightness and, as a result, you will get the same condensate.

Unglued joints and other potential holes in the vapor barrier can cause wet wall or roofs, even if there is a vapor barrier in itself.

I also want to note that the mode of operation of the house is important here. Summer country houses, in which you visit more or less regularly only from May to September, and maybe several times in the off-season, and the rest of the time the house is without heating, some vapor barrier flaws can forgive you.

But the house for permanent residence, with constant heating, does not forgive mistakes. The greater the difference between the external “minus” and the internal “plus” in the house, the more steam will flow into the external structures. And the greater the likelihood of condensation inside these structures. Moreover, the amount of condensate as a result can be calculated in tens of liters.

Why do I need a waterproofing or superdiffusion vapor permeable membrane?

I hope you understand why you need to do a vapor barrier with inner wall- in order not to let steam inside structures at all and to prevent conditions for its condensation into moisture. But the question arises, where and why to put steam permeable membrane and why it is impossible to put a vapor barrier instead of it.

Windproof, waterproofing membrane for walls

In American wall construction, the vapor permeable membrane is always placed on the outside, on top of the OSB. Its main task, oddly enough, is not to protect the insulation, but to protect the OSB itself. It's what Americans do vinyl siding other facade materials directly on top of the slabs, without any ventilation gaps or crates.

Naturally, with this approach, there is a possibility of external atmospheric moisture getting between the siding and the slab. How - this is the second question, heavy slanting rain, construction flaws in the area of window openings, adjoining roofs, etc.

If water gets between the siding and the OSB, then it can dry out there for a long time and the slab can begin to rot. And OSB in this regard is a filthy material. If it began to rot, then this process develops very quickly and goes deep into the plate, destroying it from the inside.

It is for this that, first of all, a membrane with one-tonne penetration for water is installed. The membrane will not allow water to pass to the wall in case of a possible leak. But if somehow, water got under the film, due to one-sided penetration, it can come out.

Super diffusion waterproofing membrane for roofing

Don't let the word superdiffusion fool you. In fact, this is the same as in the previous case. The word superdiffusion only means that the film passes vapor very well (vapor diffusion)

In a pitched roof, for example, under a metal tile, there are usually no plates, so the vapor-permeable membrane protects the insulation from both possible leaks from the outside and from blowing by the wind. By the way, that is why such membranes are also called windproof. That is, a vapor-permeable waterproofing membrane and a windproof membrane are usually one and the same.

In the roof, the membrane is also placed on the outside, in front of the ventilation gap.

In addition, pay attention to the instructions for the membrane. Since some membranes are placed close to the insulation, and some, with a gap.

Why is it necessary to put a membrane outside, and not a vapor barrier

But why not install a vapor barrier? And make a completely vapor-tight wall on both sides? Theoretically, this is possible. But in practice, it is not so easy to achieve absolute tightness of the vapor barrier - anyway, somewhere there will be damage from fasteners, construction flaws.

That is, some meager amount of steam will still fall into the walls. If there is a vapor-permeable membrane outside, then this minuscule has a chance to get out of the wall. But if the vapor barrier, it will remain for a long time and sooner or later, it will reach a saturated state and again the dew point will appear inside the wall.

So - a windproof or waterproof vapor-permeable membrane is always placed outside. That is, from the "cold" side of the wall or roof. If there are no stoves or other structural materials, the membrane is placed on top of the insulation. Otherwise, in the walls, it is placed on top of the enclosing materials, but under the facade finish.

By the way, it is worth mentioning one more detail, for which films are used, and the wall or roof is made as tight as possible. because the best insulation, it's air. But only if it is absolutely motionless. The task of all heaters, whether it is polystyrene or mineral wool, is to ensure the stillness of the air inside them. Therefore, the lower the density of the insulation, the higher, as a rule, its thermal resistance - the material contains more stationary air and less material.

The use of films on both sides of the wall reduces the likelihood of wind blowing through the insulation or convection air movements inside the insulation. Thus, forcing the heater to work as efficiently as possible.

What is the danger of the term vapor barrier?

The danger lies precisely in the fact that under this term, as a rule, two materials are mixed, with different purposes and with different characteristics.

As a result, confusion begins. Vapor barrier can be installed on both sides. But the most common mistake, especially in roofs, and the most terrible in terms of consequences, is when the result is the opposite - the vapor barrier is installed on the outside, and the vapor-permeable membrane is on the inside. That is, we calmly let steam into the structure, in unlimited quantities, but do not let it go out. This is where the situation shown in the popular video appears.

Conclusion: never confuse the concepts of vapor-permeable waterproofing membranes and vapor barrier - this is a sure way to construction mistakes that have very serious consequences.

How to avoid mistakes with films in a wall or roof?

Fear has big eyes, in fact, with films in a wall or roof, everything is quite simple. The main thing to remember is to follow the following rules:

In a cold climate (most of Russia), vapor barrier is always placed only on the inside, "warm" side - be it a roof or a wall
Vapor barrier is always made as tight as possible - joints, openings of communication penetrations are glued with adhesive tape. This often requires a special adhesive tape (usually with a butyl rubber adhesive base), as a simple one can peel off over time.
The most effective and cheapest vapor barrier - polyethylene film 200mk. It is desirable "primary" - transparent, it is easiest to glue the joints on it with ordinary double-sided tape. Buying "brand" vapor barriers is usually not justified.
Vapor-permeable membranes (superdiffusion, windproof) are always placed on the outer, cold side of the structure.
Before installing the membrane, pay attention to the instructions for it, as some types of membranes are recommended to be installed with a gap from the material to which it is adjacent.
Instructions can be found on the manufacturer's website or on the roll of the film itself.
Usually, in order to avoid mistakes with “which side” to mount the film, manufacturers roll the roll so that when “rolling out” it outside by design, you automatically made the installation right side. For other applications, before starting installation, consider which side to place the material.
When choosing a vapor-permeable membrane, you should give preference to quality manufacturers of the "first and second tier" - Tyvek, Tekton, Delta, Corotop, Juta, Eltete, etc. As a rule, these are European and American brands. Membrane manufacturers of the "third echelon" - Izospan, Nanoizol, Megaizol and other "isols", "brains", etc. as a rule, they are much inferior in quality, and most of them generally have an unknown Chinese origin with the brand of a trading company stamped on the film.

about the author

comfortable home

Each of us creates the conditions for our own living with our own hands: the microclimate in the room and a safe environment.

Humidity has a strong influence on human health. Maintaining her optimal value inside a dwelling is a complex technical task, which is not always provided not only by home craftsmen, but also by experienced builders.

Properly installed vapor barrier and waterproofing of all load-bearing structures building.

Commercial offers of marketers of individual manufacturers, advertising building films in terms of waterproofing, wind protection and even vapor barrier, are used to indicate the normal operating conditions of insulation materials.

But these terms are more often intended to increase sales, and ordinary people they are misleading, being a prerequisite for the creation of blunders in construction.

Principles for creating a building protection against dampness

To understand the essence of the issue, let us recall a little simple natural phenomena that constantly occur before us, pay attention to them.

Physical terms

General provisions

We have known since school that all bodies are in three states:

gaseous;
liquid;
hard.

This fully applies to water, which, in the usual sense for us, is in the form of a liquid, has fluidity. Its additional names are "moisture" and "hydro" - word formation from Greek. The term steam refers to its gaseous state, and ice is a solid.

What is steam

We assume that you immediately had an image of a kettle with boiling water and hot steam coming out of it. Let's try to dissuade that this is not a complete and partially misleading representation.

The normal gaseous state of water in the air is hidden from our view. We cannot observe the vapor dissolved inside the air. But they are capable of feeling high or low humidity in it by worsening their well-being.

If steam is completely removed from the air, then a person will not be able to live in such an environment. Experienced found that the optimum humidity for different people fluctuates between 40÷60%. Moreover, this indicator is purely individual and depends on many factors.

For supporting optimal humidity the rooms create a natural or forced ventilation, which, along with ensuring good air exchange, excludes

What is waterproofing

A similar phrase is used in construction to refer to structures that can withstand the penetration of water from external environment. For example, the roof of a building protects from the action of rain, and the coating created on the foundation - from the absorption of soil moisture from the soil by the capillaries of concrete structures.

Various materials are used to create waterproofing:

metals;
asphalts;
bituminous mastics;
plastics;
mastic sealants and other compounds.

Very good waterproofing works on a submarine, but we are now only interested in film materials for buildings.

What is vapor barrier and vapor permeable membrane

The term steam refers to the gaseous state of water. It is part of the air around us. Therefore, it is moisture that is dissolved in the air space.

If we use the analogy with waterproofing, then we must clearly understand that the vapor barrier does not let steam through at all, it isolates it, and even more so water.

The theoretical developments of scientists, which were implemented on an industrial scale by the largest manufacturers, led to the creation of membrane film materials with unique properties. Without going into their complex structure, let's pay attention to the result: they are absolutely impervious to water in the liquid state, but they pass steam well in both directions.

And since our residential buildings accumulate moisture evaporation created during cleaning, washing, cooking, due to breathing and evaporation through the skin, their excess must be removed from the premises. Microporous membranes work according to this principle.

It should be understood that the term vapor barrier implies the isolation of premises from the removal of steam, that is, it creates its accumulation and concentration.

And the function of removing steam through building structures from living rooms with simultaneous protection against the penetration of wind and raindrops, that is, water in a liquid state, is assigned to a vapor-permeable waterproofing.

For information: on the building materials market there are unique designs of vapor-permeable waterproofing, endowed with an additional property - the ability to pass water in only one direction. But their number is significantly limited, and the cost is high.

Brief conclusion:

vapor barrier materials are created to collect, concentrate steam. They do not let it through, like water, but do not work as membranes;
vapor-permeable membranes with waterproofing properties are designed to pass, remove vapors from the premises. They additionally have a very low air permeability providing good wind protection properties.

When choosing any of these materials for insulation, one should clearly understand its purpose and properties. For violation of the rules of operation will create serious problems for the entire building.

The purpose of the films in the roof and wall

Vapor-permeable membranes allow steam to pass in both directions. But, nature has so ordered that it always goes along with the flow of air from the warm side to the cold.

Given the peculiarities of our harsh climate and the duration heating season living quarters, we can confidently assume that steam most often leaves the rooms on the street, and does not enter them.

At the same time, the pattern of steam movement through walls, floors, ceilings, doors and other building elements depends on the materials and methods of manufacturing these structures. Let's consider them in more detail.

How vapor diffuses through a single layer structure

On the example of a homogeneous wall of a house, it can be argued that the penetration of steam from warm apartment into the cold outside air of the surrounding atmosphere goes equally, evenly. Even in building descriptions you can often find an allegory for this phenomenon when the authors write that the walls wooden houses"breathe" using collective image to describe the ongoing processes.

A wall made of any homogeneous building material: wood, brick, concrete, stone, aerated concrete, created in one layer, does not create obstacles for vapor diffusion. When structural element has several constituent parts, then the vapor permeability pattern changes.

How vapor diffuses through a sandwich structure

In a wall consisting of several building layers, the vapor permeability increases as it moves towards cold.

This explains the fact that steam escapes from each next layer of the wall faster than from the previous one. Therefore, there is no area inside the multi-layer wall saturated steam, when it is able to condense and fall out with real moisture - water, forming.

However, this purely theoretical explanation is very difficult to implement in practice for a number of technical reasons.

How to install vapor barrier on walls and roof

When installing building structures, for example, composite walls, it is necessary to take into account the features of the actual passage of steam through all elements. Otherwise, a situation may arise when the steam that has passed through several layers does not have time to overcome the next obstacle due to the obstacle that has arisen, and the next batch supports it from behind.

In such a place, steam will accumulate, its saturation will increase. At some point, at a certain temperature, it will reach a critical state and condensate will form at the boundary of the problematic layers with the release of water.

In our example, we encountered a "dew point" formed inside a composite wall before the last exit layer, when an obstruction appeared in the steam path, restricting its exit and leading to the formation of condensate.

In practice, this situation often occurs when outside building, its owner sheathes the walls with material with poor vapor conductivity: impregnated plywood, DSP, OSB, and there is no vapor barrier from inside the wall or it is of very low quality.

As a result, it turns out that moisture collects on the inner side of the outer skin due to condensate, and the adjacent layer of insulation is mineral wool or becomes constantly wet and ceases to fulfill its function. direct appointment. A dew point formed on their surface.

This technical issue can be resolved in one of two ways:

based on theoretical knowledge and practical experiments, select Construction Materials for each layer so that they are in general design the walls eliminated the formation of condensate and did not create obstacles for the passage of steam to the street;
install a vapor barrier inside the rooms of the building and ensure its maximum tightness.

The first method requires highly skilled workers and quality performance installation work, and the second is much simpler and consists in the fact that the steam from the living quarters is simply not allowed into the walls and roof, but is removed through the ventilation system.

A layer of hermetic vapor barrier mounted from the side of the room guarantees the absence of condensate inside the walls and roof.

Western construction companies go this way, using one of two materials:

aluminum foil;
ordinary polyethylene film with a thickness of 200 microns.

Foil has the best vapor barrier properties, but it is more difficult to install. Therefore, polyethylene is preferred.

The vapor barrier layer must be completely sealed. Since film sheets need to be joined, builders mainly use two methods:

installation of overlapping layers with an overlap;
gluing joints with special adhesive tape.

The first method is widely promoted on the Russian Internet. It's easier to perform. But it does not provide complete tightness and steam can pass through the small gaps that have arisen and form condensate right inside the walls, which is very bad.

For this reason, adhesive tape should be used, all joints should be sealed with it, and holes for pipelines and all household communications should be sealed. Only then will the vapor barrier work effectively, blocking the ingress of steam into the wall materials.

Poorly executed vapor barrier causes the formation of a wet wall or roof, the creation of excessive moisture with all the negative consequences. You can still put up with it if the building is used for living during the dacha summer period, and in winter it is idle without heating.

When do people live in such a house all year round, then the likelihood of condensation in the walls and the occurrence of dampness is very high. The volume of accumulated moisture can be measured in liters.

How is waterproofing created?

After the vapor barrier has blocked the access of moisture from the living room to the wall, it is necessary to prevent its ingress from the street. This function is assigned to a vapor-permeable membrane.

Wind protection and waterproofing of walls

In houses built using frame technology in the west, a vapor-permeable membrane protects directly outer layer OSB boards, on which facade materials are immediately mounted, for example, siding blanks. They are placed directly on the slabs, without creating air gaps crate.

In case of heavy slanting rain, due to construction defects in installed windows, leaking roof elements, and for other reasons, water can get behind the siding and accumulate there. This will lead to rotting of materials and their destruction.

For this reason, all moisture must be removed. Vapor-permeable membranes with a one-way principle of operation do not allow water to get on outer material OSB walls and at the same time, when she got there by extraneous ways, contribute to her exit to the outside.

Simultaneously with the drainage of water, the membrane provides wind protection.

The role of the waterproofing membrane on the roof

On the modern roofs using pitched technology, a superdiffusion waterproofing membrane is installed. The prefix "super" denotes increased vapor transmission properties (ensuring diffusion).

Usually, protective sheathing plates are not placed under the roof of a metal tile, and the insulation is protected by a vapor-permeable membrane from the penetration of moisture into it. It also resists wind well. Therefore, it is additionally called windproof. It is always in the roof, as well as on the wall, located outside the insulation.

Structurally, vapor barrier membranes can be manufactured for different ways placement on the insulation and mounted:

with the creation of a ventilated gap;
or up close.

Pay attention to this item during installation.

Where is the vapor barrier and waterproofing installed?

Individual building owners have a desire to save on materials and install vapor barrier layers from cheap polyethylene film on both sides of the wall. This idea can be justified when the entire construction technology is of perfect quality and does not provide a single place for moisture to leak to the building elements.

Unfortunately, in practice, to carry out such actions is simply not realistic. Therefore, a vapor-permeable membrane is always mounted outside, which ensures the exit of moisture that accidentally got inside the wall.

We draw a brief conclusion:

A vapor-permeable membrane with waterproofing and windproof properties is always mounted outside the wall or roof in such a way that it can remove excess moisture that has penetrated inside building structure.
The membrane is located, depending on its design, directly on the enclosing layer or insulation, or on a crate that provides the necessary ventilation.

Proper use of films creates a sealed volume, prevents moisture from entering the insulation, and keeps it dry. Only in this case, the air inside the foam mineral wool or another layer, has an increased thermal resistance and minimize heat loss.

Working together, vapor barrier and waterproofing films ensure the normal state of the air inside building structures, exclude the formation of high humidity, and effectively save heat.

What are the errors in terms

Marketers of manufacturers are interested in increasing sales of vapor barrier films and waterproof vapor-permeable membranes. They advertise their properties in all sorts of ways, coming up with various names. Thus, the complex word vapor barrier was created, which led to a confusion of the characteristics of two completely different materials used to solve opposite problems.

Due to this, building owners can allow the installation of a vapor barrier on both sides of the wall structure, when moisture cannot escape from the building elements and creates increased dampness and their destruction.

An even worse situation with moisture occurs when the locations of the vapor barrier, which was installed outside the wall, are mixed up with a vapor-permeable membrane mounted inside the room.

Then all the moisture from the room is directed to the wall, and its exit is blocked. As a result, mold, fungi, and dirt form.

Do not interchange the installation of protective film coatings. They perform different, opposite functions.

Let's summarize the use of film materials for the home master:

In cold climates, the vapor barrier membrane is placed exclusively from the inside of the room, regardless of the type of building structure - walls or roofs.
In order for the vapor barrier to work effectively, it must be made as tight as possible, using a construction type of adhesive tape with a butyl rubber adhesive base, which effectively glues the film for the entire period of operation.
Ordinary polyethylene film 200 microns thick works optimally as a vapor barrier. It is a good alternative to advertised "brand" models.
The place of installation of vapor-permeable superdiffusion membranes is the outer side of the building.
Before mounting the membrane, it is necessary to clarify the distance of its location from the protected surface: close or at a distance. You can find out in the instructions that manufacturers put in a roll of film and post on their website, and it is better to double-check the recommendations of sellers.
The quality of vapor-permeable membranes is higher from well-known manufacturers from Europe and America.

For a better understanding of the topic of vapor barrier and the role of vapor-permeable membranes that create waterproofing, we recommend watching the video of the owner of ASC Group.

During the construction of buildings and structures, one of essential elements is the building envelope. In simple words- this is the device of walls, ceilings, construction roofing cake, foundation and other components of the house. The enclosing structure performs many functions expressed in bearing capacity, aesthetic component, thermal insulation protection, resistance to wind, water and steam. In this article, we will consider vapor barrier and waterproofing of house structures. And since these functions are somewhat similar and sometimes interchangeable, we will understand in detail What is the difference between waterproofing and waterproofing.

Purpose of waterproofing

The main task of the waterproofing layer is to prevent water from entering the building envelope (from the street, groundwater, water leakage indoors). Consider application examples:

The enclosing structure is a roofing pie. In this case, the main waterproofing layer that provides protection against direct precipitation is roofing material(slate, metal tile and others). Further protection against moisture follows. For example, a layer of .
Basement, ground floor. To maintain an optimal microclimate and protect against moisture ingress, it is necessary to create a barrier between the structure and the soil in contact with it. By treating the outer surface with special waterproofing compounds or welded materials, you can protect yourself from the effects of groundwater.
Interior spaces in contact with water. These include the kitchen, bathroom, toilet. Unlike basements, where they fight moisture from the outside, in this case, using waterproofing materials, try to prevent unwanted ingress of water into other rooms.

The purpose of the vapor barrier

The main task of the vapor barrier layer is to prevent steam from entering the enclosing structure. Consider application examples:

The enclosing structure is a roofing pie. If the waterproofing was sorted out and completed to protect against precipitation, then vapor barrier is necessary to protect against evaporation from the room. Since the roofing cake can consist of a heater, the function of the vapor barrier is to protect the insulation from vapors from interior spaces. It is very important. If steam condenses inside the insulation, this will lead to the loss of its basic properties.
Basement, ground floor. Protecting sweat from getting inside moisture in the form of a liquid, we will not protect ourselves from steam. Since waterproofing does not always guarantee vapor tightness. Additional vapor protection in this case is also necessary. After all, dampness and fungus, you see, are not good.
Wall of the house. Here you can draw an analogy with a roofing pie. The main task is to prevent water vapor from entering the building envelope.

The fundamental difference between waterproofing and vapor barrier

Vapor barrier differs from waterproofing mainly in that both sides of the coating are completely waterproof. Vapor barrier film should not allow steam or water to pass both outside (into the house) and inside the building envelope. Waterproofing, on the other hand, should protect against external ingress of moisture and help to remove accidentally trapped water vapor. At the same time, it is necessary to clearly functional purpose each protective material and use the right combination in certain cases. Replacing the waterproofing film with a vapor barrier can lead to disastrous results.