Steam-waterproofing - hydro-vapor barrier... What films are placed and where in the roof or frame wall. Correct vapor barrier of a frame house Vapor barrier of external walls of a frame house

The most important stage in the insulation of any structure is the vapor barrier of the walls. Why is it needed, what functions does it perform, and why is it impossible to do without it in most cases? An amazing fact: in the course of normal life, a family of three releases about 150 liters of water into the environment in the form of water vapor. This volume is enough for a large, nice bay of neighbors! Meanwhile, all this moisture does not go down, but rises up and to the sides and tries to naturally leave the room through the walls and ceiling.

Wood is a very porous material that allows air to pass through and absorbs moisture. Imagine that it is now about -15° “overboard”. The house is warm. You breathe, cook borscht for lunch, do laundry, and take a hot bath in the evening. All this leads to the formation of water vapor. Moisture is absorbed into the walls and tries to come out. Somewhere in the thickness of the wall - closer to the outer or inner surface (this depends on the thickness of the walls and the quality of the insulation) - there is a “dew point”: the boundary at which water vapor turns into water.

This water freezes (it’s cold outside!), as a result of which several very undesirable processes occur at once:

Dampness of the wall and/or insulation.
Freezing of walls due to moisture trapped inside turning into ice.
Gradual destruction of the wall structure.
The appearance of fungus and mold.

Vapor barrier of the walls of a wooden house helps to avoid all this.

In extreme weather conditions, some water may get under the cover. Therefore, when building a house, ventilation gaps are made and a vapor barrier film is installed.

Installation of external and internal vapor barrier

In our climatic conditions, insulating the walls of houses is a necessity: in order to ensure a comfortable indoor temperature in winter, without spending astronomical amounts on heating, we have to use the benefits of civilization in the form of insulating materials. In order for them to work efficiently, it is necessary to vapor barrier the walls of a wooden house from the outside or from the inside - it depends on where the insulation is located. If moisture gets into the heat-insulating layer, it will significantly increase its thermal conductivity, which means heat loss and reduce the service life of the insulation - vapor barrier allows you to avoid this.

Vapor barrier films are made using the weaving method. Consists of a polypropylene base coated with laminite on one or both sides

How to insulate wooden walls from the outside

Insulated walls are a multi-layer structure. Its base is the walls of the house. A lathing made of wooden blocks is attached to them, between which insulation slabs are laid - stone wool, basalt wool. Then a vapor barrier film is attached over them, which is pressed against the sheathing with slats. Facing material is mounted on them - lining, siding, etc. As a result, an air gap is formed between the vapor barrier and the cladding. It is necessary so that moisture, condensing on the vapor barrier, gradually evaporates without getting inside the structure and without moistening the lining.

Another version of the same design provides an additional layer of wind-waterproofing, which is located immediately on the wall of the house, between it and the insulation. This prevents the insulation from getting wet vapors into the insulation from inside the house.

Scheme of vapor barrier device and insulation of the house from the outside

Vapor barrier of walls from the inside

In this case, the work is carried out in a similar way. The layers of materials are arranged in the following order:

House wall.
Frame bars, between which insulation boards are laid.
Vapor barrier membrane pressed to the frame with slats.
Wall cladding - plasterboard, lining, which are attached to slats.

The sheets are attached to each other using a stapler, then the vapor barrier is secured with pre-antiseptic 4x5 cm slats

Vapor barrier of frame house walls

Frame houses are distinguished by the fact that they do not have a rigid base - a wall - for insulation. It is located between the racks of the timber frame. In such houses, the cross-section of the walls looks like this:

External cladding (OSB boards, siding, lining, block house).
Hydro-wind protection is a membrane that protects the insulation from moisture from the outside. A ventilation gap is required between it and the outer cladding, due to which the moisture that gets on the membrane gradually evaporates from the surface due to natural ventilation.
The frame of a house with insulation embedded in it.
Vapor barrier membrane. It is necessary to install vapor barriers on walls using the rough side of the insulation film.
Lathing.
Interior wall decoration.

Since 70% of the volume of frame walls is insulation, its protection from moisture is very important. Otherwise, it loses its properties, crumples and moves away from the frame, cracks appear, and the house freezes.

When constructing frame houses, it is mandatory to use wind protection and vapor barriers

Features of laying vapor barrier on walls

Manufacturers offer different types of vapor barrier materials. The most modern and high-tech of them are vapor barrier membranes. They are made from polypropylene, with a fiberglass mesh base that gives the material strength. One or both sides of the film have a special coating that is rough to the touch. This is a layer of cellulose-viscose fibers that absorb moisture well. When it gets on the surface of the membrane, it lingers in the rough layer, without passing further and without getting into the insulation and the thickness of the walls. This moisture is then evaporated through natural ventilation. Vapor barrier materials with a metallized coating on one side are also produced. It serves to reflect thermal energy into the room, thereby reducing heat loss.

Important: the foil surface should be facing away from the insulation, towards the room.

Foil vapor barrier not only retains moisture, but also retains heat

Installation of the vapor barrier membrane on the wall is done in horizontal stripes, starting from the floor. At the joints of the strips, it is necessary to overlap them with each other by at least 10 cm. The joints are glued with a special connecting tape, which provides a tight connection. The junctions of the film with wooden or stone surfaces must also be carefully glued, achieving complete tightness. The membranes are attached to the wooden frame using a construction stapler or galvanized nails.

Laying vapor barrier on walls in a wooden house

Of course, vapor barrier of walls with your own hands is quite feasible. True, it is quite difficult for a non-specialist to carry out the entire complex of work on wall insulation: mistakes when using high-tech modern materials are fraught with serious troubles. To ensure that your new home does not require urgent repairs, it is much safer to turn to the services of professional builders.

Vapor barrier of a frame house is carried out to protect thermal insulation materials from moisture, which can affect them indoors. It is worth noting that the main requirement for installing any insulation is its high-quality and maximum tight fit to the walls and floor of the frame. If water gets on it, the material will lose its positive properties, change its shape and its effectiveness.

Naturally, the overall insulation of the home will also suffer. The only correct and reasonable solution to eliminate such situations is to use a vapor barrier. The article describes in detail how to lay it, the features of construction work and what, in fact, this component is.

About the characteristics of vapor barrier material

Vapor barrier is a special composition that has a porous structure, due to which it is possible to significantly reduce the penetrating speed of water vapor and its effect on the heat insulator. It is important to understand that the material can only significantly reduce, but not eliminate, this negative process. It has a membrane with a smooth and rough side, the “polarity” of which is extremely important during installation. The latter is designed to remove and evaporate moisture.

When fixing the described insulator, you should follow the rule: the rough side goes into the room, and the smooth side goes towards the insulating component. It is desirable that all components adhere tightly to each other, as well as to the wall or floor.

Due to the presence of a porous layer, the entire frame and surfaces of the house can “breathe”. Thus, the necessary air exchange and air circulation in the space are ensured and the greenhouse effect is eliminated. Ventilation is performed not only through open doors or windows, but also through the floor and walls of the house. According to specialist research, in a log structure, vertical building elements are capable of transmitting up to 35% of air.

Categorically prohibited Inside the frame house, use ordinary solid polyethylene with continuous laying on the walls and floor. The fact is that in such a situation, moisture will form and stagnate between these binders over time. This will certainly lead to harmful rotting and destruction of the structure of the house. Separately, let’s say that concrete walls also allow moisture and air to pass through them well.

Let us emphasize that vapor barrier is not understood as a polyethylene component with numerous holes, but as a multilayer bag with a porous structure. Existing membranes can differ quite significantly from each other in their capabilities and characteristics, which should be taken into account when calculating and planning work.

Today, vapor barriers are offered that can be used in residential and non-residential spaces. In addition, they differ in application according to the type of premises, including those with minimal, medium and high humidity. The final choice of material should be based on the frequency of operation of the structure, seasonality, characteristics of the climate zone, ambient humidity level, etc.

From all that has been said, it is clear that membrane protection is required to partially prevent the effects of moisture and water vapor on the structure of the house, including walls, floors and roofs. Unfortunately, it is impossible to completely stop this process using the indicated method.

Video No. 1. Vapor barrier of a frame house

About vapor barrier of frame houses

The vapor barrier of frame walls differs from the vapor barrier of walls of ordinary houses in that the insulation is laid not on a flat surface, but on a lathing formed by wooden components or profiles. In cross section, such structures may look like this:

external surface treatment with clapboard, siding or OSB boards;
insulation from moisture and wind penetration;
frame elements;
vapor barrier material;
heat saving components;
sheathing;
interior decoration of the house.

Please note that about 65% of this “pie” is thermal protection. Maximum attention to its arrangement, compliance with installation technology, and the use of high-quality vapor barrier will save both materials and frame elements of the house.

Specifics of laying vapor barrier

It may seem that everything is simple here; you just need to fix the protection on a vertical surface and control which side it is turned relative to the interior space of the room. Fastening is carried out using a construction stapler, and the joints are sealed with tape. In reality, there are a number of other nuances that should be taken into account. The following describes common mistakes that are unacceptable during work:

leaving even minor insulator breaks unattended;
laying the component with minimal folds;
poor sizing and sealing of seams;
wrong choice of working side;
the use of packing tape rather than construction tape.

The presence of even one of the above miscalculations can lead to the fact that within a couple of years the insulation will become unusable, absorb moisture and cease to perform its primary functions. Ultimately, there will be a need to re-insulate the house, including the walls, floor and roof. Of course, this will result in considerable financial investments.

Laying vapor barrier

According to the installation technology, the vapor barrier membrane is applied to the surface from top to bottom and cut into strips. It is recommended to overlap the edges by at least 100mm. Be sure to seal the indicated areas with a special vapor barrier tape to ensure the tightness of the protection.

The connection of the material to the wooden elements of the walls and floor is carefully controlled. Pasting and fastening along the edges is done. Installation of the membrane to the wood frame component is carried out with a construction stapler or using galvanized nails.

Video No. 2. Vapor barrier of a frame house

Conclusion

We hope that the information provided about the order of laying vapor barriers in frame houses, the specifics of installation and the technology of work will allow everyone to competently approach the issue of insulation, protection and vapor barrier of their own home.

This article was brought to me by the total ignorance on the part of both builders and buyers, as well as the phrase “vapor-hydro insulation” or “hydro-vapor insulation” that is increasingly flashing in commercial offers - because of which then all the pandemonium begins, lost money, problematic designs, etc.

So, you've probably heard about waterproofing, windproofing and vapor barrier - that is, about films that are placed in insulated roofs and frame walls to protect them. But then, a complete “steam and hydrodisorder” often begins.

I will try to write very simply and easily, without immersing myself in formulas and physics. The main thing is to understand the principles.

Steam or hydro?

Let's start with the fact that the main mistake is to confuse steam and moisture into one concept. 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, aka moisture, aka “hydra” (hydro from ancient Greek ὕδωρ “water”) is what we see with our eyes and can feel. Tap water, rain, river, dew, condensation. In other words, it is a liquid. It is in this state that the term “water” is usually used.

Steam is the gaseous state of water, water dissolved in the 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 bath, etc. But actually it is not.

Steam is present in the air always and everywhere. Even now, as you read this article, there is steam in the air around you. It is the basis of that same air humidity, which you have probably heard about and more than once complained 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 let steam through, but will not let water in a liquid state.

At the same time, particularly smart scientists, and then manufacturers, figured out how to make a material that would conduct water only in 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 in both directions, but does not allow moisture to pass through

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

Paro insulation - this is a material that does not allow anything to pass through, neither steam nor water. Moreover, at the moment, vapor barriers membranes- that is, materials that have one-way permeability to steam have not yet been invented.

Remember as “Our Father” - there is no universal “vapor-hydro membrane”. There is a vapor barrier and vapor-permeable waterproofing. These are fundamentally different materials - with different purposes. Using these films in the wrong places and in the wrong places can lead to extremely tragic consequences for your home!

Formally, vapor barrier can be called vapor barrier, since it does not allow water or steam to pass through. But using this term is a recipe for making 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 allow steam or water to pass through and are not membranes
Waterproofing steam permeable membranes (also called windproof, due to extremely low air permeability or super-diffusive)

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

Why do we need films in a 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 “at a glance” 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’ll immediately make a reservation that in reality all the processes described below are much more complicated and have a lot of nuances. But the main thing for us is to understand the essence.

Nature has decreed that steam in a house always flows 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 per year. If you add to it the days and nights when it’s colder outside than in the house, then even more.

Therefore, we can say that most of the time, the vector of steam movement is directed from inside the house, out. It doesn’t matter what we are talking about - walls, roofing or lower floors. Let's call all these things in one word - enclosing structures

In homogeneous structures, the problem usually does not arise. Because the vapor permeability of a homogeneous wall is the same. The steam easily passes through the wall and exits 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 a frame wall. Any multi-layer wall, even brick or aerated concrete with external insulation, will make you think.

You've probably heard that in a multilayer structure, the vapor permeability of the layers should increase as the steam moves.

What will happen then? Steam enters the structure and moves through 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 saturation of steam 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 achieving this in a real situation is not easy.

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

Let's look at another situation. Steam has entered the structure and moves outward through the layers. I went through the first layer, the second... and then it turned out that the third layer was no longer as vapor-permeable as the previous one.

As a result, the steam that gets 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 increase.

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

This is exactly what people often observe when the outside of their house is covered 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 poorly. Rivers of condensation flow along the inside of the outer skin, and the cotton wool adjacent to it is all wet.

Steam easily enters the wall or roof and “slips through” the insulation, which usually has excellent vapor permeability. But then it “rests” on the outer material with poor permeation, and as a result, a dew point forms inside the wall, right in front of the obstacle to the steam path.

There are two ways out of this situation.

It takes a long and painful time to select materials for the “pie” so that the dew point under no circumstances ends up inside the wall. The task is possible, but difficult, given that in reality, the processes are not as simple as I am describing now.
Install a vapor barrier from the inside and make it as airtight as possible.

It is along the second path that they go in the west, making a hermetically sealed obstacle in the path of the steam. After all, if you don’t 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 rack your brains over what materials to use in the “pie” itself, from the point of view of the vapor permeability of the layers.

In other words, installing a vapor barrier guarantees the absence of condensation and dampness inside the wall. In this case, the vapor barrier is always installed on the inner, “warm” side of the wall or roof and is made as airtight as possible.

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

In addition, I pay special attention to the word hermetically sealed. In the west, when installing a vapor barrier, all joints of the film are carefully taped. All openings from communication wiring - pipes, wires through the vapor barrier - are also carefully sealed. The installation of overlapping vapor barriers, popular in Russia, without gluing the joints, can result in insufficient tightness and, as a result, you will get the same condensation.

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

I would also like 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, can forgive you some flaws in the vapor barrier.

But a 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 getting condensation inside these structures. Moreover, the amount of condensate can ultimately amount to tens of liters.

Why do you need a waterproofing or superdiffusive vapor-permeable membrane?

I hope you understand why you need to make a vapor barrier from the inner wall - in order to prevent steam from entering the structure at all and to prevent conditions for its condensation into moisture. But the question arises: where and why to place the pair? permeable membrane and why it is impossible to install a vapor barrier instead of it.

Windproof, waterproofing membrane for walls

In American wall construction, a 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. The fact is that Americans make vinyl siding and other facade materials directly on top of the slabs, without any ventilation gaps or sheathing.

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, roof junctions, etc.

If water gets between the siding and the OSB, it can take a long time to dry there and the board can begin to rot. And OSB is a bad material in this regard. If it begins to rot, this process develops very quickly and goes deep into the slab, destroying it from the inside.

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

Superdiffusion waterproofing membrane for roofing

Don't let the word superdiffusion confuse you. Essentially this is the same as in the previous case. The word superdiffusive only means that the film allows vapor to pass through very well (vapor diffusion)

In a pitched roof, for example, under metal tiles, there are usually no slabs of any kind, so a vapor-permeable membrane protects the insulation from both possible leaks from the outside and from blowing by the wind. By the way, this is why such membranes are also called windproof. That is, a vapor-permeable waterproofing membrane and a windproof membrane are, as a rule, 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 do you need to install 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, achieving absolute tightness of the vapor barrier is not so easy - there will still be damage from fasteners and construction flaws somewhere.

That is, some tiny amount of steam will still get into the walls. If there is a vapor-permeable membrane outside, then this minuscule has a chance of coming out of the wall. But if there is a 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 waterproofing vapor-permeable membrane is always installed outside. That is, from the “cold” side of the wall or roof. If there are no slabs or other structural materials outside, 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 façade finishing.

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

Using 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 insulation to work as efficiently as possible.

What is the danger of the term vapor and waterproofing?

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 type of error, especially in roofs and the most terrible in terms of consequences, is when the result is the opposite - a vapor barrier is installed on the outside, and a vapor-permeable membrane is installed on the inside. That is, we calmly let steam into the structure, in unlimited quantities, but do not let it escape. This is where the situation shown in the popular video comes into play.

Conclusion: never mix the concepts of vapor-permeable waterproofing membranes and vapor barriers - this is the right road 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 cold climates (most of Russia), vapor barrier is always installed only on the inner, “warm” side - be it a roof or a wall
Vapor barrier is always done as hermetically as possible - joints, openings of communication penetrations are sealed with tape. In this case, special adhesive tape is often required (usually with a butyl rubber adhesive base), since simple tape can come off over time.
The most effective and cheapest vapor barrier is 200 micron polyethylene film. Preferably, the “primary” one is transparent; it is easiest to glue the joints on it with ordinary double-sided tape. Purchasing “branded” vapor barriers is usually unjustified.
Vapor-permeable membranes (super-diffusion, windproof) are always installed on the outer, cold side of the structure.
Before installing the membrane, pay attention to the instructions for it, since 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 installed the correct side. For other uses, before starting installation, think about which side to place the material on.
When choosing a vapor-permeable membrane, you should give preference to high-quality “first and second echelon” manufacturers - Tyvek, Tekton, Delta, Corotop, Juta, Eltete, etc. As a rule, these are European and American brands. Membranes from third-tier manufacturers - Izospan, Nanoizol, Megaizol and other “isols”, “brains”, etc. as a rule, they are much inferior in quality, and most of them are of unknown Chinese origin with the brand of a trading company stamped on the film.

about the author

Thermal insulation of frame buildings is very important, since heat must be retained inside the building. The technology involves the use of up to 75% insulation in the construction of walls. But this material loses its thermal insulation properties if moisture gets into it from the inside. To ensure the dryness of the entire building, a vapor barrier is used for the walls of the frame house.

What is the vapor barrier of a frame house?

This term means the use porous membranes, with the help of which excess moisture is removed from the inside and does not enter from the outside. Thus, the house can “breathe” and does not turn into a closed greenhouse. Partial air exchange is provided by wooden structures, which allow 35% of the air volume to pass through them.

Some people, when making a vapor barrier with their own hands, install ordinary plastic film instead of a porous membrane. This is wrong, as it begins to accumulate water and cause the wood to rot.

Unlike polyethylene, vapor barrier film has a more complex structure and consists of multiple porous layers. One side is smooth (it is adjacent to the insulation), the other is rough. This feature is needed for better collection of moisture and its further removal.

There are films in which both sides are the same, so they can be installed in any order. Before installation, it is better to read the instructions and find out what type of membrane you have.

There are also membranes with specific purposes. They are intended for vapor barriers only in specific conditions. For example, exclusively in non-residential premises, in harsh climates, with high humidity (baths, saunas).

What is the difference between vapor barrier for frame houses

The vapor barrier of a frame house is carried out practically according to the same scheme as for other buildings, but there are also some differences. So, load-bearing structures do not have an insulation function, and this is a significant difference. The “pie” of the wall looks like this:

External decorative finishing (siding, lining).
Waterproofing film.
Wooden frame.
Thermal insulation layer.
Vapor barrier film.
Lathing.
Interior finishing materials.

The vapor barrier material is quite easy to install. It is necessary to properly lay and secure it. To do this, you can use tape and galvanized nails or a construction stapler. But there are also some subtleties:

seal all membrane ruptures with tape so that there are no gaps;
minimize the number of folds;
seal all seams properly and check for integrity;
where the wood comes into contact with the vapor barrier, apply a special antiseptic;
a diffusion membrane can be in direct contact with the insulation; for another type, you need to leave a gap of 5 cm;
The sides of the membrane cannot be swapped, as it will lose its properties.

If you make a mistake somewhere and make a mistake, the vapor barrier of a frame house will be ineffective, and it will have to be changed along with replacing the insulation, which will cost a tidy sum. Very often, those who like to do everything with their own hands try to install the membrane faster, so they perform the installation sloppily. Because of this, the vapor barrier only lasts for 2-3 years, and then it has to be replaced.

As for the rules for laying the material, this must be done from top to bottom. There should be between layers overlap of at least 10 cm, glued with a special vapor barrier layer. You also need to carefully glue the places where the film is adjacent to the wood.

When a vapor barrier is not required

There are insulation materials that do not collapse, despite the lack of vapor barrier. Therefore, builders may not use it. But then another way to remove moisture from the room is needed.

Thus, polyurethane foam and polystyrene foam do not allow moisture to pass through, so it is necessary to install a forced air exhaust, otherwise moisture will accumulate in the room and contribute to the development of mold. Also, there is no need to carry out vapor barrier in houses without insulation.

Vapor barrier schemes in a frame building

Depending on the design of the house, different vapor barrier schemes may be used. Let's look at them below.

Double vapor barrier

In the case of double-sided wall decoration non-breathable materials(plastic, tile, oilcloth) water can collect inside, since there is nowhere for it to escape. To avoid this problem, a ventilation gap is provided between the cladding and the wall. It must ensure air circulation and release to the outside.

Elimination of excess moisture in a frame house is carried out in the following ways:

The membrane is fixed to the frame posts, after which interior finishing work is done.
A vapor barrier membrane is installed, then a sheathing is installed to secure the facing materials. This allows for a ventilation gap of about 5 cm.

The second option is best suited for residential buildings, since the likelihood of moisture accumulation inside the walls is higher there. And the construction of structures without a ventilation gap is permissible only in buildings for non-permanent use. There, as a rule, simple ventilation or a supply and exhaust system is installed to get rid of high humidity.

If the house is held high-quality ventilation system, the vapor barrier layer has virtually no beneficial effect. It is then needed only to prevent the possible accumulation of moisture inside the wall.

External building insulation and vapor barrier

As already mentioned, the vapor barrier layer should not be in direct contact with the wooden frame. Therefore, for the outside, first the wall is covered with wooden slats, the thickness of which is 25 mm. The distance between the slats is 1 m.

Next, a membrane is stuffed onto the slats rough side out, after which the sheathing is installed again. And only after that the house is insulated with heat-insulating materials, the waterproofing layer is fixed and the finishing is done on the outside.

Thanks to such a complex design, the vapor barrier of a frame house creates the necessary microclimate in the room.

As for the disadvantages of the technology, the structure will dry out for several years. In addition, all joints and grooves must be carefully sealed and treated with a sealing compound. An important requirement is the need to use exclusively hydrophobic materials for insulation.

Floor vapor barrier

The floor must be insulated and this must be done in parallel with steam and waterproofing. Firstly, moisture will constantly flow from the basement or basement. Secondly, indoor humidity can also damage the thermal insulation structure.

Installed on the subfloor waterproofing layer. Tightness is ensured by overlapping the film and gluing the joints with tape for this material.
Insulation in the form of rolls or slabs is laid between the floor joists, after which the entire structure is sheathed with a vapor barrier layer. It is also made one-piece by fastening the film overlapping with tape.
In the logs, ventilation gaps are made between the vapor barrier layer and the floor using boards that are secured with self-tapping screws.
At the final stage, a tongue-and-groove or edged floorboard is laid on top of all these structures, and a finishing coating is placed on top of it.

If you plan to make a vapor barrier for floors in a frame house, please note that it is only relevant if insulation that allows air vapor to pass through. Foam plastic does not allow air to pass through, so installing a membrane is irrelevant for it. It is best to choose mineral wool for floor insulation, the density of which is 37-57 kg/m3. m. It is very light and provides air exchange.

Ceiling insulation

Almost all ceilings of frame houses are insulated using mineral wool. Expanded clay, expanded polystyrene and ecowool are less commonly used.

Insulation is done like this:

First, a vapor barrier membrane is secured to the bottom of the beams using a stapler, after which boards are stuffed onto it. The interval between them is 40 cm.
Next, the entire ceiling is insulated with mineral wool. Important make overlaps on the walls so that there are no areas through which heat will escape. The seams should not be continuous, that is, the slabs are laid in a checkerboard pattern.
If you plan to insulate the attic, line it with another vapor barrier layer. All film joints are sealed. If there is no heating in the attic of a frame house, this stage can be eliminated. Next, they lay out the floor in the attic.

If the ceiling is correctly assembled and insulated, moisture will not collect either from below or from above.

Proper roof insulation

The principle of insulating the roof of a frame house is similar to the rules for walls, with the exception of some features.

A waterproofing layer is installed on top of the rafters, which is additionally secured with a lath on which the roofing material is supported. There is a large free space between the rafters themselves. Rigid insulation boards are laid there.
A gap is made between the slabs and the waterproofing layer so that moisture can be removed and the structural element itself can be ventilated with air. On different sides of the house they draw conclusions from this gap.
It is very important to maintain the tightness of the waterproofing. If the insulation comes into contact with water, it will quickly begin to deteriorate.
The inside of the rafters is sheathed with a vapor barrier membrane, after which it is stuffed again lathing for installation of internal facing materials.

If the attic is properly insulated and insulated from excess moisture, you can even install heating there. This will make it a full-fledged living space, and not a collection point for unnecessary things.

So, it is important to select and install vapor barrier membranes correctly. This will allow them to fulfill their function - to prevent the insulation from coming into contact with water, and also to remove excess moisture from the room.

Watch a video in which professional builders talk about the technology of vapor barrier for a frame house.

The vapor barrier of a frame house must be installed on the inner surface of the insulation layer to protect it from the ingress of vapors, which leads to damage and loss of all properties. This rule applies to frame buildings erected in cold and temperate climates.

Vapor barrier of a frame house is simply necessary, since if excess moisture escapes through the walls, the thermal insulation will certainly get wet, and in cold weather this can lead to its complete destruction.

The procedure for installing a vapor barrier is very simple: you need to attach the vapor barrier membrane to the frame posts and trim using tape and a stapler. However, this simple step in practice poses the greatest danger to the structure of a frame house.

Why do you need a vapor barrier film?

To better understand why a vapor barrier film is needed in a cake, you need to understand the physics of the movement of air vapor. You can often hear on the news about air humidity, which is close to 70-80% in wet weather. During cold weather in the home, many people turn on humidifiers to increase humidity. It usually feels like the humidity outside the house is higher than inside it. For cold and temperate climates, this statement is incorrect.

Humidity parameters directly depend on air temperature. The higher the temperature, the greater the concentration of water vapor in the air around us. If the air outside with a humidity of 75-80% is heated to the usual temperature in the house, then the amount of moisture will be the same, but its percentage will decrease, since air humidity is a relative parameter and depends on temperature.

In temperate climates, there is more moisture inside than outside. This is due to the fact that you cook, breathe, wash, take a bath, etc.
To equalize the difference in vapor concentrations outside and inside the house, all excess moisture seeks outlets: open windows and doors, ventilation ducts, ceilings and walls. The ventilation system, which is designed for constant air exchange in the house, ideally copes with excess moisture.

You can ventilate the premises from time to time by opening doors and windows. If the ventilation fails or you do not have the opportunity to ventilate the premises often, then the vapors begin to try to escape through the ceilings and walls. For a frame house, this is a very dangerous process, since the frame wall consists of 70-75% insulation. Moisture vapor, after entering the insulation, causes it to become very wet, which leads to loss of thermal insulation properties.
If the temperature outside is below zero, then freezing of the water in the insulation leads to its complete destruction. To minimize the escape of vapors through the thickness of the frame wall, a vapor barrier is installed at home. Air vapors are isolated inside the room, and the previously installed ventilation system is responsible for their removal.

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Errors in the vapor barrier device and their consequences

Installing a vapor barrier outside. Moisture vapor, passing through unhindered, condenses on the surface of the vapor barrier. The insulation gets wet. In a classic wall pie, a windproof membrane with high vapor permeability should be installed on the outside. It is she who freely removes moisture vapor. A similar situation occurs if extruded polystyrene foam is installed on the outer surface of the façade, which has a high vapor permeability index and serves as a vapor barrier membrane.

Duplicate vapor barrier in . This can be done by installing a vapor barrier layer inside and outside the frame wall. However, the vapor barrier layer is not completely sealed and can reduce, but not stop, the release of excess moisture to the outside. That is, the membrane cannot completely isolate, but slows down the movement of moisture vapor.

Even a small amount of water, getting between the vapor barrier films, will affect the insulation (it will become damp), and it simply will not have a chance of drying. By cutting off one of the vapor barrier films, you can see the black boards of the frame due to the creation of ideal conditions for the development of mold: dampness and heat. To prevent this situation, you need to remember a simple rule: a vapor barrier must be installed from the inside, and a wind barrier must be installed on the outside.

The second duplication option involves installing a second barrier on the vapor barrier, for example, ceramic tiles. The tile itself is an excellent vapor barrier. Vapors, having got through the seams of the tiles, are locked between the vapor barrier layers, which, in turn, leads to peeling of the tiles from the wall. To avoid this, you need to leave a ventilation gap between the layer of vapor barrier film and the drywall or not add a layer of vapor barrier film at all.

No vapor barrier is done. In comparison with the two above, this is not the worst option, but if you use mineral wool for insulation, this can lead to quite unpleasant consequences. The frame house cake is heterogeneous and is made from a set of different building materials with different vapor permeability parameters.

Depending on the constant air temperature, moisture vapor passing through the frame wall cake finds the dew point, namely the area where vapor condensation occurs at a certain temperature. The worst thing is if moisture condenses on the inner surface of OSB or plywood boards. For the summer, there are no problems in the absence of a vapor barrier for a frame house, but for the winter, it is at the border of the insulation and the external cladding that the vapors leaving the house will condense.

Some insulation materials are highly resistant to the destructive effects of condensation, for example, polystyrene foam and ecowool, so a vapor barrier film is not required for such a frame house. Great savings are created. But many people forget that if there is no vapor barrier, the outer skin is at risk, because it is there that the vapors encounter a barrier of less vapor-permeable materials, falling as dew on the inner surface.

To minimize condensation on the cladding of a frame house, you can apply additional insulation of the building with foam plastic over the sheathing or finish the wet façade. You can also insulate the building with ecowool or polyurethane foam, which have high vapor permeability and minimize the possibility of condensation in the frame pie.

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Poorly executed vapor barrier

Thus, a vapor-tight membrane is a high-quality polyethylene film, which is secured with a stapler to the trim and wooden frames. To ensure high-quality sealing of joints, you need to carefully glue each hole. For this purpose, tapes, mastics and glues are used.

The work of installing a vapor barrier is not difficult, but a hastily installed vapor barrier will not be able to fulfill its intended function. It is best if you do the vapor barrier for your home yourself or have it checked before installing drywall.

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Selection of vapor barrier film

Ordinary polyethylene (PE). This is the simplest but reliable vapor barrier. It is quite cheap and can be found at any hardware store. The choice should be made in favor of high-strength polyethylene (strength is measured in micrograms). When purchasing film, you need to make sure that it is tear-resistant. PE has its advantages - it can be easily glued with tape, which makes it easy and quick to create a reliable vapor barrier.

Specialized vapor barrier membranes. These membranes cost significantly more than polyethylene film. For their installation, double-sided tapes, reinforced tapes and mastics are offered. There are vapor barriers with foil coating, reinforcement, condensing surface, etc. You can choose the right membrane for certain tasks. For example, a reinforced vapor barrier can be installed without outside help, since a sheet secured with a stapler can be easily pulled to the other end of the room without being damaged.

A foil vapor barrier membrane is recommended for use in baths where it is necessary to reflect energy into the interior of the room. A specialized vapor barrier membrane is an improved polyethylene film that provides a dense vapor barrier. It performs the functions of a vapor barrier very well, provided that the sealing is done well. Before purchasing, you must carefully study the properties of specialized vapor barrier membranes.