Wall insulation installation. Features of the vapor barrier of a wooden building Vapor barrier material for walls

No matter how dry the air inside the room may seem, it contains a considerable amount of moisture vapor. And no one would pay attention to them, if in modern construction did not use energy-saving technologies. Insulation (or rather, the heaters themselves) turned out to be defenseless against moisture and vapors, since when wet, they lose their ability to retain heat indoors. To protect them, a hydro- and vapor barrier is used - the first is installed outside (in most cases it is used to protect the insulation from street moisture), and the second from inside the room. The task of the latter is to protect from water vapor contained in the indoor air of the premises. It is about him that this article will be discussed, in which, together with the website, we will deal with the purpose of this material, the types and methods of their use.

Why do you need vapor barrier walls

Wall vapor barrier: what is it for and when it is impossible to do without it

There is only one correct answer to the question of why wall vapor barrier is needed, which we have partially touched on a little higher - at least that's how it looks in a nutshell. If we consider it more extensively, then we should also touch upon the topic of moisture exchange in the premises, which occurs regardless of our desire in an invisible way for us. Moisture in the air, or rather its excess, is absorbed into the walls of a house or apartment, and with a lack of water in the air, moisture returns back from the walls. Now judge for yourself - where do you think the excess water vapor will go if you install insulation between them and the wall? Naturally, they will accumulate in it, and then, as was written above, fill all the empty space between its fibers and displace air from them, which, in fact, is a heater. It's no secret that water in all its manifestations is by no means such.

Vapor barrier of walls from the inside

Installation of wall vapor barrier is not necessary in all cases - an important condition for the absorption of moisture vapor by the insulation is the temperature difference, which is largely noticeable on the outer walls. Moisture simply condenses inside the insulation, turning into water droplets - they are the ones that are dangerous for the insulation. If this does not happen, then there is no need to install a vapor barrier - for example, there is no such effect on internal walls ah at home.

In this regard, it is possible to formulate a number of rules when it is impossible to do without the use of vapor barriers.

Highly important point, accompanying the vapor barrier of the walls from the inside and outside, is the presence of high-quality ventilation. If we talk about internal vapor barrier, then the interior rooms should be ventilated, if external vapor barrier, as in the case of siding, here it is necessary ventilation gap. Air, passing through it, removes excess moisture, which settles on the vapor barrier.

Vapor barrier material for walls: how to choose the best option

To date, there are three main types of materials used for vapor barrier walls - they all differ in their device, properties and capabilities. Let's get acquainted with it in more detail, which will give you the opportunity to choose the best among them.

In general, the principle of choosing vapor barrier materials is quite simple, and there is practically nothing to choose from. There are only two right decisions- mastic or membrane. With mastic, everything is simple, and among the membrane materials it will not be much more difficult to choose the right one.

At the end of the topic, a few words about how to lay vapor barrier for walls. There are two executive wiring diagrams- according to one of them, the vapor barrier is attached directly to the frame and pressed against the insulation with sheathing material, and according to the other, the vapor barrier material is pressed against the frame with a bar of small section. The second executive scheme for solving the question of how to fix the vapor barrier to the wall provides a ventilation gap between the vapor barrier and wall cladding, which makes it possible to ventilate the space in the area of the vapor barrier quite effectively. In most cases, the second executive circuit is used when. Indoors, it is practically not used, since its implementation requires additional space, which, as practice shows, even in such small quantities is not superfluous.

How is wall insulation installed?

Finally, I will add the fact that the vapor barrier of the walls must be carried out correctly, since this is the key to a comfortable microclimate in the premises, which can only be achieved by observing some installation rules. These include overlapping vapor barrier laying, the installation of the same ventilation gaps and the creation of the so-called circular vapor barrier, in which the laid material is a solid coating on the walls and ceiling.

191 comments

ru-two.ru 04.06.2015
- Alexander Kulikov 05.06.2015
  Well no. Styrofoam is not covered with vapor barrier. There is simply no need for this. As you rightly noted, the foam does not conduct water at all, which is good for the walls, they stop breathing and as a result many problems arise, especially if the foam is used indoors. There is such a thing as a dew point - a place where cold and heat meet and where condensation forms. So, by insulating the walls with foam plastic from the inside, you transfer this dew point to the inner surface of the walls - as a result, a fungus begins to develop under the foam plastic. In addition, in this way you create all the prerequisites for the complete freezing of the walls in the winter, which again contributes to the destruction of the walls. It is for this reason that external insulation with foam plastic or, in general, with some other material, is most preferable. The house must be insulated from the cold, not the street from the heat.
  - Tatiana 12/22/2015
    Hello, Alexander.
    We built a house from profiled timber (we will not insulate the walls). The ceiling was insulated, between the second floor and the attic with polystyrene foam. We are going to lay a vapor barrier on the ceiling. Correct or not? And what can be used to fill the inter-room frame walls for sound insulation, and do they need to be covered with vapor insulation?
    - Alexander Kulikov 22.12.2015
      Hello Tatiana. Let's go in order.
      1. Vapor barrier. It would be needed if you insulated the ceiling with mineral wool. Polystyrene works a little differently and does not care about moisture - its thermal insulation qualities do not suffer from getting wet.
      2. How to fill the walls. As a standard, mineral wool is used for this. Vapor barrier in this situation, in general, is not needed. Indoors, without contact with the street, the insulation simply cannot get wet to such an extent that it is saturated with water. Here is another nuance - quite often he goes down under his own weight. Just secure it well at the top and you'll be fine.
  - Alexander 03.07.2017
  - Dmitry 23.02.2018
    Alexander good day. Please tell me this situation. The house was made of two floors and a basement, and on the second floor the ceiling was hemmed with boards 25 and under it the vapor barrier was not expensive from Leroy ... the vapor barrier was knocked out to the logs and then the boards immediately. the top layer of cotton wool, it crunches, was saturated with moisture and the mineral wool Knauf Tyumenskaya froze, they say that it is very bad .... and the vapor barrier does not still lie correctly against the mineral wool butt with the rough side. And in the house, once again, the ceiling was hemmed to the boards with Isospan am, most likely expensive on one side, white on the other, brown ... so that the boards would not shine through under the tension. Tell me how to be?! Please. I don’t want to disassemble the ceiling, remove Izospan am from the boards and. I want to immediately hem the plywood onto the boards, and Izospan can be some kind of tension on the plywood .. but in a cold attic I don’t know what to do. Remove this Izospan and then just stone wool 50 density on the boards between the lags and my old mineral. And I don’t know how to cover it? Top Izospan or not? On cotton. can it be like that? Or I don’t know how to fall asleep with IVF cotton wool, I just don’t know how to be .. we don’t live in the house yet. Can you throw off the phone, maybe by phone I’ll tell you in detail what to do at a dead end
- Aydis 28.10.2017
  Hello, Alexander! Gonna do interior wall. The material of the wall is drywall, and inside the wall there will be pressed mineral wool. The house is made of cinder blocks, the walls are plastered (cement, sand, clay). Question: - is it necessary to sheathe over the mineral wool with a vapor barrier material, for example, isospan?
  You don't need it on your site. I just saw how it was inside at a monolithic construction site drywall partitions lined with this material. I don't know exactly what the material was.
  I recently made a veranda, and there is a stove. Type B isospan was laid on the ceiling of the veranda. I'm not sure if the isospan insole is correct. If you lay isospan type B on shelves with outer side. To fill it with sawdust and clay on top of it.
  Question: - which side to lay isospan type B so that it passes steam and does not let cold air back?
  We laid the smooth side up. They fell asleep on top.
- Natalia 26.10.2018
  A similar question: is it worth doing a vapor barrier when insulating walls with polystyrene foam from the inside. The situation is as follows: the kitchen is combined with the loggia, the wall on the loggia with the window opening is laid out in a brick floor. It was decided to insulate it with an additional 20mm foam potterol (it was fixed to the wall with the help of special glue and doubile mushrooms), then opinions were divided again) Some masters suggest simply sheathing the GKL wall further, while others suggest using an additional vapor barrier in the form of penofol, which will be additionally with insulation and vapor barrier, and then only sheathe the plasterboard. Tell me, please, what do you think, is it necessary to make an additional vapor barrier on the loggia when the wall is insulated with polystyrene foam from the inside? And should I leave air gap between drywall and vapor barrier?
Artem 09.07.2015
Alexander, as I understand from the comments, insulation with basalt wool from the inside with proper vapor barrier will be better than insulation with foam plastic without vapor barrier?
or am I wrong?
Ivan 03.09.2015
Alexander, I ran into a question, a block-type house, I’m going to sheathe metal siding, between them there is a high-density wool insulation, according to your article, it will be enough just to vapor barrier outside the insulation, or hydro vapor barrier, i.e. so that the outside does not allow moisture to pass through, but from the inside it releases steam?
Oleg 09/04/2015
Pavel 07.09.2015
Hello, Alexander! After reading a bunch of forums and instructions, I decided for myself to insulate the outer brick wall in a high-rise building (the wall is thick, more than half a meter, but cold in winter) from foam glass. It is important for me to use environmentally friendly materials. I decided to stick foam glass on a brick wall in 2 layers, each 20 mm thick, and then plaster it and paste wallpaper. Can you tell me how correct this is? and the dew point will not be violated?
Marina 16.09.2015
Hello, Alexander! I have a new house made of timber, the second floor gets wet inside because of the rains, can I tighten the walls from the outside with isospan V. and which side of it is to the timber, and then lay the insulation on it closely (min. plate or better styrex?), then isospan A and siding?
- Alexander Kulikov 16.09.2015
  Hello Marina. Apparently, somewhere a mistake was made during construction. Are you 100% sure that it is the walls that get wet? Maybe it's all about the roof? In general, it is strange that this happens - the walls should not get wet. Well, if this is still the case, then, in principle, wooden structures can be sheathed with a ventilated facade. Only this must be done at once, and not in parts. Izospan V is mounted with a smooth side to the insulation - at the same time, there should be a small gap between the wall of the house and Izospan (its rough side). You need a crate made of a thin rail (10 -15 mm), on which Izospan is attached with a stapler. Then, on top of Izospan, a siding frame is already being assembled, the space between the carrier rails is filled with insulation. Then again Izospan (smooth side to mineral wool). Again, a gap for ventilation, which is again created by a thin rail, on which the siding itself is already being assembled.
Peter 20.09.2015
Hello, Alexander!
Thanks for the detailed advice, but it's not entirely clear which cell from the 10x15 mm rails. fill the entire surface of the wooden wall of the house? This is the first time I hear about it, I have never seen it in practice!
Please tell me, how does Izospan B work, why is it always to the heater - with the smooth side?
And then, why fill the crate again to achieve a ventilated gap? After all, it is achieved by the height of the siding frame.
Alexander, please, please highlight the issue of external insulation of a brick wall with foam plastic, if the inside of the house is simply sheathed - clapboard. (brick wall thickness 70 cm). Do I need a vapor barrier on the outside of the brick? And how and how tight (maybe on mounting foam), sew penoplex to the wall?
Sincerely, Peter. Kuzbass.
- Alexander Kulikov 20.09.2015
  Hello Peter. Let's go in order.
  1. The cell is wooden. It forms a ventilation gap between the walls of the house and the insulation, or rather isospan, which is located with the fleecy side towards the house. Pile, it is needed in order to retain moisture. But where does she need to go next? For this, ventilation is necessary, or rather, a rail of small thickness, on which the vapor barrier is stuffed. If this is not done, moisture will go into the walls of the house - and this is dampness and the like.
  2. Next - you need to create space for insulation - as you say, this is a crate for attaching siding.
  3. Insulation, you need to protect the outside from moisture. Right? To do this, after it is placed between the crate, a hydrobarrier is pulled over it, which does not allow the insulation to get wet.
  4. Then again the ventilation gap, which will remove moisture from the hydrobarrier. If this is not done, then it will spoil the crate and create prerequisites for fungus in summer and ice in winter. To do this, you need to fill a thin rail on the vertical boards of the crate, to which the siding is already attached.
  Well, as for the question of how the vapor barrier works, it is an ordinary one-way membrane that allows moisture vapor to pass in one direction and does not allow it to pass in the other direction. That is, the moisture leaving the walls of the house partially penetrates the insulation, and partially lingers on the vapor barrier - the one that lingers (its excess) is removed by ventilation. This is a kind of dispenser that allows only the right amount moisture, which in turn is removed through the second membrane to the street, where it is again removed by ventilation. This is what is called, breathing walls or, in other words, a ventilated facade.
  Regarding the insulation of walls with foam, or polystyrene, or polystyrene, I wrote in an article. You can read if interested.
Alexander 07.10.2015
Please tell me which films to use and on which side. A cinder block house, then basalt wool and facing brick. We live in middle lane Ufa. Thank you.
Sergey 11/14/2015
Hello, Alexander. Please tell me how to make a vapor barrier. House made of aerated concrete blocks. outside I want to insulate with mineral wool, and the finish is brick. Thank you.
Roman 12/10/2015
Hello, Alexander.
How the ventilated facade works is very well explained. I wanted to clarify directly at the joints of the resulting “sandwich” (wall-gap-vapor barrier-insulation-wind protection-gap-siding) On four sides, our wool will be upholstered with a wooden crate, which will mercilessly let steam into the insulation, especially from the bottom. How to protect yourself from this? And is it necessary?
And another question off topic. Being sure that there is only one type of membrane, I laid it on the floor in a wooden house (subfloor - vapor barrier - insulation - vapor barrier - air gap - finishing floor) As I later found out that the first layer is placed wind protection. Did I create a greenhouse effect for the insulation? The house stands on stilts over rather damp soil.
Thank you for attention.
Tatiana 12/22/2015
- Alexander Kulikov 22.12.2015
  You see, Tatyana, it creates the effect of a thermos and with an excess of moisture in the air or, in your case, in the lining, it creates very comfortable conditions for the development of fungus and mold. If it needs to be used good ventilation, and this is at least heat loss. It's like silicone in the bathroom, with which people close up the places where the same bathtub fits with the walls. I don’t know why, but mold loves it very much, even if the bathroom has good ventilation, it still starts up on it. Here is the foam, about the same material, perhaps a little to a lesser extent. One of my acquaintances insulated the outer walls inside the house with foam plastic (one wall, since there is no access to it from the outside) - he saved centimeters. Three years without problems, and then black dots appeared - probably hiding, waiting, this fungus was gaining strength. In the end, after a year of useless struggle, I ripped everything off, made a frame and insulated with mineral wool. Five years is a normal flight. No fungus.
Tatiana 12/22/2015
Sergey 12/30/2015
Alexander, what is your opinion on this issue.
Veranda, theoretically heated during infrequent visits in winter
Frame walls, cake: (outside-in) imitation of timber on the crate, OSB, Isospan vapor barrier, 15 cm of basalt wool, Isospan vapor barrier, OSB plate. In the summer I want to sheathe the inside with MDF wall panels. Do I need to install them on the crate, do I need to lay another layer of some kind of membrane, or can I immediately put them on the cleats on the OSB without the crate?
Anatoly 11.01.2016
Hello! I have such a question for you. There is a garden with walls made of cinder blocks, and I can’t decide what and how and with what to insulate the walls. I live in the Urals and winters are not quite warm. as I was told, they advised me from the street to the walls, first with a vapor barrier, then with mineral wool in two layers in a checkerboard pattern and again with a vapor barrier, and only then by cashing. as for the inside of the house, the walls still need to be leveled, since the plaster is done this way and the walls are far from even with the naked eye, it is very clear what catches the eye and I want to level it with drywall, the question is whether it makes sense to put something between the drywall some kind of insulation and whether vapor barrier is needed. I wanted to use sound-heat insulation as a heater
Eugene 01/12/2016
Good day!
I have such a situation. There is a wooden house with an outbuilding. To the annex goes U-shaped frame veranda under one pitched roof with attachment. They decided to make two rooms from the veranda, separated by a partition: a bathroom and a tabmour. The veranda is like this: a shallow foundation, on it lies a strapping beam along the perimeter of the veranda, with a section of 150x150. On this beam, vertical racks of the same material and section are installed. The rafters are supported on the racks, united with the outbuilding. We decided to insulate with stone wool, with a density of 45 kg / m3.
They decided to insulate the walls like this (from the inside out):
– plastic panels vertically (in the vestibule mdf panels);
- horizontal wooden crate 25x50;
– OSB 9.5;
- vapor barrier, close to the insulation;
- 150 insulation;

- hydrowind protection, close to the insulation;
– vertical lathing from a metal profile;
- siding.

Roof. The roof is arranged in this way: metal tile; ruberoid; frequent crate 25-30mm thick; rafters - timber 100x100. Is this insulation suitable (from top to bottom):
- on the sides of the rafters, using a 25x50 rail, fix the hydro-wind protection, thereby creating a 50 mm ventilation gap between the roof sheathing and the insulation;
- close to the protection of 150mm insulation;
- horizontal wooden crate 50x50, between the crate 50 insulation;
- vapor barrier;
– OSB 9.5;
- wooden crate 25x50;
- plastic panels.

1) Is it necessary in the bathroom on OSB or on wooden crate additionally install some kind of insulation both on the walls and on the ceiling and floor (for example, foil film, which is made in saunas).
2) Is it necessary to isolate the partition between the bathroom and the annex from the side of the bathroom (beam 150x150).
3) The design of the house involves the device on the veranda also underground. In other words, the floor level from the ground will spread up to 1000 mm. Thus, the wall will be divided into 2 zones: to the floor, above the floor. The question is, can the same type of insulation be used for the area below the floor, or does this part of the wall need to be insulated differently? What?
4) Due to the level of the floor, the question of the thickness of the ceiling pie is very critical, can it be made smaller in thickness by using a different insulation, for example?
5) Is it possible to leave roofing material in the roof?
6) Is it necessary to steam, waterproof the insulation in the partition between the vestibule and the bathroom.
7) Is it necessary, taking into account such an underground, to insulate the floor? If so, how? In the vestibule, the floor is divided into two zones: the floor and the flight of stairs.
The temperature drops to -35 maximum, the soil is clayey, the moisture is close to the surface of the earth.
Gennady 27.01.2016
Good afternoon. Tell me how to properly redo the insulation of the second floor of the attic house. The rooms are heated. I had the rooms insulated as follows: drywall was screwed to a wooden, almost dense, crate of the wall, the crate was stuffed on wooden racks, between the racks there was just a heater (mineral wool). It was cool in the rooms and I decided to add more insulation, but I ran into a problem - my insulation turned out to be damp (condensate was collecting there). And now I'm thinking of stuffing a vapor barrier film between the posts. But the question arises: is it necessary to fill the slats between the wooden crate and the vapor barrier film for the movement of steam? Then you get a wall: drywall, wooden crate, slats for ventilation, vapor barrier film, insulation. between the walls and roof rafters there is an unheated attic space.
- Alexander Kulikov 27.01.2016
  Hello Gennady. The meaning of the crate for drywall is more to level the surface than to create any gap - if the pitch of your attic racks was 600mm, then the gypsum could be attached directly to them. By the way, does it crack at the seams? Or have you plastered the drywall yet? The fact is that the tree leads, depending on temperature and humidity, and it pulls gypsum along with it. As a result of cracks at the seams, the issue is resolved by the manufacture of an independent frame, which has a minimum of points of contact with wood. Let's get back to insulation - mineral wool must be protected from moisture from both sides. From the street, even from the side of a cold attic, moisture also penetrates into it - a windproof film is placed from the side of the street. In principle, it can be installed from the inside of the room and fixed to the risers - make it so that it creates a bag between them. Put insulation in this bag and close it with a vapor barrier. If you are not afraid of cracks, then you can then restore your wooden crate and screw drywall to it, as it was.
Sergey 01/27/2016
Hello! I bought an apartment, panel 2 storey. In winter, it turned out that there were drops of water in the corners of the kitchen, mold appeared upstairs. Covered the façade in summer facade plaster. The walls themselves are very cold, it is not possible to insulate from the outside because it is on the 2nd floor. I'm thinking of insulating the interior. Please advise how to do it right.
Sergey 01/30/2016
Good afternoon! I picked up a lot of options, but I didn’t even consider cotton wool. As far as I know, cotton wool is gradually gaining moisture. Previously, I settled on the use of Styrofoam or Penoplex i.e. cleaning and processing the walls, then we put insulation on the tile glue, fill the joints with foam, then stretch the mesh and plaster. There are a lot of things offered on the Internet, but this option seemed more realistic to me. Additionally, you can first stick a vapor barrier, but honestly I don’t know if it is needed.
Lena 14.02.2016
Alexander, I always have some ideas of my own, so my question may be unusual for you. I am looking for the cheapest and easiest way, which, without anyone's help, would allow me to at least slightly insulate the wall in the apartment from the inside (corner square on last floor, in winter there is a lot of cold from the wall). This is a five-story brick building. Tell me, please, is it possible to stick vapor barrier directly on the wallpaper, and on it - dense furniture fabric (I would generally prefer warm fabric on the walls, rather than wallpaper, I like everything soft and fluffy). If you do this, will the wallpaper get damp there, behind the vapor barrier? And the wall, in theory, should not be so cold already, and cool the air heated by the batteries in the room?
Rodion 21.02.2016
Hello, Alexander. There is a street wall with windows that I want to sew up with drywall and insulate with mineral wool, how should I make a vapor barrier?
Rodion 22.02.2016
Nikolay 05.03.2016
I have a house made of timber 145 by 145 in the Moscow region. I want to insulate it (50 thick) with arugula. Do I need a vapor barrier between the wall and the insulation? And what rukovol can be used for insulation?
Alexander 09.03.2016
Do we need a vapor barrier from inside the house or some kind of film from the outside. Wall cake 1st floor - silicate brick, expanded clay, block. Second floor - silicate brick, foam chips, block. We want to sheathe the house with clinker thermal panels based on expanded polystyrene.
Sergey 30.03.2016
Hello Alexander! I plan to insulate the house from a bar 150 * 150. Am I scheduling the work correctly?
- treatment external walls antiseptic;
– installation of vertical racks from edged board 2.5 - 3 cm thick;
- fixing the waterproofing Izospan-V;
- installation of horizontal bars 5 * 5 cm;
– installation of rockwool light butts mineral wool and fixing it with anchors;
- fixing the vapor barrier Izospan-AM;
- installation of vertical bars 5 * 2.5-3 cm;
- installation of a block house.
I correctly understood the technology of insulating external walls, with the arrangement of ventilation gaps between the timber and the insulation and between the insulation and the Block House.
Thank you in advance.
- Alexander Kulikov 31.03.2016
  Hello Sergey. In principle, it is correct, but not quite - there are unnecessary elements in your design. There is no gap between the house and the vapor barrier.
  1. Wrap the house with a vapor barrier membrane (observe the direction of its installation and do not forget about the overlap)
  2. Immediately install vertical bars on the vapor barrier (create a cavity for the insulation). If its thickness is 50 mm, then yes, a beam of 5 by 5 cm will do, but usually this amount of insulation is not enough. Put 100mm. Accordingly, the timber is needed not 5 cm, but 10 cm (100 by 40 mm board is excellent) - you can not press the insulation, as it loses its qualities.
  3. Then install the insulation
  4. Tighten with a hydraulic barrier along the vertical posts. Fasten it with a bar (in your case, 5 * 2.5-3 cm) and get an indent from the membrane - that is, a ventilation gap. You can install these bars both vertically and horizontally - it all depends on the direction in which the lining will be mounted.
  5. A block house is mounted on this bar.
  That's all
  - Sergey 31.03.2016
    Alexander, thanks for your reply. Initially planned exactly as you described. It was embarrassing that in some articles they write that wooden beam will give off moisture in the form of steam, and the absence of a ventilation gap between the timber and the insulation can lead to:
    - 1. Moisture remains in the timber and, as a result, fungus or mold;
    - 2. Moisture will penetrate into the insulation, reducing its heat-conducting qualities.
    Are such reasoning correct? Thank you.
  - Tatyana 09/12/2017
    Hello, Alexander! Is it possible to put mineral wool on a damp board? We make a kitchen in a cafe from a USB frame. They put min cotton wool on usb then ecospan b. Everything got sweaty. We put the smooth side to the insulation. And in the attic they put the isover and ecospan ceiling on the rough board on the rough side. help me please
Dmitry 11.04.2016
Hello, Alexander! The question is: old house with a gable roof, externally galvanized (1951), then 3-4-layer roofing felt (from Soviet times), shingles (preserved in front of the roof). I plan to insulate the slopes with 150mm mineral wool. Wind-moisture protective film (membrane - A) or is glassine (3 mm) better on the inside of the crate? Ventilation is possible. For the best option, tell me how ... There are no varicos to disassemble the roof or any ... (although it should be so). After all, air flows can be directed freely along half of the slopes from the first anchor to the 6th (house 12 meters) in terms of the presence of half logs in the crate .... The distance between the floor logs is 100-150mm, the height from the rafters is 40-50mm. Is there enough such a gap to attach a wind-moisture film or glassine directly to the old crate from the inside, or is it necessary to create a new (mini crate) between the spans of the rafters .... What actions do you recommend in such a situation?
Ivan 04/12/2016
Alexander, hello!
Rather, he asked a question on March 31, 2016, which worries a lot of people, including me. Could you answer it? Much where it is written that between the membrane and timber wall air must be left. But then the meaning of warming is lost, as far as I understand. If the insulation is taken away from the wall, then what kind of insulation is it? Or am I wrong?
Alexey 04/16/2016
Hello, Alexander!
Please help me with the following question:
In the attic, two side outer walls (which are under the roof) are upholstered with a board, then 200 mm cotton wool is laid, then after 60 cm a 20 * 40 rail is vertically fixed to which a draft wall (OSB sheet) will be screwed.
The question is, is it possible to stretch the vapor barrier (IZOVOND B) tightly against the insulation with a TURNING VAPOR INSULATION OF THIS RAIL 20 * 40, to which the draft wall (OSB sheet) will then be screwed.
Thus, between the insulation, the vapor barrier and the draft wall, a ventilation gap of 5-7 cm will be obtained.
I also ask you to tell me, do you need to stretch the vapor barrier with a rough or smooth side to the insulation?
Thank you very much in advance!
Olga 05.05.2016
Alexander, good day! need your advice! The house is a timber 15 cm, old, sheathed gradually and without observing technology. We have such a pie: siding-lining-glassine-bar-glassine-hardboard. Those. the beam is locked in glassine. Wet and moldy corners in the house. We want, without touching the outer walls, to disassemble inner lining and sheathe the house with clapboard. Do you need a vapor barrier? Insulation, I think, will be superfluous?
We also plan to insulate the floor from below and make a vapor barrier (the foundation is tape shallow, there is no black floor, board-floor-laminate). How to do it right?
Olga 06.05.2016
Alexander, thanks for your reply! That is, without disassembly outer skin can't get by at home? I really would not want to touch the house from the outside ... The house is warm, in winter it warms up with a stove and keeps it warm (we visit), in summer it is cool. And if there is a siding-lining-glassine-beam-lining, provided that we insulate and isolate the underground (it is ventilated, 2 vents for every 6 meters of the foundation)? Those. without vapor barrier, wood+wood inside?
andrey 11.05.2016
going to fix the old one log house(having built a ventilated frame). Basalt wool as a heater. How to fix the internal wind and vapor barrier film to the wall? How about a heater? After all, the log is not even, then there are depressions or bulges. Should the insulation be laid without repeating the contour of the logs? Thanks.
Alexey 18.05.2016
Hello, Alexander.
Two questions:
1) We have a metal frame of the building. Roof. I want to put a profiled sheet with a small wave on the runs, then put a beam on top of the profiled sheet in place of the runs and fix it to the runs. Fill the spaces between the timber with polystyrene PSB-15. Put a professional sheet H-60 on top of the timber. Do you need steam or wind protection? do you need a ventilation gap (because the profiled sheet has a wave 60 mm high, through which it can be ventilated)
2) Walls. The same metal frame. There are columns. Channel bars are welded to the columns horizontally along the perimeter of the building at a distance of 1 meter from each other (in height). I want to sew up the walls from the inside and outside with a profiled sheet (attaching it to the channels). As a heater, basalt wool with a density of 70-120. Do you need steam or moisture protection? Is a vent needed? Sheet C8
Vladimir 06/12/2016
Alexander, Good afternoon.
The question correlates with one of the first ones on this page () about Styrofoam. There is such material extruded (extruded) polystyrene foam (it looks like a kind of foam). I want to use it for warming the loggia (not combined with housing, warm double-glazed windows on the “window”, I would not want to do heating). Because of the first answer, several questions arise - is it possible to use such material in such a room and, if so, whether a vapor barrier is needed and what type. I wanted to insulate all the walls (except the one for the apartment), the floor and the ceiling.
Sasha 06/30/2016
Yuri T. 06/30/2016
Good time Alexander. My father-in-law decided to finish summer kitchen. This room is made of bricks, there is not even plaster inside. He filled the timber directly onto the brick vertically in increments of 60 cm (just for laying insulation), and sewed up the OSB on top. As a result, the OSB walls inside the room became damp and in some places immediately overgrown with green mold. Out of frustration, he dismantled part of the walls, but he didn’t manage to finish it, he had a stroke ((Of course, this is a different story. I would like to finish the room, but my mother-in-law won’t go for significant alterations. What do you say if I take off all the OSB, and fill the slats on top with a film for vapor barrier, then the insulation is in place, but on top of the film, and on top of the insulation there is another film, and then only the OSB. I just don’t understand which side to attach the film to, where to remove moisture. And in general why the OSB turned green. Maybe you can’t do this at all?
Yuri T. 07/01/2016
Good time Alexander. There is a brick room not plastered. The father-in-law filled the slats with a step of 60 cm and laid the insulation and sewed up the OSB. The result on OSB is green mold. Father-in-law got upset, got a stroke. Question. Can I change everything from minimal cost. For example, make a waterproofing film. On top of the rails, a layer with a stapler, then a heater and another layer of film. Then OSP. Will this solve the problem and which side to apply the waterproofing film

Tell me please.
I stuffed a crate on a wooden house, and already put a vapor barrier on top of it (then already a heater, waterproofing, again a crate and exterior finish).

That is, it turned out to be an indent from the log house to the vapor barrier.

I did this because it was not possible to put a vapor barrier inside the rooms - the lining was already full.
And I added an indent so that the condensate, which will be delayed by the vapor barrier, was not in direct contact with the log house (I don’t remember, I read it somewhere).

It turned out like this: http://doma-zagorod.ru/d/573916/d/%D0%A3%D1%82%D0%B5%D0%BF%D0%BB%D0%B5%D0%BD% D0%B8%D0%B5_150%D0%BC%D0%BC.jpg

This gap does not have access to the street, just a 3 cm indent from the log house to the vapor barrier.
.
I saw above that you wrote that there should not be a gap between the insulation and the house. Does this apply to my situation? Do I need to tear off the facade and remove the gap, or can I score and nothing irreparable will happen?

Pavel 07/23/2016
Good afternoon! Tell me, when performing insulation from the outside, the walls and partitions of the frame are vapor-insulated from the insulation. This is right? Will the frame rot under the vapor barrier? Thank you!
Pavel 07/24/2016
Alexander, I understand this and meant something else. You can’t get anywhere from the dew point and the insulation will still get wet and, accordingly, the frame crate along with it. I am interested in whether it is necessary to separate the frame crate from the insulation with a vapor barrier? I mean the ability to do this with insulation from the outside.

Alexander, good afternoon.
I have a question about interior walls in a sip-panel house. I plan to use acoustic mineral wool slabs laid inside a wooden frame to soundproof rooms. From two sides OSB walls and GKL. Tell me, please, is it necessary to use a vapor barrier film in this case. And what can you say about this "pie"?

Ilya 10.08.2016
Hello Alexander. Please tell me the correct pie of the partition between the room and the hallway (poorly heated), I plan (from the room): open the gap-vapor barrier with the smooth side to the insulation-insulation-? (And here is the question, vapor barrier and which side to where or wind-moisture?) - vent gap and osb.
And I’m also interested in the interfloor partition (from bottom to top; osb-vent gap-vapor barrier with the smooth side to the insulation-insulation-? (and again the same question, what’s next for steam or wind-and-moisture insulation) - vent gap-finishing floor.
Mineral wool insulation everywhere.
Stanislav 15.08.2016
Hello. Such situation. A house made of 150 mm timber was insulated in 2 layers of rockwool scandic butts in 2 layers of 50 mm each, then metal guides were installed and only then a windproof membrane was installed on them, and metal siding was immediately installed on the membrane. That is, between the insulation and the membrane, the gap turned out to be 27mm. The builders assured that there was nothing wrong with that, and they had been building for 15 years and nothing. Tell me, can this be correct, and if not, is their mistake in the gap between the insulation and the membrane critical?
Willow 23.08.2016
hello, tell me please, I’m going to insulate a log house from the outside, am I going to do it right, 1 vent gap, 2 vapor barrier, 3 frame with insulation, 4 wind and moisture protection, 5 vent gap, 6 OSB and then I’ll bring some decor, Thank you in advance for your answer.
Alexander 30.08.2016
Alexander, I combined the loggia with the room. I insulated the walls and the floor with foam plastic (comfort), I propelled everything. On the floor there are logs, penoplex, a draft floor (small cracks foamed) osb plate. Plaster walls.
What's even better to do? I think to make foil polystyrene on top of foam plastic. Ceiling - cork cloth and stretch ceiling. Or what's right?
Marina 21.09.2016
Hello, Alexander.
We have a block house. In winter, the wall freezes. We want to insulate the house and sheathe it with siding. We wanted to buy penoplex, but we were told that only the basement is insulated.
What is the best way to insulate and in what order?
Thank you!
Vladimir 26.09.2016
Hello, Alexander. I live in an apartment in a panel house. In the room, one wall (5 m long) overlooks an unheated stairwell (in winter, the temperature is not lower than +5). The wall is only about 100 mm thick, so I would like to insulate it. Warming is necessary from the inside. If I attach to the wall wooden blocks 50 * 50, lay 50 mm foam between them, attach drywall on top? Is a vapor barrier required?
Olga 29.09.2016
Hello, Alexander! We laid window openings with aerated concrete 150mm
Inside we plan lining with plasterboard sheets with 50 mm mineral wool insulation
How to do everything right so that it is warm .. heating electric convectors
Olga 10/17/2016
Good afternoon Alexander.
Please tell us what is the best thing to do in our situation. We have a house made of timber with an attic. The attic was insulated with 150 mm mineral wool. The cake consists of waterproofing then insulation and vapor barrier with a smooth side to the insulation. It seems that everything was done correctly, but then they noticed that moisture was collecting on the ceiling on the inside of the (smooth) vapor barrier. With what it can be connected? Maybe we didn’t quite hermetically lay the vapor barrier and the vapors from the interior got into the insulation?
- Alexander Kulikov 17.10.2016
  Hello Olga. There may be several reasons - at least two. Firstly, this may be due to insufficiently good insulation - this may be a banal condensate, which is formed as a result of a small draft. Somewhere the cotton wool was not inserted well enough or it was pressed strongly. Secondly, the effect can be created due to the waterproofing membrane - it may not let moisture out if it is laid in the wrong direction, or a banal film was used as it. Well, as for the insufficiently tight laying of the vapor barrier, this is not the reason - it's another matter if you laid it on the wrong side. But did you do it right? Read the features of your vapor barrier and compare - it should remove moisture into the insulation, from it through the waterproofing membrane to escape to the outside. Therefore, if it gets to the heater and gathers there, it is logical to assume that it does not go outside. Alternatively, there may be no ventilation gap between the roofing material and the waterproofing film.
  - Olga 10/18/2016
    Alexander, we looked at the vapor barrier instructions again. It says smooth side to the insulation. Most likely this is not the problem. I'm now worried about the issue of waterproofing. You write that it should be a waterproofing membrane. And for us it was Izospan D. Perhaps the problem is that this waterproofing does not let moisture out? And it is reflected, falls through the insulation on the vapor barrier? What do we do? Disassemble all the walls and ceiling and change the waterproofing to the membrane?
Alexander 31.10.2016
Hello, Alexander. I read all the comments and did not find the answer to my question. There is a 2-storey panel house, which we want to insulate with mineral wool 2 layers of 50mm. Do walls need to be insulated? Concrete panels, I think, do not let a lot of steam through, but the joints concrete panels can. Is it necessary to leave a vent. gap between wall and insulation Or how to properly insulate such a house?
Alexandro 02.11.2016
Good afternoon! Finishing a panel house facade panels with 2 layers of insulation. The panels are concrete, covered with stone chips. I would like to clarify the technology of siding installation. Wall, then vapor barrier (should it fit snugly against the wall? is it better to remove the crumbs from the walls so that they are even? or do not use vapor barrier film?), then 2 layers of insulation, then windproof membrane, air gap and siding?
Oleg 04.11.2016
Hello, Alexander. On the second floor of a private house, the walls are laid out in one brick ( facade walls), the house has central heating. Initially, the walls were insulated as follows: brick-vapor barrier type B (rough stone to the wall) - mineral wool 100mm-GKL. Moisture accumulated on the vapor barrier. We decided to redo the walls. Now we are building a wall like this: brick - vapor barrier B (the old one was not removed but dried) - a frame with 30 mm profiles - DSP slab 10 mm (for an air gap) - 100 mm of mineral wool - vapor barrier type B isospan (rough side to the insulation) - GVL 12 mm. I ask you to indicate whether there are errors in the wall insulation, we are very afraid of making a mistake again.
Oleg 05.11.2016
Alexander, thanks for your reply. I will take note of the need for a gap between the vapor barrier “B” and GVL.
I answer your question about the air gap - an air gap of 30 mm between the brick wall and the “false wall made of DSP-insulation-GVL” was made so that the cold from the frozen wall was not transmitted to the “false wall with insulation. The air gap should, as it were to separate the frozen wall from the “false wall”. Please explain how the air gap works in your opinion. Joints between CSP boards sealed with foam during installation.
Igor 12.12.2016
Hello Alexander.

Tell me please, I plan to insulate a small guest house with bath. Walls made of gas silicate.
I would like to clarify the installation technology. Outside, I plan to 100mm mineral wool to the wall with glue and fix it with umbrellas, then a windproof membrane, a 4cm ventilation gap and a blockhouse. From the inside, the walls are finished with clapboard, I didn’t plan to plaster, does it make sense to attach a foil vapor barrier to the wall, then a crate 3-4cm and a lining?
Tatyana 12/18/2016
Alexander, please help! Such a problem. The apartment is on the 2nd floor of a 2-storey residential building built in 1957. Problem with the bathroom. There was a remodel. Now the c / a is combined, and there is a home-made shower "cabin" (curtain). The walls began to rot. 10 years ago, ori were covered on the inside with ordinary household oilcloth. One of the walls is definitely made of drywall (I didn’t do it, I don’t know the details). Today, I tore off the self-adhesive film from the side of the corridor - the wall was through and through, it turned out to be rotten. But not much. There is a basement smell.
Question.
1. How can you replace the walls with your own hands (taking into account the weight of the material so that the ceiling of the neighbors does not break through - shingles of the wall)?
2. How to cover the walls (material)? I looked at waterproofing. How to attach it to such walls without reducing the internal space?
3. How can you decorate the walls later? Tape again? Tiles will not lie on flimsy walls, they will slide off. Putting sheets of plastic? The lining will simply let moisture pass onto the wall again.
4. Is it necessary to do ventilation for such walls? Bathroom area maximum 3 sq.m. We also have a washing machine.
Alexander 08.01.2017
Good day. Available brick house wall thickness 38-40 cm plastered from the inside in a year or two we are going to insulate with cotton wool. this year we want to sheathe the inside with clapboard, should I use films and what type? Bar 20 mm + lining 15 mm. Ventilation is poor. Windows all the time sweat.

Vapor barrier is one of milestones building a house out of wood. It protects building materials from exposure to steam, deformation, as well as the occurrence of fungus and mold.

Vapor barrier: necessary or not

A steam protection device is required if:

If the base is insulated from the inside with mineral wool. This is due to the fact that moisture adversely affects the properties this insulation. For this inside the building.
Frame houses, the walls of which consist of more than one layer.
If brick walls insulated on the outside with mineral wool and. In this case, the vapor barrier will perform a windproof function that protects the walls of the house from strong blowing. From the made windproof layer, the ventilation gap removes excess moisture.
For external walls located in close proximity to the foundation, where condensate forms most actively.
Walls made of logs or timber of natural moisture. Drying of such timber is carried out, being directly in the clearing, and the tree reaches the optimal moisture content only not earlier than after 5 years. The maximum degree of moisture content changes during the first year, so the bars are erected under the roof and left to dry for at least a year.

From which the walls of the house are erected, it is dried to low humidity even at the stage of its production, it has sealing recesses, slight dimensional fluctuations, as well as slight shrinkage.

The material is impermeable and provides optimal restriction of steam penetration into the thermal insulation layer.

Therefore, walls erected from timber are a good vapor barrier. Often they do not need an additional protection device.

Laying a vapor barrier for a wooden house can be carried out one year after its construction. This saves thermal insulation and reduces the level of vapor transmission.

It is not recommended to mount a vapor barrier on both sides, this prevents the wood from drying out naturally.

Vapor barrier of walls outside

Steam isolation can be done in several ways, depending on the type of log used:

When building the walls of a house from round log the insulation layer is attached directly to the tree by means of construction stapler. Ventilation gaps in this case are not required, it will be provided by the voids formed at the junction of the bars.
If the beam has a rectangular or square section, the surface is smooth and the air movement is not enough. Then planks 2.5 cm thick are stuffed onto the logs with a step between them of 1 meter. A vapor barrier material is laid on the completed crate and fixed with a stapler.

The following materials can be used to provide vapor barrier:

Plain polyethylene film. It should be noted that this material is not very effective, its main drawback is the formation of a greenhouse effect, it does not allow moisture or air to pass through. Some experts advise to perforate the film with your own hands, that is, to make many small holes on the roller, on which the nails are planted. However, this option is not feasible, the formed pores conduct moisture in two directions, and, accordingly, it will not be possible to provide membrane insulation from steam. The cost of the film depends on the manufacturer and ranges from 500 to 1100 hryvnia.
membrane films. Such material is able to pass air, while retaining moisture. There are three types of membranes: diffusion, superdiffusion and three-layer. The films are made according to a two-layer principle, one of which provides protection from steam from the outside, the second one - promotes the penetration of steam from the insulation to penetrate inside the house. The quality of the film depends on the vapor permeability index, the higher it is, the better. The price of membranes fluctuates on average from 750 to 4500 rubles per roll.
Mastic. The material is intended for application to the base prior to facing works. The cost varies from 32 to 92 rubles per 1 liter.

Consider how to properly install vapor barrier on outside house walls.

Laying vapor barrier directly on the outer surface of a wooden wall is not recommended.

The wood base, compared to a brick or concrete wall, has a strong thermal resistance, which can be compared to the heat transfer resistance of a thermal insulation layer.

The redistribution of temperature and moisture content in the insulated base layer can be such that on the inside of the film the temperature will be lower than the temperature required to cool the air so that the vapor begins to condense into dew. This contributes to the formation of condensation on the inside of the insulator and moistening the wall.

As a result, a ventilation gap of up to 5 cm is needed along the line of the base and the film, due to which the temperature in the room is set equal to the temperature of the room, that is, exceeding the dew point.

To remove the formed moisture, it is necessary to equip special channels near the foundation and the eaves of the house.

Vapor barrier of walls from the inside of a wooden house

Vapor permeability wooden base largely depends on the impermeability of sealing joints, grooves, as well as the absence of cracks in the wood.

Therefore, the walls of a wooden house often require auxiliary protection.- devices of a vapor barrier layer during their insulation.

Vapor barrier can be performed according to inner surface tree, but this solution will not be entirely correct. The best option - the device of the crate, which in the future will serve as a frame for the interior lining.

To do this, wooden planks are stuffed on the surface of the base in a vertical direction, which are set according to the level (wedges are stuffed along the depressions, and the material is removed on the ledges). First, the extreme rails are set, along which the intermediate strips are aligned by means of a thread.

The insulating material is stretched onto the crate from the bottom up and fixed with a construction stapler.

Lay the insulation in such a way that the matte, rough side is directed inward, this reduces the formation of condensate. It is not necessary to stretch the film very much, because after a while the wood will dry out, the tension may increase and the vapor barrier will simply break.

The sheets are overlapped and glued with moisture-proof adhesive tape.

A fabric with a self-adhesive strip along the edge will help speed up the process, thanks to which the joints are securely glued without additional time spent on their subsequent gluing.

For the device vapor barrier indoors, the following materials are used:

polyethylene film, the thickness of which is more than 0.1 mm;
membrane film;
mastic (great for a drywall base, the material is breathable while retaining moisture);
aluminum foil, at least 1.02 mm thick.

The foil is laid with a reflective surface towards the air space, this ensures a decrease in the degree of heat transfer.

Estimated cost of the material (depending on the manufacturer), the price is for 1 roll:

aluminum foil - 800–6300 rubles;
connecting tape - 150-500 rubles.

For an effective vapor barrier device, certain rules must be followed:

Inside the house, vapor barrier materials are mounted on walls that divide the living space into zones. These zones are often insulated with mineral wool, which, by accumulating moisture, loses its positive properties. Therefore, it is recommended to lay a vapor barrier on top of the insulation.
It is best to attach the film on the inside of the base wooden planks pre-treated with an antiseptic. Lay it on both sides of the partition walls. At the junction, an overlay of sheets of approximately 2.5–3 cm should form, while the edges on both sides should not coincide with each other, and the distance between them should exceed half a meter.
For effective ventilation of the walls and an optimal environment, the insulation is mounted on the inside of the heat-insulating layer.

Materials that prevent the penetration of steam, often confused with waterproofing materials Therefore, when buying, you should pay attention to the purposes for which they are intended.
To ensure high-quality insulation from the steam of the walls from the inside, it is necessary to maintain a distance from the film to the finish of at least 3 cm. This contributes to the free circulation of air and the removal of moisture formed on the membrane.
Vapor barrier material reduces the ventilation of the walls to zero, therefore, it is necessary to install auxiliary ventilation, such as valves on windows, fans in walls and vents.
Due to the fact that certain internal linings have their own vapor barrier, the layers in the thickness of the wall should be placed so that the vapor barrier properties increase from the inside to the outside.
During laying, the material must adhere tightly to thermal insulation material , firmly attached to the component parts of the mounting system. Loose sections and sagging should also not be.
Steam insulation should form a solid contour with the basement and attic floors.
Before performing the vapor barrier layer, it is necessary to check the surface of the base for the presence of seams, cracks and seal it with a sealant.

The main task in the construction of any building is to protect the entire structure from direct exposure to moisture. It is so destructive that it can destroy any construction material. In addition to humidity, another serious enemy is also known, this is steam.

When building houses, it is important to carry out a vapor barrier of the house from the inside. This is due to the fact that moisture eventually destroys any material.

If you neglect the protection against emerging steam, mold, fungus will appear on the surface of the walls, and dampness will appear. That's why every home needs a vapor barrier on the inside of the walls.

Some Features

This is simply necessary in damp and at the same time warm rooms. A prime example maybe a sauna, maybe a heated basement. Such premises are located underground, they are most exposed to dampness attacks.

In such rooms, steam is always formed in the form of warm air, with a huge amount of tiny droplets of water. The resulting couple just needs to find a way out of such a room. He looks for ways and finds them in the form of the walls of the building, its ceiling.

The formation of steam in this case becomes constant, the destruction of building structures occurs, the building becomes emergency. To protect the walls of the building, a special vapor barrier is made, which does not allow steam to enter from the inside, as a result, the life of the walls and partitions is extended.

Installation of vapor barrier is not limited to baths and basements. It is also necessary to install vapor barrier of internal walls in buildings that have external insulation, when the walls have a homogeneous material.

I must say that there is no special vapor barrier material suitable for all rooms in the same way. The type of vapor barrier depends on the existing structural component of the internal wall structures.

Back to index

Situations when it is necessary to install internal vapor barrier of walls?

Vapor barrier walls must be done in several cases.

Mineral wool is a breathable material, however, with this type of insulation, vapor barrier is a must.

If the walls have mounted internal insulation. Moreover, mineral wool was used as a thermal insulation material. Excellent thermal insulation properties are shown by mineral wool from the group of "breathing materials". But it has one negative property, mineral wool is not friendly with moisture. It quickly gets wet, gradually its properties deteriorate, it begins to quickly collapse. To prevent such cases, apply from inside the building. Frame houses with wall structures consisting of several layers must certainly include a vapor barrier material. This also applies to buildings with internal insulation.
A powerful windproof function for buildings with a ventilated facade is performed by the laid vapor barrier layer. It doses and softens the air flow. As a result, the outer insulation is less overloaded, it acquires free "breathing". For example, a wall made of brick, which has external insulation made of mineral wool heat insulator and upholstered with siding. In this case, the vapor barrier becomes a kind of wind barrier, it reliably protects the walls of the building from powerful blowing. The existing ventilation gap removes excess moisture from the installed wind protection layer.
In order to ensure a good microclimate in the room, it is necessary, together with a vapor barrier, to install efficient and reliable ventilation that operates in a constant mode.

Back to index

What materials do builders use today for laying vapor barrier?

Nevertheless, the expression "wall vapor barrier" does not mean that such a protective barrier does not allow any steam to pass through. The membrane materials that builders use today are endowed with the ability to pass a certain amount of air flow. This is done for one purpose only.

There should not be a "greenhouse effect" in the room. The installed membrane retains excess moisture that has passed through it, the air that has passed through it will not be able to negatively affect the internal walls of the house and the laid insulation material. When the thermal insulation has an internal "fur coat", then the flow of the wet mass through the exhaust ventilation occurs.

Back to index

Varieties of vapor barrier materials

The classic vapor barrier material is polyethylene. This material requires careful handling, since if the film is pulled hard, it can tear at the moment of changing climatic conditions. But there is one very important condition. Polyethylene must be perforated, otherwise it will not let in, apart from steam, also air. It will not be possible to get a comfortable microclimate in the building with such a film. If this polyethylene is used as a membrane, it will interfere with the entry of air mass, it cannot be used for vapor barrier.

It is possible to perforate a polyethylene film with a special device. Take a roller with driven nails. Such a "modernization" of the polyethylene film will not be able to provide reliable vapor barrier for internal walls. Of course, membrane materials are very similar to polyethylene film, but they differ greatly from it in their multilayer structure.

Builders often use special mastics as vapor barrier materials. After application, such a mastic is able to pass air, while retaining moisture. Surface treatment with such mastic begins to be done before the start of finishing.

Membrane films have become a modern material that is used today when laying a vapor barrier.

This material is able to prevent the entry of moisture, and at the same time pass the air flow. Such membranes have a certain vapor permeability, which ensures the normal operation of the insulation. When such a vapor barrier is installed, the cotton wool insulation does not get wet, the walls “breathe”, there is no freezing.

Vapor barrier for the walls of a wooden house is a good protection for wooden structural elements and insulation material. It protects from moisture and dampness, which prolongs the life of the structure. But the buildings are different purpose, age, shape and wall thickness. The choice of material for vapor barrier and the method of its installation largely depend on these factors.

A significant advantage of a wooden house is the excellent heat-shielding characteristics of wood. A wooden house, due to the naturalness of the material, does not produce emissions that are dangerous to the health of others.

Along with such advantages, there is a serious danger of material damage, which can occur due to violations of the rules for the equipment and operation of the building. Wood is able to absorb moisture well.

A residential building may have sufficient steam sources. This can happen when cooking or when wet cleaning rooms. A serious reason for the formation of steam can be the use of the bathroom. Steam evaporation is formed during the breathing of residents and with a significant accumulation of plants in the premises of the house.

A wooden house is a general designation for the following buildings:

Srub. It is erected from calibrated, planed or glued beams. Logs can have a round or rectangular profile.
Frame building or fachwerk. For the walls of the building being built wooden frame, which is sheathed with a board or OSB plate, wooden panels or boards. Inner space the frame is used to fill with insulating material.

The constant accumulation of moisture in the wood and its drying will cause the material to warp, cracks appear, and the tightness of the joints is broken. The presence of moisture in wood dramatically reduces the level of heat transfer of the material. Subsequently, the appearance of mold and fungal diseases, the reproduction of wood pests may occur. Eventually, the tree will lose its characteristics and begin to biodegrade.

To avoid this, it is necessary to equip the building with vapor insulation. It will allow air to pass freely and will retain moisture. In the presence of a vapor barrier, wooden elements structures will be protected from moisture, and steam will leave the building through ventilation shafts or naturally.

Vapor barrier materials include a variety of films, polymers and membranes. Each of them is used for a certain method of building a wooden house.

Steam protection materials

There are several types of materials for equipping a house with vapor barrier. All of them have good vapor barrier characteristics, but differ in their composition and properties:

Polyethylene film. It is recommended to use reinforced film. Most a budget option, affordable and widespread in trading network. Significant disadvantages include the complete absence of air and moisture penetration. This leads to the fact that condensate accumulates on the surface, which reduces the vapor barrier characteristics. In addition, it has low strength, which leads to a relatively short period of operation.

Laminated polyethylene film with aluminum coating. It has another name - aluminum foil. Its thickness is only 0.02 cm, but it has excellent vapor barrier characteristics. Installation of such a vapor barrier is carried out with an aluminum coating inside the room. As a result of this installation, heat is reflected from the film and remains inside the building. The disadvantages include the cost of the material.
diffusion membrane. This vapor insulator is made of several layers. The number of layers is determined based on the degree of humidity in the building. The membrane can be single-sided or double-sided. In addition to steam insulation, it additionally performs the functions of waterproofing and thermal insulation. The disadvantage of this material is its high price and the impossibility of installation from the outside of the building.

Before installing the film, it is necessary to study its marking. The film must be installed with the logo inside the room.

Polypropylene film. The characteristics are similar to polyethylene film. But, unlike her, more durable. Cellulose fillers in a polypropylene film do not allow condensation to form on its surface.
foil polymer. It includes such vapor barrier materials as kraft paper with a metallized layer, kraft paper with a metallized-lavsan layer, fiberglass with a foil coating.

They can be used in a combined version, as they have good thermal insulation characteristics. Installation is carried out with the foil side inside the building. Just like with aluminum foil, heat is reflected and remains inside the building.

Roll vapor barriers. It can be roofing material - a material saturated with fiberglass with a layer of bitumen. Rolled materials include roofing, which is cardboard impregnated with tar. You can use glassine, which is cardboard impregnated with bitumen. Roll materials are used to equip the exterior of buildings with vapor barrier. The main positive feature roll materials is excellent adhesion. It makes it possible to retain not only steam, but also moisture on the surface of the mastic.
Izospan. A relatively recent invention that combines films of various strengths and vapor barrier membranes. Easy to install, but very costly.

You can choose any protection against steam, depending on the age of the building, filling the walls, financial possibilities.

Work accessories

In order to perform high-quality vapor barrier wooden walls, you will need a small set of tools. This list will include:

construction stapler;
hammer;
screwdriver or drill;
building level or cord;
chisel;
wood saw;
construction knife.

The set of materials for the work will be: vapor barrier material, thin laths for the crate, wide adhesive tape, self-tapping screws and nails.

Vapor isolation methods

Vapor barrier is equipped with both wooden houses made of beams and logs, and different type timber frame buildings. An obstacle is often the incompletely dried wood, which remains saturated with moisture for five years after it is cut down. In the process of drying, it is deformed, cracks may appear.

You can wait until the wood dries and spend Finishing work. If there is no desire to wait, then the equipment of the building with a vapor barrier can be carried out taking into account this shortcoming. Steam protection can be installed in the following ways: from the outside and inside of the building.

Insulation on the outside of the building

On the outside of the building, the vapor barrier is laid, after the insulation and before protective coating. This is very important, since the insulation must be protected from external influences of moisture.

Insulation from the inside of rooms

Installing a vapor barrier on the inside or outside of a building often depends on temperature regime in the region. If the climatic conditions are cold, it is recommended to install a vapor barrier inside the premises. If the climate is warm or hot, then vice versa.

General issues of installation of steam protection

Before proceeding with the installation of a vapor barrier, it is necessary to perform a series of general recommendations. They are performed regardless of whether the installation is carried out outside or inside the premises. They consist of the following:

installation of the material must be carried out by marking on itself;
canvases should overlap each other;
construction adhesive tape for gluing strips must be at least 10 cm;
exit strips at window and doorways should be carried out with a margin. The stock is folded, necessary in case of deformation of the wood.

Do not confuse waterproofing and vapor protection. Waterproofing serves to protect against moisture, which may be the result of rain, fog, melting snow or ice. The vapor barrier protects against the formed condensate, creates conditions for the normal movement of air.

The vapor barrier material must be protected from direct exposure to sunlight.
Before starting installation, the work surface must be cleaned of dust and dirt. The presence of dust can subsequently lead to clogging of micro-holes, and the material will stop breathing.
The wood must be debarked, treated with a fire-resistant liquid, a solution against pests and fungal diseases. It is forbidden to use wood material that has diseases or defects.

Installation of vapor barrier on the outside of the building

The basis for long-term vapor barrier materials is the arrangement of materials in the so-called roofing "pie".

If the materials are arranged correctly, then the “pie” will look like this (from inside to outside):

Crate. Mounted on the building with self-tapping screws. Performs additional function ventilation gap. Its thickness can be up to 3 to 10 cm.
Vapor barrier film. Fastened to the crate with a construction stapler. The insulator strips are overlapped about 10 cm. The joints are sealed with construction tape.
Warming material.
Waterproof film.
Crate. Fastened with long nails that will pierce the entire "pie" and attach it to the wall.
Finishing material.

If the insulation is cotton wool, a vapor barrier film must be installed. It will protect the cotton wool from the vapors that come from the interior.

Installation of vapor barrier from the inside of the house

If necessary, the installation of vapor insulation can be done from inside the premises. A significant disadvantage such installation is that the outer part of the walls will be exposed to moisture.

To install a vapor barrier indoors, you must:

From the inside of the room, attach the crate to the wall with self-tapping screws.
Attach a waterproofing film to the crate. Its installation is carried out using a construction stapler.
Install ceiling hangers on the wall.

The installation of suspensions should be carried out at a distance slightly greater than the width of the insulation. This will ensure the fit of the insulation, reduce its waste and labor costs for cutting.

Install insulation in suspensions.
Attach a vapor barrier film to the insulation. The strips of the vapor barrier should be overlapped 10 cm to each other and glued with adhesive tape.
Install the crate with long nails that will pierce the entire "pie" and attach it to the wall.
Attach finishing material.

Output

If you install the vapor barrier correctly, this will greatly increase the life of a wooden house, reduce heat loss in the house and create comfort in it. A good ventilation system can provide good removal of the resulting vapors.

In modern construction, wooden houses with single-layer walls are rarely found. The desire of the owners to make the building warmer led to the emergence of multilayer walls, in which, in addition to the wall itself and the interior decoration, there is also a layer of insulation. As a result, the design of the house began to react differently to couples who are full in the interior and who are looking for a way out. If in single-layer walls steam circulated evenly between the street and the house due to the “breathing” properties of wood, then in the wall cake it began to “get stuck” due to the different resistance of materials. And the moisture inside prevents the insulation from properly performing the function of heat saving and leads to the destruction of wooden structures. To avoid such unfortunate consequences, a vapor barrier is created - another layer in the wall cake, the task of which is to keep steam out of the insulation.

log thickness;
type of material processing;
number of cracks;
sealing quality of crowns, grooves, etc.

If the house is made from chopped log, carriage or semi-carriage, then the wood in it has a natural moisture content. The walls will dry out gradually, already standing in a log house. As a rule, the box will reach the level of optimal humidity somewhere in 5 years. But the most active period is the first year. The moisture level of logs varies greatly and can lead to deformations, cracks, wall shrinkage. It is not for nothing that the first year the house is allowed to “stand up”, bringing the log house under the roof and stopping all work on this. If in the future the tree is not isolated from steam, then it will “play” for many years.

Other types of timber (rounded, glued) are already dried at the factory to the level of the required minimum moisture content, so such houses are less susceptible to shrinkage and deformation processes. Due to factory grooves and clearly calibrated dimensions, the walls turn out to be airtight and themselves become a barrier to steam, which penetrates them much more slowly. As a rule, such a house does not need a vapor barrier device.

Rounded timber due to factory drying becomes quite tight and does not need vapor barrier

When to start laying the vapor barrier layer

Option 1. We wait 5 years until the logs are completely dry, and only then we proceed to the installation of the wall cake and interior decoration. If all the cracks that appeared as a result of shrinkage are qualitatively caulked, then you can not lay a vapor barrier at all, but make a three-layer wall consisting of an outer wooden layer, a heater and an interior plasterboard finish. In this case, you will save a unique microclimate that only a wooden structure can create. But steam will enter the insulation, because both wood and drywall are permeable. With this design, it will be necessary to periodically (every 5-6 years) open the finish and change the insulation, which will lose thermal insulation characteristics when saturated with moisture. To prolong the life of the heat insulating layer, purchase materials that say "water-repellent treated" and "heavy density".

Option 2. If there is no time to wait so many years, there is only one way out - vapor barrier. By doing this, you will save the insulation, reduce the degree of passage of vapors, but the climate of the wooden house will “suffer”, because all the properties of the tree will “hide” under the vapor barrier. But the heat saving and durability of structures will increase markedly. It is possible to create a vapor barrier layer, however, like the entire wall cake, already a year after the construction of the log house.

The vapor barrier material closes the insulation from vapors penetrating into it from the inside of the premises.

How is vapor barrier laid for external insulation of the house

Wall cake with external and internal insulation home is different. External insulation of houses is carried out when an old wooden house is inherited and it needs to be given more modern look while maintaining wooden base. Internal insulation is usually done in new houses to leave the beauty of the logs open to the eye, or in cases where the exterior has already been finished.

Let's consider how to properly lay the vapor barrier if the insulation is done from the outside.

Since the log remains inside, then on its outer side, facing the street, the vapor barrier material will spread. For these purposes, you can choose a vapor barrier or ordinary film, roofing material, aluminum foil. Of the proposed options, the most short-lived are ordinary polyethylene and roofing material, because they have a short service life.

The roofing felt should be bituminous, having a double-sided coating, the film - more than 0.1 mm thick, the foil - more than 0.02 thick. Foil, in addition to vapor barrier, has the ability to beat off internal heat, returning it back to the rooms, so heat saving in such houses is higher than in buildings with another vapor barrier.

There must be a ventilation gap between the wood and the vapor barrier layer, which is created using wooden slats

Features of installation of vapor barrier films

If you create protection with a vapor barrier film, then when buying, carefully read what the coating is intended for. Vapor barrier is often confused with waterproofing. In our case, the film should not let steam through. Waterproofing films are permeable to steam. They create a barrier only for water. This option does not suit us, because if steam penetrates the insulation, then there is no point in creating a vapor barrier at all.

You also need to pay attention to which side to lay the vapor barrier. The manufacturer indicates this in the instructions, but if you did not find any instructions, then the principle of laying out the roll is as follows: lay it on the log with the side that is adjacent in the course of rolling the roll, i.e. external.

Among waterproofing films, there is one type that can also be laid as a vapor barrier. They are called anti-condensation films. One side of such films is smooth, and the other side is fleecy due to the cellulose layer. Look carefully which side to attach the vapor barrier: the smooth side is fixed to the log, and the fleecy side will be facing the insulation. Why exactly? The smooth side creates protection for steam. But not a single film can give a 100% guarantee that steam will not seep inside, because even the manufacturer does not give this guarantee. Caught on inside anti-condensation coating, moisture does not flow down, but "entangles" in the cellulose fibers, and then with the air flow goes out through the ventilation gap. This property is very beneficial for a heater that will not absorb the flowing moisture from below and will remain dry.

Vapor barrier device outside the house

How vapor barrier materials are installed

Regardless of the type of the above materials, the sheets overlap. In this case, the layers should be on top of each other by 2 cm or more. To seal the joints, use self-adhesive tape, and for foil - metallized tape.

If the house is made of a round log, then the vapor barrier layer is fixed directly on the tree, because the ventilation gap will be provided by the voids formed at the junction of the logs. If the timber with a rectangular or square section, then the surface is smooth, and air circulation will not be enough. In this case, narrow laths 2.5 cm thick are stuffed onto the logs in increments of about a meter, and a vapor barrier material is fixed on them with a stapler.

After the vapor barrier layer, a frame of timber is laid, into which insulation is laid, then waterproofing and exterior finish.

If funds allow, then you can buy a material that will be both a vapor barrier and a heater. These are foil polymers, i.e. foamed polyprofen, foam foam, etc., or fiberglass, on which foil spraying is applied on one side. Such materials are especially popular for warming baths. Remember which side to put the vapor barrier with such coatings: foil to the crate or logs, insulation to the outside.

When insulating with foil polymers, the foil should “look” inside the building

Vapor barrier device for internal insulation of the house

If the owner plans to hide the walls of a wooden house for interior decoration, then you can lay insulation from the inside. Although this option causes a lot of controversy and is considered less successful for wooden buildings than external insulation.

Consider why a vapor barrier is needed for internal insulation, and in what place of the wall cake it is created:

A waterproofing layer is applied along the log, which is needed to protect the walls from moisture from the outside. It must be fixed on the crate to get a ventilation gap of 3-5 cm.
The waterproofing is fixed with a stapler, and a metal profile frame is laid on top if it is planned to finish with drywall.
Insulation is laid out in between the frame.
A vapor barrier film is laid over the insulation.
Lay drywall boards.

Variants of vapor barrier and insulation of wooden walls of the house

As you can see, the vapor barrier separates the insulation and interior trim. Even if you finish the house with clapboard, and not drywall, then vapor barrier is needed, because the tree passes steam molecules well, which means it harms the insulation.

Wooden housing construction has its own specifics, so before warming the house it is better to consult with professionals. When incorrect installation wall cake will quickly destroy even the most resistant wood.