Penoplex is used today as a universal insulation material. The material's properties are superior to many analogues. He's different low level moisture absorption, does not allow steam to pass through and does not release heat from the room. Many people have questions about whether additional waterproofing is necessary when insulating with Penoplex? To understand, you should know some features of the insulation process.

Is it necessary to insulate surfaces and insulation?

If you do not protect the foundation and walls from moisture, the structure will not last long. Many building materials, be it brick, concrete or gas silicate, are moisture-absorbing. Before finishing, you need to carefully isolate the surfaces from liquid penetration. For this purpose, roll and penetrating materials are used. If you buy insulation High Quality, but if you don’t take care of preparing the surface in time, you may regret it more than once. It is highly moisture resistant, but due to the joints on the slabs it does not protect the foundation or walls from water ingress.

Waterproofing for floors

The moisture-proof coating is laid on the rough base. For these purposes it is used bitumen mastic, cellophane film or roofing felt. You don’t have to waterproof the penoplex itself, but you definitely need to treat the joints. They can be glued with special tape or glue. The top of the penoplex is filled with a concrete screed. simple plastic film. For floors on the ground, you need to do waterproofing not under the material, but along it.

Vapor barrier of walls inside and outside

When insulating walls with Penoplex, you don’t have to resort to. The joints of the slabs must be coated with foam or bitumen. Waterproofing is also necessary in this case; it can be provided with special glue.

Waterproofing films for roofing

When using Penoplex as roof insulation, the insulating layer should be located on top of the slabs. It is important not to forget about treating the material with anti-flammable substances. Waterproofing the material is desirable, but to a greater extent it depends on the characteristics of the room that they plan to insulate.

Waterproof the part from which moisture can penetrate. The floors are insulated from below, and the roof is insulated on top. The most minimal requirements for additional processing extend when processing walls. It is important to lay penoplex correctly, since without following the technology you can waste both time and money.

No matter how dry the indoor air may seem, it contains a considerable amount of moisture vapor. And no one would pay attention to them if modern construction did not use energy-saving technologies. Insulation (or rather, the insulation materials themselves) turned out to be defenseless against moisture and vapors, since when they get 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 latter’s task is to protect against water vapor contained in the indoor air. This is exactly what we will talk about in this article, in which, together with the website, we will look at the purpose of this material, the types and methods of their use.

Why do you need a vapor barrier for walls?

Vapor barrier of walls: why is it needed and when it is impossible to do without it

To the question of why a vapor barrier is needed on walls, there is only one correct answer, which we partially touched on a little higher - at least that’s what it looks like in short. If we consider it more broadly, then we should also touch upon the topic of moisture exchange in rooms, which occurs regardless of our desire in a way invisible to us. The moisture in the air, or rather its excess, is absorbed into the walls of a house or apartment, and if there is a lack of water in the air, the 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 it 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 the insulation. It's no secret that water in all its manifestations is not like that at all.

Vapor barrier of walls from the inside

Installation of a vapor barrier on walls is not necessary in all cases - an important condition for the absorption of moisture vapor by the insulation is the temperature difference, which is significantly noticeable on the external 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, such an effect is absent on the internal walls of the house.

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

Very important point, accompanying the vapor barrier of walls from the inside and outside, is the presence of high-quality ventilation. If we talk about internal vapor barrier, then the interior spaces must be ventilated; if we talk about external vapor barrier, as is the case with siding, then a ventilation gap is needed here. The air passing through it removes excess moisture, which settles on the vapor barrier.

Material for vapor barrier of walls: how to choose the best option

Today, there are three main types of materials used for vapor barrier of walls - they all differ in their design, properties and capabilities. Let's take a closer look at it, which will give you the opportunity to choose the best one 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 correct solutions - mastic or membrane. Everything is simple with mastic, but among membrane materials choosing the one you need won't be much more difficult.

To conclude the topic, a few words about how to lay vapor barrier for walls. There are two executive installation schemes - 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 to the frame with a beam of small cross-section. The second executive scheme for solving the problem of how to attach a vapor barrier to a wall provides a ventilation gap between the vapor barrier and the wall cladding, which allows the space in the area of ​​the vapor barrier to be ventilated quite effectively. In most cases, the second actuator circuit is used when. It is practically not used indoors, since its implementation requires additional space, which, as practice shows, is not superfluous even in such small quantities.

How to install vapor barrier on walls

Finally, I’ll add the fact that vapor barrier of walls must be done correctly, since this is the key to a comfortable microclimate in the premises, which can only be achieved by following certain installation rules. These include laying vapor barriers overlapping, installing the same ventilation gaps and creating a so-called circular vapor barrier, in which the laid material is a solid covering along the walls and ceiling.

191 comments

1. ru-two.ru 06/04/2015
   • Alexander Kulikov 05.06.2015

     Not really. Foam plastic is not covered with a vapor barrier. This is simply not necessary. As you correctly noted, polystyrene foam does not conduct water at all, which is good for walls; they stop breathing and as a result many problems arise, especially if foam plastic is used indoors. There is such a thing as the dew point - the 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, fungus begins to develop under the foam plastic. In addition, in this way you create all the prerequisites for the walls to completely freeze in winter, which again contributes to the destruction of the walls. It is for this reason that the most preferable is external insulation with foam plastic or, in general, some other material. The house needs to 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 between the second floor and the attic was insulated with polystyrene foam. We are going to lay steam insulation on the ceiling. Right or wrong? And what can you do to fill between rooms? 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 were insulating the ceiling 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. Inside the room, without contact with the street, the insulation simply cannot get wet to such an extent as to be saturated with water. There is another nuance here - quite often it knocks down under its own weight. Just secure it well at the top and everything will be fine.

     • Alexander 07/03/2017
     • Dmitry 02/23/2018

       Alexander Good day. Please tell me this situation. The house is made of porevit, two floors and a basement, and on the second floor the ceiling was lined with 25 boards and under it an inexpensive vapor barrier from Leroy... the vapor barrier was added to the joists and then boards immediately. And in the cold attic 250 mm of cotton wool was laid. In January I climbed onto the roof and in some places cotton wool upper layer it crunches, it is saturated with moisture and frozen mineral wool Knauf Tyumenskaya they say that it is very bad.... and the vapor barrier is still not positioned correctly against the mineral wool, with the rough side adjacent to it. And in the house, the ceiling was once again hemmed with Izospan am boards, most likely expensive, on one side it’s white and on the other it’s brown... so that the boards don’t show through under the tension. Tell me what to do?! Please. I don’t want to disassemble the ceiling, remove Izospan am from the boards and... I want to immediately hem plywood onto the boards, and maybe some kind of Izospan and tension on the plywood... but in a cold attic I don’t know what to do. Remove this Izospan and then just use 50 density stone wool on the boards between the joists and your old mineral wool. And I don’t know, cover it? Isospan on top or not? On cotton wool. is it possible? Or I just don’t know what to do with IVF cotton wool... we don’t live in the house yet. Can you drop off your phone number? Maybe I’ll tell you in detail by phone if I’m at a dead end what to do

   • Aydys 10/28/2017

     Hello, Alexander! I'm going to do interior wall. The wall material is plasterboard, 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 cover the mineral wool with a vapor barrier material, such as isospan?
     It's not written on your website. I just saw how it was inside at a monolithic construction site plasterboard partitions sheathed with this material. I don’t know exactly what material was there.
     I recently built a veranda, and there is a stove there. Type B isospan was laid on the ceiling of the veranda. I am not sure whether the isospan insole is correct. If you lay isospan type B on the shelves from the outside. To cover it with sawdust and clay.
     Question: – which side should I lay isospan type B so that it allows steam to pass through and does not let cold air back in?
     We laid the smooth side up. They fell asleep on top.

   • Natalia 10/26/2018

     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 a loggia, the wall on the loggia with a window opening is laid out in the floor with bricks. It was decided to insulate it additionally with the remaining 20mm polysterol foam (it was fixed to the wall using special glue and mushroom dowels), then again opinions were divided) Some craftsmen suggest simply sheathing the wall further with gypsum plasterboard, while others suggest additionally using a vapor barrier in the form of penofol, which will be additionally with insulation and vapor barrier, and then just cover it with gypsum plasterboard. Please tell me, do you think it is necessary to add an additional vapor barrier to the loggia when insulating the wall with polystyrene foam from the inside? And is it necessary to leave an air gap between the gypsum board and the vapor barrier?

2. Artem 07/09/2015

   Alexander, as I understand from the comment, insulation basalt wool from the inside with proper vapor barrier will be better than foam insulation without vapor barrier?
   or am I wrong?

3. Ivan 09/03/2015

   Alexander, I’m faced with a question: the house is of a block type, I’m going to cover it with metal siding, between them there is high-density mineral wool insulation, according to your article, it will be enough just a vapor barrier on the outside of the insulation, or a hydro-vapor barrier, i.e. so that the outside does not allow moisture to pass through, but the steam releases from the inside?

4. Oleg 09/04/2015
5. Pavel 09/07/2015

   Hello, Alexander! After reading a bunch of forums and instructions, I decided to insulate an external 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 clean materials. I decided to stick foam glass on the brick wall in 2 layers, each 20 mm thick, and then plaster it and glue the wallpaper. Tell me how correct this is? and the dew point will not be disturbed?

6. Marina 09/16/2015

   Hello, Alexander! I have a new house made of timber, the second floor gets wet inside due to rain, can I cover the outside walls with isospan V. and which side is facing the timber, and then lay insulation on it closely (min. slab or better Stirex?), then isospan A and siding?

   • Alexander Kulikov 16.09.2015

     Hello Marina. Apparently, somewhere a mistake was made during construction. Are you 100 percent sure that it is the walls that get wet? Maybe it's all about the roof? In general, it’s strange that this happens - the walls shouldn’t get wet. Well, if this is true, then in principle, wooden structures can be covered with a ventilated façade. Only this needs to be done at once, and not in parts. Izospan B is mounted with the smooth side to the insulation - in this case, there should be a small gap between the wall of the house and Izospan (its rough side). You need a sheathing made of thin lath (10-15mm), onto which Izospan is attached with a stapler. Then, on top of Izospan, a frame for siding is assembled, the space between the supporting slats is filled with insulation. Then again Izospan (smooth side to mineral wool). Again, there is a gap for ventilation, which is again created by a thin strip, onto which the siding itself is already assembled.

7. Peter 09.20.2015

   Hello, Alexander!
   thanks for detailed tips, but it is not entirely clear which cell is made of 10x15 mm slats. stuff over the entire surface of a wooden wall of a house? This is the first time I’ve heard about this, I’ve never seen it in practice!
   Please tell me how Izospan B works, why is the smooth side always facing the insulation?
   And then, why refill the sheathing to achieve a ventilated gap? It is achieved by the height of the siding frame.
   Alexander, please, please shed some light on the issue of external insulation of a brick wall with penoplex, if the inside of the house is sheathed simply with clapboard. (brick wall thickness 70 cm). Do you need a vapor barrier on the outside of the brick? And how and how airtight (maybe using polyurethane foam) should I sew penoplex to the wall?
   Best regards, Peter. Kuzbass.

   • Alexander Kulikov 20.09.2015

     Hello Peter. Let's go in order.
     1. Wooden cell. It forms a ventilation gap between the walls of the house and the insulation, or rather isospan, which is located with the fleecy side facing the house. Pile, it is needed to retain moisture. But where does she need to go next? For this, ventilation is necessary, or rather a thin lath on which the vapor barrier is placed. 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 the insulation - as you say, this is a sheathing for attaching the siding.
     3. Insulation, you need to protect the outside from moisture. Right? To do this, after it is placed between the sheathing, a water barrier is stretched over it, preventing the insulation from getting wet.
     4. Next is the ventilation gap again, which will remove moisture from the hydrobarrier. If this is not done, then it will spoil the sheathing and create the preconditions for fungus in the summer and ice in the winter. To do this, you need to stuff a thin strip onto the vertical boards of the sheathing, to which the siding is already attached.
     Well, as for the question of how a 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 coming out of the walls of the house partially penetrates into the insulation, and is partially retained on the vapor barrier - that which is retained (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 called breathing walls or, in other words, a ventilated façade.
     I wrote about insulating walls with penoplex, or polystyrene foam, or polystyrene in an article. You can read it if interested.

8. Alexander 07.10.2015

   Please tell me which films to use and on which side. The house is made of cinder blocks, then basalt wool and facing bricks. We live in the middle zone of Ufa. Thank you.

9. Sergey 11/14/2015

   Hello, Alexander. Please tell me how to properly make a vapor barrier. House made of aerated concrete blocks. I want to insulate the outside with mineral wool, and the finishing is brick. Thank you.

10. Roman 12/10/2015

    Hello, Alexander.
    How a ventilated facade works is very well explained. I wanted to clarify directly at the joints of the resulting “sandwich” (wall-gap-vapor barrier-insulation-windbreak-gap-siding). On four sides, our wool will be lined with wooden sheathing, 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 is not entirely on 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 - finished floor) As I later found out, the first layer is a wind barrier. Have I created a greenhouse effect for the insulation? The house sits on stilts above fairly damp soil.
    Thank you for attention.

11. Tatiana 12/22/2015
    • Alexander Kulikov 22.12.2015

      You see Tatyana, it creates the effect of a thermos and when there is excess moisture in the air or in your case in the lining, it creates a very comfortable conditions for the development of fungus and mold. If you use it you need good ventilation, and this means at least heat loss. This is the same as silicone in the bathroom, which people use to seal the contact areas of the same bathtub with the walls. I don’t know why, but mold loves it very much, even if there is good ventilation in the bathroom, it still grows on it. Here is foam plastic, about the same material, perhaps to a slightly lesser extent. One of my friends insulated the external walls inside the house with polystyrene foam (one wall, since there is no access to it from the outside) - he saved centimeters. Three years without problems, and then black spots appeared - this fungus was probably hiding, biding its time, gaining strength. In the end, after a year of useless struggle, I tore everything down, made a frame and insulated it with mineral wool. Five years – normal flight. No fungus.

12. Tatiana 12/22/2015
13. Sergey 12/30/2015

    Alexander, your opinion on this issue.
    The veranda will theoretically be heated during infrequent visits in winter
    Frame walls, pie: (outside-inside) imitation timber on sheathing, OSB, Izospan vapor barrier, 15 cm of basalt wool, Izospan vapor barrier, OSB board. In the summer I want to cover the inside with MDF wall panels. Do they need to be installed on the sheathing, is it necessary to lay another layer of some kind of membrane, or can it be done directly on the clasps on OSB without sheathing?

14. Anatoly 01/11/2016

    Hello! I have a question for you. I have a garden with walls made of cinder blocks, and I just can’t decide what and how and with what to insulate the walls. I live in the Urals and the winters are not very warm. as I was told on advice from the street, first apply a vapor barrier to the walls, then mineral wool in two layers in a checkerboard pattern and again a vapor barrier and only then cashing. As for the inside of the house, it is still necessary to level the walls since the plaster is made this way and the walls are far from even, with the naked eye it is very visible what catches the eye and I want to level it with drywall, the question is whether it makes sense to put some kind of insulation between the drywall and whether a vapor barrier is needed. I wanted to use noise-heat insulation as insulation

15. Evgeniy 01/12/2016

    Good day!
    I have this situation. There is a wooden house with an outbuilding. There is a U-shaped path leading to the annex. frame veranda under one pitched roof with an extension. They decided to make two rooms from the veranda, separated by a partition: a bathroom and a tabmur. The veranda is like this: a shallow foundation, on which lies strapping beam along the perimeter of the veranda, section 150x150. Vertical posts of the same material and cross-section are installed on this beam. The rafters, integral with the annex, rest on the posts. We decided to insulate it 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 sheathing 25x50;
    – OSB 9.5;
    – vapor barrier, close to the insulation;
    – 150 insulation;
    
    – hydro-wind protection, close to the insulation;
    – vertical lathing from a metal profile;
    – siding.

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

    1) Do you need OSB or OSB in the bathroom? wooden sheathing 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 insulate the partition between the bathroom and the annex from the bathroom side (beam 150x150).
    3) The design of the house requires the installation of an underground space on the veranda. In other words, the floor level from the ground will be 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 in a different way? Which one?
    4) Due to the floor level, the issue with the thickness of the ceiling pie is very critical; can it be made smaller in thickness by using another insulation, for example?
    5) Is it possible to leave roofing felt in the roof?
    6) Is it necessary to steam and waterproof the insulation in the partition between the vestibule and the bathroom.
    7) Is it necessary, given such an underground space, 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, moisture is close to the surface of the earth.

16. Gennady 01/27/2016

    Good afternoon. Tell me how to properly redo the insulation of the second floor of an attic house. The rooms are heated. I insulated the rooms in the following way: drywall was screwed to a wooden, almost solid, wall sheathing, the sheathing was stuffed onto wooden studs, and there was just insulation (mineral wool) between the studs. 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 (condensation was collecting there). And now I'm thinking about stuffing a vapor barrier film between the studs. But the question arises: is it necessary to stuff slats between the wooden sheathing and the vapor barrier film for the movement of steam? Then you will get a wall: drywall, wooden sheathing, slats for ventilation, vapor barrier film, insulation. There is an unheated attic space between the walls and roof rafters.

    • Alexander Kulikov 27.01.2016

      Hello Gennady. The point of sheathing for gypsum board is more to level the surface than to create any gap - if the pitch of your attic racks was 600mm, then the plaster could be attached directly to them. By the way, is it cracking at your seams? Or haven't you putty the drywall yet? The fact is that wood behaves depending on temperature and humidity, and it pulls gypsum with it. As a result of cracks at the seams, the issue is resolved by manufacturing an independent frame that has a minimum of points of contact with the wood. Let's return to insulation - mineral wool needs to be protected from moisture on both sides. From the street, even from the side of a cold attic, moisture also penetrates into it - a windproof film is installed on the street side. In principle, it can be installed from inside the room and secured to the risers - so that it creates a bag between them. Place insulation in this bag and cover it with a vapor barrier. If you are not afraid of cracks, you can then restore your wooden sheathing and screw drywall to it, as it was.

17. Sergey 01/27/2016

    Hello! I bought an apartment, panel 2 floors. In winter, it turned out that there were droplets of water in the corners of the kitchen and mold had appeared at the top. In summer the façade was covered facade plaster. The walls themselves are very cold, it is impossible to insulate from the outside because it is on the 2nd floor. I'm thinking of insulating it indoors. Please advise how to do it correctly.

18. Sergey 01/30/2016

    Good afternoon I selected many options, but didn’t even consider cotton wool. As far as I know, cotton wool gradually gains moisture. Previously, I settled on using Expanded Polystyrene or Penoplex i.e. cleaning and treating the walls, then we put insulation on the tile adhesive, 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 on a vapor barrier, but honestly I don’t know if it’s necessary.

19. Lena 02/14/2016

    Alexander, I always have my own ideas, so my question may be strange to you. I’m looking for the cheapest and easiest way that would allow me, without anyone’s help, to at least slightly insulate the wall in the apartment from the inside (corner apartment on the top floor, in winter there is a lot of cold from the wall). This is a brick five-story building. Please tell me, is it possible to stick a vapor barrier directly onto the wallpaper, and a dense one on top of it? furniture fabric(I would generally prefer warm fabric on the walls rather than wallpaper, I love everything soft and fluffy). If you do this, won't the wallpaper get damp behind the vapor barrier? But the wall, in theory, shouldn’t be so cold and cool the air heated by the radiators in the room?

20. Rodion 02/21/2016

    Hello, Alexander. I have a street wall with windows that I want to cover with plasterboard and insulate with mineral wool, how should I make a vapor barrier?

21. Rodion 02/22/2016
22. Nikolay 03/05/2016

    I have a house made of 145 by 145 timber in the Moscow region. I want to insulate it (50 thick) with arugula. Do you need a vapor barrier between the wall and the insulation? And what kind of rukvol can be used for insulation?

23. Alexander 03/09/2016

    Do we need a vapor barrier from the inside of the house or some kind of film from the outside. Wall cake 1st floor - sand-lime brick, expanded clay, block. Second floor - sand-lime brick, foam chips, block. We want to cover the house with clinker thermal panels based on polystyrene foam.

24. Sergey 03/30/2016

    Hello Alexander! I am planning to insulate a house from 150*150 timber. Am I planning my work correctly?
    - treatment external walls antiseptic;
    – installation of vertical racks from edged boards thickness 2.5 – 3 cm;
    – fixing Izospan-V waterproofing;
    – installation of horizontal bars 5*5 cm;
    – installation of Rockwool Light Butts mineral wool against the background and securing it with anchors;
    – securing the vapor barrier Izospan-AM;
    – installation of vertical bars 5*2.5-3 cm;
    – installation of a block house.
    I correctly understood the technology for 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’s correct, but not entirely – there are unnecessary elements in your design. There is no need for a 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 50mm, then yes, a 5 by 5 cm beam will do, but usually this amount of insulation is not enough. Set to 100mm. Accordingly, the timber needed is not 5cm, but 10cm (a 100 by 40mm board is perfect) - the insulation cannot be pressed, as it loses its qualities.
      3. Then install the insulation
      4. Tighten the hydraulic barrier along the vertical posts. Secure it with a block (in your case 5 * 2.5-3 cm) and you get a distance 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 installed.
      5. A block house is mounted along this block.
      That's all

      • Sergey 03/31/2016

        Alexander, thanks for the answer. Initially I planned it exactly as you described. I was confused by the fact that in some articles they write that wooden beam will release 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 thermal conductivity.
        Are such arguments fair? Thank you.

      • Tatiana 09/12/2017

        Hello, Alexander! Is it possible to damp board put mineral wool? We make a kitchen in a cafe from a USB frame. They put cotton wool on the USB and then ecospan b. Everything is foggy. We laid the smooth side to the insulation. And in the attic they put an isover and ecospan ceiling on a rough board with the rough side. help me please

25. Dmitry 04/11/2016

    Hello, Alexander! The question is: an old house With gable roof, externally covered with galvanization (1951), then 3-4 layers of roofing material (from Soviet times), shingles (preserved in the front part of the roof). I am planning to insulate the slopes with 150mm mineral wool. Wind-moisture-proof film (membrane - A) or better glassine (3 mm) on the inside of the sheathing? Ventilation is possible. For the best option, tell me how... There are no roof vents to disassemble or any... (although this is necessary). After all, air flows can be directed freely along the halves of the slopes from the first anchor to the 6th (house 12 meters) in terms of the presence of half logs in the sheathing... The distance between the floor logs is 100-150mm, the height from the rafters is 40-50mm. Is this gap enough to attach a wind-moisture film or glassine directly to an old sheathing with inside or do you need to create a new (mini sheathing) between the rafter spans…. What actions do you recommend in such a situation?

26. Ivan 04/12/2016

    Alexander, hello!
    I quickly asked a question on 03/31/16, which worries a lot of people, including me. Could you answer it? In many places it is written that between the membrane and timber wall you need to leave some air. But then the meaning of insulation is lost, as far as I understand. If the insulation is removed from the wall, then what kind of insulation is it? Or am I wrong?

27. Alexey 04/16/2016

    Hello, Alexander!
    I ask for help with the following question:
    In the attic, the two side outer walls (which are located under the roof) are covered with boards, then 200mm of mineral wool is laid, then a 20*40 strip is vertically fixed after 60cm to which the rough wall (OSB sheet) will be screwed.
    The question is, is it possible to stretch the vapor barrier (IZOVOND B) tightly to the insulation with the VAPOR INSULATION TURN OF THIS 20*40 RAIL, to which the rough wall (OSB sheet) will then be screwed.
    Thus, between the insulation, vapor barrier and the rough wall there will be a ventilation gap of 5-7 cm.
    I also ask you to tell me whether the vapor barrier should be stretched with the rough or smooth side facing the insulation?
    In advance Thanks a lot!

28. Olga 05/05/2016

    Alexander, good day! I need your advice! The house is a 15 cm old timber house, it was sheathed gradually and without following technology. We have the following pie: siding-lining-glassine-beam-glassine-hardboard. Those. the timber is locked in glassine. The corners of the house become wet and moldy. We want, without touching the outer walls, to dismantle the internal lining and cover the house with clapboard. Do you need a vapor barrier? I think insulation will be superfluous?
    We also plan to insulate the floor from below and make a vapor barrier (shallow strip foundation, no subfloor, laminate board). How to do this correctly?

29. Olga 05/06/2016

    Alexander, thanks for the answer! That is, without disassembly outer skin Can't get by at home? I really wouldn’t want to touch the outside of the house... The house is warm, in the winter it is heated by a stove and keeps it warm (we visit), and in the summer it’s cool in there. And if there is siding-lining-glassine-timber-lining, provided that we insulate and insulate the underground (it is ventilated, 2 vents for every 6 meters of the foundation)? Those. without vapor barrier, wood+wood inside?

30. Andrey 05/11/2016

    I'm going to insulate the old one log house(by building a ventilated frame). Basalt wool is used as insulation. How to attach the internal wind and vapor barrier film to the wall? Pull it directly onto the wall or nail slats to the wall and put the film on them? How's the insulation? After all, the log is not even, it has depressions and bulges. Should the insulation be installed without following the contour of the logs? Thank you.

31. Alexey 05/18/2016

    Hello, Alexander.
    Two questions:
    1) We have a metal frame of the building. Roof. I want to put a corrugated sheet with a small wave on the purlins, then put a beam on top of the corrugated sheet in place of the purlins and fasten it to the purlins. Fill the spaces between the beams with PSB-15 foam plastic. Place N-60 corrugated sheet on top of the timber. Do you need steam or wind protection? Is there a need for a ventilation gap (after all, the profiled sheet has a 60mm high wave through which it can be ventilated)
    2) Walls. SAME metal frame. There are columns. Channels 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 cover the walls inside and outside with corrugated sheets (attaching them to the channels). Basalt wool with a density of 70-120 is used as insulation. Do you need steam or moisture protection? Is a ventilation gap necessary? Sheet C8

32. Vladimir 06/12/2016

    Alexander, Good afternoon.
    The question correlates with one of the first on this page () about polystyrene foam. There is such a material as extruded polystyrene foam (similar to a type of polystyrene foam). I want to use it to insulate a loggia (not shared with housing, there are warm double-glazed windows on the “window”, I wouldn’t want to do heating). Because of the first answer, several questions arise - can such material be used in such a room and, if so, is a vapor barrier needed and what type. I wanted to insulate all the walls (except the one next to the apartment), the floor and the ceiling.

33. Sasha 06/30/2016
34. Yuri T. 06/30/2016

    Good afternoon Alexander. My father-in-law decided to get off summer kitchen. This room is made of brick, there is not even plaster inside. He laid timber directly onto the brick vertically in increments of 60 cm (just for laying insulation), and covered everything with 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 didn’t have time to finish it, he had a stroke ((Of course, that’s a different story. I would like to finish the room, but my mother-in-law won’t do significant alterations. What do you say if I remove all the OSB, and fill the slats with vapor barrier film on top, then the insulation is in place, but on top of the film, and on top of the insulation there is still film, and then only OSB. I just don’t understand which side to attach the film to, where to remove the moisture. And in general, why the OSB turned green. Maybe it’s not possible to do this at all?

35. Yuri T. 07/01/2016

    Good afternoon Alexander. There is a brick room that is not plastered. The father-in-law filled the slats with a pitch of 60 cm and laid insulation and sewed up OSB. Result on OSB green mold. The father-in-law was upset and had a stroke. Question. Can I redo everything with minimal costs. For example, waterproofing with film. Layer a layer of stapler on top of the slats, then insulation and another layer of film. Then NDE. Will this solve the problem and which side should I apply the waterproofing film on?

Please tell me.
I put lathing on a wooden house, and then put a vapor barrier on top of it (then insulation, waterproofing, again lathing and external finishing).

That is, there was an indentation 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 filled.
And I added an indentation so that condensate, which would be retained by the vapor barrier, would not be in direct contact with the log house (I don’t remember, I read it somewhere).

It turned out something 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 indentation from the frame to the vapor barrier.
.
I saw above that you wrote that there should be no gap between the insulation and the house. Does this apply to my situation? Do I need to tear down the façade and remove the gap, or can I just hammer it in and nothing irreparable will happen?

36. Pavel 07/23/2016

    Good afternoon Tell me, when insulation is carried out from the outside, the walls and partitions of the frame become vapor-insulated from the insulation. This is right? Will the frame rot under the vapor barrier? Thank you!

37. Pavel 07/24/2016

    Alexander, I understand this and meant something else. There is no escape from the dew point and the insulation will still get wet and, accordingly, the frame sheathing along with it. I'm wondering if I need to use a vapor barrier to separate the frame sheathing from the insulation? I mean the possibility of doing this while insulating the outside.

Alexander, good afternoon.
I have a question about the internal walls in a house made of sip panels. I plan to use acoustic mineral wool slabs laid inside to soundproof the rooms. wooden frame. On both sides OSB walls and gypsum board. Please tell me whether it is necessary to use a vapor barrier film in this case. And what can you say about this “pie”?

38. Ilya 08/10/2016

    Hello Alexander. Please tell me the right pie partitions between the room and the hallway (poorly heated), I plan (from the room): osb - vent gap - vapor barrier with the smooth side facing the insulation - insulation -? (and here is the question, vapor barrier and which side 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 facing the insulation - insulation -? (and again the same question, what’s next for steam or wind-moisture insulation) - vent gap - finished floor.
    The insulation is mineral wool throughout.

39. Stanislav 08/15/2016

    Hello. Such situation. A house made of 150mm 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 the installation of metal siding immediately began on the membrane. That is, the gap between the insulation and the membrane was 27mm. The builders assured that there was nothing wrong with this and they had been building like this for 15 years and nothing. Tell me, can this be correct and if not, then isn’t their mistake in the gap between the insulation and the membrane critical?

40. Willow 08/23/2016

    hello, please tell me 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 add some decor, Thank you in advance for your answer.

41. Alexander 08/30/2016

    Alexander, I combined the loggia with the room. I insulated the walls and floor with penoplex (comfort), foamed everything. On the floor there are logs, penoplex, subfloor (small cracks were foamed) OSB board. The walls are gypsum.
    What's even better to do? I’m thinking of making foil polystyrene on top of the penoplex. The ceiling is cork and suspended ceiling. Or which is correct?

42. Marina 09/21/2016

    Hello, Alexander.
    We have a block house. In winter the wall freezes. We want to insulate the house and cover it with siding. We wanted to buy penoplex, but we were told that they only insulate the base. How true is this?
    Tell me what is the best way to insulate and in what order?
    Thank you!

43. Vladimir 09/26/2016

    Hello, Alexander. I live in an apartment in a panel house. In the room, one wall (5 m long) faces an unheated forest landing (in winter the temperature is not lower than +5). The wall is only about 100 mm thick, so I would like to insulate it. It is necessary to insulate from the inside. If I attach 50*50 wooden blocks to the wall, lay 50 mm foam plastic between them, and attach drywall on top? Is a vapor barrier necessary?

44. Olga 09/29/2016

    Hello, Alexander! The window openings were filled with 150mm aerated concrete
    We plan to line the interior with gypsum plasterboard sheets with 50 mm mineral wool insulation.
    How to do everything correctly so that it is warm.. heating electric convectors

45. Olga 10/17/2016

    Good afternoon, Alexander.
    Please tell me what is best for us 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 the smooth side facing the insulation. Everything seemed to be done correctly, but then we 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 install the vapor barrier completely hermetically and the vapors from interior space got caught in the insulation?

    • Alexander Kulikov 17.10.2016

      Hello Olga. There may be several reasons - at least two. Firstly, this may occur due to insufficient good insulation- this may be a banal condensate that forms as a result of a small draft. Somewhere the cotton wool was not inserted well enough or it was compressed too much. Secondly, the effect can be created due to the waterproofing membrane - it may not allow moisture to pass out if it is laid in the wrong direction or if a common film was used as it. Well, as for the insufficiently tight installation of the vapor barrier, this is not the reason - it’s another matter if you laid it on the wrong side. But you did it right? Read the features of your vapor barrier and compare - it should remove moisture into the insulation and evaporate out through the waterproofing membrane. Therefore, if it gets to the insulation and collects there, it is logical to assume that it does not come out. Alternatively, there may be no ventilation gap between roofing material and waterproofing film.

      • Olga 10/18/2016

        Alexander, we looked again at the vapor barrier instructions. It says smooth side to the insulation. Most likely this is not the problem. I am now concerned about the waterproofing issue. 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 allow moisture to pass out? And is it reflected and falls through the insulation onto the vapor barrier? What do we do? Disassemble all the walls and ceiling and replace the waterproofing with a membrane?

46. Alexander 10/31/2016

    Hello, Alexander. I read all the comments and did not find an answer to my question. There is a 2-storey panel house, which we want to insulate with mineral wool, 2 layers of 50mm each. Is it necessary to do a vapor barrier on the walls? Concrete panels, I think, do not allow a lot of steam to pass through, but the joints concrete panels they can. Is it necessary to leave the vent. gap between the wall and the insulation? Or how to properly insulate such a house?

47. Alexandro 11/02/2016

    Good afternoon We finish the panel house with facade panels with 2 layers of insulation. The panels are concrete, covered with stone chips. I would like to clarify the siding installation technology. The wall, then the vapor barrier (should it fit closely to the wall? Is it better to remove crumbs from the walls so that they are even? Or not use a vapor barrier film?), then 2 layers of insulation, then windproof membrane, air gap and siding?

48. 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) - 100mm gypsum plasterboard mineral wool. Moisture accumulated on the vapor barrier. We decided to redo the walls. Now we are building the wall like this: brick - vapor barrier B (the old one was not removed but dried) - frame with 30mm profiles - 10mm DSP board (for the air gap) - 100mm mineral wool - vapor barrier type B isospan (rough side towards the insulation) - 12mm GVL. I ask you to indicate whether there are any mistakes in the insulation of the wall, we are very afraid to make a mistake again.

49. Oleg 05.11.2016

    Alexander, thanks for the answer. I will take note of the need for a gap between the vapor barrier “B” and the gypsum plasterboard.
    I answer your question about the air gap - the air gap is 30 mm between brick wall and the “false wall made of DSP insulation - GVL” was made so that the cold from the frozen wall would not be transferred to the “false wall with insulation.” The air gap should, as it were, separate the frozen wall from the “false wall.” Please explain how the air gap works in your opinion. Joints between DSP slabs sealed with foam during installation.

50. Igor 12/12/2016

    Hello, Alexander.

    Please tell me, I’m planning to insulate a small guest house with a bathhouse. Walls made of gas silicate.
    I would like to clarify the installation technology. Outside I plan to apply 100mm mineral wool to the wall with glue and secure it with umbrellas, then a windproof membrane, a 4cm ventilation gap and a blockhouse. The inside of 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 3-4cm sheathing and clapboard?

51. Tatiana 12/18/2016

    Alexander, help, please! Such a problem. Apartment on the 2nd floor of a 2-story residential building built in 1957. Problem with the bathroom. There was a redevelopment. Now the bathroom is combined, and there is a homemade shower “cabin” (curtain). The walls began to rot. 10 years ago, the ori were covered on the inside with ordinary household oilcloth. One of the walls is definitely made of plasterboard (I didn’t do it, so I don’t know the details). Today I tore off the self-adhesive film from the corridor side - the wall is completely rotten, it turns out. 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 as not to break through the neighbors’ ceiling - shingle walls)?
    2. How to cover the walls (material)? I looked at the waterproofing. How to attach it to such walls without reducing the internal space?
    3. How can you decorate the walls later? Again with film? The tiles will not fit on flimsy walls and will slide off. Should I put plastic in sheets? The lining will simply let moisture through to the wall again.
    4. Is it necessary to do ventilation for such walls? Bathroom area maximum 3 sq.m. We still have a washing machine.

52. Alexander 01/08/2017

    Good day. Available brick house The thickness of the walls is 38-40 cm, plastered from the inside, in a year or two we are going to insulate it with cotton wool. This year we want to line the inside with clapboard. Do we need to use films and what type? 20 mm block + 15 mm lining. Ventilation is poor. The windows are leaking all the time.

Vapor barrier when insulating with foam plastic is necessary, but only in some cases. In this article we'll take a closer look at why.

Why is it necessary to do a vapor barrier?

What is dangerous is not so much the steam itself, but the condensation, which also causes the insulation to become wet. Moist air, passing the dew point (the temperature at which moist air begins to turn into dew), condenses and penetrates the insulation and over time, mold and mildew develop in it. Protection against steam is especially important in winter, when the difference in temperature in the house and outside reaches its maximum value.

In what cases is vapor barrier necessary?

Reasons for installing a vapor barrier

1. Prevent the formation of mold and mildew in the insulating “pie”.
2. Prevent the wall from freezing. When steam penetrates under the insulation, it begins to slowly reach the entire structure.

Vapor barrier films

Special vapor barrier films protect building envelopes from the harmful effects of steam and condensate. The film can be used to protect ceilings, walls, floors, roofs (both flat and pitched). They are compatible with all types of insulation: foam plastic, expanded polystyrene, basalt wool, etc.

When a vapor barrier is not needed

• If the walls are “breathable”.
• If the walls were insulated on the street side.
• In a cold roof, only waterproofing needs to be done.

1 Features and purpose

• Penoplex.

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• Balconies and loggias;
• Walls inside;
• Walls outside;
• Ceilings and roofing.

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2.2 Vapor barrier of walls from the inside

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2.3 Vapor barrier of external walls

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A little theory

Diagram of heat loss in a house.

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We insulate the walls from the inside

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We insulate the wall from the outside

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We insulate the roof of the house

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We insulate the floor of the house

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• foam insulation;
• vapor barrier;
• waterproofing;
• hammer;

1. Insulation of walls inside the house.
2. Insulation of the roof of the house.
3. Insulation of floors.

Vapor barrier films

When a vapor barrier is not needed

• If the walls are “breathable”.

Do you need a vapor barrier for polystyrene foam? This question can only be answered unambiguously if you know exactly what kind of building you are dealing with.

When laying any type of insulation, the question arises about the need for a vapor barrier.

The fact is that walls made of different materials have varying degrees of vapor permeability.

A little theory

We all know that during the cold season, a large number of warm air, which, according to the laws of physics, rushes out and penetrates the walls. In the language of physicists, this process can be called diffusion. If warm air masses are not able to pass through the barrier, then condensation will form. And then saying in simple language, the wall begins to get wet, and this is fraught with the appearance of mold and subsequent destruction of the wall.

Diagram of heat loss in a house.

There are a huge number of materials for building houses, and each of them has its own diffusion coefficient. For example, wood, red brick or plaster have excellent diffusion properties. That is, warm air masses passing through a brick or wooden wall, they cool evenly and do not form condensation. But cast concrete or panel walls diffusion is very difficult, and it is often in such houses that the walls are susceptible to getting wet. That is why you should be aware of what material the house is built from. Then you will understand. Do you need a vapor barrier for your building?

So, is a vapor barrier necessary if the walls are insulated with foam plastic? Needed. But not in all cases. If you are dealing with “breathing” walls, then a vapor barrier is not needed, since the walls will ventilate on their own. But if the material from which the house is built has a sufficiently high diffusion resistance, then to avoid condensation it is necessary to take care of the vapor barrier.

It should also be noted that polystyrene foam is universal insulation and the scope of its application is quite wide. Today, polystyrene foam can be used to insulate the walls of a house both outside and inside.

Polystyrene foam is excellent and inexpensive insulation for the floor, ceiling and even the roof of the house.

In general, this material is truly unique of its kind. However, in order for the effect of the insulation to be obvious, certain points must be observed in each specific case.

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When is a vapor barrier needed for polystyrene foam?

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We insulate the walls from the inside

Scheme of insulating walls with foam plastic from the inside.

If you decide to insulate the walls with foam plastic from the inside of the house or you do not have the opportunity to carry out external wall insulation work, then you should know that in this case you will need to take care of arranging a high-quality and well-functioning vapor barrier. If this requirement is met, warm air masses, or, in other words, steam, simply will not reach the walls, and then the risk that the walls and finishes will become wet will be minimal. An additional advantage in this case will be good ventilation of the room and the building as a whole. In this case, air masses will constantly circulate in the room, uniformly heating the entire area.

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We insulate the wall from the outside

Scheme of insulating walls with foam plastic from the outside.

The outside walls of the house are usually insulated if the building is private. As in the previous case, you must clearly know the material of the walls. If it is concrete, then you can safely glue foam sheets to the wall, having first plastered it. IN in this case vapor barrier layers will not play a big and decisive role, since the foam itself has great resistance to the passage of steam. However, outdoors the risk of condensation on the walls is minimal, which is why there is no need for an additional layer of vapor barrier. But if you are dealing with “breathing” walls of a house made of other materials, insulating the wall with foam plastic in this case requires a completely different technology. A gap is left between the wall and the insulation, which acts as a kind of ventilation system. Here, the resulting moisture from condensation will be able to flow down the inner walls and will not accumulate between the walls and the insulation, thus causing their destruction and reducing the thermal insulation properties.

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We insulate the roof of the house

Scheme of roof insulation with foam plastic.

You can even insulate the roof of a house with polystyrene foam. And here you will definitely need to use not only vapor barrier, but also waterproofing. After all, it is the roof that bears the main load in the form of seasonal precipitation. You will need to build a kind of “pie”: waterproofing, polystyrene foam, vapor barrier. Moreover, the waterproofing layer will have to be located on top of the insulation, and the vapor barrier - below. In this case, moisture seeping through the roofing will be prevented by the waterproofing, and the appearance of condensation from rising warm air will be prevented by the vapor barrier layer.

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We insulate the floor of the house

Scheme of floor insulation with foam plastic: 1. Floor slab. 2. Leveling plaster layer. 3. Foam plastic. 4. Waterproofing layer. 5. Cement-sand screed. 6. Finishing floor covering.

Most often, floors are insulated as follows: special wooden logs are installed on the rough surface in increments of approximately 50 cm. Next, foam plastic is placed in the resulting voids, which is pre-cut into blanks the right size. If small gaps or voids remain during the installation of polystyrene foam, they must be thoroughly foamed with polyurethane foam. In this case, the vapor barrier layer must be placed directly on the wooden joists, and the foam plastic must be laid after. There is another method that does not involve installation wooden logs. In this case, a layer of vapor and waterproofing is applied to the cleaned surface, then polystyrene foam is placed, and on top of it, sheets of plywood can be mounted, on which they have already been laid finishing coat(linoleum, laminate or carpet).

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How to insulate with foam plastic and what tools and materials are needed for this?

In order for the thermal insulation work to be successful, you will need the following materials and tools:

Tools and materials for insulating walls with foam plastic.

• foam insulation;
• glue with which you will fix the insulation (excellent for these purposes) regular one will do polyurethane foam, which will not only reliably fix the foam to the surface, but also, thanks to its properties, will foam all joints and gaps);
• vapor barrier;
• waterproofing;
• construction knife or saw with fine teeth;
• for greater reliability, you can fix the foam sheets with special “umbrellas” - long nails with a wide head;
• hammer;
• wooden blocks (if insulation is planned on the joists);
• putty, spatula and reinforcing mesh (if you plan to plaster the walls after thermal insulation).

The stages of foam insulation work in each specific case have their own specifics. You could see this above, but the main part of the work is similar and consists of the following steps:

1. We clean the work surface from dust, debris and dirt. If necessary, it is restored and leveled.
2. Depending on where the thermal insulation is carried out, a layer of vapor barrier and waterproofing is applied.
3. Next, the foam sheets are installed. Fastening is carried out through the use of special glue for foam boards or polyurethane foam. According to the rules, insulation sheets must be installed in a checkerboard pattern. The insulation is also additionally fixed with disc-shaped dowels or, in other words, “umbrellas”. They are placed as follows: one in the center of the sheet, and one more in the corners.
4. Again, if you are insulating the walls from the inside of the house, you need to lay a layer of vapor barrier at this stage of work. And skip the second point, while the insulation sheets should fit tightly to the wall.
5. Finishing. This can be absolutely any material: siding, plaster, drywall, etc.

So, now you know exactly whether a vapor barrier is needed in each specific case and how it is installed. In fact, by insulating your home with polystyrene foam, you can achieve significant results. The main thing is to strictly follow the rules for thermal insulation of the house, and then you will be able to reduce heating costs significantly.

Frame house construction is sufficient promising direction in the construction of private houses. They do not require powerful foundations and are easy to install. During construction frame house it will require much less financial investment than when constructing a brick building. To ensure that savings do not end at the construction stage, it is necessary to think in advance about ways to preserve heat indoors. One option would be to insulate a private frame house with polystyrene foam.

What is expanded polystyrene

Expanded polystyrene is a foam material of artificial origin. There are two types of polystyrene foam for do-it-yourself insulation of walls and other building structures:

1. Styrofoam;
2. extruded polystyrene foam.

The most affordable option for thermal insulation is polystyrene foam. It consists of small balls with a cavity filled with air inside. Air is one of the most effective insulation materials, only inert gases prevent heat loss better. Do-it-yourself insulation with expanded polystyrene allows you to achieve excellent results thanks to the following material characteristics:

• availability and low cost;
• high thermal insulation characteristics;
• resistance to biological effects (mold, fungus);
• ease of working with the material and installing it yourself;
• the material does not shrink over time;
• safety for humans.

• low strength (additional protection of the foam from mechanical stress is required);
• instability of the material to high humidity at low temperatures, can easily crumble into individual balls;
• instability to fire.

All these shortcomings are compensated by the low price of the material, but it is possible to take them into account and reduce the negative manifestations to zero.

Wall insulation

Insulation scheme with curtain façade: 1 - interior decoration; 2 - vapor barrier; 3 - frame stand; 4 - expanded polystyrene; 5 - siding; 6 - vapor-permeable moisture-proof membrane.

Insulation of a frame house with polystyrene foam in this case is carried out between the frame posts. After that, sheathing is done on both sides. Work is carried out in the following order:

1. frame processing: cleaning from dirt and dust, eliminating unevenness, removing unnecessary sharp objects;
2. laying a waterproofing layer on the outside of the walls;
3. laying insulation;
4. laying a vapor barrier layer;
5. wall covering.

When using polystyrene foam, there is no need to install a ventilated façade, unlike the equally popular mineral wool.

Option with using OSB as water and wind protection

Waterproofing is installed to protect the wall material from moisture penetration from the outside. When building a house with your own hands, you can use the following as a waterproofing layer:

• plastic film;
• modern moisture-proof, vapor-permeable membranes;
• OSB-3.

The waterproofing material is laid with an overlap of 10 cm, the joints are sealed with a special tape. Manufacturers present polystyrene foam as a material that has a low degree of water absorption, but it must be remembered that in winter it can collapse if exposed to moisture.

To prevent this unpleasant phenomenon, it is necessary to provide waterproofing of the walls.

Additional foam insulation on the outside

It is important to remember that waterproofing is always located on the cold air side (when insulating walls from the outside), and vapor barrier on the warm air side. Polyethylene film can be used as a vapor barrier for walls.

Insulation of floors

There are several options for using polystyrene foam:

• insulation of floors above a cold basement or technical underground;
• insulation attic floors in the presence of a cold attic;
• promotion soundproofing characteristics interfloor ceilings.

In the case of a frame house, the material is laid between the joists. When using extruded polystyrene foam, insulation under a reinforced cement-sand screed is possible.

When insulating floors with your own hands using polystyrene foam, it is important to correctly observe the order of layers. In the floor structure of the first floor, waterproofing is first laid, followed by foam plastic, and vapor barrier on top. For interfloor and attic floors, the vapor barrier and waterproofing layers must be swapped.

Attic floor insulation scheme

As a compromise between price and quality, you can use polystyrene foam insulation in the following form: a main layer of foam is laid inside the floor pie, and a layer of extruded polystyrene foam of small thickness is laid on the outside. This will increase the strength of the insulation layer without large financial costs.

Insulation of attic roof

The order of layers when insulating the attic

When building a private house, the option of using the under-roof space as an attic is becoming increasingly popular. In this case, it is necessary to provide comfortable living conditions and reliably protect the room from the cold. The main heat losses occur through the roof, so sufficient attention should be paid to its insulation.

In the vast majority of cases, polystyrene foam is placed between the rafters. Fastening is carried out using adhesives and special nails to the rafter legs. The bottom sheathing acts as additional reinforcement.

The thickness of insulation in the main territory of the country will be in the range of 150-200 mm. It is important to remember that the height rafter legs cannot be taken less than the thickness of the insulation layer. In the case of polystyrene foam, a ventilated air layer is not necessary. To protect structures and foam from negative internal and external influences The following materials are used:

• vapor barrier;
• waterproofing;
• wind protection

As the second and third layers, modern moisture-windproof membranes can be used, which are mounted outside the heat-protective material.

Installation technology

Sealing joints with polyurethane foam

The main difficulty when working with polystyrene foam is maintaining the exact spacing between the slabs of the material. Expanded polystyrene is subject to thermal expansion; it is to compensate for this that it is necessary to provide small gaps. The joints of the plates are glued with a special adhesive tape, it can also be foil tape.

Fastening to the surface from the outside and inside can be done using adhesives or dowels. The latter provides reliable connection, but violates the integrity of the layer. When using expanded polystyrene adhesive composition Several requirements apply, but one of them is the most important: the glue must not contain chemically aggressive components. The taboo applies to:

• acetone and other solvents;
• petrol;
• kerosene;
• formaldehyde;
• formalin;
• toluene;
• benzene;
• aggressive resins.

Insulating a frame house using polystyrene foam is a simple but effective measure that does not require large financial costs. With its help, without special training, you can insulate walls and other structures. The long service life of the material will allow you to forget about the problem of heat loss for a long time and significantly save on heating a private home.

Insulation with penoplex or expanded polystyrene has acquired very serious proportions in our time. Indeed, the use of these materials leads to a significant reduction in construction costs.

However, when working with polystyrene foam or penoplex, you need to know some nuances. For example, about installing a vapor barrier. The question of whether additional vapor barrier is needed for polystyrene foam insulation is one of the most frequently asked questions on construction forums.

Insulated with penoplex interior wall, rarely needs vapor barrier

In this article we will try to give you a detailed and detailed answer. By the way, we recommend buying polystyrene foam in Ufa.

1 Features and purpose

First, let's look at all the basic information. Expanded polystyrene materials began to be produced not so long ago. But their invention created a real boom in the construction industry.

Lightweight, cheap and reliable, expanded polystyrene has become very popular around the world. After all, with its help it is possible to take care of the insulation of buildings without resorting to expensive analogues.

Two types of insulation are produced from this material:

• Directly foam of the usual type;
• Penoplex.

Ordinary polystyrene foam is a type of expanded polystyrene. It consists of small balloons that are glued together. Polystyrene foam is quite convenient to use, but it is a fragile material, practically vapor-proof and, very importantly, has a flammability rating.

Yes, indeed, polystyrene foam burns in fire. And it burns quite intensely. Exceptions include processed materials. But it was not possible to completely get rid of this problem. If the foam burns and maintains combustion on its own, then the treated samples simply melt without dying out.

Penoplex is a type of polystyrene foam. To be more precise, penoplex is a type of extruded polystyrene foam.

The polystyrene foam is melted under high pressure. They call it, as you might have guessed, extrusion. The result is a material that is quite interesting in its structure.

Structure of extruded polystyrene foam, close up

It consists of melted balls like M45 penoplex, which are monolithically interlocked and mixed, forming a single slab with air bubbles with a diameter of up to 1 mm.

Penoplex is characterized by increased strength, especially when compared with polystyrene foam. It either does not burn in a fire or only melts slowly.

Note that both materials practically do not allow moisture and steam to pass through. This leads to a logical question: is a vapor barrier necessary? After all, if the material does not allow steam to pass through anyway, is it worth spending money on additional protection? Let’s answer – it’s worth it, but not always.

To understand this point, let us turn to the features of vapor barrier as such. And let's figure out why it is needed at all. Vapor barrier is a special material that is used to prevent moisture and hot steam from penetrating into structures.

As a rule, a vapor barrier is installed inside the house and is installed where it is necessary to protect against excess moisture. The vapor barrier is made from a special membrane film. It is laid on top of structures, under screeds or in any other suitable places.

Vapor barrier allows you to protect structures from moisture penetration into them. And it is very destructive for them. The process of moisture penetration occurs naturally. The temperature indoors is higher most of the time than outside.

As a result, steam is constantly generated in it, albeit in small quantities, as in penoplex for insulating the foundation, part of which will come out through the supporting structures. It will escape through any cracks, because steam has an extremely low density. If this process is not prevented, the steam will accumulate in the walls or ceiling, where it will settle as moisture.

Moisture in walls, especially brick or concrete, is a real problem. Through certain time they will begin to slowly collapse. An unpleasant musty odor may appear in the room, and dampness will emanate from the affected structure. The apotheosis of all these processes will be the appearance of fungus or mold.

And at this stage you have already formed big problems, since it is very difficult to fight fungus or mold. This is a long and expensive process. And it is far from a fact that it will end in complete success.

Sealing the joints of the vapor barrier film with aluminum tape

The main nuance in using vapor barrier and penoplex is that both materials are considered vapor-tight. But penoplex, of course, may not seem to have the same high parameters as a vapor barrier film. Yes and completely monolithic structure you can't make it out of it.

All the same, the M35 penoplex may come apart somewhere, lie loosely at the joints with adjacent slabs, etc. Even a millimeter gap will be enough. However, it all depends on the specific situation.
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2 The need to install a vapor barrier depending on the situation

So, we have already figured out that even with penoplex insulation, a vapor barrier is needed. But not always. Now let's look at this issue in more detail.

To begin with, let's highlight the most basic insulation procedures where penoplex or polystyrene foam is used. They all differ largely in the type of insulated structure. Most often insulated:

• Balconies and loggias;
• Walls inside;
• Walls outside;
• Screed on the floor using glue for extruded polystyrene foam;
• Ceilings and roofing.

Let's analyze each situation separately.
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2.1 Vapor barrier of balconies and loggias

Penoplex is most often used for balconies and loggias. This is due to the fact that this material has very low weight and high strength. Even for a hollow balcony, a slab up to 7-8 cm thick should be sufficient.

As for the use of vapor barrier, here it is really needed. A fitted penoplex will, of course, eliminate most of the openings, but it is simply impossible to fit it perfectly. At the same time, steam and condensation most often form on balconies. After all, they are in contact with the street throughout their entire area.

Loggia protected by an additional layer of vapor barrier

And the area of ​​window glass (namely, they most often have a lower temperature) on the balcony and loggia is much larger.

Therefore, a vapor barrier on the balcony is needed. Moreover, it is recommended to use not even ordinary membranes, but foil-clad polyethylene with a foam base.

The base will further stabilize all processes and will not allow steam to pass through, and the foil will be able to repel heat waves into the room.

Thus, you will completely get rid of the problem of steam penetration, condensation and excessive waste of thermal resources. In addition, you don’t have to spend a lot of money on a vapor barrier for a balcony. Still, the area that needs processing here is quite limited. And penoplex will make its own positive changes.
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2.2 Vapor barrier of walls from the inside

The inner part of the walls, insulated with penoplex on façade panels with insulation, also needs vapor barrier. But only if you did not insulate the walls outside. In this case, the “dew point” in the structures shifts, which is responsible for the formation of condensation.

The presence of high-quality vapor barrier will allow you to get rid of these problems and significantly extend the life of load-bearing structures.

Let us note in advance that the material of the walls plays a big role here. So, concrete and brick walls need vapor barrier, since penoplex will not provide them with sufficient protection. And concrete and brick are too exposed to condensed moisture.

An example of using foil vapor barrier to protect internal walls

While wooden walls and other breathable structures do not always require the installation of a vapor barrier film. The degree of insulation provided by properly installed penoplex is enough for them.
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2.3 Vapor barrier of external walls

If internal protection While steam walls are needed in some cases, external protection is extremely rarely needed. In the vast majority of cases, the level of protection provided by penoplex will be sufficient.

This is because almost no steam is formed outside, and if it does appear, it does not penetrate deep into the load-bearing structures.

The only exception is the finishing of baths. As you yourself understand, steam is constantly generated in the bathhouse, and here we have to resort to extreme measures. If this is not done, the building will quickly fall into disrepair.
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2.4 Vapor barrier of the floor (screeds)

The situation with floors is ambiguous and depends on environmental conditions. So, a screed on a balcony or loggia should be protected with a vapor barrier, but special conditions arise there.

Interfloor ceilings do not need to be protected from the floor side. Several factors have an influence here.

Firstly, the technology of installing foam plastic on the floor itself makes it possible to fit and insulate it well. Secondly, the screed in mandatory waterproof, and the waterproofing layer also helps protect against steam.

Yes, and you should understand that the load on the floors is very small, since according to the laws of physics, warm air and steam always tends upward. Below, it does not linger, being replaced by colder air.

Ceiling insulated with polystyrene foam boards

Again, all exceptions are the finishing of floors above a bathtub, bathhouse, etc. Here the amount of steam can reach critical levels and even pass through concrete interfloor ceilings. Therefore, penoplex alone will not cope. You will have to lay a vapor barrier, and then mount all the structures that are located above.
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2.5 Vapor barrier of ceilings and roofs

But in this case, a vapor barrier is definitely needed. Moreover, the need for it is dictated by the very laws of nature. Steam always strives upward and looks for ways to pass through all structures that impede it.

No penoplex, even perfectly installed, can completely block its passage. All the same, there will be gaps somewhere, but nothing more is required.

Moreover, here the vapor barrier is installed first. It is she who must take the first blow. Then there will be a layer of insulation, and then the floor slab itself.

In cases with a roof, you will also need to install waterproofing. But waterproofing is installed on the inside of the slopes, and vapor barrier on the outside.
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2.6 The vapor barrier was not installed correctly (video)

Vapor barrier when insulating with foam plastic is necessary, but only in some cases. In this article we'll take a closer look at why.

Why is it necessary to do a vapor barrier?

What is dangerous is not so much the steam itself, but the condensation, which also causes the insulation to become wet. Moist air, passing the dew point (the temperature at which moist air begins to turn into dew), condenses and penetrates the insulation and over time, mold and mildew develop in it. Protection against steam is especially important in winter, when the difference in temperature in the house and outside reaches its maximum value.

In what cases is vapor barrier necessary?

1. Insulation of walls inside the house. When the walls are insulated inside the house, the vapor barrier layer is attached on top of the insulation, and the waterproofing is placed in front of the insulation, protecting it from moisture from the street.
2. Insulation of the roof of the house. If you insulate the roof of a house, you will also need vapor and waterproofing. Since the roof takes the brunt of seasonal precipitation. The “pie” will be similar: a vapor barrier protects the insulation inside from negative impact steam, waterproofing - from water drops.
3. Insulation of floors. Floors are usually insulated in this way: wooden logs are installed in half-meter increments, and cut insulation is placed in the gaps. If there are gaps, they are filled with foam. The vapor barrier is placed directly on the logs themselves, and then the foam.

   Another way is to have no lag. A vapor-waterproofing layer is mounted on the cleaned surface, then foam plastic, on which sheets of plywood are mounted. Next, apply the finishing coating (laminate, parquet or carpet).

Reasons for installing a vapor barrier

1. Prevent the formation of mold and mildew in the insulating “pie”.
2. Prevent the wall from freezing. When steam penetrates under the insulation, it begins to slowly reach the entire structure.

Vapor barrier films

Special vapor barrier films protect enclosing structures from the harmful effects of steam and condensate. The film can be used to protect ceilings, walls, floors, roofs (both flat and pitched). They are compatible with all types of insulation: foam plastic, expanded polystyrene, basalt wool, etc.

When a vapor barrier is not needed

• If the walls are “breathable”.
• If the walls were insulated on the street side.
• In a cold roof, only waterproofing needs to be done.

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