Let's look at a few typical mistakes, which are allowed when insulating buildings by private developers. What needs to be done to ensure that the insulation of a house is reliable, durable, and meets heat conservation standards?
Now in private housing construction, three-layer walls are especially popular, in which the inner and outer (facade) walls are laid out of brick or similar small-piece material, and between them there is a layer of insulation. In this case the same error is repeated.
Poor quality insulation
The fact is that the insulation in a three-layer wall is difficult to replace without destroying... the entire wall. Including inner layer, because it contains connections with the outer layer, and in order to restore them after the destruction of the outer layer...
In general, if the insulation layer becomes unusable, the owners will simply be left with cold walls and the prospect of expensive repairs.
When constructing expensive, durable three-layer brick walls Usually everyone wants to use the cheapest foam plastic as a heat insulator. But this material is not durable, over time it tends to crumble into individual granules, and they lose their integrity and voids appear. In addition, mice eat polystyrene foam and are happy to live in it - after all, it’s warm there.
If the foam is not completely covered with a durable plaster layer, as in the “ Wet facade", then rodents will get to it, and this is a common occurrence with three-layer walls, then the foam insulation will be damaged within a season.
But that's not so bad. Polystyrene foam (expanded polystyrene foam) can become moistened and, as a result, quickly deteriorate, mold and mildew grow on it, the walls become moistened, and their thermal insulation properties are significantly lost.
This can happen if the material is simply sandwiched between two bricks, which is often the case. In this case, the vapor permeability of different layers of the wall becomes close (the vapor permeability coefficient of foam is 0.05 mg/(m h Pa)), or the outer layer of dense clinker brick is more resistant to steam movement than the inner layers. Moisture will accumulate inside the wall in cold weather with the ensuing consequences....
So how to control the movement of steam?
At odds with the movement of steam
If the movement of steam is not controlled correctly, then any insulated structure consisting of two or more layers will become wet, will collapse, and heat loss will increase significantly. If you use expensive dense mineral wool in a three-layer wall in the same way as polystyrene foam in the previous example, the consequences will be even worse (wetter), because wool accumulates water much better.
And the exit is correct use insulation in a three-layer structure. There it is preferable to use dense (from 60 kg/m3) mineral wool that does not lose its shape over time, durable, like the brick itself, which rodents and other living creatures “hate”.
But it must be constantly ventilated in the same way as a ventilated façade system, for which a vent is left in place. gap and holes are made in the outer layer. The cotton wool is either covered with a windproof membrane, or denser samples are used - 80 - 180 kg m3. having their own high resistance to air movement.
You can also use extruded polystyrene foam, and the thickness of the wall will be reduced, since a vent is not needed. the gap and thickness of the insulation will be 25 percent less. But the guarantee against rodent access inside the wall must be ironclad. 
Those. The sand-cement-concrete cladding must cover the internal insulation on all sides and be especially reliable. And extruded polystyrene foam is always at peace with steam, since it simply does not let it through and does not accumulate water. As a result, the layers are separated by steam, the wall is dry and does not breathe.
Sprayed polyurethane foam is close to these properties, but only the most high density. So you can blow into the wall... But the option with a ventilated “eternal” mineral wool still looks preferable.
Foam plastic is a favorite insulation
Another inconsistency with steam is the coating of lightweight porous materials with foam. Then the rule is simply broken - the more vapor-permeable layer should be on the outside.
They usually try to insulate two popular surfaces with polystyrene foam - wooden walls and foam concrete blocks. In any case, the layer that is more difficult for steam to move does its job - the load-bearing layers become wet, become unusable, and the wood quickly deteriorates at the point of contact with synthetics. Of course, it is possible and necessary to use polystyrene foam, but only where it belongs.
We neglect the superdiffusion membrane - it’s expensive
Instead of a superdiffusion membrane (vapor permeable from 1700 g/m sq. day) of the required quality (sometimes particularly heat-resistant is required), some developers try to cover the mineral wool in the roof or on the wall with a perforated film, or even just a piece of polyethylene, without delving into the essence of the issue. As a result, steam does not escape from the insulation layer, the insulation gets wet along with the structure and everything collapses.
It is worth noting that according to the latest research, hydrophobized mineral wool with a density of 80 kg/m3 for a wind zone up to 5 and 180 kg/m3 for any wind zone can be used in the system curtain façade and in roofs without a membrane, since their own air permeability is very low.
Those. air actually does not flow through such insulation and there is no convection removal of heat from the insulation layer. Of course there must be a tight fit mineral wool slabs to structures and the absence of gaps between them.
But it is worth considering that the membrane on the roof and on the wall is sometimes also provided for by the project as additional protection from water leaks, then there’s no way without it.
It's the other way around
Finally, there is a case where things can’t get any worse – the insulation is attached to the enclosing structures from the inside of the building. Because it seems like it’s faster and cheaper. Insulation from the inside is an extreme case and a necessary measure. In principle, it can be done, but only according to certain rules and it still incurs a lot of costs.
So let's insulate according to the rules - from the outside, with insulation provided by the design, of the required thickness, with ventilation if necessary, and with required quality materials used.
| 7 years ago | tanya (Builderclub expert) First, I’ll describe the principle of operation. properly made insulated roof, after which it will be easier to understand the reasons for the appearance of condensation on the vapor barrier - pos. 8. If you look at the picture above - “Insulated roof with slate”, then vapor barrier placed under the insulation in order to retain water vapor from inside the room, and thereby protect the insulation from getting wet. For complete tightness, the joints of the vapor barrier are glued vapor barrier tape. As a result, vapors accumulate under the vapor barrier. To ensure that they erode and do not soak the internal lining (for example, gypsum board), a gap of 4 cm is left between the vapor barrier and the internal lining. The gap is ensured by laying the sheathing. The insulation on top is protected from getting wet waterproofing material. If the vapor barrier under the insulation is laid according to all the rules and is perfectly sealed, then there will be no vapors in the insulation itself and, accordingly, under the waterproofing too. But in case the vapor barrier is suddenly damaged during installation or during operation of the roof, a ventilation gap is created between the waterproofing and insulation. Because even the slightest, invisible damage to the vapor barrier allows water vapor to penetrate into the insulation. Passing through the insulation, vapors accumulate on the inner surface of the waterproofing film. Therefore, if the insulation is laid close to the waterproofing film, it will get wet from the water vapor accumulated under the waterproofing. To prevent this wetting of the insulation, as well as for the vapors to erode, there must be a ventilation gap of 2-4 cm between the waterproofing and the insulation. Now let's look at the structure of your roof. Before you laid insulation 9, as well as vapor barrier 11 and gypsum board 12, water vapor accumulated under vapor barrier 8, there was free access of air from below and they evaporated, so you did not notice them. Up to this point, you essentially had the correct roof design. As soon as you laid the additional insulation 9 close to the existing vapor barrier 8, the water vapor had nowhere else to go except to be absorbed into the insulation. Therefore, these vapors (condensation) became noticeable to you. A few days later, you laid vapor barrier 11 under this insulation and sewed up gypsum board 12. If you laid the lower vapor barrier 11 according to all the rules, namely with an overlap of at least 10 cm and taped all joints with vapor-proof tape, then water vapor will not penetrate into the roof structure and will not the insulation will be soaked. But before this lower vapor barrier 11 was laid, insulation 9 had to dry out. If it has not had time to dry, then there is a high probability of mold forming in the insulation 9. This also threatens the insulation 9 in the event of the slightest damage to the lower vapor barrier 11. Because the steam will have nowhere to go except to accumulate under the vapor barrier 8, soaking the insulation and promoting the formation of fungus in it. Therefore, in an amicable way, you need to completely remove the vapor barrier 8, and make a ventilation gap of 4 cm between the vapor barrier 11 and the gypsum board 12, otherwise the gypsum board will get wet and bloom over time. Now a few words about waterproofing. First, roofing felt is not intended for waterproofing pitched roofs; it is a bitumen-containing material and in extreme heat the bitumen will simply flow down to the roof overhang. In simple words- roofing felt will not last long pitched roof, it’s hard to even say how long, but I don’t think it’s more than 2 - 5 years. Second, the waterproofing (roofing felt) was not installed correctly. There must be a ventilation gap between it and the insulation, as described above. Considering that the air in the under-roof space moves from the overhang to the ridge, the ventilation gap is provided either by the fact that the rafters are higher than the layer of insulation laid between them (the rafters in your picture are just higher), or by laying counter-lattice along the rafters. Your waterproofing is laid on the sheathing (which, unlike the counter-lattice, lies across the rafters), so all the moisture that accumulates under the waterproofing will soak the sheathing and it will also not last long. Therefore, in an amicable way, the top of the roof also needs to be redone: replace the roofing felt with a waterproofing film, and lay it on the rafters (if they protrude at least 2 cm above the insulation) or on a counter-lattice laid along the rafters. Ask clarifying questions. answer |
To reduce the costs associated with heating your home, it is definitely worth investing in wall insulation. Before delving into the search for a team of façade designers, it is advisable to prepare properly. Here is a list of the most common mistakes that can be made when insulating a house.
Absence or poorly executed wall insulation project
The main task of the project is to determine the optimal thermal insulation material (mineral wool or polystyrene foam) and its thickness in accordance with building codes. Also, a pre-prepared house insulation project gives the customer the opportunity to clearly control the work performed by contractors, for example, the layout of insulation sheets and the number of fasteners on square meter, and workarounds window openings, as well as much more.
Carrying out work at temperatures below 5° or above 25°, or during precipitation
The consequence of this is that the glue between the insulation and the base dries too quickly, as a result of which the adhesion between the layers of the wall insulation system is not reliable.
Ignoring site preparation
The contractor must protect all windows from dirt by covering them with film. In addition, (especially when insulating large buildings) it is good if the scaffolding is covered with a mesh, which will protect the insulated facade from excessive sunlight and the wind, allowing finishing materials dry more evenly.
Insufficient surface preparation
The surface of the insulated wall must have sufficient bearing capacity and be smooth, level and free of dust to ensure good adhesion for the adhesive. Uneven plaster and any other defects must be corrected. It is unacceptable to leave mold, efflorescence, etc. residues on insulated walls. Of course, it is necessary to first eliminate the cause of their occurrence and remove them from the wall.
No starting bar
By installing the base profile, the level of the bottom layer of insulation is set. Also, this bar takes on part of the load from the weight of the heat-insulating material. And, in addition, such a strip helps protect the lower end of the insulation from the penetration of rodents
There should be a gap of about 2-3 mm between the slats.
Installation of slabs is not staggered.
A common problem is the appearance of gaps between slabs.
The insulation slabs must be installed carefully and tightly in a checkerboard pattern, that is, offset by half the length of the slab from bottom to top, starting from the corner wall.
Incorrect application of glue
It is incorrect when gluing is carried out only by applying “bloopers” and does not apply a layer of glue around the perimeter of the sheet. The consequence of such gluing may be the bending of the insulation boards or the marking of their outline on the final finishing of the insulated facade.
Options for correctly applying glue to foam:
- along the perimeter in the form of stripes with a width of 4-6 cm. On the remaining surface of the insulation - dotted “bloopers” (from 3 to 8 pieces). The total area of the adhesive should cover at least 40% of the foam sheet;
- applying glue to the entire surface with a ridge spatula - used only if the walls are pre-plastered.
Note: the adhesive solution is applied only to the surface of the thermal insulation, never to the base.
Gluing mineral wool requires preliminary puttying of the slab surface. Thin layer cement mortar rub into the surface of the mineral wool.
Insufficient fastening of thermal insulation to the load-bearing surface
This may be the result of careless application of adhesive, the use of materials with inappropriate parameters, or too weak mechanical fastening. Mechanical connections are all kinds of dowels and anchors. Do not skimp on the mechanical fastening of insulation, be it heavy mineral wool or lightweight foam.
The place of fastening with a dowel must coincide with the place where the glue (blooper) is applied on the inside of the insulation
The dowels must be properly embedded in the insulation. Pressing too deeply leads to damage to the insulation boards and the formation of a cold bridge. Too small and it will cause a bulge that will be visible on the façade.
Leaving thermal insulation unprotected from weather conditions.
Exposed mineral wool easily absorbs water, and polystyrene foam in the sun is subject to surface erosion, which can impair the adhesion of wall insulation layers. Thermal insulation materials must be protected from atmospheric influences, both when they are stored on a construction site and when they are used to insulate walls. Walls insulated with mineral wool must be protected by a roof to prevent them from getting wet by rain - because if this happens they will dry very slowly and wet insulation is not effective. Walls insulated with foam plastic cannot be exposed to prolonged exposure to direct sunlight. By long-term we mean more than 2-3 months.
Incorrect laying of insulation boards in the corners of openings
To insulate walls in the corners of window or door openings, the insulation must be cut appropriately so that the intersection of the slabs does not occur at the corners of the openings. This, of course, significantly increases the amount of waste thermal insulation material, but can significantly reduce the risk of cracks in the plaster in these places.
Not sanding the glued foam layer
This operation takes a long time and is quite labor intensive. For this reason, it is not popular among contractors. As a result, curvature may form on the facade.
Mistakes when laying fiberglass mesh
The reinforcing layer of wall insulation provides protection from mechanical damage. It is made from fiberglass mesh and reduces thermal deformation, increases strength and prevents the formation of cracks.
The mesh must be completely immersed in the adhesive layer. It is important that the mesh is glued without folds.
In places vulnerable to loads, an additional layer of reinforcement is performed - in all corners of window and door openings, mesh strips measuring at least 35x25 are glued at an angle of 45°. This prevents cracks from forming in the corners of openings.
To strengthen the corners of the house, corner profiles with mesh are used.
Not filling the seams between the insulation
The result is the formation of cold bridges. To fill gaps up to 4 mm wide, façade mounting foam is used.
Not using primer before coat decorative plaster
Some people mistakenly apply finishing decorative plaster directly to the mesh layer, abandoning the special (not cheap) primer. This leads to improper gluing of decorative plaster and the appearance of gaps gray from glue and the rough surface of the insulated facade. In addition, after a few years, such plaster cracks and falls off in pieces.
Mistakes when applying decorative plaster
Thin-film plasters can be performed after 3 days from the date of completion of the reinforcing layer.
The work must be organized so that the team works without interruptions on at least 2 or 3 levels of scaffolding. This prevents the appearance of uneven color on the facade due to its drying at different times.
In this article I will consider the issues of ventilation of the inter-wall space and the connection between this ventilation and insulation. In particular, I would like to understand why a ventilation gap is needed, how it differs from an air gap, what its functions are, and whether a gap in the wall can perform a thermal insulation function. This issue has become quite relevant lately and causes many misunderstandings and questions. Here I give my private expert opinion, based only on personal experience and on nothing else.
Denial of responsibility
Having already written the article and re-reading it again, I see that the processes occurring during the ventilation of the inter-wall space are much more complex and multifaceted than I described. But I decided to leave it like this, in a simplified version. Particularly meticulous citizens, please write comments. We will complicate the description as we work.
The essence of the problem (subject part)
Let's understand the subject matter and agree on terms, otherwise it may turn out that we are talking about one thing, but mean completely opposite things.
This is our main subject. The wall can be uniform, for example, brick, or wood, or foam concrete, or cast. But a wall can also consist of several layers. For example, the wall itself (brickwork), a layer of insulation-thermal insulator, a layer of external finishing.
Air gap
This is the wall layer. Most often it is technological. It turns out by itself, and without it it is either impossible to build our wall, or it is very difficult to do it. An example is an additional wall element such as a leveling frame.
Let's assume we have a newly built wooden house. We want to finish him off. First of all, we apply the rule and make sure that the wall is curved. Moreover, if you look at the house from a distance, you see a quite decent house, but when you apply the rule to the wall, it becomes clear that the wall is horribly crooked. Well... there's nothing you can do about it! WITH wooden houses that happens. We level the wall with a frame. As a result, a space filled with air is formed between the wall and the external decoration. Otherwise, without a frame, it will not be possible to make a decent exterior decoration of our house - the corners will “disintegrate.” As a result, we get an air gap.
Let's remember this important feature the term in question.
Ventilation gap
This is also a layer of the wall. It looks like an air gap, but it has a purpose. Specifically, it is designed for ventilation. In the context of this article, ventilation is a series of measures aimed at removing moisture from the wall and keeping it dry. Could this layer combine the technological properties of an air gap? Yes, maybe that’s what this article is being written about, in essence.
Physics of processes inside the wall Condensation
Why dry the wall? Is she getting wet or what? Yes, it gets wet. And you don't need to hose it down to get it wet. The temperature difference from the heat of the day to the coolness of the night is quite enough. The problem of getting the wall, all its layers, wet as a result of moisture condensation might be irrelevant in a frosty winter, but here the heating of our house comes into play. As a result of the fact that we heat our houses, warm air tends to leave the warm room and moisture condensation occurs again in the thickness of the wall. Thus, the relevance of drying the wall remains at any time of the year.
Convection
Please note that the site has a good article about the theory of condensation in walls
Warm air tends to rise and cold air tends to sink. And this is very unfortunate, since in our apartments and houses we live not on the ceiling, where warm air collects, but on the floor, where cold air collects. But I seem to have gotten distracted.
It is impossible to completely get rid of convection. And this is also very unfortunate.
But let's look at a very useful question. How does convection in a wide gap differ from the same convection in a narrow gap? We have already understood that the air in the gap moves in two directions. On a warm surface it moves up, and on a cold surface it goes down. And this is where I want to ask a question. What happens in the middle of our gap? And the answer to this question is quite complicated. I believe that the layer of air directly at the surface moves as quickly as possible. It pulls along layers of air that are nearby. As far as I understand, this happens due to friction. But the friction in the air is quite weak, so the movement of neighboring layers is much less fast than the “wall” ones. But there is still a place where the air moving up comes into contact with the air moving down. Apparently in this place, where multidirectional flows meet, something like turbulence occurs. The lower the flow speed, the weaker the turbulence. If the gap is wide enough, these swirls may be completely absent or completely invisible.
But what if our gap is 20 or 30 mm? Then the turbulence can be stronger. These vortices will not only mix the flows, but also slow down each other. It seems that if you make an air gap, you should strive to make it thinner. Then two differently directed convection flows will interfere with each other. And that's what we need.
Let's look at some funny examples. First example
Let us have a wall with an air gap. The gap is blank. The air in this gap has no connection with the air outside the gap. On one side of the wall it is warm, on the other it is cold. Ultimately, this means that the inner sides of our gap also differ in temperature in the same way. What happens in the gap? The air in the gap rises along the warm surface. When it's cold it goes down. Since this is the same air, a cycle is formed. During this cycle, heat is actively transferred from one surface to another. And actively. This means that it is strong. Question. Does our air gap perform a useful function? Looks like no. It looks like it is actively cooling the walls for us. Is there anything useful in this air gap of ours? No. There doesn't seem to be anything useful in it. Basically and forever and ever.
Second example. 
Suppose we made holes at the top and bottom so that the air in the gap communicates with the outside world. What has changed for us? And the fact is that now there seems to be no cycle. Either it is there, but there is also air leaking and venting. Now the air is heated from the warm surface and, perhaps partially, flies out (warm), and cold air from the street takes its place from below. Is it good or bad? Is it very different from the first example? At first glance it gets even worse. The heat goes outside.
I will note the following. Yes, now we are heating the atmosphere, but in the first example we were heating the casing. How much worse is the first option? better than second? You know, I think these are approximately the same options in terms of their harmfulness. My intuition tells me this, so, just in case, I don’t insist that I’m right. But in this second example we got one useful function. Now our gap has become an air ventilation gap, that is, we have added a remote function humid air, and that means drying the walls.
Is there convection in the ventilation gap or does the air move in one direction?
Of course have! In the same way, warm air moves up and cold air moves down. It's just not always the same air. And there is also harm from convection. Therefore, the ventilation gap, just like the air gap, does not need to be made wide. We don't need wind in the ventilation gap!
What's good about drying a wall?
Above, I called the process of heat transfer in the air gap active. By analogy, I will call the process of heat transfer inside the wall passive. Well, maybe this classification is not too strict, but the article is mine, and in it I have the right to such outrages. So here it is. A dry wall has a much lower thermal conductivity than a damp wall. As a result, heat will flow more slowly from inside warm room to the harmful air gap and being carried outside will also become less. Simply, convection will slow down, since the left surface of our gap will no longer be so warm. The physics of the increase in thermal conductivity of a damp wall is that vapor molecules transfer more energy when colliding with each other and with air molecules than just air molecules colliding with each other.
How does the wall ventilation process work?
Well, it's simple. Moisture appears on the surface of the wall. The air moves along the wall and carries away moisture from it. The faster the air moves, the faster the wall dries out if it is wet. It's simple. But it gets more interesting.
What wall ventilation rate do we need? This is one of the key questions of the article. By answering it, we will understand a lot about the principle of constructing ventilation gaps. Since we are not dealing with water, but with steam, and the latter is most often just warm air, we need to remove this warm air from the wall. But by removing warm air, we cool the wall. In order not to cool the wall, we need such ventilation, such a speed of air movement at which the steam would be removed, but a lot of heat would not be taken away from the wall. Unfortunately, I cannot say how many cubes per hour should pass along our wall. But I can imagine that it’s not a lot at all. A certain compromise is needed between the benefits of ventilation and the harm from heat removal.
Interim conclusions
The time has come to sum up some results, without which we would not want to move on.
There is nothing good about an air gap.
Yes indeed. As shown above, a simple air gap does not provide any useful function. This should mean it should be avoided. But I have always been kind to the phenomenon of an air gap. Why? As always, for a number of reasons. And, by the way, I can justify each one.
Firstly, the air gap is a technological phenomenon and it is simply impossible to do without it.
Secondly, if I can’t do it, then why should I unnecessarily intimidate honest citizens?
And thirdly, damage from the air gap does not rank first in the ranking of damage to thermal conductivity and construction mistakes.
But please remember the following to avoid future misunderstandings. An air gap can never, under any circumstances, serve to reduce the thermal conductivity of a wall. That is, the air gap cannot make the wall warmer.
And if you are going to make a gap, then you need to make it narrower, not wider. Then the convection currents will interfere with each other.
The ventilation gap has only one useful function.
This is true and it's a shame. But this single function is extremely, simply vitally important. Moreover, it is simply impossible to live without it. In addition, we will next consider options for reducing harm from air and ventilation gaps while maintaining the positive functions of the latter.
A ventilation gap, as opposed to an air gap, can improve the thermal conductivity of the wall. But not due to the fact that the air in it has low thermal conductivity, but due to the fact that the main wall or thermal insulation layer becomes drier.
How to reduce damage from air convection in the ventilation gap?
Obviously, to reduce convection means to prevent it. As we have already found out, we can prevent convection by colliding two convection currents. That is, make the ventilation gap very narrow. But we can also fill this gap with something that would not stop convection, but would significantly slow it down. What could it be?
Foam concrete or gas silicate? By the way, foam concrete and gas silicate are quite porous and I am ready to believe that there is weak convection in a block of these materials. On the other hand, our wall is high. It can be 3 or 7 meters or more in height. The greater the distance the air has to travel, the more porous the material we must have. Most likely, foam concrete and gas silicate are not suitable.
Moreover, wood, ceramic brick, and so on are not suitable.
Styrofoam? Not! Polystyrene foam is also not suitable. It is not too easily permeable to water vapor, especially if it needs to travel more than three meters.
Bulk materials? Like expanded clay? Here, by the way, is an interesting proposal. It could probably work, but expanded clay is too inconvenient to use. It gets dusty, wakes up and all that.
Low density wool? Yes. I think very low density cotton wool is the leader for our purposes. But the cotton wool is not produced in a very thin layer. You can find canvases and slabs at least 5 cm thick.
As practice shows, all these arguments are good and useful only in theoretical terms. In real life, you can act much simpler and more prosaically, which I will write about in a pathetic way in the next section.
The main result, or what, after all, should be done in practice?
- During construction personal home there is no need to specially create air and ventilation gaps. You won't achieve much benefit, but you can cause harm. If the construction technology allows you to do without a gap, don’t do it.
- If you can’t do without a gap, then you need to leave it. But you shouldn’t make it wider than circumstances and common sense require.
- If you have an air gap, is it worth expanding (converting) it to a ventilation gap? My advice: “Don’t worry about it and act according to the circumstances. If it seems like it would be better to do it, or you just want it, or this is a principled position, then make a ventilation one, but if not, leave the air one.”
- Never, under any circumstances, use materials that are less porous than the materials of the wall itself when constructing external finishing. This applies to roofing felt, penoplex and in some cases to polystyrene foam (expanded polystyrene) and also to polyurethane foam. Please note that if a thorough vapor barrier is installed on the inner surface of the walls, then failure to comply with this point will not cause harm other than cost overruns.
- If you are making a wall with external insulation, then use cotton wool and do not make any ventilation gaps. Everything will dry out wonderfully right through the cotton wool. But in this case, it is still necessary to provide air access to the ends of the insulation from below and above. Or just on top. This is necessary so that convection, although weak, exists.
- But what to do if the house is finished with waterproof material on the outside using technology? For example, a frame house with an outer layer of OSB? In this case, it is necessary to either provide air access into the space between the walls (bottom and top), or provide a vapor barrier inside the room. I like the last option much better.
- If a vapor barrier was provided when installing the interior decoration, is it worth making ventilation gaps? No. In this case, ventilation of the wall is unnecessary, because there is no access to moisture from the room. The ventilation gaps do not provide any additional thermal insulation. They just dry the wall and that's it.
- Wind protection. I believe that wind protection is not needed. The role of wind protection is wonderfully performed by the external finishing itself. Lining, siding, tiles and so on. Moreover, again, my personal opinion, the cracks in the lining do not contribute enough to the blowing out of heat to use wind protection. But this opinion is my own, it is quite controversial and I do not instruct on it. Again, wind protection manufacturers also “want to eat.” Of course, I have a substantiation for this opinion and I can give it for those interested. But in any case, we must remember that the wind cools the walls very much, and the wind is a very serious cause for concern for those who want to save on heating.
ATTENTION!!!
To this article
there is a comment
If there is no clarity, then read the answer to the question of a person for whom everything was also not clear and he asked me to return to the topic.
I hope that the above article answered many questions and brought clarity.
Dmitry Belkin
Article created 01/11/2013
Article edited 04/26/2013
Similar materials - selected by keywords
When insulating walls wooden house many make at least one of the four most insidious mistakes that lead to rapid rotting of the walls.
It is important to understand that internal warm space The house is always full of steam. Steam is contained in the air exhaled by a person and is formed in large quantities in bathrooms and kitchens. Moreover, the higher the air temperature, the greater the amount of steam it can hold. As the temperature drops, the ability to hold moisture in the air decreases, and the excess falls out as condensation on colder surfaces. What will moisture replenishment lead to? wooden structures– it’s not difficult to guess. Therefore, I would like to identify four main mistakes that can lead to a sad result.
Insulating walls from the inside is highly undesirable, since the dew point will move inside the room, which will lead to moisture condensation in the cold wooden surface walls.
But if this is the only one affordable option insulation, then you must take care of the presence of a vapor barrier and two ventilation gaps.
Ideally, the wall “pie” should look like this:
- interior decoration;
- ventilation gap ~30 mm;
- high-quality vapor barrier;
- insulation;
- membrane (waterproofing);
- second ventilation gap;
- wooden wall.
It must be remembered that the thicker the insulation layer, the smaller the difference in external and internal temperatures will be required for the formation of condensation on wooden wall. And in order to ensure the necessary microclimate between the insulation and the wall, several holes are drilled into the bottom of the wall. ventilation holes(vents) with a diameter of 10 mm at a distance of approximately one meter from each other.
If the house is located in warm regions, and the temperature difference between inside and outside the room does not exceed 30-35 ° C, then the second ventilation gap and membrane can theoretically be removed by placing the insulation directly on the wall. But to say for sure, you need to calculate the position of the dew point at different temperatures.
Using a vapor barrier for external insulation
Placing a vapor barrier on the outside of the wall is a more serious mistake, especially if the walls inside the room are not protected by this same vapor barrier.
The timber absorbs moisture from the air well, and if it is waterproofed on one side, expect trouble.
The correct version of the “pie” for external insulation looks like this:
Interior finishing (9);
- vapor barrier (8);
- wooden wall (6);
- insulation (4);
- waterproofing (3);
- ventilation gap (2);
- external finishing (1).
Using insulation with low vapor permeability
Using insulation with low vapor permeability when insulating walls outside, such as extruded polystyrene foam boards, will be equivalent to placing a vapor barrier on the wall. Such material will prohibit moisture on a wooden wall and will contribute to rotting.
Insulation with equivalent or greater vapor permeability than wood is placed on wooden walls. Various mineral wool insulation and ecowool are perfect here.
No ventilation gap between the insulation and the exterior finish
Vapors that have penetrated into the insulation can be effectively removed from it only if there is a vapor-permeable ventilated surface, which is a moisture-proof membrane (waterproofing) with a ventilation gap. If the same siding is placed close to it, the escape of vapors will be greatly hampered, and moisture will condense either inside the insulation, or, even worse, on a wooden wall with all the ensuing consequences.
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Is a vapor barrier necessary when insulating a wooden house made of timber from the outside? What is the difference between a vapor barrier and c c d top and bottom
The brick has high level water absorption. Therefore, when facing a house with brickwork, ventilation gaps are made for weathering. excess moisture. The thermal insulation properties of brick walls are not high enough, and in order to create comfortable living conditions, insulation is prerequisite when constructing houses from this building material. When using the method of three-layer masonry of load-bearing structures with internal insulation They also leave gaps for ventilation.
What are gaps and why are they needed?
By gaps we mean the distances between the walls, which promote ventilation and prevent the accumulation of condensation inside the structure. In such gaps you can place thermal insulation material for insulation. With this method brickwork outer wall the house consists of three layers:
- Basic structure.
- Insulation.
- Facing.
It is used to increase the thermal insulation of a home and to save energy resources. Thermal insulation material protects inside the structure load-bearing wall from freezing. In addition, it itself is reliably protected from damage. And the existing air gap between the insulation layer and the facing masonry promotes ventilation and evaporation of excess moisture.
Process technology and gap sizes
The width of the hole should not be more than 2 cm. Masonry begins with the construction of a supporting structure. Then they lay out the wall facing bricks, leaving a gap between them for air circulation and, if necessary, for insulation. The distance should be 1.5-2 cm or within 5-15 cm in the case of thermal insulation and depending on the thickness of the material layer. An air cushion is made in order to exclude deviations from the norm in the vapor barrier indicator.
The vapor permeability of all layers must be combined. This will help prevent moisture from accumulating on the internal sides brick structures, which will prevent the formation of mold and mildew, as well as preserve the heat-shielding properties of the insulating material and extend its service life.
Regardless of the presence of insulation inside the wall, for air circulation between load-bearing structure and make special gaps in the form of embroidered vertical seams in the facing masonry. They are located at the top at the eaves and at the bottom at the plinths of the building. The number of such holes depends on the size of the walls, and their width is 2-4 cm.
Gaps when insulating brickwork
The choice of insulation depends on the material of the external structure of the house, since the vapor permeability coefficient of elements of all layers should be taken into account. As insulation you can choose:
You can insulate the wall using polystyrene foam. - mineral wool;
- expanded polystyrene;
- bulk insulation.
When using insulation in the form of slabs, all structural elements are fastened together using flexible connections that are installed on a load-bearing wall. Afterwards they post it facing masonry to their level and impaled on them heat insulating material. Waterproofing is attached to the insulating layer and a gap is left for ventilation. To create it, use connections that have a plastic washer with a latch. It presses the insulation against the wall and prevents it from slipping and deformation. The width of the air cushion varies between 4-6 cm. Bulk insulation they simply fill the void formed between the walls without creating air gaps, after the height of the walls being erected reaches a meter.
