How to insulate the walls from the inside of an apartment or house and how to do it right
New building materials, consisting of several layers, perfectly keep heat. Houses built from them are much cheaper to maintain than buildings from the times of the USSR built from brick or reinforced concrete panels. This is especially noticeable during the heating season - for a house built from modern materials, the coolant will require significantly less. But after all, nobody is going to demolish most of the old Soviet houses, and many of us live in them. So let's talk today about how to insulate the walls from the inside of such a building or any other building and how to do it right.
Do walls insulate at all from the inside
Many professional builders and manufacturers of insulation argue about this hoarsely. Someone says that this event will not give anything, while others object - they say, a good result is obtained when the walls of the room are sheathed with heat-insulating material. But both sides unanimously argue that facade insulation is a much more effective option than internal wall insulation.
And what about us, ordinary residents of panel high-rise buildings, whose thin walls freeze through in the winter? After all, warming such a house from the outside is a difficult task, and sometimes even completely impossible. After all, there are different situations: for example, close proximity to the elevator shaft or stairwell. And you can’t touch the facades of architectural monuments, houses in the historical center and those that are decorated with expensive materials. But you won’t go against the city authorities, so you have to freeze.
This situation can be clarified a little by contacting GOSTs and SNIPs issued after the collapse of the USSR. They clearly make it clear that it is the facade part of the building that should be insulated, and inside the house there should be stone, concrete or brick. They make up the so-called “cold” layer, which should have low vapor permeability and conduct heat well.
Than bad insulation of the building from the inside
To understand why so many experts advocate against internal insulation, we will consider in detail all its shortcomings. Some of them are not particularly significant, but there are those that make you think about the feasibility of the venture. In any case, knowing the possible consequences, one has to act with great caution. So what are these unpleasant consequences?
- Firstly, the area of the room when sheathed with a heat insulator will significantly decrease - this is a fact. For example, having carried out internal wall insulation in a room with an area of 20 square meters, we find that 0.5 to 2 square meters of usable area has become lacking.
- It is possible to lay thermal insulation only in the room from which all things are taken out or moved away from the walls. That is, it will be problematic to use this room for some time, but it is not very convenient.
- Just sheathe the walls with insulation - not an option. It is necessary to provide additional ventilation, and take measures to protect the heat insulator from condensation. Otherwise, the insulation will quickly fail.
- Carrying out warming according to all the rules, without forgetting anything, you may be surprised to find that all this will cost a pretty penny.
If you listen to the opponents of the insulation of the inner part of the walls, you can learn a lot about the unpleasant physical processes occurring inside the heat insulator. Unfortunately, these are not tales at all, but obvious facts. For example, this is the formation of mold and fungus, the dripping of streams of evaporating water. Such phenomena slowly but surely destroy the interior decoration of the room. And sometimes even supporting structural elements can be damaged. But all this happens only when the process of regulating humidity is not debugged properly.
We will reveal the secret of what is happening inside the insulated walls
In the summer, while warm, nothing special happens under the walls. But as soon as the cold sets in, the air temperature inside the apartment begins to differ sharply from the outside temperature. And here the walls insulated from the inside can manifest themselves in all its glory. All the power of frost and wind falls on the shoulders of the outer walls, officially called "enclosing structures."
The main opponent of the walls insulated from the inside, is such a harmless ordinary water. As soon as she freezes, she turns into a powerful enemy, sometimes just tearing walls from the inside and increasing cracks in the joints. And wet insulation ceases to fulfill its function of thermal insulation. And as soon as it gets warmer, harmful bacteria and fungi begin to rage, for which water is life. Such an unsightly picture is sometimes the warming of walls from the inside, which, however, can be solved, but more on that later.
Perhaps, it becomes unclear to someone why the outside air temperature and humidity of the insulated walls are so closely related to each other. It turns out that water vapor condenses from air at a certain temperature. It is called the “construction dew point”. When this temperature is reached, water droplets — condensate — form on surfaces that are well cooled. The dew point has a floating value, which increases with increasing air humidity in the room. If humidity reaches 100 percent, then the temperature of the air is equal to the dew point. However, this is slightly approximate - we will not delve into complex formulas.
According to the sanitary rules for apartments and residential buildings, the air temperature in them should be in the range from 20 to 22 degrees. And humidity, optimal for living, is 55 percent. The dew point under such conditions is plus 10.7 degrees Celsius. Thus, if one of the layers of the insulated wall reaches this temperature, condensation will inevitably appear on it. Since in winter we turn on the heating, the walls inside warm up. Fluctuations in the outside temperature cause the dew point to move inside the walls - the colder it is on the street, the farther it is from the facade.
Where exactly the dew point is formed depends on several factors. This is the location of the layers of the structure relative to each other, and their thickness. For example, imagine a situation where the wall is not insulated and the dew point is inside it. Then, when you turn on the thermal imager on its screen, you can see that thermal rays are emanating from the wall. And no matter how much you heat a room in such a building, it will still be cold in it, since it gives off heat to the outside.
If the facade of the building is insulated, then the wall is completely warmed up, it saves precious heat. And the dew point moves closer to the facade, in a heat-insulating layer. For this reason, ventilated facades were invented - because the insulation must be ventilated for drying. Otherwise, he will lose his properties.
If the walls are insulated from the inside, then in winter the heat-insulating layer does not allow heated air from the room to them. Therefore, bearing walls, freezing to the ground, begin to collapse faster. As a rule, the dew point is on the inside of the wall, shifting with increasing temperature in its middle. In this case, the condensate that appears between the heat insulator and the wall minimizes the effect of insulation.Frozen water and the glue on which the insulation is planted destroys. And then on the wet walls, mold blooms violently, and a fungus appears. Nothing good, in a word.
How to avoid unpleasant consequences with internal insulation
It is difficult to carry out measures to warm the walls inside. This is done only when the facade is not allowed to be insulated, or it simply cannot be reached.
Having opened the Code of Rules SP 23-101-2004, which is called "Design of the thermal protection of buildings", we can read that it is strongly not recommended to isolate the inside of the walls for insulation. The reason is that moisture can accumulate in this heat insulating layer. If it is vitally important and necessary to insulate the wall in the apartment from the inside, then you need to lay a solid layer of high-quality vapor barrier, which should be durable and durable.
Thus, if we want to have warm and dry walls, we will try to protect that part of them, where the dew point will be, from moisture. What measures should be taken for this? In general, there are not so many of them.
1. The film for vapor barrier is selected of the highest quality, with its connection, thorough sealing of all joints is carried out.
2. The thermal insulation material should not have a very high vapor permeability. The lower this indicator, the better. Ideally, the permeability of the load-bearing wall is greater than that of the heat insulator. In this case, the steam will go outside.
3. When we glue the insulation, we try to keep it as small as possible behind the wall. Do not use the “beacons” method when gluing it; it is better to apply glue with a comb to ensure full contact of the insulation with the wall.
4. To reduce humidity in the apartment, use forced ventilation of a mechanical type. On the windows they put valves.
5. The thickness of the insulating layer for insulation must be carefully calculated, taking into account the characteristics of its climate zone. It is not recommended to take insulation thinner than this calculated value.
6. Before carrying out wall insulation, they must be treated with a special composition that prevents the appearance of fungus and mold. You can start insulating only after the walls have completely dried.
The elimination of the so-called "cold bridges" is one of the primary tasks. Indeed, in those places where the bearing walls are connected to the ceilings, as well as with the walls inside the building, insulation cannot be carried out. Therefore, it is necessary to apply a heat insulator to these problem areas by applying a vapor barrier. Then they can be disguised using false columns or baskets.
Choose a heater
Traditional mineral wool
When deciding what is better to insulate the walls from the inside, most people usually choose mineral wool. It is simply laid inside a drywall construction. The vapor barrier is neglected, the work is carried out quickly, the material is cheap, but the result cannot please. This method of warming not only does not bring the desired benefits, but rather, on the contrary, is very harmful. It is especially bad if they are insulated with ordinary mineral wool in rolls - it has too little coefficient of thermal resistance.
Mineral wool lovers say that it "breathes", but this is just bad. Due to such properties, it is not at all suitable for internal thermal insulation. Through the fibers of this material, moisture quite calmly gets to the dew point, and then mineral wool absorbs it. There are, of course, its special varieties, whose characteristics are similar to expanded polystyrene foam, but they do not give a 100% guarantee of dryness.
Even if you glue this material very carefully and with the best glue, take care of high-quality vapor barrier - the risk of moisture will remain. And all this because the vapor permeability of mineral wool is much better than at the walls of the building. And all the work will go down the drain, and the money will be thrown into the wind if, as a result, muddy streaks appear on the walls.An even more unpleasant consequence is the appearance of a fungus.
The inner wall is insulated with pressed mineral wool.
Expanded polystyrene - extruded and ordinary
Today, this material is considered to be the best insulation for insulating walls on the inside. Pushing aside the traditional warming of walls with mineral wool from the inside, it is increasingly being used both in European countries and in Russia. After all, this material has the most suitable properties for insulation. Next, we list them.
- Expanded polystyrene conducts heat very poorly.
- It almost does not absorb moisture, and its vapor permeability is very low.
- This material can easily withstand very substantial loads.
- He does not care either strong compression, or a large tearing force.
- Expanded polystyrene weighs very little and is also easy to handle - it is easily cut with a knife. Therefore, the installation of such plates is not difficult.
Thus, if you use expanded polystyrene, both foamed and extruded, it is possible due to the thin layer to bring the thermal insulation of the entire structure to normal. After all, a material that does not absorb water will not only not change its properties as a heat insulator. He also will not allow moisture to the dew point, so when using it you can easily not lay a vapor barrier.
Only about the "cold bridges" do not forget. It is not difficult to isolate these places where the plates are connected to each other and adjoin the walls. Here you can apply polyurethane foam and join the plates with each other and with the wall using it. But you need to apply foam on the entire surface of the sheet.
And manufacturers for convenience produce foam plates with a special edge with stepped edges. Thanks to this, the joints are smooth and airtight.
Expanded polystyrene with a notch.
You can mount these plates inside the apartment in the same way as on the facade of the building. For this, a plate-type dowel is used. In addition, the plates are planted on glue.
The internal wall warmed by expanded polystyrene.
Expanded polystyrene also has a minus - it does not protect well from noise. And it can also collapse if its temperature exceeds 80 degrees Celsius. But this is not so relevant in our case, as is the fact that EPS plates can dissolve in organic solvents.
Polyurethane foam - an excellent modern insulation
And how to insulate the walls of the house from the inside efficiently and quickly? Surely such a question was asked by many. In this case, the use of polyurethane foam is the best option. It is a wonderful heat insulator. Its thermal conductivity is 0.025 watts per meter per Kelvin. The sealed polyurethane foam cells are filled with either air or an inert gas. Moisture cannot penetrate inside, therefore this material does not get wet and does not pass water. And when using it does not need waterproofing.
However, this does not end the advantages of polyurethane foam insulation. It is also very convenient in use - because this material does not need to be glued or mounted inside a special frame. Everything is much simpler - it is sprayed directly onto the wall. The composition consists of two components, which, when connected, foam on the wall plane. In a few seconds, the polyurethane foam freezes. Using this method, there are many advantages.
- This material has excellent adhesion to virtually any surface. It can be sprayed onto the ceiling, and “bridges of cold” can be sealed with it.
- Polyurethane foam adheres to the wall so tightly that they are one piece. Moisture fails to get to where the dew point is.
- Since the spray coating does not have a single seam and does not form cracks, we have the opportunity to conduct insulation of walls of any configuration. At least a round room, at least a room with curved corners - polyurethane foam will cope with all this.
- Since the work is done extremely quickly, and a little material is required, you can save on shipping and storage.
- Using a nylon mesh, you can plaster this insulation using facade technology.
Application of polyurethane foam.
What else can you insulate the walls inside
Research is underway, every year new construction materials are produced. Some can be used for internal insulation of apartments. Sometimes manufacturers so praise a new tool, they trumpet with might and main about its merits. And they are modestly silent about the shortcomings. Here are some examples.
Warm plaster - looks spectacular, but hygroscopic and has too good vapor permeability. In addition, it retains heat much worse than foamed materials.
Foamed polyethylene having a foil coating can hold heat well. But it is quite difficult to install. The fact is that when it is used, an air gap should remain between the wall and this material. And above, under the lining, you also need to provide a clearance. Even many professionals cannot do everything perfectly.
A millimeter layer of a liquid ceramic heat insulator is equivalent to five centimeters of mineral wool. This material is a lot of bubbles with air inside. Thermal conductivity of ceramics ranges from 0.8 to 0.15, and air - 0.025 watts per meter per Kelvin. Where did the manufacturers get the indicator of this coefficient of 0.0016 for liquid ceramics? It seems like a bluff.
A little studied material called "thermal paint" may be good, but there are examples when nothing good came of using it. Let's see further.
We calculate the thickness of the insulation
So, we found out whether it is possible to insulate the walls from the inside and how to do it correctly. Then we chose the material that suits us best. An important thing remained - the calculation of the required thickness of the insulator.
First, measure the wall thickness D, and determine R - the real resistance to heat transfer. We use the formula:
R = D / L
L is the coefficient of thermal conductivity of the material. For example, take a brick wall 50 centimeters thick. We get the following:
R = 0.5 / 0.47 = 1.06 square meters-degree Celsius per watt.
In Moscow and the Moscow Region, the normative value of this indicator is 3.15 or more. We calculate the difference, which amounted to 2.09 square meters-degrees Celsius per watt. This difference must be compensated for by warming the walls.
To determine the thickness of the insulation you need the inverse formula:
D = L ∗ R
For expanded polystyrene, for example (L = 0.042), this value is obtained:
D = 0.042 ∗ 2.09 = 0.087 meters, otherwise, 8.7 centimeters. It is better to take with a margin of 10 centimeters, then the dew point will definitely be inside the heat insulator.
Video. Internal insulation
