We insulate the apartment from the inside: risks and difficulties

Many apartment owners begin considering ways to keep their homes cozy and warm when the colder months arrive. If external insulation is not an option, it may seem like a simple solution to insulate the apartment from the inside. But there are drawbacks to this strategy as well.

Although internal insulation can lessen heat loss and increase comfort, it’s crucial to be aware of any possible hazards. Inadequate insulation can lead to a number of problems, including moisture accumulation, the growth of mold, and a reduction in living space.

We’ll go over the typical challenges of interior apartment insulation in this post, enabling you to make wise choices and steer clear of expensive blunders.

Risk or Difficulty Description
Condensation and Mold Insulating walls from the inside can trap moisture, leading to condensation and mold growth, which can damage the structure and affect health.
Reduced Living Space Adding insulation inside the walls reduces the available living space, which might be a concern in smaller apartments.
Thermal Bridges If not done correctly, internal insulation can create thermal bridges, where heat escapes through uninsulated areas, reducing overall effectiveness.
Material Selection Choosing the wrong insulation material can lead to issues like poor insulation performance or incompatibility with existing walls.

Although it may seem like an easy way to increase comfort and energy efficiency, insulating an apartment from the inside has a lot of risks and difficulties. These include the possibility of moisture accumulation, which can result in the growth of mold, and the loss of priceless living space. Before beginning such a project, it is essential to be aware of these challenges to make sure it doesn’t cause more issues than it fixes.

The danger of insulation from the inside

Alexey Shamov, head of the building materials of Leroy Merlen:

Panel series house owners frequently deal with particular issues. This is primarily the result of moisture buildup in the walls and facade freezing. These unfavorable elements cause the apartment’s wintertime temperature to drop and the interior decor to fall apart. In apartments with panel houses, wallpaper peels off, mold grows beneath the ornamental wall covering, and other strange things happen.

This must be dealt with, but, according to modern building codes, insulation of the walls of any room is done only from the outside. The reason is in the "dew point", which can be both outside and inside the room. Depending on its location, the wall either remains dry or becomes wet inside. The latter is unacceptable according to building codes, since the formation of condensation in the room under the insulation layer leads to the appearance of mold and mildew on the wall. Materials for insulating an apartment from the inside can be installed only after conducting a heat engineering calculation. The calculation reveals a number of parameters: wall thickness, radiator performance, average temperature, dew point location, and others. Based on these parameters, there should be no condensation on the walls under the insulation layer.

Cheap materials: pros and cons

Anton Toskuyev, head of the construction department of the TNOMER ready-made repair solutions service, agrees with his colleague:

There’s a reason the heat doesn’t stay in an apartment during the winter when it’s damp and cold. Because facade work is required if the wall or interpanel seams are damaged, we first advise performing a thermal imaging survey to determine the cause of freezing.

Insulating the walls will keep the apartment warm if the location of the house or apartment is the reason for freezing, but thermal insulation inside is strongly discouraged. The reason for this is that when the insulation and the exterior structure (cold wall) collide, a "dew point"—or, to put it more simply, the release of condensation—occurs at the intersection of warm and cold. As a result, internal thermal insulation is rarely utilized, and when it is, it must be installed and the material chosen carefully to prevent the growth of mold and fungus over time.

Today, there are many options available for insulation; polystyrene foam and mineral wool are popular choices. There are two types of plastic foam: extruded and conventional foamed. Let’s examine the benefits and drawbacks of each material in isolation.

Since formaldehyde and urea resins are absent, mineral wool in slab form is completely safe. Mineral wool doesn’t release smoke, burn, or react to fire in any way.

Because mineral wool has a very low thermal conductivity, heat from the room cannot pass through to the cold structure, effectively shielding the apartment from heat leaks. The material’s ability to block out sound is also appealing. All materials are about the same in terms of installation complexity; however, mineral wool is flexible and can be bent and wrapped around corners. Polystyrene foam is more difficult to work with, more rigid, and comes in some very fragile varieties.

Moisture absorption and vapor permeability are two drawbacks. This doesn’t matter for thermal insulation on the facade, but it becomes problematic when insulating an apartment’s interior walls because the mineral wool will get wet if the dew point is moved toward it and won’t dry because it will be covered in a layer of plasterboard.

Ordinary foamed polystyrene foam with a structure of white balls glued together is an inexpensive option. Since air is a good heat insulator, it still makes up the majority of the volume of polystyrene foam.

The drawbacks of regular polystyrene foam are shared by all varieties of the material: it burns toxically when it catches fire. Additionally, mice can easily gnaw through polystyrene foam.

Alternative to polystyrene foam

Extruded polystyrene foam is more costly than both regular polystrene foam and mineral wool, but it does have one clear benefit: it is twice as warm due to its two times lower thermal conductivity coefficient. Only 60 mm of extruded foam will be required in situations where 100 mm of mineral wool or foam insulation is needed. It thus conserves space twice.

Additionally, you can only plaster it with reinforced extruded polystyrene foam rather than hanging drywall, which will free up an additional two centimeters of space.

In summary, we will discuss the benefits of each insulation type in terms of cost, storage capacity, and ease of installation.

  • the most affordable material is ordinary foam;
  • On average, insulation “eats” 12 cm from each wall: about 10 cm insulation layer and 2 cm drywall. Extruded foam plastic will allow you to reduce this figure by half due to its higher density and the possibility of installation without drywall;
  • Mineral wool boards benefit from ease of installation due to their flexibility.

The advantage of PIR boards for insulating apartments

Ilya Kaukin, Head of Research Department, ProfHolod LLC

PIR board is a universal hydro- and heat-insulating material. With a coefficient of thermal conductivity of 0.022 W/(m*K), it is twice as good as other types of insulation. The boards are simple to install and long-lasting.

Plasterboard should be placed over the PIR board once it has been installed on the rough wall. No specialized equipment is needed. The top layer of plasterboard will hold the PIR board in place if you choose not to fasten it with a mushroom dowel.

The board gets thicker in colder climates; Krasnodar works well with 30 mm, while more northern areas benefit from 50 mm.

Among PIR boards’ benefits are:

  • increased energy efficiency. 100 mm of polyurethane foam is insulated in the same way as 160 mm of polystyrene foam and 260 mm of mineral wool;
  • reasonable thickness;
  • saving in building material consumption compared to others.

Particularly in older buildings, insulating an apartment from the inside can make it warmer and cozier. But there are certain unique difficulties with this strategy that need to be carefully taken into account.

The possibility of moisture accumulation, which can result in the growth of mold and structural damage, is one of the main worries. To avoid these problems, proper ventilation and the use of the right materials are crucial.

The efficacy of the insulation may also be lowered by the loss of internal space and the potential for thermal bridges. A professional installation and careful planning are essential to overcoming these challenges.

In the end, even though internal insulation can be a great solution for many, it’s crucial to consider the risks and take the required safety measures to guarantee a positive result.

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Veronica Gerasimova

Interior designer, author of books on the design of residential premises. I will help you make your home not only functional, but also beautiful.

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